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Thread: E24 89 635csi PROBLEMS

  1. #1
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    E24 89 635csi PROBLEMS

    Hello all. Had this car for about 2 weeks and having some weird issues. So the car starts every time on the first crank, and stays running, however the idle does sometimes spike a little but and dive. But the big issue is a weird hiccup when driving. It happens when pulling away from a stop, and under heavy load. Most times when pulling away, the car dies or almost dies if I don't give it more gas. And if I try a 3rd gear pull will jitter multiple times in a row around 3k rpms. Someone help. Getting really annoying as its almost impossible to drive in traffic. car is automatic.
    Last edited by Aviveiros27; 02-09-2019 at 11:32 PM.

  2. #2
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    Things that come to mind--rotor and distributor cap, fuel pump relay, vacuum leaks. Check out http://hiperformancestore.com/Motronic.htm for troubleshooting.

  3. #3
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    Engine wise +1 by LYK NU 6.


    Tranny wise:
    Had the same problem for 30 years until I did a 5 speed swap.
    Had it checked out, told me it was the TCU (Transmission control unit) behind the knee bolster on drivers side.
    Mostly happened on the 1 to 2 shift, I just lived with it by not stomping the go peddle in E mode.
    Last edited by 1986series6; 02-11-2019 at 08:44 AM.

  4. #4
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    So I did more looking today and noticed an obvious disconnection at the tps, and someone placed a weird cap over the receiver on the tb. Now the car idles perfect at 750 rpms and the kick down works now. However the car still bucks when coming to a stop and bucks around 3k. I also have noticed that if I slightly touch the transmission selector, the dashlight for the gear selected shuts off. If I pull it down ever so slightly the light stays on.
    Update: Idle sucks. Car starts right up, ha's a steady idle for like 5 seconds, then jumps and stalls. Someone please help, I need a expert over here. Anyone in the southeast Massachusetts area??
    Last edited by Aviveiros27; 02-11-2019 at 03:04 PM.

  5. #5
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    So i replaced the coil, and spark plugs. Still have to do fuel filter. Checked the ecu, and the the ecu is fine, CPS is fine,and all grounds are fine. Any other things to look at. Car us definitely at its worst right now: doesn't idle at all, stalls, smells like fuel (really rich).

  6. #6
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    It doesn't help that you started two threads on the same symptoms. However, to summarize, it looks like you replaced coil and spark plugs and have checked and confirmed the following to be OK: ECU, grounds, icv, afm plug, and cts. If there are other things you've done and confirmed to be OK, please list them here. In particular, have you replaced the distributor rotor and cap and the relays like I suggested?

  7. #7
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    Pull the dipstick and see if that affects idle. If it doesn't, you have a vacuum leak somewhere. If it does, you can rule out a vacuum leak issue.
    81 Euro undergoing total nut and bolt restoration
    pictures at: flickr.com/photos/bertsphotos

  8. #8
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    Quote Originally Posted by ldk View Post
    It doesn't help that you started two threads on the same symptoms. However, to summarize, it looks like you replaced coil and spark plugs and have checked and confirmed the following to be OK: ECU, grounds, icv, afm plug, and cts. If there are other things you've done and confirmed to be OK, please list them here. In particular, have you replaced the distributor rotor and cap and the relays like I suggested?
    I haven't done the dizzy and cap yet but I didn't bother because the symptoms are just so inconsistent. I opened up the ecu to try to find any cold solder joints or corrosion and there wasn't anything. I still have a strong feeling it's a fuel delivery issue within the filter.

    I guess it would also help to know that before I purchased the car, the PO told me it sat for 3 months because he stores it for the winter.

  9. #9
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    "I still have a strong feeling it's a fuel delivery issue within the filter"

    Sitting for 3 months will have absolutely nothing to do with your problem.

    Before you guess that it might be the fuel filter, get a pressure gauge

    on the rail to monitor the pressure. If it stays somewhat steady while

    running, the problem won't be fuel from the delivery. Maybe @ the injectors,

    don't guess @ this stuff. You have to do methodical testing or you'll drive us crazy.

    BTW, did you receive the TPS and did it work any better?

    Bob V

  10. #10
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    Quote Originally Posted by 1986series6 View Post
    "I still have a strong feeling it's a fuel delivery issue within the filter"

    Sitting for 3 months will have absolutely nothing to do with your problem.

    Before you guess that it might be the fuel filter, get a pressure gauge

    on the rail to monitor the pressure. If it stays somewhat steady while

    running, the problem won't be fuel from the delivery. Maybe @ the injectors,

    don't guess @ this stuff. You have to do methodical testing or you'll drive us crazy.

