2003 Corolla Fuel Milage And Vibration Issues - Toyota Corolla, Chevy Prizm (1998-2008)

Hi guys,

I have a 2003 corolla AT that has been a fine automobile for 120k. Just recently I have had issues. I live in Texas but this past winter I took a 1200 mile trip up to ohio. When I went up there the car was great, getting near 40 mpg, slight vibrations had started( I figured the engine mounts were going) and the check engine light had been on for a while because of the rear oxygen sensor/cat. I did not want to get this fixed at the local toyota dealership do to price so I took it to a shop my family has been going to in ohio for 20 years. They did a 120K service including the cat and oxygen sensor. They said the sensor wire was pinched, so they put a new one on the light came on again so they replaced the cat, no light, great....... Then the car got hit while parked and ended up in the body shop for minor drivers side front end damage.(new bumper, headlight, intake resonance chamber.....)

Now the problems start. No check engine light, but the car is now getting 32-34 highway mpg and 22 mpg round town. I ran it, changed oil and transmission fluid, reset the ecu. Still bad gas milage. from 36-40 to 30-34 highway and 30-32 to 20-24 around town. All the while the engine vibration has been worsening with miles. I had a fuse blow out on me in New Mexico, only to find the body shop had not hooked up the primary ground from battery to chassis. took it to the toyota body shop where they promised to check everything including electrical. I have just now discovered that though it appeared fine after the toyota shop, the airbox is missing a bolt and my hood is not closing all the way.(bout a half inch gap at the nose, can push it to the right spot but wont hold.) So the car needs to go back to the body shop. In the meantime I took it to a shop here in texas to look at it under a Napa repair warranty. They found nothing wrong with the car, had them replace the front O2 sensor. Drove the car back to ohio, same shop as before. They looked at it, could not find anything wrong, asked them to replace the motor mounts. They only replaced the front and rear lower motor mounts(said that they where visually damaged), at idle the vibration has become horrible, especially in drive with the brake on. I have read that the passenger side mount has been a problem for some, I wedged a crow bar in, does not seem to make a difference, though I would like to replace the other two mounts, cant wedge a crow bar in the drivers side mount.

My friend suggested that I might be losing a cylinder at idle, so I checked by unplugging each coil, engine appears to be running on all 4 cylinders at idle.

I plan to do a compression check for myself and plan to do at least the passenger side mount if not the other.(hopefully that fixes the vibration)

Do you all have any ideas what could be causing my fuel milage issues? To much of a coincidence that it started after the 120K service and body shop, has to be something one or the other did. What else could have been misassembled in the airbox area? Could a shorting ground fry some electrical components? I guess I will look at the mass airflow sensor next....

I am hoping the other two mounts fix my vibrations........

Thanks for your help!

Andrew

I know from experience that these engine are very sensitive to electrical noise and brand of sensors/plugs/emission parts used. Most people find that Denso O2 sensors and NGK/Denso iridium plugs are preferred replacement parts. Some have had luck with other brands - but the majority saw less problems with OEM parts. Myself, saw a good 10%-15% drop in fuel economy using an aftermarket O2 sensor - though in my case, it was the upstream sensor. The downstream (post cat) sensor doesn't influence fuel economy. An aftermarket catalytic converter could also be a potential source for reduced economy - if it doesn't get up to temp as quickly or if they used one that doesn't flow as well as OEM part (dyno tests proved you typically only lose about 1HP between running the OEM cat vs a straight pipe).

This could be a be tough one to diagnose, as there is a lot going on, separate issues that could all be contributing to the overall issue at hand. Body damage that was not fixed properly or correctly can interrupt the overall aerodynamics of the car. The 2003 Corolla actually has a fair amount of work down to keep areo drag in check, in fact - to the wind, the 9th gen looks "slipperier" than the smaller 8th generation Corollas. That slight gap in the front could be enough to hurt overall fuel economy 5-10% easily. Leaks in the induction system, restrictions there can also contribute to lower overall fuel economy.

I know from experience that these engine are very sensitive to electrical noise and brand of sensors/plugs/emission parts used. Most people find that Denso O2 sensors and NGK/Denso iridium plugs are preferred replacement parts. Some have had luck with other brands - but the majority saw less problems with OEM parts. Myself, saw a good 10%-15% drop in fuel economy using an aftermarket O2 sensor - though in my case, it was the upstream sensor. The downstream (post cat) sensor doesn't influence fuel economy. An aftermarket catalytic converter could also be a potential source for reduced economy - if it doesn't get up to temp as quickly or if they used one that doesn't flow as well as OEM part (dyno tests proved you typically only lose about 1HP between running the OEM cat vs a straight pipe).

