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Old 07-15-2020, 03:09 PM
dkuchan dkuchan is offline
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Join Date: Apr 2018
Location: Michigan
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I do not believe the shop did a compression or leakdown test. I can see that causing the misfire codes, but that's not currently my problem (at least the not the biggest one). I still have this idle issue with the car and have been simply dealing with it for years now. I just let the car idle for 90 seconds, it stumbles and surges, and then it's good to drive.

I thought that it was the secondary air system once I realized that this system runs for exactly 90 seconds on cold-start. I thought I must have a bad air pump or a sticky valve, etc. However, even though the documentation I have found shows this system and its parts, I do not appear to physically have this system on my N62 like the literature states I should. I don't know if someone deleted it or if my particular model year just didn't have it or what, but now I'm back to trying to figure out what happens at 90 seconds on cold-start that triggers this.

I can say that it starts fine, idles ok for a bit, then surges a tiny amount for a while (like 100rpm) until at 90 seconds something happens and it surges and the rpms jump up and down wildly and then level out. It shakes the car. I can also say that it sounds like a small exhaust leak during this 90 seconds which I haven't tracked down yet, but it sounds like the drivers side of the engine. It goes away after the surging. This surging period only lasts about 5 seconds.

It's as if there is a valve or something opening/closing at 90 seconds and the computer is having trouble dealing with the inputs prior to. I have a cheap scanner and it shows that the timing is being retarded prior to 90 seconds, and after 90 seconds it's advancing. I don't know if it's seeing knock during that period or what...maybe that exhaust leak sound (whatever it actually is) is tripping the knock sensor?.?.?...

I FINALLY have a spare car now so I don't have to be terrified to work on it, so hopefully I can make some progress or get up nerve to sell this pile.
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2004 - E53 - 4.4i (N62B44)

Last edited by dkuchan; 07-15-2020 at 03:15 PM.
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