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Thread: 1989 735 M30 Motronic Throttle Position Sensor

  1. #51
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    http://i1376.photobucket.com/albums/...psmcxxwl92.jpg
    This is the photo of the newly discovered oil from this morning. This is a development that seems to occurred at the same time the misfiring and idling issues occurred.
    I also discovered 1/2 of a heavy washer , approx. 5/8 of an inch diameter, right in the center of the oil.
    I'm wondering if I haven't somehow broken an intake manifold bolt off, but I can't explain why I would have an oil leak there also.

  2. #52
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    now someone who knows the M30 well has to chime in.
    Shogun tricks and tips for the E32 series are HERE!

  3. #53
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    Quote Originally Posted by shogun View Post
    now someone who knows the M30 well has to chime in.
    Please. The wife has to drive it to work in 36 hours. I gotta get this figured out, or life isn't going to be pretty for me!
    On the up side, if I do get it squared away, I get bonus hero points!

  4. #54
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    EDIT;
    Not sure how I posted this here as I thought I was replying the throttle pos sw issue, Anyway, you get it.
    The best I can offer is that you need PN 13 63 1 708 605, it is specific to automatic transmission cars. Your car is NOT EML equipped.
    I tried looking it up at various aftermarket sites and invariably found the one for manual cars (rectangle 3 pin connector)listed so your searches should be limited to a PN search, not application.
    I checked my parts stash and found no joy. Two members here come to mind that may have one of these are south42 and dmetk, both frequent the E34 subforum.
    good luck
    Last edited by ross1; 04-07-2019 at 10:35 AM.

    If you can leave two black stripes from the exit of one corner to the braking zone of the next, you have enough horsepower. - Mark Donohue

  5. #55
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    Quote Originally Posted by ross1 View Post
    EDIT;
    Not sure how I posted this here as I thought I was replying the throttle pos sw issue, Anyway, you get it.
    The best I can offer is that you need PN 13 63 1 708 605, it is specific to automatic transmission cars. Your car is NOT EML equipped.
    I tried looking it up at various aftermarket sites and invariably found the one for manual cars (rectangle 3 pin connector)listed so your searches should be limited to a PN search, not application.
    I checked my parts stash and found no joy. Two members here come to mind that may have one of these are south42 and dmetk, both frequent the E34 subforum.
    good luck
    Thank you sir. However, I've solved the original tps issue, and I should have started a new thread, but this is just a continuing saga of chasing the same symptom through various systems I'm afraid. Thus, in my haste to post without having to relist symptoms I left it here.
    At this juncture, I've replaced the TPS and IACV with pretty good results for a brief period.
    However, the symptoms have returned with an exponentially worse vengeance.
    Currently, I believe, based on my reading and members advice I am chasing an air leak at the intake side, of some sort. In the midst of that I also discovered a nasty oil leak, that I hope is related, as I don't want to tackle two major problems at once.

    - - - Updated - - -

    Okay, my sadistic brethren, is it possible that all of this could simply be caused by a faulty O2 sensor?

  6. #56
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    http://i1376.photobucket.com/albums/...ps0m6advvo.jpg
    Is this a normal condition, to see oil residue at the back side of the throttle body?

  7. #57
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    seems like u got alot of blow by, perhaps your crankcase ventilation is not working well..yeah i agree someone with m30 expertise have to chime in.
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  8. #58
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    Some rain on your parade...

    I don't think this is going to be a reliable car in 36 hours.

    Oil leaks have approximately nothing to do with running condition (that said, the amount of fresh oil in the above photo is troubling). Operating temperature has little to do with running condition, not enough to cause crazy idle issues like you have.

    I see a lot of digital ink spilled about wire counts and part numbers, and not much in the way of actual diagnosis. Check engine lights on pre-OBD2 vehicles are not very useful; I've seen them lit on perfectly-running vehicles, and (much more often) not lit on engines two steps shy of a smoking paperweight. Don't rely on yours.

    ...that'll hopefully make something good grow.

    Are you near an auto parts store? "Rent" (buy and return for full refund) 1. a compression tester, 2. a fuel pressure gauge, and 3. a leakdown tester if available. Use. Do you have an air compressor? If so, buy a smoke tester (~$70 eBay for an ammo-can type) and 4. use it. If not, pay a shop to smoke-test your car. Look up the resistance values for your TPS and 5. measure them with a multimeter (also a "rental" tool, but good to own). Also pull a spark plug or six and 6. tell (better yet, show) what you see. Report back with all six results. You need hard data, not guesses. Throwing parts at a problem is a waste of time and money.