This could be a be tough one to diagnose, as there is a lot going on, separate issues that could all be contributing to the overall issue at hand. Body damage that was not fixed properly or correctly can interrupt the overall aerodynamics of the car. The 2003 Corolla actually has a fair amount of work down to keep areo drag in check, in fact - to the wind, the 9th gen looks "slipperier" than the smaller 8th generation Corollas. That slight gap in the front could be enough to hurt overall fuel economy 5-10% easily. Leaks in the induction system, restrictions there can also contribute to lower overall fuel economy.

Thank you for the reply. I am suspect of the aftermarket cat, though I dont think the rear oxygen sensor has any effect on fuel economy. I have not lost fuel economy sense they replaced the front sensor. I will check and see what brand they used. The car will go into the body shop for sure to get things fixed. I just dont know where else to look, as I really dont think the hood is the issue(it is a minor minor gap) I worry that some electronic could have had a short when the ground was unhooked and failed.

Right now the vibrations when at idle are driving me crazy. I hope the other two engine mounts will do the trick, otherwise this car will drive me crazy.

I am trying to order the passenger side and drivers side motor mounts but am having some difficulty. Napa lists only front and rear, not right or left. The shop already did the lower front and rear mounts. Are some of the mounts the same part? The lower ones look beefier and larger, the passenger side looks smaller, cant really see the drivers side to well on the car.

I checked and the front oxygen sensor is a denso, I hope the rear is too, though it seems less important.

I looked at the car and it seems that the motor mounts do seem to match up to the pictures on NAPA. the passenger side labeled as front with "right" listed under the comment and the drivers side listed as rear with "automatic transmission" in the comment. The other two mounts look like the lower front and rear already installed.

Napa

I hope that if I replace the right and left mounts, it will stop the vibrations.

Keep in mind that after replacing the mounts - it could take a little time before they "break" in and help with some of the vibration. But you'll know you are on the right track if the vibrations are immediately different.

Well my problems continue. It was never the engine mounts, they have all been replaced. The car is still vibrating and getting poor gas milage and now apparently burning oil. I seafoamed the car before a long trip, for at least one tank of gas I got over 500 miles, some 36 MPG, not the best but about what I would consider normal(I have been topping off for extended range 13 gallons). The cam/timing chain and gears have been replaced now, it did appear to be stretched. The head was also planed and valve seals checked. I was told the seals were fine and everything appeared to be in order. For the first time ever, the car seemed to magically burn off some 2.5-3 quarts of oil, it has never burned oil before. This was after 1200 miles of highway driving, we realized it just after putting the car back together after the timing chain service. On my return highway drive, my check engine light came on again saying my catalytic converter is not operating correctly. I have switched to GTX high milage oil and I replaced the pcv valve. I ran a compression test and I have 180 psi on all cylinders dry, going up too 220-240 psi "wet". My compression is fine, I realize now that there was no point in doing a "wet" test as 180 is well within spec and it must have just been the displacement of the extra oil that caused the increase in pressure on the "wet" test. I am starting to suspect I might have multiple issues.

So I have good compression and apparently a good valve train. The mechanic that helped me did not replace the cam chain tensioner, his after thoughts were that we should have done this as maybe mine was faulty, causing the chain to stretch. So I am going to pull the valve cover off again to check that there is no wear to the cam lobes and to check my valve clearances myself. When I do this I will install a new tensioner as well. I have now read up on oil burning issues for the 1zz-fe engines before 2005 and I think this might explain the burning of oil. I will treat that as a separate issue, I am going to try soaking the cylinders in seafoam overnight as well as running it through the oil 30 miles before a change. Hopefully this will reduce my oil consumption.

Could my catalytic converter be burned up in 15,000 miles? I am hoping not. I don't know if the fault code is do to burning oil or my fuel milage issue.

If the cams and valve clearances are within spec, I am going to assume my engine is fine, despite the possibility of sludged oiling holes and stuck oil rings on my pistons.

If the engine itself is fine, then it has to be an accessory causing my problems of rough idle and poor fuel milage.

