Misfire under load

[gtn116]

I'm getting a misfire in gears 3-4-5. It's only when I've been cruising for a bit at lower RPM's. If I'm in 5 and shift to 3 and give it the beans, it'll misfire for a bit and usually clear up and scream. If I'm cruising along at say 3500 in 3rd and get into it, it typically just goes without a problem. The car is a 91 200 20v avant with a 2Bennett 2.5bar RS2 chip and the 034 RS2 injectors with a K26. I've been running 91-93 octane, the NGK BKR7E and it runs 20psi usually. Would it make sense that maybe it's loading up a little too much with fuel and it has to burn it off/clean the plugs before it runs right?


I'm planning on getting a turbo to better match my tune, thinking either an RS2 turbo of some variation, maybe a k26/3071 hybrid or Cary suggested a k26/to4e hybrid. Thoughts on that?

[loxxrider]

So it will not misfire if you keep running it hard?

[PRY4SNO]

Knock sensors?

Mine acted like that when they started going, then they just got progressively worse...

[gtn116]

Exactly Chris. If you keep the rpm's up and stay in it, no problem. I can try the knock sensors, it can't hurt to have new ones anyway.

[loxxrider]

What if you've been driving hard, then get on it from low rpm. The point I'm trying to get tois wwhether it does it at torque peak consistently or only after idling or cruising for a while. To me, that means the difference in it being fuel or spark related.

[gtn116]

That makes sense. I'll beat the piss out of it when I go Christmas shopping later.

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[loxxrider]

[gtn116]

Update. It happens all the time, even after a high rpm cruise. I think it's coming from my knock sensors, the one wire is trashed (insulation cracked and falling off)

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[amd is the best]

My brothers S6 did nearly the same thing on RS2 software/fueling and a stock K24 turbo. Would misfire pretty bad on the initial boost onset then clear right up and rip at the top end. Maybe it has something to do with the software being programmed for a turbo that spools later... Just a guess.

[gtn116]

Hard to tell. I'm going to be switching to PNP vems hopefully soon. I think I'm selling my 5k project too... Or parting it out.

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[Justin517]

yeah, might not be ready for a faster spool or it is and its dumping more fuel because it is expecting more air volume at the same psi and going super rich.