So I finally got a chance to change my plugs today (from stock NGK's to Denso Iridiums), and have to say it wasn't that bad. The second and third time was definitely faster (and I'll tell you in a moment why), so I can prolly do it under 30-min now...

Unfortunatley, after bolting her back up to take a test run, the car actually ran worse than before... And I mean WORSE! We're talking barely drivable here, with the CEL, ABS, and the ESP lights going off and everything. It was almost like I put a really agressive cam in there, so you can imagine the idle. I was PISSED to say the least. So, I opened her back up, hoping to find a loose wire, bolt, spark plug, anything...! Well there was nothing.[:@] So I take out the Ir's, put back in the NGK's, double/triple-check everything, and fire it up again. Same ****. So at this point I've obviously eliminated the plugs, and figure my MAF or one of the airbox sensors must've taken a ****, but I'm not sure. So Itake out the NGK's, put back in theIr's, and fire it up. Same ****.[&:]

Any ideas? I've been chasing this hesitation/surging issue for a while (https://www.audiforums.com/m_550588/tm.htm), and it'sbeen gettingworse lately (but still no codes yet), so I'm hoping this is related. Either way I'm taking her into the dealer and have my warranty solve the problem... hopefully .

Please help...

 

Did you gap the plugs correctly? I believe it should be .28

 

i had the same problem when i changed my plugs and i thought it was the gapping as well. it turned out to be faulty wires. they arent that expensive to replace and if you are somewhat mechanically adept you can test if all the plugs are firing by using a spark plug tester available at most auto parts stores. all the tester really is a spark plug with gap in it so that you can see if the electric current is jumping from one end to the other. they are also inexpensive just try not to electricute yourself. good luck

 

you should never try to gap iridium plugs because the tip breaks off ( capped for life as they say ),
warranty is the correct way to go about it but I recon its and electrical problem like arcing and could be between the coil pack and the spark plug so difficult to see ( you might be able to hear it click though ) you could spray the rubber from the coil pack to the plug with a sealer which would prevent arcing and check the wires going to the coil packs for cracks and and ground wires for poor connection

 

Alright, well now I'm really confused...

So I go out this AM expecting to climb into my cammed-S4, when the unexpected happens: she starts up rusty again, but then immediately smooths out like normal. In fact, as I let it idle for a few minutes, not only did it run smooth, but my nagging rough idle problem dissappeared also. So I get on the road and keep close watch on my boost guage, and notice that the "fluttering" at constant throttle between 2000-3000RPM has dissappeared too!!! No movement at all, where as before the needle would bounce from 10-20inHg all the time. After she gets up to temp I get on her hard, and she pulls strong and smooth all the way to redline; noticably stronger than before!

So my only guess is that the stock plugs were so bad that my ECU was adjusting/compensating for them, and when I installed the new plugs it had to readjust/relearn...? Any thoughts?

My check engine light is still on (although the others have dissappeared), but I assume this is just cause it was throwing codes like crazy yesterday. I plan to scan & clear them today at AutoZone to see what happened. HOPEFULLY everything is fine and it was just cause of the new plugs (knock on wood), cuase she's running great for now!

BTW, I did not know about gapping the Ir's, but I was def. paraniod with that 0.4mm tip! I gapped them to 0.30 though (like some of the DIY's suggested), cuase they came at 0.4 so I thought this was probably too much (especially when I get chipped).

Thanks,

 

it sounds like it was your plugs and they can cause that, the CEL probably just needs to be reset

 

Yeah, thanks for the input Dave. I just never expected it to runny so horribly by just changing plugs, so it must've been really out of whack! I'm gonna hit up AutoZone and hopefully clear the CEL and any codes.
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