Does anybody have any suggestions as to what I should check next? Since I got the good gas milage for a bit and that was after seafoam and while running shell v-power, I suspect maybe I having a sticking fuel injector. I am going to pull them off to look at them and then check the spray on each to see if it does not appear to be conical or they aren't opening correctly.

Any other ideas would be appreciated. It will be nice to know that everything inside the engine itself is ok(aside from the piston oiling issues). At least then I can narrow it down to external less permanently destructive issues. The car has 132K miles now, I would like to avoid rebuilding the engine until at least 200K. My poor little brother will have to get a different car for college. I no longer trust anybody except myself to work on it, someone needs to pay extra attention to it, as I now this consider the car to be an old piece of $#*& that will be needing constant attention. We cant sell it now either as I need to get my money out by driving it, its only worth 5K at best and I have put almost that much into it. It is really unfortunate to be having so many issues at such low milage, it seems as though Toyota quality has gone down the toilet. My old toyotas never had any issues until 200K, my friends 4runner is over 300K with no major issues ever. All my friends seem to agree that the quality dropped off significantly in 1998 and then again around 2004. I would buy a Ford over a new Toyota and I never ever thought I would say something like that. I wish I could afford a new fiesta now.

Oil consumption on a 9th generation Corolla is unusual, but possible. A number of things could be potential culprits for the oil consumption - from stuck piston rings, scored cylinder walls, to broken piston rings. Though being a freshly machined head, there could be some oil consumption initially. Real problem will be if the oil consumption doesn't back down.

Topping off the gas tank is not recommended, though much less sensitive than the 8th generation (1998-2002) Corollas, topping off the tank can cause the vapor canister to clog with raw fuel, can cause all sorts of headaches down the road. Just fill until the pump automatically clicks off or listen to the vent tube as gas is going in and stop when you can hear the pitch change drastically.

Compression numbers seem fine - as long as there is no more than a 15 PSI variance between cylinders, should be good to go. Interested in how much material was skimmed off the cylinder head - was this done to just clean up the mating surfaces, or was the head actually warped? There isn't a whole lot of wiggle room between the top of the piston crown and the valves. I'm hoping that if there was warping, it was less than 0.0020" (0.05mm) - if it was greater than that, the head cannot be salvaged, it is scrapped instead.

Stretched timing chain is again unusual for this engine, do you remember by how much the chain was stretched? How did the cam gears look, where the teeth worn? Yeah, I'd definitely recommend replacing the chain tensioner - around this mileage, they are prone to start leaking past the o-ring. Only runs about $30, and you can remove install this without have to disassemble the top end. Though it would be helpful to visually verify that the tensioner "plunger" has popped out and touching the chain.

As for the catalytic converter - depends on which aftermarket one you picked up. I have seen and had some aftermarket cats (OEM fitment and "performance" high flow ones) die after 20-30K miles. If the car wasn't running 100%, they would die off much quicker (too much fuel dumped into exhaust, overheated and damaged cats). In your case, could be just fouled from the sudden oil consumption - I'd reset the CEL and see if it comes back again or not. Over time, the cat will burn off the residue, assuming you find out what is causing the oil consumption in the first place.

Other areas I'd start looking into - oil control valve and oil control valve filter (OCV). Part of the VVT-i system, and very sensitive to oil quality. If this filter clogged with debris, it will start the OCV of oil and pressure, would cause the timing to be too far retarded or advanced for the engine load/engine speed - can cause excessive oil consumption and driveability issues (poor idle, poor fuel economy). Assumed that you already checked out the throttle body, read the plugs, cleaned the MAF sensor, checked the IACV on the throttle body. Another possible problem area would be the oil pump. On some 1ZZ-FE and 2ZZ-GE engines, this was a problem area. Not having enough oil pressure to key areas of the engine could explain a lot, especially the timing chain - as the chain is really hard on the motor oil. Starving it of enough lubrication is surefire recipe to stretch that chain out.

Check valve clearances and see where they are at. A sticking injector can also explain a lot. Reading the plugs should give you some indication of what is going on there. You can play around with swapping coil packs and injectors from one cylinder to another - just to see if it runs differently. Can always send the injectors to a shop to ultrasonically clean and flow test. They'll tell you right away if one injector is sticking or not.

Might also be useful to send in some used motor oil to be chemically tested. See if there is an issue with excessive wear metals, any coolant in the oil, if the oil has been sheared down past the point of decent protection/been heavily contaminated with fuel. For around $25 - gives you that one extra piece of information that could give you some insight of what is going on.

