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2000 Corolla: Hesitation, Low Rpm Shutdown And Rotten Egg Smell



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crypticlineage

Hello everyone,

I am back here after a really long time. From those of you who remember, my 2000 corolla VE had problems accelerating beyond 70 mph. A distinct hesitation as if caused by intermittent fuel supply problems, was apparent at speeds above 70 or so. I have lived with this problem for years by simply maintaining the speed below 70. In the meantime, my CEL has constantly had P0420 code. Even after replacing oxygen sensors I hadn't been able to get rid of it.

Last night however, things took a turn for the worse. I was on a 300 mile trip back home, and couldn't accelerate above 65mph. The car was hesitating like crazy with accelerator pressed or depressed at those speeds. I stopped to refill the tank and dropped some Techron fuel injection cleaner which didn't seem to help at all.

Then after about 100 miles, I couldn't accelerate above 60mph. At a couple of stop signs along the way, the engine cut off at low RPM. Then a few miles later, I heard a very peculiar sound kind of like release of high pressure air accompanied by really strong rotten egg smell that lasted for a good 5 minutes.

These all sound like classic symptoms of the failure of catalytic converter. I have replaced this part before when my car used to burn a lot of oil. It's been more than 5 years since then. The cat was replaced right after swapping the motor. The new motor also burns oil, albeit much slowly than the previous one. But five years of oil burning has probably taken a toll on the cat.

So my question is, should I just go ahead and replace the cat? I plan to get the aftermarket one but not sure if I should get direct fit or universal fit. The cat I have now is welded onto the exhaust pipe. So I am thinking universal fit should be fine. If you guys have any recommendations, please share.

Thanks for reading.

Edit: Drove car again this evening. Engine cuts off constantly when stopped. Had to keep revving it up with one foot on break. Definitely looking like choked cat.

Aftermarket cat should be fine, as long as your emissions regulations says you can use them (some states only allow OEM catalytic converters). Note that most aftermarket cats don't last that long - hence the price break.

Unusual for a cat to clog up like that - though possible - pretty unlikely, even with heavy oil consumption. Before you spend money on a cat - get a compression test and leak down test - make sure the compression is good and that the valves are not burned. Might also want to double check engine timing - as burned valves, low compression, and missed timing can all affect the engine in the way you described.

crypticlineage

I have got some terrible news. Before I called the tow truck to take it to a mechanic, I decided to pull the spark plugs and check compression. My findings are as follows:

- Oil on all coils

- All spark plugs were rusted and showed signs of oil burning (white tips - will post pics soon)

Compression test (dry)

Cyl#1: 0 PSI

Cyl#2: 0 PSI

Cyl#3: 30 PSI

Cyl#4: 60 PSI

I ran the dry compression test multiple times to make sure I wasn't doing something wrong. There was never any compression on cylinder 1 & 2. Cylinders 3 and 4 stopped showing any compression after multiple tests.

Wet taste on cylinder 1 showed no increase in compression. I take it that the pistons on 1 & 2 are permanently damaged/stuck.

There was no point in taking it to a mechanic at this point since I am not in the mood to spend upwards of $2000 on rebuilding the engine or getting another donor (this was my second donor which lasted about 5 years). So I brought it back home.

Someone suggested to me that timing chain may be broken. How could that result in any compression at all on cylinder 3 and 4 though? Also, will the engine still turn if the chain was broken?

I could potentially do some work on my own at home, so any suggestions/ideas for testing are much appreciated. I will be looking for a new car soon. Thanks guys.

That sucks. If the timing chain was broken, as you surmised, you wouldn't record any compression on any cylinder. Possible that the timing jumped a tooth or two - carbon build up was more significant on cylinders #1 and #2, which resulted in a bent valve on those cylinders. Cylinders #3 and #4 could have "just" have enough clearance to keep them from completely being damaged, but damaged enough to report low compression.

You can pull the valvecover and manually turn the engine over by hand (turn crankshaft pulley with a wrench) - to see if the chain is broken. Can also do the sparkplug hole trick - put something like a thin dowel or similar in through the sparkplug hole - turn the engine over by hand and see if the dowel or rod moves up and down with the top of the cylinder.

