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BMW 3-Series (E90 E92) Forum
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Too lean and throttle surging, Throttle body gone bad??
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01-08-2023, 06:36 PM | #1 |
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Too lean and throttle surging, Throttle body gone bad??
Car has been running great but on last few cold mornings it will run super rough sometimes when cold, then when driving throttle lurches a bit and when i let off throttle it goes down and comes back up a bit without any input.
MHD stage 2+ no issues until now, and still get codes on stock map Reset throttle body adaptions and still get the same result. I’m thinking maybe possible vacuum leak, bad throttle body, failing fuel pump, or o2 sensors by the codes. I think o2 sensors are unlikely because why would both go out at same time like this unexpectingly. All vacuum lines are brand new aswell so doubt a vacuum leak but may have i ever looked something. I really don’t know where to start here, any help would be appreciated. Here are the codes |
01-09-2023, 01:22 PM | #2 |
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I've had intermittent rough idles of late on my MHD 2+ as well, and I also have that subtle surge when I let off from part throttle (part meaning, it's barely open).
I figured it was just a nuance of the tune (the surge), but perhaps it is related to the rough idle. Yesterday I took the car out for a wash, and it idled like shit the entire time (~28* outside). Today, 35 degrees, she's idling smooth like a sewing machine. I thought maybe my valve cover was cracked again. Or maybe shitty injectors again (I think I'm series 11). |
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01-09-2023, 02:58 PM | #3 |
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AWD Addict ghynds Consider changing your intake manifold gaskets, I had the 2D2E code for months but no drivability issue until the weather dipped here in South FL (40's) car started up fine and STFT would go lean and rough idle and bog the engine until it would almost shut off, eventually also giving me the same mixture control codes.
After 2 starts I'm assuming the gaskets expand and sort of "seal" and compress when the engine gets cold producing the issue. I replaced the intake manifold gaskets and haven't had the issue since. |
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01-09-2023, 03:48 PM | #4 |
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Interesting take. I'll put that on the list.
* New Series 12 injectors (gag $$$) * Valve cover gasket/valve cover crack * Throttle body leak * intake manifold gasket |
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01-09-2023, 09:29 PM | #5 |
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Have fairly new index 12s, bought when they were much cheaper, and valve cover aswell is new.
Most recent thing that car has done was a walnut blasting, would assume shop replace the intake manifold gaskets but maybe not, probably start with replacing that and throttle body gasket Also will try to change back to the stock TMAP sensor aswell (has 3.5 bar) and update back |
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12-06-2024, 10:15 PM | #6 | |
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