Oil consumption on a 9th generation Corolla is unusual, but impossible. A number of things could be potential culprits for the oil consumption - from stuck piston rings, scored cylinder walls, to broken piston rings. Though being a freshly machined head, there could be some oil consumption initially. Real problem will be if the oil consumption doesn't back down.

Topping off the gas tank is not recommended, though much less sensitive than the 8th generation (1998-2002) Corollas, topping off the tank can cause the vapor canister to clog with raw fuel, can cause all sorts of headaches down the road. Just fill until the pump automatically clicks off or listen to the vent tube as gas is going in and stop when you can hear the pitch change drastically.
Compression numbers seem fine - as long as there is no more than a 15 PSI variance between cylinders, should be good to go. Interested in how much material was skimmed off the cylinder head - was this done to just clean up the mating surfaces, or was the head actually warped? There isn't a whole lot of wiggle room between the top of the piston crown and the valves. I'm hoping that if there was warping, it was less than 0.0020" (0.05mm) - if it was greater than that, the head cannot be salvaged, it is scrapped instead.
Stretched timing chain is again unusual for this engine, do you remember by how much the chain was stretched? How did the cam gears look, where the teeth worn? Yeah, I'd definitely recommend replacing the chain tensioner - around this mileage, they are prone to start leaking past the o-ring. Only runs about $30, and you can remove install this without have to disassemble the top end. Though it would be helpful to visually verify that the tensioner "plunger" has popped out and touching the chain.
As for the catalytic converter - depends on which aftermarket one you picked up. I have seen and had some aftermarket cats (OEM fitment and "performance" high flow ones) die after 20-30K miles. If the car wasn't running 100%, they would die off much quicker (too much fuel dumped into exhaust, overheated and damaged cats). In your case, could be just fouled from the sudden oil consumption - I'd reset the CEL and see if it comes back again or not. Over time, the cat will burn off the residue, assuming you find out what is causing the oil consumption in the first place.
Other areas I'd start looking into - oil control valve and oil control valve filter (OCV). Part of the VVT-i system, and very sensitive to oil quality. If this filter clogged with debris, it will start the OCV of oil and pressure, would cause the timing to be too far retarded or advanced for the engine load/engine speed - can cause excessive oil consumption and driveability issues (poor idle, poor fuel economy). Assumed that you already checked out the throttle body, read the plugs, cleaned the MAF sensor, checked the IACV on the throttle body. Another possible problem area would be the oil pump. On some 1ZZ-FE and 2ZZ-GE engines, this was a problem area. Not having enough oil pressure to key areas of the engine could explain a lot, especially the timing chain - as the chain is really hard on the motor oil. Starving it of enough lubrication is surefire recipe to stretch that chain out.
Check valve clearances and see where they are at. A sticking injector can also explain a lot. Reading the plugs should give you some indication of what is going on there. You can play around with swapping coil packs and injectors from one cylinder to another - just to see if it runs differently. Can always send the injectors to a shop to ultrasonically clean and flow test. They'll tell you right away if one injector is sticking or not.
Might also be useful to send in some used motor oil to be chemically tested. See if there is an issue with excessive wear metals, any coolant in the oil, if the oil has been sheared down past the point of decent protection/been heavily contaminated with fuel. For around $25 - gives you that one extra piece of information that could give you some insight of what is going on.

So does my 2003 have the newer piston design? The oil consumption happened on a trip of 1200 miles solid driving. Took the car to a friends "country" mechanic, who was supposed to be good and cheap. He was fairly certain the timing chain was causing the vibration, although after he did it, it did not fix it. When he showed it to me, there was quite a bit of slack between the cam gears, where there should be none. I do wonder, now that I don't trust him, whether he might have removed the tensioner to create this slack. Either way I did not pay much for his services and he did put a new chain, sprockets, water pump and gaskets. He took the head to his friend who worked at a machine shop to have the valve seals done. His friend apparently said the seals were fine and then just planed it a little for re fitment. It was not warped.After he put the car back together, he discovered the car had burnt off the oil. To be honest I am embarrassed to say it had been some 2-3K miles sense I had checked.(car has never ever burned a drop in its life.) It is now running GTX high milage instead of the amsoil I run in all my vehicles. Having seen under the valve cover, having purchased a haynes manual and no longer trusting anyone except myself; I am now prepared to do all the work myself on the car. Surprising to me, the engine looks like a larger version of my motorcycle engine with some transmission differences.(I worked as a motorcycle mechanic for a couple years) Starting by checking everything "he" did and everything else, I plan to rectify my issues. The car actually really runs quiet well which is suprising giving all the vibration, bad gas milage, burning oil, etc....