    You might also test the AFM and ICV. The test procedure for the former is more involved IIRC.

    Minor oil residue on the throttle plate is nothing to worry about. The oil leak is likely unrelated; blow-by and burning oil don't look like fresh oil. My guess there is a leaking valvecover gasket, but verify with your eyes: what is the highest/frontmost point you see fresh oil?
    Last edited by moroza; 04-08-2019 at 12:01 PM.

  9. #59
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    Pulled all 6 plugs yesterday. Nothing terribly unusual. No considerable oil fouling, outside of what I would expect from a 30 year old car with 140,000 miles on it.. What I did see was that the plugs were severely off correct gap. We recently ( the last 6 month's) let our mechanic change them, and it looks like they were just taken out of the box and installed. They were checking in at 1.2mm, the big blue book specifies .7-.8mm. So, I corrected the gap and reinstalled.
    I will pull them, and take photos for you to look at.
    Then I will try to get the data on the tps, and post that.
    I'll have to track that procedure down again. I will have to research the procedure for testing the MAF in order to get that data to you.

  10. #60
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    TPS results: good continuity between pins 4 & 6 at closed throttle. Good continuity between pins 4 & 5 at WOT.

  11. #61
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    http://i1376.photobucket.com/albums/...ps03hp5si7.jpg
    From left to right cylinders numbered 1-6 , from front to back.

  12. #62
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    moroza is offline MORΩN ΛABIA BMW CCA Member
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    Plugs look good enough that they aren't your problem (that said, the huge gap wasn't helping; also, your engine deserves better than Autolite). Of the tests I mentioned, smoke test is probably most important, followed by compression and leakdown.

  13. #63
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    Quote Originally Posted by moroza View Post
    Plugs look good enough that they aren't your problem (that said, the huge gap wasn't helping; also, your engine deserves better than Autolite). Of the tests I mentioned, smoke test is probably most important, followed by compression and leakdown.
    Most definitely deserves better, but per my (former) mechanic, they were all that was available to him at the time that had the removable tip, so as to accept the existing ignition wires.
    Here's the latest update; circa 2100 hrs last night. After looking at all possibilities that were visible ,for vacuum leaks , both massive to minute( sans smoke testing), I came up with nothing of any real significance. Temporarily repaired a small crack in the ccv tube, until the new one arrives, and repaced the gasket between the throttle body and plenum. Neither of those seemed to be of the magnitude to cause the size of issue we've been having.
    After reassembly, and reconnecting the battery, I cranked the car only to experience the same issue, with only minimal improvement.
    At that point, I began reconstructing the timeline of events leading up to the catastrophic meltdown, looking for anything that changed that could have caused this incident. The only thing that coming to mind, was that we had replaced the IACV, three days prior. So, as a last ditch effort, I reinstalled the old part, and disconnected the battery again.
    After 30 minutes had passed, I tried again. The idle smoothly settled in around the 850-900 range, with only the most modest of occasional misses. I then performed the stomp test after having let the car idle for 15 minutes, and a short test drive (approx. 5 miles), receiving only the 1444 code.
    The wife drove it approx. 130 miles today, and reports only a very slight occasional stumble at stoplights.
    She's happy, I'm happy.
    Next, I'll systematically address the slight stumbles and misses.
    First item up, is to replace the fuel filter. Secondly, I'm going to replace the plugs with a set of platinums, as well as new ignition wires( I discovered several cracks in the existing ones). Thirdly, I'm going to rebuild the evap canister, and replace all old vacuum lines.
    I'm certain we're not home free, but we're living and gaining ground.
    Thanks to all who have helped thus far, and please keep That input coming. All of your knowledge has helped immensely.

  14. #64
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    Nice, looks better now.
    How to Clean BMW IAC ICV Idle air control valve and what symptoms to look for https://www.youtube.com/watch?v=3KPkslbjfJg
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  15. #65
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    New ignition parts (cap and rotor too, yes?) might be all it needs to clear up the remaining misses. Also, how long's it been since the valves were adjusted?

  16. #66
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    Quote Originally Posted by moroza View Post
    New ignition parts (cap and rotor too, yes?) might be all it needs to clear up the remaining misses. Also, how long's it been since the valves were adjusted?
    Yep, she had a new cap and rotor at the start of this fiasco. So that's covered. Although, I haven't looked at them after all of the misfiring issues. It's possible that there's a bit of carbon fouling in there due to the myriad of misfires.
    Won't hurt to take a peak.
    I'm extremely happy to report that there is no oil leaking from or in the area that was causing such fear a few weeks back. All of those deposits are dried, and no new oil at the throttle body either.
    There is still a significant leak in the lower front. I can't see it well enough to be 100% certain, but I'm confident that leak is just an old front main that is due to be changed. That's a little bit of a daunting thought, but I'll get to it, and through it.
    The remaining minor misses I feel confident are related to vacuum leaks.
    Haven't gotten set up for the smoke test yet, due to the plethora of other emergencies that have come up, but we'll get there.
    Thank you to everyone that helped me through this fiasco. I'm certain however, that it won't be the last.

