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Author Topic: B34 versus B35 tune  (Read 6377 times)


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B34 versus B35 tune
« on: September 14, 2013, 07:09:54 AM »

I've had a minor issue with my '87 535is which has a euro M30B34 motor, 10.5-1 compression, small port/valve B34 head, Gen. 3 MAF, Motronic 1.3 conversion using an E34 M30B35 harness and 179 ECU. I use a B34 tune that works real well, good power, idles fairly smoothly, passes Socal smog like a new motor. But on a cold start, the engine fires immediately but only euns a few seconds and stalls. Then I fire it back up, starts immediately and runs but the speed "hunts" for several seconds until it smooths out. Mechanically the car is in good shape with new fuel pump/filter/injectors so I don't think it has a cold fuel delivery problem. But I got to thinking the B34 uses a cold start injector mounted in the bottom of the intake, the B35 harness doesn't have that connection for the extra injector. Should I be using a B35 tune which might use different fuel settings for a cold start? I fiddled some with the tune but didn't see any difference. I am going to try  loading up a std. B35 179 tune and see if there's a difference, just wondering if anyone else has run across this. Thanks, Mike


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Re: B34 versus B35 tune
« Reply #1 on: April 07, 2015, 08:50:33 PM »

Have any other offer or not.