I have yet to solve this issue. The car stalls at idle after a minute of idling, and when pulling off, the car jerks/boggs/stutters/bucks, as if the fuel is cutting out intermittently. And it does this exact same thing at 2800 rpm. Car also seems down on power. ICV is in working condition. Anyone have a graph or diagram of all the sensors in the engine bay? Any advice/answers are much appreciated.
Anyone know someone is southeast Massachusetts area who is an expert on these?
I'd be interested in checking out the AFM. If you have a few select RPM ranges where you're running into trouble, a worn-out AFM is notorious for those sorts of symptoms.
Did you try the stomp test yet? I know it sounds like I made it up, but your car will flash codes. Turn the key to 'run' but don't start it. Rapidly pump the accelerator five times, then wait and see if the check engine light flashes. If not, repeat that process until it does. If you're successful, the CEL will flash out a pattern of codes. The "all clear" is 1215 IIRC.
Your car's complete electrical system is detailed in the BMW ETM. It's overwhelming at first, but it eventually makes sense. Here's a site to grab a copy: http://wedophones.com/Manuals/BMW/
This website has been incredibly helpful for me personally: http://hiperformancestore.com/Motronic.htm
Be aware that most of that article is for the earlier Motronic 1.1. Your car is the last version, with an M30B35 running Motronic 1.3.
Other things I've had go awry:
My crank position sensor bracket has a habit of getting loose.
Those crank position sensors don't last forever. Test it with an ohmmeter or DMM. IIRC you should see about 680 ohms between pins 1&2. The other pairs (1&3, 2&3) should be very high, like 100K ohms.
Main or fuel pump relays can go bad
Fuel pump can fail to deliver enough pressure, especially if the lift pump in the tank has died. Plugged fuel filter too.
I've had bad coil wires that intermittently failed when they flexed, especially the 'king' plug wire, from the dist to ignition coil.
Ditto for dist caps and rotors.
A worn-out AFM can cause all sorts of havoc. Unplug it when the car is stalling and see if the problem goes away.
TPS can be flaky or misadjusted.
If your car is an automatic, you might have a bad inhibit/interlock switch...I believe that's inside the shifter assembly.
Ignition switches occasionally go bad, exhibiting random stalling.
Last edited by DesktopDave; 02-13-2019 at 09:46 PM.
Save the manuals!
'08 128i 6MT, '86 635CSi 5MT (B32, Motronic 1.3, WBO2, G265, 18# FW, 3.46 torsen)
Past projects:
'96 318iS, sold 4/23 '90 535iM, RIP 1/23 '90 535iA RIP 6/22 '91 318i, sold 7/19 '97 M3 sedan, sold 11/18 '85 735i, RIP 2/18 '92 325iC, sold 7/16 '91 318iS, sold 6/16 '84 745i, sold 10/14 '82 633CSi, traded 9/12 '90 325i, RIP '87 325 sold '89 525i, traded '87 325iS, RIP
Yep. It's all listed in the BMW TIS but I'm not sure where. It's hard to find the older cars, but here's a link to the complete E24 section. I'd also recommend the Bentley manual. There isn't a version for the E24, but the E28 covers our cars pretty well. It's listed on Amazon probably the best $22 you'll ever spend on your car.
Save the manuals!
'08 128i 6MT, '86 635CSi 5MT (B32, Motronic 1.3, WBO2, G265, 18# FW, 3.46 torsen)
Past projects:
'96 318iS, sold 4/23 '90 535iM, RIP 1/23 '90 535iA RIP 6/22 '91 318i, sold 7/19 '97 M3 sedan, sold 11/18 '85 735i, RIP 2/18 '92 325iC, sold 7/16 '91 318iS, sold 6/16 '84 745i, sold 10/14 '82 633CSi, traded 9/12 '90 325i, RIP '87 325 sold '89 525i, traded '87 325iS, RIP
So here's the most simple list of symptoms
1. Stalls at idle sometimes.
2. Stalls or severely bucks whenever starting off.
3. When it bucks, the mpg gage goes to max 40 mpg as if the fuel is cutting off.
4. Poor acceleration.
5. Same stutter and fuel drop at 2800 rpms.
Some updates: I tested the icv with a multimeter and it was within spec, afm plug was within spec, cts within spec, however I tested the coil at contacts 15 and 4 and my reading was all over the place, so I just bought one and still waiting for it.
I would also like to know how to test the tps with the round plug. All I have seen is the test for the 3 pin one.
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