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Join Date: Jan 2007
Location: Savannah
Posts: 9
1994 325i idle problems

I am having problems with the idle on my 1994 325i. I am up to 198,000 miles. The car is a 5-speed manual. I have performed excellent preventative maintenance on this car using parts from Pelican. The car still routinely gets 28 MPG on my daily commute. The idle fluctuates constantly, whether it is cold or warmed up. It frequently dies while at a stop.
I have accomplished the following: replaced idle control valve with new, checked spark plugs, replaced intake gaskets and vacuum hoses, replaced O2 sensor, cleaned MAF. I get a check engine light that will come on when I start the car and eventually go out once the car is warmed up. It will usually come back on while the car is stopped with an associated severe dip in idle RPM.
I just placed an order for a coolant temp sensor, based on some other posts that I have read. This problem is really driving me crazy because I have to grab a handful of e-brake at a stoplight while I shift into neutral and feather the gas so that the engine will not die. From some other posts that I have read, the following has also been suggested: carbon buildup on inlet valves, injector sticking open, fuel pressure regulator failed. Should I go down this path if the coolant temp sensor does not fix it? Any ideas?
Old 01-18-2007, 09:31 AM
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Well, I just replaced the coolant temp sensor. It was about a fifteen minute job. I took the car for a test drive and it seemed at first to run better. I returned home and parked the car in the garage. I let it idle for a minute and the check engine light came back on and the idle dipped down below 500 RPM. The engine began to run rough, just as before. I know that the check engine light is the O2 sensor message (1221), but it is a result of the problem, not the cause.
I'm at a loss guys. Anyone have any ideas? The next stop is taking it in to my local BMW auto repair shop - and they charge by the hour - ouch.

-Brian
Old 01-25-2007, 09:24 AM
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I received the following advice from a BMW expert and I thought I'd share it with everyone.

"What you have described sounds exactly like a faulty idle control valve. You have the Bentley E36 3 Series Service Manual, correct? I'd like to you to verify idle control valve function using a digital voltmeter, and I'd also like a pin-out test from the ECU to the idle control valve -- could be a wiring problem or even a corroded connector at the ICV. I'd also like you to diagnose the intake air temperature sensor at the MAF."

I had a buddy of mine send me copies of the pages I needed from his Bentley manual. Wow, what detail. I am impressed with the manual. Anyway, I will post the results of my troubleshooting efforts when I am finished.

-Brian
Old 02-07-2007, 09:21 AM
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How about cleaning the intake valve body with carb spray and paper towels.

I had a Nissan that had dipping idle problems and there two little vacuum holes by the intake butterfly that I cleaned along with everything else in the area and it seemed to help/fix it.
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Here: 1997 M3/4 Byzanz/Magma ~ 2001 330i Silver/Grey ~ 1997 R1100RT ~ 1991 Ford F-150 5.8l
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Old 02-07-2007, 10:51 AM
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Thanks for replying Jeron. Yes, I have cleaned the intake valve body with carb cleaner and paper towels (though I did not look for any vacuum holes in the butterfly-thanks, I'll check). I cleaned out the intake ducting, changed out the air cleaner and basically made sure that everything was in good order and connected properly. I have not had the chance to do the suggested troubleshooting as listed above. I just pulled into the garage today and as soon as I shut the car off and got out, the coolant expansion tank cracked and dumped a good portion of my coolant onto my garage floor. Old man winter is having fun with my car. Looks like I'll be riding the R75/5 to work for a few days. I'll let everyone know what I find once the troubeshooting is complete.

-Brian
Old 02-08-2007, 12:20 PM
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Okay, I finally figured it out. While the car was running, I sprayed WD-40 at the base of my fuel injectors and boy did the car kick and sputter. This is where I am getting air. I held my palm against the intake, cutting off the supply of air and the car continued to run. This lead me to look for an intake leak. After all of the intake hoses were checked/replaced and the intake gaskets were replaced, I started looking elsewhere and found the fuel injector o-rings leaking. The part number is 13-64-1-730-767-M213.
Old 02-20-2007, 04:04 PM
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Glad you figured it out.

They make spray to test like you did with the WD40 that might be less messy.

Congrats
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Here: 1997 M3/4 Byzanz/Magma ~ 2001 330i Silver/Grey ~ 1997 R1100RT ~ 1991 Ford F-150 5.8l
Gone: :'( 98 Camry V6 97 Camry I4 97 Mazda 626 I4 :'(93 Sentra SE-R 88 Toyota Truck I4
Old 02-20-2007, 05:17 PM
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Old 02-20-2007, 05:17 PM
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