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7 Series - E38 (1995 - 2001)

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  #1  
Old 08-27-2014, 03:25 PM
Jaysbmw7 Jaysbmw7 is offline
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Angry 1995 730I e38 wont rev past 2900rpm???

Hi guys this is my first time using this forum, Im hoping to get some expert knowledge as ive had no luck with my bmw mechanic so far, anyway, I have a 1995 730i e38 right hand drive bmw and it will not rev past 2900rpm, when it hits 2900rpm it "spikes" or feels like a sensor turns off and it kills the power, I have taken it to my local bmw mechanic and had it plugged on the diagnostic machine and it came back with the "crank shaft sensor pulse generator" so I bought a brand new 1 from bmw and fitted it to the car which made no difference, also tried a different harmonic balancer / crank shaft pulley and made no difference either, my bmw mechanic doesn't really have a clue as to what it is now, he now thinks it could be the ecu not processing the crank sensor right or something like that, hope some1 else has had this problem before and can help me! Engine light is not on and car still drives perfectly fine as long as I don't put my foot down, it is also petrol 3l v8. Please help! Thank you

Last edited by Jaysbmw7; 08-27-2014 at 03:28 PM.
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  #2  
Old 08-27-2014, 05:36 PM
tomloans tomloans is online now
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Maybe this might shed some light on it

http://www.bimmerfest.com/forums/sho...ar+dies+at+rpm
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  #3  
Old 08-27-2014, 05:47 PM
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What have you replaced lately on the car???
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  #4  
Old 08-28-2014, 03:57 AM
Jaysbmw7 Jaysbmw7 is offline
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Recently ive replaced the harmonic balancer and crankshaft sensor.
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  #5  
Old 08-28-2014, 09:24 AM
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What i meant was, what repairs if any did you do to the car say in the last six month, before the problem arose. Even if it is a small item. Think about it and let us know.
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  #6  
Old 08-28-2014, 09:57 AM
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Quote:
Originally Posted by Jaysbmw7 View Post
Hi guys this is my first time using this forum, Im hoping to get some expert knowledge as ive had no luck with my bmw mechanic so far, anyway, I have a 1995 730i e38 right hand drive bmw and it will not rev past 2900rpm, when it hits 2900rpm it "spikes" or feels like a sensor turns off and it kills the power, I have taken it to my local bmw mechanic and had it plugged on the diagnostic machine and it came back with the "crank shaft sensor pulse generator" so I bought a brand new 1 from bmw and fitted it to the car which made no difference, also tried a different harmonic balancer / crank shaft pulley and made no difference either, my bmw mechanic doesn't really have a clue as to what it is now, he now thinks it could be the ecu not processing the crank sensor right or something like that, hope some1 else has had this problem before and can help me! Engine light is not on and car still drives perfectly fine as long as I don't put my foot down, it is also petrol 3l v8. Please help! Thank you
you need to run diagnostics and get us the codes again. It can't be the only code showing up...
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  #7  
Old 08-28-2014, 03:53 PM
Jaysbmw7 Jaysbmw7 is offline
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Quote:
Originally Posted by tomloans View Post
What i meant was, what repairs if any did you do to the car say in the last six month, before the problem arose. Even if it is a small item. Think about it and let us know.
Thoose are the only repairs ive done to it, I bought it 6 months ago with the problem and the previous owner told me it was the harmonic balancer so I bought another 1 of those and it made no difference so I took it to the bmw mechanic to get the codes and it only comes back with crankshaft sensor and both rear wheel abs sensors , that's it.
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  #8  
Old 08-28-2014, 04:02 PM
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Quote:
Originally Posted by Jaysbmw7 View Post
Thoose are the only repairs ive done to it, I bought it 6 months ago with the problem and the previous owner told me it was the harmonic balancer so I bought another 1 of those and it made no difference so I took it to the bmw mechanic to get the codes and it only comes back with crankshaft sensor and both rear wheel abs sensors , that's it.
OK,,, well... let's keep going... the car starts and runs fine until you get it up to 2900 rpms and then shutsdown... Have the codes cleared and remove the battery terminals and tie them together to get a fresh start. leave them tied together for about an hour. Then reconnect and restart and see if it does it again. Maybe the crankshaft replacement worked but need to be reset.

Are their any knocking or ticking sounds from the engine?

Do you have any warning lights on the dash?

Any oil leaks?

sorry I dont have a quick fix for you. You have to try hard to deduce what is going on here. This is wierd for sure but it is probably also simple.

My first guess is fuel starvation - bad fuel pump but this seems to easy...And why at exactly 2900 RPMs every time? Hmmm.

Call Amir at 510-490-6700. He might have seen this before. he has work on many e38s. tell him Tom sent you... But first try the battery thing above and clear the codes!
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  #9  
Old 08-29-2014, 04:18 AM
Jaysbmw7 Jaysbmw7 is offline
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Quote:
Originally Posted by tomloans View Post
OK,,, well... let's keep going... the car starts and runs fine until you get it up to 2900 rpms and then shutsdown... Have the codes cleared and remove the battery terminals and tie them together to get a fresh start. leave them tied together for about an hour. Then reconnect and restart and see if it does it again. Maybe the crankshaft replacement worked but need to be reset.

Are their any knocking or ticking sounds from the engine?

Do you have any warning lights on the dash?

