Rough running....then won't start...smoke thru the intake

E28 technical advice asked and given! Troubleshooting, modifications and more.
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krellboy
Posts: 111
Joined: Feb 12, 2006 12:00 PM
Location: Indianapolis, IN

Rough running....then won't start...smoke thru the intake

Post by krellboy »

As a back ground my long time mechanic has retired and it seems to be difficult to find a shop that knows about these old 535's.....especially one like mine which is a swap....now a M30B35.

I had a non BMW mechanic help me out with a ongoing slight rough running issue from low throttle to upper rpm....once above 1K rpm or so would run well and pull nicely. He thought it was a maf issue or tps.....so I replaced the maf, tps and icv. Randomly the car wouldn't start or if it did would stall out at the low RPM....then not start again at all unless I let it sit for awhile....like an hour or two...or overnight.

It's undriveable at this point b/c it will randomly stall and not start..... to get to another shop so I'm looking for some input from you all. I also should mention that the last time I started it that it produced smoke out of the intake manifold thru the air filter.....

I'm thinking it may be related to the position sensor (cam sensor?) on the front of the crank or related to ignition timing in the distributor. I'm a rookie on how to test this so maybe point me to a way to do some troubleshooting. Gurus please chime in.....

I've made a start up video which shows what I'm up against....maybe someone will know straight away where the problem will lie. Trying to avoid having to tow it to an unknown shop.

Below is a link to the short video.....2 minutes

https://photos.app.goo.gl/8rmQ71gaqFok5gYy8

Second video below.....3 minutes (if you have the time)

https://photos.app.goo.gl/SqLTihrsRJ5rzqvn9
krellboy
Posts: 111
Joined: Feb 12, 2006 12:00 PM
Location: Indianapolis, IN

Re: Rough running....then won't start...smoke thru the intake

Post by krellboy »

Mission accomplished....

All up and running. Checked distributor cap and rotor.....they were both oldish looking although no cracks in the cap or arc tracings. Rather than resurface the contacts a new cap and rotor were installed.

Starts runs well and good to go.

Now if I could figure out why I have a wonky tach that comes and goes....fuses ok and reads ok when working. Scratching my head on this....but will remove the cluster as the last time my mechanic had the car he disabled the SI indicator lights....wondering if he messed up some connections inside that are related to tack.
demetk
Posts: 8431
Joined: Aug 09, 2007 8:58 AM
Location: CT, USA

Re: Rough running....then won't start...smoke thru the intake

Post by demetk »

I'm assuming the 179 ECU is in the same place as the original? Check how he got the tach signal from the new ecu and how it's connected to the c103 plug in the glove compartment. Maybe it's loose. Otherwise check for broken solder joints on the cluster board.
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