Misfiring wtf!?!?!

[Mr_Safeway]

ok,

I have a Z3 swap and jrsc, 650cc injectors. All of a sudden I started to throw a code for misfiring in cylinder 1&3. I am running denso ik24 plugs. checked them and they are black! So I put in a set of ngk bkr8eix and am now throwing a code for misfires in 1,2, and 3! Wtf....

[BlownSi05]

The car has been tuned on a dyno I am assuming?

[talonXracer]

Check for any vacuum leaks. Then reset the ECU. We are coming off winter blend fuel. Go for a 60 mile ride and see how she runs. Wouldnt hurt to do some street tuning.

[Mr_Safeway]

Check for any vacuum leaks. Then reset the ECU. We are coming off winter blend fuel. Go for a 60 mile ride and see how she runs. Wouldnt hurt to do some street tuning.

It was tuned on a dyno with the IK24 plugs. How do I reset the ecu? Pull it's fuse? Street tuning? Oh man! Better learn how.

[HondaFreak]

You can also tighten the belt some more. I had the same codes and issue's running 550cc RC's. Went for a dyno tune, replaced the Dayco for a Gatorback and tightened the shit out of the belt. No more codes. AND I agree with Talon 100% on leaks. Pull fuse, or use KManager to re-upload and reset DTC's and trouble codes would be better.

Christian

[Mr_Safeway]

Anyone thought it could be a bad O2 sensor? I was driving around kproing along and a P0134 (no primary 02 sensor activity). Need a new o2 sensor??

[talonXracer]

Yes it could be the A/F sensor that is causing the codes for misfire, that tells me your tune is significantly wrong, a properly tuned engine/ECU should never be more than a percentage point or so from a correct A/F with the sensor inoperative, ie open and closed loop operation.

[Mr_Safeway]

Couldn't it just be a bad O2 sensor then? I really dont think the tune is bad. The car ran like a dream until just recently. I swapped in my buddies O2 sensor, that was also bad, but threw a different code. So now it throws just a p1166, and that's it.

[whatisthis]

Yes it could be the A/F sensor that is causing the codes for misfire, that tells me your tune is significantly wrong, a properly tuned engine/ECU should never be more than a percentage point or so from a correct A/F with the sensor inoperative, ie open and closed loop operation.

if that were totally true then there would be no purpose to the sensor at all. it still runs obd2 so the ecu needs that input. without it, it's running pretty blind. you can run strictly off a tune without sensor input but why would you? if you have no o2 input then it's gonna dump fuel to protect the engine. fuel trims will run as much as an extra 20%.