  17. #67
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    Does TPS voltage should slowly drop and increase for the engine ECU input when plate moves same as potentiometer for the automatic transmission ? Thanks !
    Last edited by Annddrriy; 10-03-2023 at 01:04 PM. Reason: TPS

  18. #68
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    I have a question about TPS idle and full load when TPS plate opens only %50 what voltage should be ?

  19. #69
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    I have a question about TPS idle and full load when TPS plate opens only %50 what voltage should be at the engine ECU input pin 53 is WOT ? Between idle and WOT there is potentiometer it should works same way like in an automatic transmission potentiometer with 3 wires or it should just when one’s throttle plate moves from idle 3mm it will be 5 volts but not 2v ? Thanks in advance for your feedback !
    TPS gives to the engine ECU and an automatic transmission TCM information about the idling deceleration rate of acceleration and the fully open throttle valve state (WOT). TPS is a three wire potentiometer and the idle micro switch is power on/off then after idle there’s movement sweep wiper on the two tracks as a potentiometer for both options to ECU and TCM the first wire a voltage of +5V is applied to the sensor resistive layer which is supply power to the idle of the ECU pin 52 and the second wire disconnect idle from the first idle wire when idle circuit open then second and third wires get connected. TPS t1 idle t2 throttle plate open and third wire is grounded to the engine ECU pin 19. I have now sourced that my TPS might be faulty when do not get a constant ohm reading when doing the WOT test and it's inconsistent when feathering off the throttle according to readings.

  20. #70
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    I am not the electr. expert: For the M1.3 for the M30: if you go to the ETM version 02/1989 you see on page 1210.2-01 the diagram for injection electronics. There it is very simple for the throttle valve, it only detects via the throttle switch 1. idle speed, 2. full speed, and there is 3. to mechanical linkage (with AEGS) = cars with automatic trans, so only in case of cars with automatic transmission with AEGS the AEGS control module gets the info about the opening angle. You either have continuity at WOT or you do not.

    On M20 and M30 engines, a throttle position switch provides an idle and full throttle position signal to the ECM. If you are reading (measuring) this with a multimeter and using the signal setting (beep) on the Ohm scale you will get a beep at closed throttle and a beep and WOT. Not much more simple than that. The entire procedure on testing this is in the Bentley page 130-8 in the Fuel Injection DME section.

    If you believe after your testing your TPS is faulty, buy a new one and install it.
    Shogun tricks and tips for the E32 series are HERE!

  21. #71
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    I set multimeter on 20 volts scale then idle it shows reading 5 volts and when I moved throttle plate 3mm from idle it shows on multimeter 0.7 volts and when moved throttle plate to full load it shows on the multimeter same 0.7 volts. My question is if TPS t1 wire feed power to ECU idle and TCU idle ?

  22. #72
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    Sorry forgot to mention. Yes sparkplugs also changed ! But that shouldn’t have any effect on the TPS right ! That’s what keeps me confused. The car runs better with the TPS disconnected. But I read several places that other people had problems with their car and the car ran better without the TPS connected. Some of them bought new TPS but the problem was still there. So I want to measure the volts out the TPS because my money doesn’t grow on a tree and I won’t spend money on a new TPS without being sure its faulty ! But can’t find a guide as I’m having 6 wires out my TPS instead of the usual 3 wires like the manual states !

  23. #73
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    One of the mechanic said the TPS idle and WOT need to check with multimeter on 100 Ohms scale. To be make sure it is working properly.

  24. #74
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    The engine ECU pin 52 and 53 power supply to TPS then when micro switch at idle the ECU supply power 5 volts to TPS pin 6 and pin 4 and when throttle plate moves to WOT the engine ECU pin 53 supply power to TPS pin 5 that will be closed circuit with TPS pin 4 and pin 5 and TPS pin 6 idle will be open circuit.

  25. #75
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    Why for example if at some point the brain receives a signal about the maximum gas and the throttle is really closed then not only are the injectors pouring but also the advance angle shifts to a very early one according to the nameplate it’s too early and with such parameters there’s no point in driving it you can't think and the starter can fight back.

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