Any oil leaks?

sorry I dont have a quick fix for you. You have to try hard to deduce what is going on here. This is wierd for sure but it is probably also simple.

My first guess is fuel starvation - bad fuel pump but this seems to easy...And why at exactly 2900 RPMs every time? Hmmm.

Call Amir at 510-490-6700. He might have seen this before. he has work on many e38s. tell him Tom sent you... But first try the battery thing above and clear the codes!
Thanks for you help, will tying the terminals together for an hour completely reset the ecu?
Theres no knocking or ticking sounds, ABS is the only warning light on because of rear abs wheel sensors. I cleaned all the sparkplugs and coils out yesterday the leftside 4 were pretty oiled up, didn't make any difference to the revs but did run smoother obviously, will probably put new fuel filter on it aswell just incase.
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  #10  
Old 08-29-2014, 05:25 AM
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supertech777 supertech777 is offline
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Throttle body might be bad and it's position sensor


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  #11  
Old 08-29-2014, 02:03 PM
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BMWFatherFigure BMWFatherFigure is offline
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Tying the terminals removes the'learnt' part of the programming and resets to 'factory' basic. +1 on the TPS and also try the air flow sensor connections etc. I am guessing it is electrical rather that fuel related. I guess the fuel filter is clean?
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  #12  
Old 08-29-2014, 02:54 PM
Jaysbmw7 Jaysbmw7 is offline
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Ok awesome ill go tie them together now, I've checked most the sensors, wouldn't run at all without crankshaft sensor, would run without afm but worse, also ran without camshaft sensor but a bit worse... It seems weird to me that the crankshaft sensor is the only code coming back on the diagnostics so it must be the wiring between the sensor and ecu ? does anybody have a ecu wiring diagram for this so I can test the continuity in the wire ?
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  #13  
Old 08-29-2014, 05:18 PM
Jaysbmw7 Jaysbmw7 is offline
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Ok so I reset the ecu and hasn't made a difference, I just noticed if I gradually build up the revs slowly it will go to 3300 before cutting but when I accelerate quickly it cuts at 2500-2900
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  #14  
Old 08-29-2014, 08:09 PM
Mayorchuck Mayorchuck is offline
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Also seen the MAF and cats do this. Try unplugging the MAF and take it for a spin. It should run worse but if it runs better, there ya' go. The MAF and Cam sensor are notorious for not throwing codes when they are dying. It may sound weird but I would also try a battery nap. Remove both cables from the battery for 10 min. Touch them together for a minute before putting them back on. Not sure about your car but the '95 M60's DME does always respond to a new sensor for some reason without a reset.
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  #15  
Old 08-30-2014, 03:13 PM
Jaysbmw7 Jaysbmw7 is offline
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Ive tried the MAF and it ran werse, also tried the "battery nap" and made no difference, I done a resistance test on my sensors yesterday and found out the original crankshaft sensor that was in there read 570ohms and the brand new 1 I just installed read 670 ohms so it has a higher resistance but it made no difference to the revs at all by changing that sensor so therefor I think it must have to be the wiring going from the sensor to the ECU or the ECU not processing the sensor properly ?
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  #16  
Old 08-30-2014, 07:38 PM
Mayorchuck Mayorchuck is offline
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If the crank sensor was bad, it would be way out of range. Since you know how, check the cam position sensor. Should be around 1250-1300 ohms I believe. Again, if it's bad, it will be way out. If it were mine, I would have a shop check the flow thru the cats or pull the pre cat sensors to see if it improves any. Just to rule them out. I had similar symptoms with mine but had an obvious rattle in the one.
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  #17  
Old 08-31-2014, 08:46 PM
Jaysbmw7 Jaysbmw7 is offline
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I unplugged both the cat sensors and made no difference cam shaft sensor read 1500
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  #18  
Old 08-31-2014, 09:15 PM
tomloans tomloans is online now
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you might want to read through this link...it is not happy news but it might shed some light on this annoying issue you have...


http://forums.bimmerforums.com/forum...er-briefly-M62
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  #19  
Old 08-31-2014, 09:16 PM
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Quote:
Originally Posted by Jaysbmw7 View Post
I unplugged both the cat sensors and made no difference cam shaft sensor read 1500
The car just stops running at 2900 rpm. It just cuts out? What do you do when this happens? When can you restart it again...? Give us some detail...
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  #20  
Old 08-31-2014, 09:24 PM
tomloans tomloans is online now
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Here is yet a another similar issue. try what this guy did and see if it works for oyu. He removed the o2 sensors. Unfotunately if this works, there is a good chance your catlytic convertors are gone...

http://forums.bimmerforums.com/forum...talls-pls-help
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  #21  
Old 08-31-2014, 09:27 PM
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http://forums.bimmerforums.com/forum...4&d=1266899482

This is the guts of a catalytic convertor and I guess why they will plug up your system once they fail.
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Old 08-31-2014, 09:28 PM
Mayorchuck Mayorchuck is offline
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Quote:
Originally Posted by Jaysbmw7 View Post
I unplugged both the cat sensors and made no difference cam shaft sensor read 1500
Sorry if I didn't make it clear. I meant for your to remove the pre cat sensors.
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  #23  
Old 09-08-2014, 03:25 PM
Jaysbmw7 Jaysbmw7 is offline
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This is pretty much exactly what it does, my bmw mechanic has now checked through the whole loom and wiring + every sensor, am now trying to track down another ECU for it to test that.
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