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Michaellong
06-29-2017, 02:41 PM
I just bought a 2001 Audi A4 auto 1.8t fwd that had a p0600 code and would not shift gears. The engine shakes and misfires a lot especially in gear. I tried putting in my manual A4 1.8T quattro ecu into my auto A4 and it did not help. So I tried removing the TCM and it was soaked in water. It is severely corroded, so I removed it. The car now idles better and can also drive better. I'm surprised it can even drive without a TCM, but it still shakes and misfires. I was wondering, does anyone know where the water may have come from and if there are any other modules located under the carpet that may have gotten wet? I am thinking of the sunroof drains or maybe because the previous owner took very good care of the car and washed it every week since new. Maybe he used engine degreaser and jet sprayed the engine bay with a water hose? It is a very clean engine bay. I plan on getting a used TCM from the junkyard this weekend. I appreciate any input!

down_n_dapper
06-29-2017, 03:14 PM
get a used tcm, check the sunroof drains although your rough idling could be a coilapack on its way out as well. you need vcds to scan for codes to narrow it down really

Search for water in carpet or tcm wet on here and see how many posts there are about it and you'll find your info

Michaellong
06-29-2017, 03:22 PM
I replaced the coil packs. It did not improve the issue at all. The car idles fine at first, then it begins to misfire a little. If I put it in gear, it shakes a lot. The ignition coil wires have also been replaced.

down_n_dapper
06-29-2017, 05:37 PM
get a scan, can't diagnose without one

Michaellong
07-07-2017, 12:01 AM
I finally got the used TCM. I first put in a TCM from a 1.8T fwd Passat with different part numbers. That didn't work. Then I got one from Ebay with the same exact part numbers and the car was able to shift gears. As for the misfiring, it turns out that the wrong spark plugs with too large gaps were used and that caused the misfire. It runs great now. However, it feels a little low on power and the guys at Autozone think it may be a boost leak. I don't know how a normal 1.8T stock A4 feels though.