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I am having a strange and annoying issue with my NB8A which I can't seem to solve so opening it up to the brains trust here....

Car was running fine 10mths ago when put in shed. Started it and Took it for a run two months ago and the miss was there.

Car only runs on 2cyl at idle but runs fine at full noise.
The strange thing is that it's cyl 1 and 3, not 1and4 or 2and3 as the coil wiring for wasted spark is..

Car runs Toyota COPs and swapping coils between 2 and 3 leaves 3 as the dead cylinder so it's not the COPs themselves.
I've swapped plugs and stays the same so not plugs either. I put new ones in anyway.

I've had the injectors cleaned (and they were close anyway) so not them.

Fitting the plug to the dead cyl COP and starting car shows spark on that cyl.

The injectors pulse when running also.

I've also synched the throttle bodies. And filled the tank with fresh fuel, which has since cycled through?.


I'm out of ideas . The fact that it is two non paired cylinders and only happens at idle is what's confusing me..

Anyone have any ideas/suggestions as to what it might be?

Thinking aloud ... if you swapped 2 and 3 injector wiring does the miss move from 3 to 2? If it does then does that mean an internal wiring failure that only arises when the alternator is not running fast enough to deliver full voltage, or what? If it doesn't, and you know the injectors are good, then is there an injector earth issue or a cam/crank angle sensor or ECU issue or do you need to repeat the exercise with spark instead? Also what else may not run too well only when voltage is low?

Thinking further about spark ... my Toyota COPS are a little sensitive to low voltage. Have you measured volts at idle, especially near the connectors into 1 and 3?

Probably time for a compression test. Can you check the valve clearances yourself?

Aiming Faster wrote:Probably time for a compression test. Can you check the valve clearances yourself?

Did both of them already. Forgot to mention in first post. Compression test came out good. 210, 207, 210, 210 so pretty close to ideal.
I actually pulled the rocker cover and checked clearances as the first step (previous history hangover) and all were in spec except for inlet valve 1 on cyl4 ( 3thou tight) so nothing to cause the issue there either.

Have been busy with nye and house prep so haven't looked at car since yesterday, but I'll try manga's advise and check voltages at the COPs for anomalies as my next step. (also cos I don't have any other steps to try...)