    BTW, did you receive the TPS and did it work any better?

    Bob V
    I did receive it and the micros witch does seem to click better, but the idle is still terrible. So I'm not sure.

  11. #11
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    Quote Originally Posted by Aviveiros27 View Post
    ... I opened up the ecu to try to find any cold solder joints or corrosion and there wasn't anything...
    A word of caution on inspecting the ECU. I once had problems with mine. I opened it up and re-flowed a couple of suspect connections. Didn't work. I opened it back up and re-flowed every single connection, regardless of what it looked like. That worked.

    Best test at this point is to get someone local to loan you a known working ECU. Next best is to buy one, maybe on eBay, that the seller claims works. You'll want a working spare for the future anyway, like you want working spares for lots of things--especially the aforementioned relays.

  12. #12
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    Quote Originally Posted by Aviveiros27 View Post
    I haven't done the dizzy and cap yet but I didn't bother because the symptoms are just so inconsistent. I opened up the ecu to try to find any cold solder joints or corrosion and there wasn't anything. I still have a strong feeling it's a fuel delivery issue within the filter.

    I guess it would also help to know that before I purchased the car, the PO told me it sat for 3 months because he stores it for the winter.
    So you're troubleshooting some aspects by "assuming". Check this link and read posts 11 and 12, don't just look at the pics...

    https://www.bimmerforums.com/forum/s...lofut+no+start

  13. #13
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    Quote Originally Posted by slofut View Post
    So you're troubleshooting some aspects by "assuming". Check this link and read posts 11 and 12, don't just look at the pics...

    https://www.bimmerforums.com/forum/s...lofut+no+start
    Thanks for the tip. That will be my next move. Also if any of you know anyone or if anyone on here is from around Massachusetts with a spare ecu that would help a lot, thanks.
    Is any 179 ecu direct replacement?
    Any help identifying these plugs as well, I went to touch these and they crumbled.Snapchat-196185977.jpg
    Snapchat-1466801395.jpg
    Snapchat-547409955.jpgI
    Last edited by Aviveiros27; 02-25-2019 at 03:32 PM.

  14. #14
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    Quote Originally Posted by ldk View Post
    It doesn't help that you started two threads on the same symptoms. However, to summarize, it looks like you replaced coil and spark plugs and have checked and confirmed the following to be OK: ECU, grounds, icv, afm plug, and cts. If there are other things you've done and confirmed to be OK, please list them here. In particular, have you replaced the distributor rotor and cap and the relays like I suggested?
    So I just did the cap and rotor, and at the first start up the car ran perfect. I went to put it in reverse and as soon as I pressed the gas it stalled. Started it and unplugged the tps and then pulled off without issues. Drove for about 2 minutes until most of the stalling symptoms recurred but on a lesser scale.

  15. #15
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    Here is a video. Car still has problems. Can't figure it out.
    https://youtu.be/WnFfWai4EJ0

  16. #16
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    150 and 179 ECU are on the same page. although the 179 ECU is way better.
    https://www.programainc.com/item_det...ategory=39&sf=

    This is currently onsale for 69 bucks.. steal if you ask me..


  17. #17
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    I think last resort is the ECU as I just replaced ignition wires and that did nothing.
    To date I've done:
    Spark Plugs, Dizzy cap and rotor, spark plug wires, ignition coil, coolant temp sensor, tried a different tps, cleaned icv, cleaned and inspected the afm.

  18. #18
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    You really need to get some diagnostic tools on this one my man.

    other wise this meme sums up this thread.
    2wgbvw.jpg


  19. #19
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    I'd disagree with that meme. All the parts I've replaced needed replacing anyway. Cts was out of spec, ignition wires were burnt, coil was way out of spec, spark plugs were fouled, and the rotor and cap were original parts. So..nothing has been wasted. Just unfortunate it didn't happen to be any of those.

  20. #20
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    It still hasn't solved your problem though, so the meme does hold some truth!

    Hope you get to the root cause of the problem soon, one problem with these cars is that you need an old school mechanic and they are getting scarce. The younger generation of mechanics are very proficient at OBD-diagnostics and then replacing parts according to the warranty manual.

    I'm especially interested what the fix will be.

  21. #21
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    Quote Originally Posted by Nullified View Post
    It still hasn't solved your problem though, so the meme does hold some truth!

    Hope you get to the root cause of the problem soon, one problem with these cars is that you need an old school mechanic and they are getting scarce. The younger generation of mechanics are very proficient at OBD-diagnostics and then replacing parts according to the warranty manual.

