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E34 (1989 - 1995)

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  #1  
Old 10-11-2010, 11:03 AM
papokergod papokergod is offline
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Mein Auto: 92 535i
Torque Converter not locking up?

1992 535i, automatic (obviously)

Recently I have noticed highway mileage has dropped off quite a bit. From about 19pmg to about 15-16mpg.

I am suspecting the TC is not locking up. 60MPH RPM is about 2500 RPM. 70MP is about 3000ish.

Car also seems to buck a little with erratic throttle response with the cruise control on. Suspect maybe a fuel filter, TPS or fuel pump issue, but have not confirmed. Again no codes showing on message display and no CEL.

I have been led to believe researching this that the trans is also "load sensing" as well? Which leads me to a possibility of a vacuum leak. but since I am able to get the trans to down shift using the A/M switch while on the highway, I don't think that is it either.

There is no Transmission warning on the message display when driving but it does come on when the key is turned on/off without engine running, which I believe through my searching is normal?

Anyway I guess what I am asking is if the 2500RPM @ 60mph and ~3000RPM at 70MPH normal and if not does it sound like the TC is not locking up @ 60?

Last edited by papokergod; 10-11-2010 at 11:23 AM.
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  #2  
Old 10-13-2010, 03:43 PM
papokergod papokergod is offline
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Mein Auto: 92 535i
Just got back from a Cottman Transmission, his Snap On scanner he had was not able to hook into the trans but was able to into the motor ecu. It gave him several options (about 10) to chose as far as the transmission goes, of course he didn't know which one to use, so we just took it on a test drive. He said he didn't see anything wrong with it at all. Every shift was a quality shift. (of course I already knew that) And it is shifting into 4th ad dropping it into 3rd on the highway downshift (of course I already knew that).

The trans in this I believe is the ZF 4hp22. Not the GM 4L30E. The "tech" had mentioned the ZF trans does not have a lockup converter in it. So no lockup "5th gear". He said the 4L30E did however. Which I believe is what the 525 e34's got?

Anyway, reading and searching about the "sport and winter" modes on this, I have read that there should be a light on the dash that lights up to tell you your either in winter or sport mode. However, nothing lights up on the dash to indicate the A/M switch is in A or M position nor does it indicate sport mode when in M position and 3 / 2 / 1 shifter position. DO I have this wrong about the light or is something else going on here as well. BTW the switch itself seems to work properly. Just no light on dash. (Maybe just a bad bulb?)
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  #3  
Old 10-13-2010, 11:22 PM
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BmwMan92 BmwMan92 is offline
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Mein Auto: 1985 318i// 1988 325e
where your screen lights up and tells you what you are in as in p,r,n,d.1.2.3 there will be a E next to it until you switch into 3rd which then will light up S3 on your dash then you pull down the manual switch next to your shift lever than it will say M1,M2,M3 if that doesnt work than your a/m switch probably needs replaced and to answer your thoughts i believe your car is in need of a tune up i also believe it is said that your cars mpg is changed by weather changes. id try regular maintenance before jumping into a conclusion so drastic yes the rpm range is normal at those speeds if i left anything out please let me know
Brandon
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Originally Posted by v8bimmer View Post
I just dont see any other logical way around this problem.
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  #4  
Old 10-14-2010, 08:04 AM
robertobaggio20 robertobaggio20 is offline
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1. Why do you feel the lock up clutch is not locking up? That is a serious failure and error messages on your dash would flash for that.
2. Such sudden drops in mpg are usually a failure of something else such as a vacuum leak as you suggested. I second Brandon's comment that you should tune up your car in general to see if anything's wrong. Your mpg drop seems typical of an o2 sensor failure.
3. When the code scanner was run on your car, did you find any other errors? If found, did you delete them?


rgds,
Roberto
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  #5  
Old 10-19-2010, 06:37 AM
papokergod papokergod is offline
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hey thanks guys, sorry for the late reply as I am not getting email notification of replies.

anyway, he did not mention any other faults on the scanner motor wise.

Thanks Brandon (that's my name too) for confirming the RPM range for me, that makes it heck of alot easier. This is the one and only reason why I was thinking the TC was not locking up.

Looking at this thing better in the light, I can see the gear indicator but seems to go blank after a while ie no light. Not sure how to fix that. When I can see it it does indicate M and E etc, so I know for a fact that switch is working. It's just not staying lit and it no lit very bright to start with either. I would think it's supposed to be as bright as the message indicator?

Next on my list of things is to double check the TPS is set correctly. Then see if i can find any vacuum leaks anywhere. Also change the fuel filter. Maybe these will take care of the slight pinging issue.

Seems to miss quite a bit when cold too. But when it finally warms up it idles perfectly. IACV has been cleaned and working properly to my knowledge too.

BTW I do have the Bentley ESM which is one thing I am using to go through some stuff.

And damn the plug wires/dist cap/rotor are expensive on this thing. lol. The plugs in it are relatively new.
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  #6  
Old 10-19-2010, 08:02 AM
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BmwMan92 BmwMan92 is offline
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is there a distributor on the 535? and pinging what kind of pinging from the engine or the inside of the car and no problem nice to meet ya
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Quote:
Originally Posted by v8bimmer View Post
I just dont see any other logical way around this problem.
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  #7  
Old 10-19-2010, 09:17 AM
papokergod papokergod is offline
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Location: Wilkes-Barre, PA
 
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yes there is a distributor. Is yours a 525? Mine is white as well. have not changed the cap or wires etc etc. Pinging from engine ie, ignition ping. not real loud and I can play with the throttle to make it come and go ie. more throttle and less throttle. Maybe a dead spot in the TPS?? Could also be just carbon build up on the pistons I am thinking. Might try some seafoam as well.
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  #8  
Old 10-19-2010, 10:18 AM
robertobaggio20 robertobaggio20 is offline
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Check the plugs and ignition leads. One or more might be lose/plugs might not have been properly screwed in. It happens. I really doubt its carbon buildup on your piston tops.
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