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Old 06-15-2019, 08:31 AM   #1
Join Date: Oct 2018
Location: Comox, BC
Posts: 5
Surging Idle after Rebuild

Hereís the details: 1990 (10/89) 325i Convertible
Just finished refreshing the motor: rebuilt head w/ 272 cam & HD rockers etc, all new belts, wires, cap&rotor - the works in other words. Get it all back together and it idles like total crap. Surges from 500-650 constantly. Once you get the RPMs up its better.

Get it smoke tested and find a bunch of leaks - bitch tube etc. Fixed those and it idles better but not great. It idles like a 1/4 mile drag car - lopey. Mechanic thinks itís fuel (car has 208k on it). So I swap out the original injectors for some new Bosch units and swap the TPS. Still no love.

So I start testing the ICV (three wire). Voltage and resistance check out and I double checked the TPS as well - both good. Bentley says the ICV should be partially open with a warm engine and the key on. Mine snaps closed as soon as the key is turned to the on position.
Is this the issue?

Thx, Pat
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Old 06-17-2019, 02:05 PM   #2
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Join Date: Mar 2019
Location: Abilene
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Are lifters are adjusted properly??
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Old 06-17-2019, 04:29 PM   #3
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Join Date: Feb 2007
Location: WOT-Tech, Florida
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Surging is a sure sign of vacuum leaks post-AFM on these cars.
Transaction feedback: Here, here and here. Thanks
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Old 06-17-2019, 08:54 PM   #4
Join Date: Oct 2018
Location: Comox, BC
Posts: 5
Smoke tested and fixed the leaks. After running for a few days the surging is gone but itís a really lumpy 700ish rpm idle. I didnít think a 272 cam would make it that bad. Itís stock (for the moment) other than the cam. Is this something that would be cured by a ssquid chip? Or should it idle better even with the 272?
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Old 06-18-2019, 12:26 AM   #5
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Chip to bump up idle speed
89 E30 325is Lachs Silber - currently M20B31, M20B33 in the works, stroked to the hilt...

new build thread http://www.r3vlimited.com/board/showthread.php?t=317505

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