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Join Date: Jul 2004
Location: Brisbane, Queensland, Australia.
Posts: 80
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Engine Hunting at speed.
My 91' 318i manual M40 engine, has developed an interesting problem when cruising at speed (throttle held steady between 80kph and up).
the engine pulses, the revs dont change but it sounds like they are. It causes no driveability concerns but i would be interested to find out what is causing it or if anybody else has encountered it. I have removed the idle air control valve and checked it has full range of motion and is not sticking, all seems to be ok. I have cleaned the throttle body and butterfly piviot also. Any ideas would be appreciated, Luke.
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11-13-2005, 02:52 PM
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Join Date: Sep 2003
Location: Portland, OR
Posts: 1,001
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Oh man, those are the hard things to figure out... the slight oddities. I'd say it may be your MAF (mass air flow) sensor, or a vacuum leak somewhere.
My ride started hunting for idle last night. I pulled it out of the garage to head to the gym, and as I rolled in neutral down my street a bit, the engine hunted around a little at idle... like it was pulsating. Once I stopped the car from rolling, the idle went smooth and steady. Totally odd... I think my ride might be a little possessed!! ...but just a little ;-) |
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11-16-2005, 12:45 PM
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Join Date: Jul 2004
Location: Brisbane, Queensland, Australia.
Posts: 80
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Shhh i'm hunting Vacume...
Thanks for the tips, is there any maintanance items with the MAF sensors? I hate playing with those bloody things but i hate paying $1500 for a new one even more.
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11-17-2005, 01:55 AM
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Location: Portland, OR
Posts: 1,001
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LOL!
As far as I know, there isn't much that can be done to them. I think inside they have a porous matieral that gives off electrical properties as air flows over (kind of like an O2 sensor works). Once they get clogged, go weird, or what ever happens to them, I don't know if they are 'cleanable'. Best bet might be to get a used one off Ebay or something. But then again, that presumes the MAF is bad. Has your ride ever backfired recently?? I've heard that can tank the MAF. |
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11-18-2005, 12:44 PM
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Join Date: Jul 2004
Location: Brisbane, Queensland, Australia.
Posts: 80
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No backfires...
She is one of the cleanest high K cars i have ever seen. I still even detail the engine bay. I'll wait till it becomes noticeable to somebody other than just me and i might get it looked at. With the vacume leaks, i found two lines up on the throttle body perished but not compleatly gone. I replace them both but no visible change. Thanks for the help Blkongry. Luke.
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11-20-2005, 12:25 AM
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Join Date: Jul 2004
Location: Brisbane, Queensland, Australia.
Posts: 80
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Update:
Talking to the boys down at the Stealer when I bought my Oil filter the other day and it was suggested that it may be a driveline imbalance. I have a new Guibo and all of the unis are in top order so next step is to get the tail shaft balanced. Anybody else come across this? I'll keep you posted.
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12-05-2005, 01:57 PM
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I've heard that when you replace the Guibo you need to mark the shaft to make sure it is bolted back together in the same orientation.
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HPDE Instructor (BMW / PCA / Apex) Here: 1997 M3/4 Byzanz/Magma ~ 2006 Yamaha R6 ~ 1997 R1100RT ~ 1991 Ford F-150 5.8l ~ 2015 Kia Optima Gone: 2001 330i Silver/Grey ~ 98 Camry V6 ~ 97 Camry I4 ~ 97 Mazda 626 I4 ~ 93 Sentra SE-R ~ 88 Toyota Truck I4 |
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12-05-2005, 03:27 PM
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1997 BMW M3 3.2L I6