I am going to pull it all apart Saturday. So I need to make a list of everything I need to do. I was unable to secure a cam chain tensioner in time, so I hope that is not an immediate issue in my case. I will be checking valve clearences, thickness of the lifters, checking the cams for wear. cleaning the MAF, OCV, IACV, throttle bodies. I have already changed the PCV. I have a new accessory belt tensioner and gaterback belt. I will be changing the oil and transmission fluid and filters. I plan to look at the fuel injectors and see if they spray nicely with 12v applied. gonna gap the plugs for the heck of it too. I have a multimeter I will use to check everything I can. Thanks again for your help, anything else i should be doing? The compression was 180 even on all 4 cylinders and assuming the valve seals were actually looked at, I dont know were I could be loosing the oil. I think he did overfill the oil a bit and the check engine light came on while traveling back 1200 miles. The oil is at the high mark now and does not seem to be burning off. After i changed the PCV the check engine light turned off for a bit, and I swear the vibration was gone. Its back on now and the vibration is for sure there so that was an odd mystery to me. Is there anything that putting on a new PCV and running compression tests could have done to make my car run right for a while? It was not long enough to confirm good gas milage. I have been running shell V-power. Thanks again for your help.

Correct, the 2003+ 1ZZ-FE engines have a slightly revised pistons (8 versus 4 holes), different oil control rings, and oil channels/passageways in the short block itself - mainly to support a different powerband (less low end torque, and more in the middle and top end).

Assuming they just used whatever oil they had on-hand after the chain was replaced? Possible it was just some cheaper bulk oil, it is possible that it just burned off during the long trip. You mentioned running synthetic oil in all your cars - was the Corolla the same way? Did you notice the oil consumption with synthetic in it or only after it was refilled with something else?

Yeah, unfortunately, running it over that period of time - tough to say what the real culprit is, was it improper work or something as simple as not filling the crankcase all the way or overfilling too much (too much pressure, could leak out).

Have an uneasy feeling about the shop decking the head. With the 1ZZ-FE, you don't want to shave any material off - tolerances and thickness are super tight and thin in this engine. It is fortunate that the valve seals were OK, as most shops will also cut the valve seats while they are at it - which cannot be done on the 1ZZ-FE. Seats are laser welded/sputtered on - cutting down like you would in a conventional head, you'd cut right into the water jacket right behind the valve seats.

Only other places I'd check is to do a quick inspection, see if oil is dripping down the side of the engine. Paying particular attention to the valvecover area, timing chain tensioner, and timing chain cover. Probably couldn't hurt to verify timing is correct - toss a timing light on there - just to make sure the chain hasn't jumped tooth. Double check chassis grounds and look for ground loops (use the voltmeter set to the millivolt scale - touch two ground points, should be zero volts). This family of engine is very sensitive to electrical noise - can cause all sorts of headaches, be tough to diagnose.

Did you get a chance to pull the OBD-II code? As for the PCV - pretty much straight forward, no way to get it backwards here - but you could be temporarily sealing a vacuum leak around the PCV hose. If that hose is dry rotted or cracked - replace it. Even a small vacuum leak can cause poor idle and vibrations - might want to double check that there are no leaks anywhere there. Same goes to the airbox and the piping to the throttlebody. Interesting that after messing with the PCV and doing a compression test, the car was running well for a short time. PCV = could be a vacuum leak, as for the compression test - depends on if you did it with the injectors enabled or disabled. If enabled, they could have washed off some deposits on the top of the pistons that would have cause detonation and knocking later.

Has running premium fuel (Shell V-power 93 octane) help at all with the vibration? How did the plugs look when you had them out? Pretty even deposits on them? Gap should be pretty good on these, but doesn't hurt to double check. Recommend sticking with OEM iridium plugs only, other having run copper and platinum plugs have reported poor running. Gap is 0.044".

Correct, the 2003+ 1ZZ-FE engines have a slightly revised pistons (8 versus 4 holes), different oil control rings, and oil channels/passageways in the short block itself - mainly to support a different powerband (less low end torque, and more in the middle and top end).

