Tony @ MPH

I recently swapped an old set of Mototron stamped 60lb injectors for a new flow-matched set from Racetronix. After the injector swap, I hosed down the engine bay and started the car up. I started getting misfires on 6/8 cylinders. One cylinder (#2) was particularly worse than the others.

I noticed the new injectors look physically the same but have a different stamping on them (instead of saying anything about Mototron, they just have the number "107961" and a serial number stamped on them).

I am going to swap back to the old set to see if this makes the problem go away. In the mean time, is there any difference between the Mototron stamped 60lb injectors and the non-Mototron stamped 60lb injectors? If it's not the injectors, then maybe some water got into a connector somewhere it shouldn't have, but if that were the case I would expect to see misfires across all cylinders and I wouldn't expect one cylinder to be much worse than the others.

exploder

New o-rings with injectors???

0Jake@EPP

I would check for vac leaks and check AFR.

Tony @ MPH

This is either coincidental or some condition exacerbated by swapping the injectors, but the problem ended up being my passenger bank was totally fouled out. After logging misfires in a lengthy drive up and down the interstate it became apparent that the passenger bank by and far had the most misfires, so on a whim I had the plugs swapped and sure enough...

After swapping plugs and resetting fuel trims the car ran great but started leaning towards misbehaving again. Possibly a faulty O2 sensor? I reset trims and set my car so it wouldn't learn trims or go into closed loop ever until I can figure it out. It seems happy like this I spent a lot of time with a wideband dialing in my VE and MAF tables so even though the car is very modified it runs pretty good in open loop MAF.

AVB

Glad to hear you've narrowed it down to most likely a tune or bad 02. Out of curiosity are you able to check the afr on the passenger side? My passenger side is richer, definitely, than the drivers so I would expect a little but it may be interesting to see what it looks like. You've most likely done this already but if not....


Arnel

stevieturbo

Dont ya think the water could be part of the problem ?

Scubanme

Tony @ MPH

At first I did, but since the problem persisted until the plugs were replaced, and also since the problem *came back* until I forced the car into open loop, it has to be O2 related. It was relearning bad fuel trims just idling -- started sputtering, clicked the fuel trim reset, and it was happy again.