Surging/dipping At Part Throttle - BMW Forum - BimmerWerkz.com
3-Series (E21, E30) Chat relating to the BMW 3-Series from 1975-1983 and 1984-1991 line. Specific models: BMW 315, BMW 316, BMW 318, BMW 318i, BMW 320/4, BMW 320i, BMW 320/6, BMW 323i, BMW 320i. E30 Family models include: BMW 325e, BMW 325i, BMW 325is, BMW 325ix.

 
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#1 (permalink) Old 04-04-2005, 02:18 PM
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offabroadway is an unknown quantity at this point
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Hello everyone. Sortof a half-noob question, sorry if its been posted already, but under part throttle when the car first wakes up, it tends to surge and then drop away a bit and surge and drop away a bit. Only happens the first 100m from a dead cold start, but in varying degrees. One time I slammed on the gas from a dead stop in Drive with the engine cold and it revved up for half a second, and then dropped completely like there was no throttle at all for a second, and then the throttle kicked back in (I had it down the whole time) and I got shunted forward like I had a freight train run into me.

Seems to happen only in the 1000-2000rpm range, which would be fine, except that thats the main area my 325e revs at during my city excursions.

At idle, sometimes it will do the same thing. Dropping it in and out of Drive seems to help. When its warmed up, it only happens very occasionally at idle.

Anyways, the question: is this the ICV valve that's causing this? Because if it is, it's getting replaced pronto. Along with my slightly squeaky drivebelts. I want her running at her best.

So, diagnosis anyone?

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Changed the car's name, now it's - Roxanne -1985 325e
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#2 (permalink) Old 04-04-2005, 08:45 PM
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offabroadway is an unknown quantity at this point
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C'mon guys, don't leave me hangin here.

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Changed the car's name, now it's - Roxanne -1985 325e
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#3 (permalink) Old 04-06-2005, 08:46 PM
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offabroadway is an unknown quantity at this point
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To add more to the saga, if it helps, the fuel pumps, filter, transmission fluid, and iginition system were all inspected recently, and the ignition wires/etc were replaced.

It did it again this morning, scared the crap out of me. Revved up and took off and then all of a sudden I lose power and the car is idling (with my foot in the gas!) and then it took off again. Did this three times. When I left work the car was a little warm, so it was surging and dipping again, but not completely dropping off. When it dipped it sounded horrible, like I was running on 3 cylinders or something, and then came back with a throaty roar.

You can't tell me nobody here has seen this. Please help!

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Changed the car's name, now it's - Roxanne -1985 325e
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#4 (permalink) Old 04-10-2005, 07:37 AM
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snoopy325e is an unknown quantity at this point
Hiya

I currently have the same surging problem. I found if I disconnect the o2 sensor that the surging stops so I had the o2 sensor replaced a few days ago and she idled like a dream. The car was fine for a day and guess what the surging is now back a little stronger with slightly erratic idling. After reading some of the previous posts I am gonna get my icv and throttle body cleaned.

I hope someone who knows a little more about this than myself can guide us both through this problem...

Cheers


Quote:
Originally posted by offabroadway@Apr 5 2005, 04:48 AM
Hello everyone. Sortof a half-noob question, sorry if its been posted already, but under part throttle when the car first wakes up, it tends to surge and then drop away a bit and surge and drop away a bit. Only happens the first 100m from a dead cold start, but in varying degrees. One time I slammed on the gas from a dead stop in Drive with the engine cold and it revved up for half a second, and then dropped completely like there was no throttle at all for a second, and then the throttle kicked back in (I had it down the whole time) and I got shunted forward like I had a freight train run into me.

Seems to happen only in the 1000-2000rpm range, which would be fine, except that thats the main area my 325e revs at during my city excursions.

At idle, sometimes it will do the same thing. Dropping it in and out of Drive seems to help. When its warmed up, it only happens very occasionally at idle.

Anyways, the question: is this the ICV valve that's causing this? Because if it is, it's getting replaced pronto. Along with my slightly squeaky drivebelts. I want her running at her best.

So, diagnosis anyone?
[snapback]325284[/snapback]
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#5 (permalink) Old 04-10-2005, 11:40 AM
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do you let the engin warm up?
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#6 (permalink) Old 04-10-2005, 12:30 PM
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http://www.mesaperformance.com/faqs/idle.html

That is about the best thing out there for this problem.

The first thing I would look for is a vacuum leak. The whole oil system is vacuum so even if your oil dipstick isnt fully sealing, you've got a vacuum leak.

Finally pulled the M50 from the donor car.
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#7 (permalink) Old 04-10-2005, 05:36 PM
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Quote:
Originally posted by e30driver@Apr 11 2005, 02:10 AM
do you let the engin warm up?
[snapback]329418[/snapback]
Yes it especially does it if I go for a drive and after returning, let the car sit and half cool down. I will be talking to my BMW mechanic today and will pass on any info...

Cheers
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#8 (permalink) Old 04-11-2005, 10:15 AM
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offabroadway is an unknown quantity at this point
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Quote:
Originally posted by snoopy325e+Apr 10 2005, 01:36 PM--><div class='quotetop'>QUOTE(snoopy325e @ Apr 10 2005, 01:36 PM)</div><div class='quotemain'><!--QuoteBegin-e30driver@Apr 11 2005, 02:10 AM
do you let the engin warm up?
[snapback]329418[/snapback]
Yes it especially does it if I go for a drive and after returning, let the car sit and half cool down. I will be talking to my BMW mechanic today and will pass on any info...

Cheers
[snapback]329593[/snapback]
[/b][/quote]

I've always gone by the instructions in the book, and the book says that the best way to get the car to operating temperature is to drive it.

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Changed the car's name, now it's - Roxanne -1985 325e
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