Assuming they just used whatever oil they had on-hand after the chain was replaced? Possible it was just some cheaper bulk oil, it is possible that it just burned off during the long trip. You mentioned running synthetic oil in all your cars - was the Corolla the same way? Did you notice the oil consumption with synthetic in it or only after it was refilled with something else?
Yeah, unfortunately, running it over that period of time - tough to say what the real culprit is, was it improper work or something as simple as not filling the crankcase all the way or overfilling too much (too much pressure, could leak out).
Have an uneasy feeling about the shop decking the head. With the 1ZZ-FE, you don't want to shave any material off - tolerances and thickness are super tight and thin in this engine. It is fortunate that the valve seals were OK, as most shops will also cut the valve seats while they are at it - which cannot be done on the 1ZZ-FE. Seats are laser welded/sputtered on - cutting down like you would in a conventional head, you'd cut right into the water jacket right behind the valve seats.
Only other places I'd check is to do a quick inspection, see if oil is dripping down the side of the engine. Paying particular attention to the valvecover area, timing chain tensioner, and timing chain cover. Probably couldn't hurt to verify timing is correct - toss a timing light on there - just to make sure the chain hasn't jumped tooth. Double check chassis grounds and look for ground loops (use the voltmeter set to the millivolt scale - touch two ground points, should be zero volts). This family of engine is very sensitive to electrical noise - can cause all sorts of headaches, be tough to diagnose.
Did you get a chance to pull the OBD-II code? As for the PCV - pretty much straight forward, no way to get it backwards here - but you could be temporarily sealing a vacuum leak around the PCV hose. If that hose is dry rotted or cracked - replace it. Even a small vacuum leak can cause poor idle and vibrations - might want to double check that there are no leaks anywhere there. Same goes to the airbox and the piping to the throttlebody. Interesting that after messing with the PCV and doing a compression test, the car was running well for a short time. PCV = could be a vacuum leak, as for the compression test - depends on if you did it with the injectors enabled or disabled. If enabled, they could have washed off some deposits on the top of the pistons that would have cause detonation and knocking later.
Has running premium fuel (Shell V-power 93 octane) help at all with the vibration? How did the plugs look when you had them out? Pretty even deposits on them? Gap should be pretty good on these, but doesn't hurt to double check. Recommend sticking with OEM iridium plugs only, other having run copper and platinum plugs have reported poor running. Gap is 0.044".

Well everything that happened was told to me by the "country" mechanic. They might have done nothing to the head except check it. His friend worked a professional shop so I would hope he would know what to do and what not to do, he must have known about the valve seals. Is there any obvious way to see if any of the valve guides are bad?

I have ran amsoil in this car since about 30K miles at 8K intervals with the correct filter. Not once has the oil ever looked bad or has a drop been burnt. According to the mechanic it was off the end of the dipstick when he checked it. He had already put in GTX high mileage by the time I got there. When he did the compression tests, he said one cylinder was low so he recommended the high mileage oil. The car does have 132K miles on it now, I assume high mileage oil is a good idea. I have always used the amsoil in everything and even did back to back dyno runs on my bike proving that the amsoil actually made more power then the mobile 1 synthetic, not to mention it holds up longer then any oil I have used.

I took the car to autozone and they scanned the code, catalytic converter below performance threshold. I have always suspected an electrical issue and or vacuum leak. I will look carefully to try and find one. I really dont think the car has any major internal issues. There is for sure no oil leaking. I cant be certain the car ever did burn off that oil as I did not see it myself, the mechanic might have just been trying to cover the fact that the timing chain did not fix the vibration. I have started running the premium since someone told me that ethanol content had gone up in the regular and could be contributing to the poor gas mileage. Also I trust the stuff to run clean, bike always likes it. Does not seem to have made a difference in my car. The car has the iridium plugs replaced at 116K, I was under the impression that there was no need to gap the plugs but of course it cant hurt. The plugs seem to be evenly coated, though it is more of a light chocolate tan, not the almost white tan I believe these newer vehicles should be. Obviously the car is burning more gas and or oil then it should, explaining the color and the code.

I guess I will know more after everything on Saturday. I will buy a can of starter fluid and see if I can find a vacuum leak. Thanks again for your help.

Fish,

I do have a question for you.

Did a lot of stuff to no avail. However I did take a multimeter and put it on dc milliamps to measure any possible currents in the chassis. I touched all around and found nothing, including grounding the to the battery terminal. Then I touched a bolt on the drivers side strut tower and got a reading of 2-12 milliamps, if I applied both leads to different parts of the battery ground wire I also got 2 milliamps. I am not experianced with electrical systems, but does this indicate a short somewhere?

