I seem to have an intermittent misfire at idle. It only does it at low resting idle and not all of the time at that. My durametric indicates that it is on cylinder 4 which I think is the passenger side farthest rear cylinder. I'm going to swap around my spark plug and coil to check them. I am wondering if there is anything in my log to indicate that it could be an injector issue. This log is with my boost control valve unplugged in 3rd gear, so running on wastegates. The car rus great otherwise.

 

Probably bad coil, spark plug or connector/wiring to the coil.

An injector issue is possible, but unlikely. Throw some injector cleaner into the fuel tank just for kicks.

 

I swapped the coil between cylinder 4 and 5 as well as installing new spark plugs. I'm still getting that same misfire. So my next possibilities are: wiring issue to the coil, compression issue, or a fuel issue.

 

This could also be an intake lifter stuck at high lift.

 

I'm going to try running one coil off with a spark plug in it to ground to see if it is sparking in time. I'll know it isn't electric then. I have a cyl compression test also so I'll try that too.

 

Check the wiring to the injector as well.

 

I think it has to be the injector otherwise it would miss at higher rpm. I wish they weren't so hard to swap.

 

Try some fuel system cleaner in the tank. You might get lucky.

It worked for me once.

 

I put ratchet drive rod up to the injector and listened. It does sound like it is ticking properly. Next up I'm going to spin the motor with a compression tester connected to 4 and then 5 to see how that looks. Tomorrow.

 

The compression in that cylinder is good, showing 125 psi with a quick turnover, throttle plates closed. We are down to a stuck lifter (sounds fine) and a bad injector. I'm betting it is the injector, not looking forward to getting in there.

 

When I had a bad injector on #5 I pulled the engine instead of going in from the top. That side - oh, my it looks difficult with the engine in the car.

 

I think the driver side is actually worse. I got the air pump out, I think I'll be able to get at it. I'm just going to replace that one injector with a new one and hopefully that gets it. What was your injector doing?

 

Now that I think about it my dead injector was #5 as well. It was completely dead, no click or anything. The front bolt for the fuel rail was hard to get to with the engine out.

 

Changed the injector (not fun). This did not fix my problem unfortunately. I ran the car through the mountains and had a ton of fun though. Runs great when not sitting at idle for a while. I'll have to explore this further in the off season.

 

the prior owner to my car had a weird misfire issue. it ended up being a cracked bracket that holds the cam sensor I believe. he had all the coils and plugs changed be fore they found it. I think it is a fairly common but weird issue on these