Zeepak

"New" 2007 Lexus with below 60K miles, check VSC, TC and Engine lites popped on. Autozone code showed a cylinder misfire #6. The misfire is in primarily in reverse or at idle, it smooths out at neutral or park. The coil appears to be an aftermarket, and the clip on the male connector is broken. I zip tied it back but it seems the misfire is worse, regardless, the car purrs and cruises at a flat 90 mph, my mpg is about 25.

So I have a Denso coil here, a plug and am waiting for the new connectors, which I guess I should do first. . Anything else I might be missing? Could the coil have been damaged by the bad connector? I assume no matter what, I should pull the plug.

Hayk

iTrader: (1)

Try swapping the aftermarket coil with the one next to it. For example #4 and #6. Don’t remove the spark plug.

Replicate the misfire and check for new codes. If the code moved to cylinder #4 it’s the coil. If it’s still on #6, then go after the spark plug.

Then repeat and retest. Always troubleshoot with one part at a time to narrow it down.

The connector clips are very common to break from heat cycles, so there is a common zip tie trick for Toyota coil connectors to get them to sit securely. The best solution is always to replace the connectors, but a zip tie works in a pinch.

iceblast

The coils do not last forever (tons of heat/electrical pulsing).

I changed them all out at the spark plug interval, after have 1 or 2 fail before that time.

Hayk

iTrader: (1)

What was the age and mileage of your factory ignition coils and what part of the world are you in?

In my experience, Japanese ignition coils do not need to be replaced until they fail unlike European cars that are recommended to have their coils replaced at the same time as the spark plugs. Still driving with original coils on my 24 year old 300k mile ES300 for reference.

ellocovg

iTrader: (1)

The labor to get to the rear ones is quite intensive. If you are able to do the work yourself then it’s fine if you want to wait until the coils go to swap them. But if you are paying a shop to do the work it doesn’t make sense to not swap at least the rear ones. If you decide to save a few dollars and then a few months later you have to pay for the job all over what did you really save? The front ones are easy enough to get to since the plenum doesn’t have to come off for those. A popular cost saving option is to swap all of the plugs and the rear coils, then save the working old rear coils and reuse them on the front if and when one dies.

chuyrobles

#6 is at the front, far right as you face the engine. Easy to replace. 3 and 5, in the back, are tough to access; 1, back left, is not too bad. Broken tab on the connectors should not be an issue. All mine are broken and I dont even use zip ties. I do check them when I open the hood, but after about 100k, none have ever slipped off the coils. Same for all the other Toyota products in my household. I have found Yec Flamma coils are best aftermarket coils.

ESh

I bought 6 Ema coils for $80 4 years ago and they still work with no issues.

Zeepak

Finally braved the cold to fix it. First, replaced the connector. The old one was so deteriorated that the wires just fell out. Didnt solve the problem.

Pulled the plug, Denso Iridium. It showed electrode wear. No fouling. Change it. Start her up, here come the lights again..

Changed the unmarked, unlabled coil with a Denso from Rock Auto (half price compared to the local places). Check the connections, drop the hood and start her up. Smooth and quiet, no jerking at idle, take off for a test drive finished off with a 100 mph stretch, voila, she fixed.

Next task, the annoying creak in the rear.