Milliamps or millivolts? Since you mentioned DC scale (voltage) I'm assuming you meant millivolts. Millivolts of that range, might just be ambient noise, depends on the multimeter and if is a high=impedance model (most are). Try scraping at the metal a bit and see if you get the same reading. 10s of millivolts consistently could indicate there is something amiss. If it was 2-12 milliamps - measuring current, then you definitely have an issue - showing that there is current flowing through that connection.

How are you making that measurement - from the negative battery terminal to the driver's side strut bolt? If yes, then find the main chassis grounding wires - they'll be obvious - a wire that attaches to the chassis via a bracket, straight to the sheetmetal, or directly to the engine block. Disconnect the negative battery terminal - disconnect those grounding points and clean up any corrosion (sandpaper, steelwool, wire brush, etc.) Both the terminal and the grounding point, re-secure tightly and coat them with some grease to keep moisture out of the connection. Reconnect the negative battery terminal and recheck the voltages to the various ground points. If it doesn't change or gets worse, you have some parasitic drain somewhere. Could be almost any source, but most commonly associated with new audio equipment and alarm / keyless entry systems.

It is milliamps, I am able to get the same reading off the engine as well. If I scrap down its a solid 12 milliamps, and only when the ignition is on. When my car was hit while parked, I remember some sort of heatsink or something on the inside of the drivers wheel well. I can not find this in my manual, I am wondering if you have any idea what that could have been. I do not trust the body shop that fixed the car so I am thinking they might have screwed something up there. Unfortunatly I would have to take the wheel well skirt off to see it.

Wanted to add an update. The problem is still there.

I have replaced the cam chain tensioner, measured valve clearances as well as wear on the cam lobes. Checked for vacuum leaks. Everything is perfect.

The vibrations seem to be getting worse with time. The newest symptom is now that we have some colder weather, the vibration is significantly worse. I am at a loss. I am assuming that the issue is not mechanical.(I have confirmed the car is not burning oil) This leaves some sort of electrical issue, wish I had a check engine light to tell me what.....

What is the idle speed when it first starts up? Probably a range of RPMs, but I'm interested in seeing what the highest RPMs are and once it warms up, what the RPMs drop to.

On this generation, there was an issue with the composite intake manifold leaking - was solved with a revised intake manifold gasket. Just wondering if that was the case here, as potential vacuum leak right at the manifold.

As for electrical cause for excessive vibrations - that is a needle in a haystack sort of thing.

What is the idle speed when it first starts up? Probably a range of RPMs, but I'm interested in seeing what the highest RPMs are and once it warms up, what the RPMs drop to.

On this generation, there was an issue with the composite intake manifold leaking - was solved with a revised intake manifold gasket. Just wondering if that was the case here, as potential vacuum leak right at the manifold.
As for electrical cause for excessive vibrations - that is a needle in a haystack sort of thing.

It idles at around 2k when really cold, settling down to 800 or so. The vibrations are not noticeable until the idle settles down, particularly when you load the engine in drive and it goes down to 600-700.

The car is now back in the body shop and I think the insurance is going to pay for all the electrical to be replaced.

I did use a vacuum gauge to check for any issues and nothing behaved a abnormally.

Yeah, that was a long shot anyways - sounds like the car is idling perfectly fine. Hopefully this time they will be able to get those electrical bugs out of the system. Let us know what they eventually changed out and if the problem seem to be solved.

Yeah, that was a long shot anyways - sounds like the car is idling perfectly fine. Hopefully this time they will be able to get those electrical bugs out of the system. Let us know what they eventually changed out and if the problem seem to be solved.

I had a bit of a tussle with the service department at the dealership, of course because the check engine light was on for the catalytic converter and nothing else. They assured me the vibrations were from the last engine mount(even though the engine is under the hood bucking) I have isolated that last mount on my own and have determined the mounts had nothing to do with my issue long ago.... His next claim was that the engine was burning extra fuel because of the aftermarket cat, he says when the check engine light comes on, the ecu retards the timing, causing the poor gas milage. Of course the gas milage was bad for the 15-20K miles when the check engine light was not on and why would a car with a failing cat increase its emissions.... Of course then he wanted $200 for a new valve cover gasket, cause it was weeping a bit.

So the insurance is calling them up to tell them to replace all the electrical. God bless USAA.