Ever since H/C/I install I've been having a flashing SES light. Autotap shows a misfire on #3 cylinder. All cylinders show 0 misfires except #3 will climb to about 50-80 and #2 will sparatically go to 10-20. I've swapped wires, plugs, Coils, pulled valve cover and pushrods and rockers seem fine. This has been going on for 3 months now. Motor runs fine and there is no noticable miss. Last night I ran a 11.70 @116 with autotap and tech II showing a misfire on #3. What should I check? Any suggestions? I'm also getting a lean bank 2 O2 error. Could a faulty O2 cause a missfire on a single cylinder?

Dan
99 TA MTI Heads, C2 Cam, LS6 intake, slp headers.

 

My friend had the same problem with his 99... Try changing the plugs to TR55 ot the TR56.. Also replace the coil pack on that cylinder.. Those two things were his problem.. He thought it was bad gas, but that wasn't the case..

 

O2 cant affect a single cylinder. SES flashes when ? only at idle?

 

No the SES flashes at different times, mainly while normal driving...

 

Flashing SES is Cat protection mode you may have a bad O2 sensor does the car start to run bad if you drive it when the SES flashes? Mine did I replace the O2 sensor and the problem is gone, as far as the Misfire I also have H/C and I had to Edit out the misfires because they made my converter unlock (A4) Car runs fine and no more SES lights.

Ozz

 

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by Ozz:
<strong>Flashing SES is Cat protection mode you may have a bad O2 sensor does the car start to run bad if you drive it when the SES flashes? Mine did I replace the O2 sensor and the problem is gone, as far as the Misfire I also have H/C and I had to Edit out the misfires because they made my converter unlock (A4) Car runs fine and no more SES lights.

Ozz</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">See wrencher's response.. <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" /> <img border="0" title="" alt="[Razz]" src="gr_tounge.gif" />

Anyway Tag, try doing the plug/coil pack/wire swap on adjacent cylinders as well (1 & 5) and monitoring again.

<small>[ September 16, 2002, 04:35 PM: Message edited by: 98blackSS ]</small>

 

I agree that O2 does not effect a single misfire but the SES and the misfire are 2 different problems, FIX the SES with the O2 replacement and the misfire could be real or not I agree that if its a real misfire replace plug/wire/coil but the flashing SES is a O2 issue "Cat protection mode"

 

Not sure if this will help but when I did my header install I was showing a misfire in #5 when we did a code scan with ATAP. Car still ran fine (wasnt rough, didnt cut off, etc.). When I tracked it I couldnt even post a new best (in decent weather).

We ATAP'd the car to monitor the O2 sensors and i was RIDICULOUSLY rich (around .99 - 1.00+). We popped in the MAFT and leaned it out somewhat (need to tune it), once I did that - my misfire code went away.

Part of me thinks that I was flooding the engine with so much fuel that there wasnt enough spark to ignite thus showing the misfire. Havent thrown a code since then - maybe just a coincedence.

I know you are showing lean - but maybe they are related?

 

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by Ozz:
<strong>I agree that O2 does not effect a single misfire but the SES and the misfire are 2 different problems, FIX the SES with the O2 replacement and the misfire could be real or not I agree that if its a real misfire replace plug/wire/coil but the flashing SES is a O2 issue "Cat protection mode"</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Flashing SES is ALSO engine misfire alert. I'm betting they are related and not two different problems.

Hannibal, that's interesting. I wonder if that's what it was afterall. I thought you had already swapped things around though?

 

I had a broken valve spring that caused mine. Could you valve spring height be off on that cylinder?