From the description you mentioned - rust on the plugs - if the rust is on the electrode end (piston side), that sounds like a head gasket let go and you were consuming coolant. If the rust is on the coil side - then you probably got stuck rings, broken rings, bent valves, etc. Anyway you look at it - sounds like something catastrophic let go in the engine. That it held on for this long shows that these engines are pretty tough, but doesn't help you now.

As far as other things to check - check coolant levels, check oil level. See if there is any signs of cross-contamination. Use a flash light to illuminate the inside of the radiator tank after you removed the radiator cap - should see clean, fins in there. If you see any deposits or weird oil slick/scum on the top of the coolant - that means oil got in there. Same with crankcase oil - if there are any gummy deposits on the dip stick, underside of the oil fill cap - then water/coolant got in there.

Very unfortunately that you had such a bad run on luck on this car. You've pretty much did everything you could to resolve the previous engine issue, swapped in another engine, discovered all the issues that could come from engine swaps, even from the same generation or same family of engines, then run into some catastrophic issue now.

Not sure how much time/money you want to pump into the car - just get it running so it can be dropped off at a dealership for a trade, or don't do anything and give it away to a tech school to hone student skills or one of those car donation sites (for tax deduction purposes).

As far as lower cost things you can do to atleast get it to run. Have to pull the valvecover to see if there are any signs of other damage to the engine. Verify if the timing chain is damaged or not. If timing chain is OK - possible valvetrain is still good to go. That leaves the short block - could be a simple re-ring and you are good or could be a significant rebuild. If there are signs that the timing chain jumped a tooth or coolant contamination, could be looking at new valvetrain, cams, bearings, rod bearings, re-deck the block and head, new pistons, rings, polish crank, hot tank the block to remove all bits of metal and gunk, etc. If that was me at that point - I wouldn't sink in any more of time into it at all - just part out or salvage to recoup some money.

crypticlineage

Fish: Thank you for such a detailed analysis and all the information.

Here are some pictures of the spark plugs.

My plan is to open up the valve cover and do some inspection in the next few days and see if I can fix anything myself. I will report back with more pictures once I open the top up.

Plugs don't look too bad. White deposits are a common occurrence for oil consumption and fuel additives (both already in the gas and any additional ones you can add to the tank). Gap looks like it is a little more open than usual, but not excessive. Note that even carbon buildup up to the first thread on the plug and the color change on ground strap on atleast the one that is most visible, discoloration happens right at the bend - plugs were the right plugs for the engine. Threads still look pretty clean, some oil squeezed by, some signs of the anti-seize compound still on the threads. Otherwise - doesn't look like a plug from a totally blow up engine.

Hopefully, the loss of compression happened just at the end of your last run. That would give you some chance to revive the engine enough to drive a bit more, or allow you to drive it to a lot to trade in on something else.

crypticlineage

Thanks fish. I don't think any coolant leaked into the engine. I have unadulterated oil and the coolant level is just fine. Next thing I am going to do is open the valve cover. Can you give some pointers on what things I should check? I have Haynes manual but not sure how helpful that will be.

Definitely check to see if the chain broke or jumped a tooth. Visually note if the chain is on the sprockets - how much slack there is on the chain. If you manually turn the crank, i.e., pull a big wrench on the crank pulley, turn it slowly, observe of the camshafts are turning. If yes, timing chain is OK. If not, timing chain could be broken.

If the timing chain is OK - then keep turning the crank manually until you see two match marks on the camshaft sprockets line up across from each other (should be illustrated in the Haynes Repair Manual). If they line up - timing "might" be OK, if not - timing likely screwed up.

After this - might be able to get a borescope (rent one) - and look down into each sparkplug tube, try and see if you can see the top of the pistons. Observe any contact with the valve train, broken or melted parts in there. Might be able to get it with a bullet camera - I've managed to whittle down a cheap NTSC video camera from a baby monitor, wire in an LED, and it was just small enough to fit into a plug well to look at some of my earlier project cars. Borescope would make it a lot easier, see more though.