2006 Avalon 39,000 Miles, Dreaded PO351 Code....

[tellefan]

First and for most, I want to thank everyone on this forum. I joined a while back and really have not posted because I've not had any problems until now.

EDIT: I have searched the forum for this and have read some posts, however they never follow up if it was fixed or not.

The other night the wife and I were driving along and the Check Engine light and VSC light came on. After getting home, I checked it with my scanner. The only code was PO351. I called the dealer to make an appointment and passed along this information.

I let the car sit over the weekend, and took it to the dealer yesterday morning. After sitting in the waiting room for two hours, an employee came over and said the ignition coil was bad and it would take four to five hours to fix. and they gave me a rental car to drive.

Luckily I have an extended warranty, and the car has 39,000 miles on it. The dealer called later in the day, the car was ready to go.

I go pick it up, I start the engine, put on my safety belt, guess what? the check engine and VSC light were on. They checked the codes again, there were a ton, I didn't write them down but all the cylinders were miss firing.

So, has anyone run across this before? What's wrong??

Thanks,
David

[inov8]

My guess: They installed another bad spark coil or damaged the common feedback wire. There appear to be 2 common failure modes for these coils. You either have no spark, or the internal spark confirmation circuit fails and the engine computer THINKS you have no spark in that cylinder (but you really do, the engine continues to run just fine). The latter failure mode seems to me more common. There is a separate spark "command" wire for each of the 6 coils, but they all share a common feedback (spark confirmation) wire. If that wire is compromised (sometimes by failure of just one of the coils), the computer may think you have misfires in all 6 cylinders. I wouldn't worry if you have a Toyota warranty. The worst (or best?) that may happen is you will get 6 new spark coils. I believe the design has been improved because the failure rate has been so high.

[CISA93]

Originally Posted by inov8

My guess: They installed another bad spark coil or damaged the common feedback wire. There appear to be 2 common failure modes for these coils. You either have no spark, or the internal spark confirmation circuit fails and the engine computer THINKS you have no spark in that cylinder (but you really do, the engine continues to run just fine). The latter failure mode seems to me more common. There is a separate spark "command" wire for each of the 6 coils, but they all share a common feedback (spark confirmation) wire. If that wire is compromised (sometimes by failure of just one of the coils), the computer may think you have misfires in all 6 cylinders. I wouldn't worry if you have a Toyota warranty. The worst (or best?) that may happen is you will get 6 new spark coils. I believe the design has been improved because the failure rate has been so high.

The design of the coils has been improved. I just purchased 3 coils (one went bad and the other two were replaced since they were on the backside (firewall) and very difficult to replace if they were to go bad).

I have a friend at Power Toyota in Phoenix, AZ, he advised me this part was revised because of the unusual failure rate. However, it goes back to the company that manufactures the coils for Toyota (Diamond Industries, a Japanese-based manufacturer).

Another piece of information I learned last week while checking my battery and charging system. The alternator has a clutch pulley and those bearings in that clutch pulley have also had a failure rate, but it's not due to bad alternator, it's the pulley design. So, the revised clutch pulley assembly has a double bearing design now. If you have a starter/alternator rebuild shop, ask them to check your electrical system. Having a faulty alternator can cause many electrical problems since the power goes to the computers (ECM/ECU) first. Best of luck

[tellefan]

I wrote a reply on 7-7, in doing spell checking, the post disappeared (puked). Out of frustration, I didn't try again until now.............

I picked up the car on the seventh, the replaced number 1 and 6 ignition coils. I have a bad feeling, this is the start of sliding down the slippery slope to problems. I appreciate the replies. I can use all the info I can get to wade through these gremlins.

Thank you,
David