Update: it was a bad ground.

"Longtime Lurker" (longtimelurker26) 06/11/2019 at 20:58 • Filed to: None

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I used my laser thermometer to measure the temp of the exhaust manifold trying to find the dead cylinder. Cyl #4 was half the temp as the others so I unplugged the #4 wire from the distributor and the engine ran exactly the same. Before pulling spark plugs out, I took my spark tester and plugged it into cyl #6 ( to be methodical), and now the car was running good. As I was unplugging the tester and found burn marks on the plug wire. The ground cable was rubbing against the wire. So I electrical taped everything and rerouted the ground wire.

!!! UNKNOWN CONTENT TYPE !!!

Autocross on Saturday, misfire on Monday.

Felt like 5 cylinders this morning, lots of vibration. Surging idle. Rough revving up in neutral. Runs correctly under acceleration. Stutters when trying to maintain constant speed. Occasional backfiring.

I’ll have to wait till after work to try diagnosing the problem.

For Sweden > Longtime Lurker 06/10/2019 at 14:47

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It’s not just running on 5 cylinders; it’s an Audi Quattro

CalzoneGolem > Longtime Lurker 06/10/2019 at 14:49

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Sounds like a stupid sensor that’s hard to get to.

diplodicus forgot his password > CalzoneGolem 06/10/2019 at 15:24

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It’s an e30, theres 2 sensors that matter. Crank position sensor and coolant temp sensor and they’re both relatively easy to access

BeaterGT > Longtime Lurker 06/10/2019 at 16:41

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Sounds like spark to me. Hope it’s something simple.

pip bip - choose Corrour > Longtime Lurker 06/11/2019 at 04:14

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plugs and/or coils?

Future Heap Owner > Longtime Lurker 06/11/2019 at 23:26

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Good sleuthin’

Dakratfink > Longtime Lurker 08/04/2019 at 00:50

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Had a very similar thing happen with one of my bikes last year, it wasn’t  QUITE misfiring, but was idling rough and it def wasn’t a fueling issue. I checked coil packs and saw minor surface crazing. At first I thought it was a cracked coil pack. Then as I started unplugging things to investigate further ( and possibly change out a coil ) I found the negative terminal on my battery was a little loose and had some corrosion. Cleaned and tightened it and no more spark issue.