    I'm especially interested what the fix will be.
    As far as testing with a multimeter, and checking hundreds of pages in multiple repair manuals, and studying wiring diagrams, I've done just about everything I can do within my knowledge. There's a guy near me who's locally known as Bobby Bimmer, and he's done these cars for 40 years, but he told me he doesn't work on other people's cars anymore. Too bad.

  22. #22
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    Too bad indeed, so close but yet so far... Terrible to be working on solving a problem and not being able to solve it especially after the amount of hours you've put in it. Damn...

  23. #23
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    Quote Originally Posted by Aviveiros27 View Post
    So I did more looking today and noticed an obvious disconnection at the tps, and someone placed a weird cap over the receiver on the tb. Now the car idles perfect at 750 rpms and the kick down works now. However the car still bucks when coming to a stop and bucks around 3k. I also have noticed that if I slightly touch the transmission selector, the dashlight for the gear selected shuts off. If I pull it down ever so slightly the light stays on.
    Update: Idle sucks. Car starts right up, ha's a steady idle for like 5 seconds, then jumps and stalls. Someone please help, I need a expert over here. Anyone in the southeast Massachusetts area??
    Have you checked out the Motronic troubleshooting page at hiperformance? There's an updated version here. It's brilliant, very methodical. Saved me like a year of frustration. I was so happy I bought a set of silicone vac hose from him. I print up a copy, put it in a binder, remove the parts that don't go with that particular motor, and leave one in every car. I even give them away with cars I've sold!

    You haven't tried a smoke test, have you? Sorry if you have and I missed it - just catching up on your thread. The Motronics are very particular about maintaining proper vacuum & voltage. I had a motor once that never idled well, the cam seal was damaged. That took some time. What about the alternator? Nice stable voltages? What kind of VDC ranges are you seeing at idle and 3K RPM?

    Did you check the inhibit switch inside the gear selector? I've seen a few threads about them going out. You swapped the fuel filter, is the in-tank lift pump working? I had one that a wire had gotten loose inside the housing.

    If the car is running really rich I'd also suspect the coolant temp sensor wiring harness. I know you replaced the CTS, but BMW had a recall campaign where they soldered an inline resistor inside the boot. It eventually fails, open cicuit, then the car never goes to closed-loop and runs rich.

    Those wiring connectors on the fenders look like the ABS sender plugs, they always do that.

    That other 3-wire connector that's fallen apart is either the position sensor or speed sensor. Both are normally clipped into the rear intake manifold support rail. They're both very important, but that plastic always crumbles. I usually just tape them securely together. Don't get the terminals mixed up. 1&2 are the signal (should ohm out to about 1K ohms IIRC) 3 is the sheath. It's a floating ground, so the 1&3 and 2&3 pairs should ohm out really high. Some ohmmeters will read out like 10K maximum, others will go infinite (open circuit).
    Last edited by DesktopDave; 03-20-2019 at 08:45 PM. Reason: Updated Motronic troubleshooting guide!
    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

  24. #24
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    I forgot about that one its a really good one site. Great suggestion Dave


  25. #25
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    Quote Originally Posted by DesktopDave View Post
    Have you checked out the Motronic troubleshooting page at hiperformance? There's an updated version here. It's brilliant, very methodical. Saved me like a year of frustration. I was so happy I bought a set of silicone vac hose from him. I print up a copy, put it in a binder, remove the parts that don't go with that particular motor, and leave one in every car. I even give them away with cars I've sold!

    You haven't tried a smoke test, have you? Sorry if you have and I missed it - just catching up on your thread. The Motronics are very particular about maintaining proper vacuum & voltage. I had a motor once that never idled well, the cam seal was damaged. That took some time. What about the alternator? Nice stable voltages? What kind of VDC ranges are you seeing at idle and 3K RPM?


    .
    Thanks for identifying those sensors on the fenders. I think the 3 prong one isn't the speed sensor but rather an oil sensor of some sort. It goes directly to the oil pan. What's funky is that the car will sometimes run perfect, but then exhibit the same symptoms again shortly after.
    I ended up opening the afm today to do a sweep test and resistances are all over the place, there's also a few oL spots. So I may, after all this, just need an afm, which are ridiculously expensive. It's beyond repair as the carbon track is all worn down.
    My battery also has a constant charge so I'd put the alternator at the back of the paper. The only good part about buying all those parts is that I've narrowed it down to a few things...the bad part...the remaining parts are the most expensive
    Last edited by Aviveiros27; 03-20-2019 at 10:19 PM.

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