1G Misfire under boost.......troubleshooting questions

[MikeGrant]

Hey I have a couple quick questions about a misfire I have just started to get on my car under boost around 4000 rpm. After the misfire started I installed new ngk br8es plugs gapped .026 and installed new ngk wires. Neither made a difference.

I just tested my coil and wanted to double check I used the correct settings on my tester when I tested the coil
PRIMARY COIL (set at 200 ohms)
-pins 2,3 1.16 ohms
-pins 1,3 1.18 ohms

SECONDARY COIL (set at 20k ohms)
-coil 1,4 12.63
-coil 2,3 12.78


I have a datalog that I will attach and you can see the misfire at approx 115 second mark.

I also was told to check if the timing belt had skipped a tooth as it can also cause the same misfire system , is there any truth in this and does it happen that often?

Thanks Mike

 

[a91eagletalon]

I had a similar problem I had my plugs gaped to.025

so I tightened up the gap to .018 because I was blowing out the spark

ever sense I did that it ran good under boost

What PSI are you running

 

[MikeGrant]

I had a similar problem I had my plugs gaped to.025

so I tightened up the gap to .018 because I was blowing out the spark

ever sense I did that it ran good under boost

What PSI are you running

I am looking to run around 24 psi peak boost but I am misfiring at 20 psi. If I use half throttle or less it will rev out and runs great besides this problem

I am going to try and find a good coil and swap it and if the problem still persist I will try and tighten the plug gap u[

 

[a91eagletalon]

So if you accelerate with out building boost it runs fine

 

[dsmgreenhorn22]

Sounds like you are getting spark blow out. Try a tighter gap and maybe a colder plug.

 

[1990TSIAWDTALON]

He's already on a cold plug, but tighten up the gap and how are your air fuel's when it misfires, do they still look ok not to lean?

 

[MikeGrant]

He's already on a cold plug, but tighten up the gap and how are your air fuel's when it misfires, do they still look ok not to lean?

AFR's are steady at 11:1 and boost is steady at 22 lbs when the misfire starts.

 

[1990TSIAWDTALON]

Make sure that the plug wires are separated and that they are not grounding out on anything. My coil faced UP so my wires pointed at the hood and I had some misfire issues. I moved my coil packs and got the wires away from the hood and the misfire went away. Just some of my issues I have had.