Sputtering, Backfiring + CEL
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Sputtering, Backfiring + CEL
Girlfriend bought a used B5 A4, ran great for a long while, now we're having a bit of a problem.
74k miles
About 4k miles ago, the CEL came on with the primary O2 sensor firing a code, I forget off the top of my head which one it was, but it was one of the "running lean/rich" codes. Still ran decently until recently.
On a cold startup, it begins ticking and sputtering and backfiring like crazy, and sounds like it's sucking in a LOT of air (vacuum leak?) It will do this for about a minute, then it will finally warm up and settle down.
It will drive decently under 2500rpm, but as soon as you start getting a little bit on the throttle (certainly not WOT), it begins to bog down and sputter just like it does at startup. Will almost completely refuse to go over 4000rpm and feels almost like it's cutting fuel completely (like a rev limiter - limp home mode maybe?)
Ran the codes again recently, it's got a misfire on Cyl# 1,2, and 4.
Any ideas? To me it sounds like
A) Horrible vacuum leak(s)
B) Bad spark plug or coil packs
I plan on replacing the plugs and packs this weekend and diagnosing any leaks as well. Any other advice on parts I should consider picking up while I'm at it, or other things to look for are much appreciated.
Thank you,
Jake
74k miles
About 4k miles ago, the CEL came on with the primary O2 sensor firing a code, I forget off the top of my head which one it was, but it was one of the "running lean/rich" codes. Still ran decently until recently.
On a cold startup, it begins ticking and sputtering and backfiring like crazy, and sounds like it's sucking in a LOT of air (vacuum leak?) It will do this for about a minute, then it will finally warm up and settle down.
It will drive decently under 2500rpm, but as soon as you start getting a little bit on the throttle (certainly not WOT), it begins to bog down and sputter just like it does at startup. Will almost completely refuse to go over 4000rpm and feels almost like it's cutting fuel completely (like a rev limiter - limp home mode maybe?)
Ran the codes again recently, it's got a misfire on Cyl# 1,2, and 4.
Any ideas? To me it sounds like
A) Horrible vacuum leak(s)
B) Bad spark plug or coil packs
I plan on replacing the plugs and packs this weekend and diagnosing any leaks as well. Any other advice on parts I should consider picking up while I'm at it, or other things to look for are much appreciated.
Thank you,
Jake
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