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weh116

Coil Packs

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Last year I bought a 2006 Corolla LE. Soon after buying it the car started hesitating and the engine light came on. A mechanic hooked it up to the computer and said #3 cylinder is missing. They replaced all spark plugs and #3 coil pack. A few days later, same problem. This mechanic called the dealership, they recommended using factory spark plugs so we changed them again with plugs from the dealer. Few more days, same problem. Mechanic recommended taking it to dealer because he was stumped. Dealer said #3 cylinder missing again, moved #2 coil pack to #3 spot and put brand new coil pack in #2. Day or so later, same problem, took back to dealer they now say #3 fuel injector may be bad but they dont know for sure. Took car to different mechanic, he said #2 cylinder missing replaced coil pack again. Next day engine light came on again, back to mechanic #3 this time, replace coil pack #3 again. Light was off for a few hours and its on again. This mechanic also ran fuel inejector cleaner and gas treatment in case water somehow got in the lines. Any suggestions on what to do next?

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trap

Replacing any of the coil packs to begin with - have complicated the diagnostic process. If #3 was suspect - I would move the #3 coil pack to one of the other remaining cylinders and see if the CEL follows the coil pack. If it does, then that would point at a bad coil pack. If not, that would point at the signal not getting to the coil pack or possible issue with #3 cylinder. Unfortunately, this didn't happen until you brought the car to the dealership. Sparkplug wise, the 1ZZ-FE engine is pretty sensitive - some aftermarket sparkplugs cause misfires. Best to stick with fine wire Iridium plugs, whenever possibly (hopefully that is what is in the car now).

 

Need a bit more information. Did any of the mechanics "read" the spark plugs? Just looking at the coloration, amount of deposits, etc. can tell you a great deal of what is happening in there. When you have these CELs - does the engine run poorly or otherwise runs differently?

 

As it stands - this "bad" coil pack or injector jumping around in that manner - especially now that they are saying possible bad injectors. I would suspect the ECM as being the most likely culprit. The ECM controls the signal to the coil packs and injectors - if the ECM is getting confused, it would explain all the issues you are seeing.

 

That and given that a small number of 2005-2007 Corollas have shown a greater than normal failure rates for ECM - this makes the likelyhood of having a bad ECM very high. The ECM is covered under the federal emissions warranty - the trick is getting the dealership to test the ECM.

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Thank you for the response.

 

I took the car back to the dealer and asked them about the ECM. They hooked it up to the computer and got the p303 which they said means # 3 cylinder is missing again. They also said EMC should be fine but Im not sure how they know that.

 

To answer your question about the CEL, after a "repair" the mechanic turns off the light. After the first attempted repair it took about 4 days for the light to come back on but after this most recent attempt the light was only off for a few hours. The car seems to hesitate most when Im just starting off or going up a hill. Once I get to about 35mph it runs better. Then when I get to about 60mph it starts to hesitate again.

 

One other thing I didnt mention earlier. The RPM gauge just jumps all around the dial, there seems to be no rhyme or reason to it. Sometimes it just stays at 0 even though the car is moving.

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Sounds like the ECU is bad, was your corolla made in California? You have to ask them if they can communicate with the ECU. Make sure you get this taken care of before you reach 80K miles, if you have not reached it already.

Edited by mikered30

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Im finding it extremely difficult to get the dealer to even consider that the problem is the ECM. During my last visit to the dealer's service center they told me that my car isn't covered by the federal emissions warranty. Everything that Ive found online regarding the federal emissions warranty says it covers cars with up to 80,000 miles, I have 67,000 miles.

 

They gave me a list of probable causes:

 

leak in a vacuum hose

pcv valve

fuel injector needs replaced

and a few others but not the ECM

 

Recent work that has been done:

new PCV valve

new spark plugs from the dealers service center

new coil packs on 2 and 3

new air filter

 

The CEL is still on any time I drive the car but now it starts flashing when I accelerate. Does this mean anything different? I drove it to autozone yesterday to purchase the new PCV valve and they plugged their computer in and got the same code, p303.

 

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Im finding it extremely difficult to get the dealer to even consider that the problem is the ECM. During my last visit to the dealer's service center they told me that my car isn't covered by the federal emissions warranty. Everything that Ive found online regarding the federal emissions warranty says it covers cars with up to 80,000 miles, I have 67,000 miles.

 

They gave me a list of probable causes:

 

leak in a vacuum hose

pcv valve

fuel injector needs replaced

and a few others but not the ECM

 

Recent work that has been done:

new PCV valve

new spark plugs from the dealers service center

new coil packs on 2 and 3

new air filter

 

The CEL is still on any time I drive the car but now it starts flashing when I accelerate. Does this mean anything different? I drove it to autozone yesterday to purchase the new PCV valve and they plugged their computer in and got the same code, p303.

 

Might want to try to go to a different dealer, you car is covered under the federal emissions warranty if it is less than 8 years or 80K miles even if you bought it used. It says it in the owners manual. Flashing CEL means misfire, among other things. You are in the US, correct? Did you ever experience idle hunting in the winter? If so, that is the only way you will get that dealer to look at the ECU, as there is a TSB that ties idle hunting and a misfire code to the ECU.

 

Also, aftermarket PCV valves usually do not fit right, for some reason, OEM PCV valves are the way to go. Give the VIN when ordering.

Edited by mikered30

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I'm with mikered30 on this - try a different dealership, as it sounds like you are getting nowhere with the one you are currently seeing. Also, a flashing CEL is a sign for misfire - it is recommended that you do not continue to drive the car, if you have another means of transportation. Doing so could potentially cause engine damage.

 

Possible that the issue is related to a bad fuel injector - though it is hard to say for sure, since so many parts have been replaced since then. A shop should be able to pull an injector off the head and see if there is a problem with it. Critical that the shop (dealership or import specialist) properly "diagnose" the problem, not swap parts. Doing so will complicate the diagnostic process down the road, when and if the problem returns.

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I think the dealer is trying to tell him that his misfire is not covered under emissions warranty, thinking that he thinks that any emissions or engine problem is covered by emissions warranty. could just be a miss-communication.

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Guest hey try this dude

hey replace all four coil packs they weaken over time before going completely bad the computer wont detect this but car will jerk- hesitate is a sign , replace all four spark plugs too at same time, if still bad replace fuel injectors

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