OBD1 S52 running issue

[JCarp90]

Hello guys,

I'm having some issues keeping my car running. Before I explain the issue, I'll first give some details on my setup.

- 91 325i
- S52 (OBD1 converted)
- M50 manifold
- M50 fuel rail (S52 injectors)
- OBD1 M50 harness from 93 525i M50TU
- OBD1 Silver 413 DME (93 325i)
- TRM Chip - EWS Delete, S52, 91 octane, stock MAF, blah blah blah
- NEW crank position sensor, camshaft position sensor, new knock sensors and all
- Treehouse Racing Harness adapter - I did not hook up the ABS power wire or the 2 oil level wires.
- ZF320
- S52 dual mass flywheel
- S52 starter
- New Bosch O2 sensor



The car idles perfectly. Sounds great. No strange noises, knock or vacuum leaks. I've spent probably 2 days total re-tracing all vacuum lines and they've all be replaced with new parts - even the giant round one on the bottom side of the manifold going to the ICV.

Anyway, when I start to drive, when I'm completely off the clutch in first gear, I was able to get to 4k RPM and then the car would instantly shut off. I tried multiple times to drive and it happened anywhere from 2500-4000rpm, no exact spot. This led me to believe it might be VSS, so we double checked that the VSS was getting signal at the harness adapter. Then, I tested revving the engine while parked and it seemed to work, until last night I tried one more time, and at 4,000 rpm, it died again. It's not like the car stumbles and you can give it more gas to start it back up, it's like a light switch and it just dies.

After the car dies, when I try to start it again, it sounds like the starter is just spinning and spinning but not catching. Then, you wait a few seconds and it slowly starts cranking and will start.

WTF?


***edit***

Videos up.

[JCarp90]

I will try and get some videos of the car running and when it dies tonight when I get home from work.

[ryanc88]

hmmmm, that kinda sounds like a low power issue. maybe check your belt, tensioner and alternator/alternator wiring?

[JCarp90]

hmmmm, that kinda sounds like a low power issue. maybe check your belt, tensioner and alternator/alternator wiring?

I can do that. I'm running a 140amp alternator from a 328i/528i and my voltmeter reads 13.6-13.8v at all times. When the engine dies, everything electrical does stay on as well.

The belt does squeal a little when the engine dies but not while running. The tensioners are not new, they were on the engine when I bought it. When I get home, I will check the alternator/starter wiring.

[JCarp90]

When I first started the car tonight, the power steering was making noise. I've since added fluid and its gone away. Idle and revving:



My attempt to drive:

[e30austin]

Hmm. My friend was having a very, very similar issue. Turns out, there was a wire under the dash that was grounding out (a little green wire that gets looped) that plugs into one of the distribution blocks. Might check that?

[JCarp90]

Hmm. My friend was having a very, very similar issue. Turns out, there was a wire under the dash that was grounding out (a little green wire that gets looped) that plugs into one of the distribution blocks. Might check that?

I did look into this but didn't see anything funny. I double-checked that everything was plugged into where it should be and that there weren't any torn or frayed wires or anything.

Also last night I pulled my cluster to verify that the wire that goes to the little green board on the bottom of the cluster was plugged in. I even tried it in all 3 spots just to be sure it wasn't plugged in incorrectly. Then I traced the VSS wire to the DME. I checked the harness, harness adapter (pulled it apart and verified the wire wasn't damaged) and verified that the body side of the harness had the wire in it as well.

What was weird is that last night when I was revving the engine while sitting still, it never did shut off, but then when I drove it, by 2500rpm it died. Anybody have any ideas?

Could this be an issue with the SI board? When I had the M20 in my car, I would experience instances where my car would simply shut off while I was driving. All electrical would stay on, but the engine would die. Also, recently my fuel gauge and temp gauge started acting funny and would pretty much do whatever they wanted.

[JCarp90]

So, upon doing some reading for myself just now, I discovered this post: http://www.r3vlimited.com/board/show...63&postcount=3

I removed my Cruise control when I installed this engine. Since my car was converted from automatic to manual anyway, It wasn't being used. I did unplug the cruse from the connector under the dash and pull it out the correct way though.

[JCarp90]

Replaced fuel filter and switched the fuel lines. Car ran for like 10 seconds after I switched them and then it died which confirms I had them on correctly. Moved them back to how I had them originally and the car runs again.

Still having the same driving issue though. :/

Any other ideas?

[jahnaboi]

Have you tried swapping the stock chip in your silver label 413?

I would try to eliminate the ecu/chip for now since it seems you've tried a few things so far. Also, I had a 1990 325i with an s52 with the cruise control wiring harness chopped off. This, in no way affected my car.

Check list you should do:

- x20 to c101
- Ecu/chip
- Differential sensor/plug harness intact

As preventative maintenance, if your money is ok, I would upgrade the fuel pump to a walboro as they aren't too expensive to come by.

I wish I could pin point the issue but the more you check the closer you get to the answer.

[7pilot]

It sounds as if the ECU is missing some sensory input regarding engine speed.
I would look into the cam position sensor, and double check that the VSS is hooked up.
If that stuff checks out, I'd swap ECUs.

m

[JCarp90]

Have you tried swapping the stock chip in your silver label 413?

I would try to eliminate the ecu/chip for now since it seems you've tried a few things so far. Also, I had a 1990 325i with an s52 with the cruise control wiring harness chopped off. This, in no way affected my car.

Check list you should do:

- x20 to c101
- Ecu/chip
- Differential sensor/plug harness intact

As preventative maintenance, if your money is ok, I would upgrade the fuel pump to a walboro as they aren't too expensive to come by.

I wish I could pin point the issue but the more you check the closer you get to the answer.

I do not have the stock chip. I bought this DME with the Chip and it was sold as a known working unit. I believe the X20/C101 is correct since it is a Treehouse Harness adapter but I will double check that as well. I was really hoping to avoid this headache, hence why I purchased the damn thing.

I'll also swap out the diff sensor. This was the sensor in my 4.10 open my car had before I installed the S2.93 though. :/

As far as the fuel pump goes, this is a new OEM one I purchased last summer when my old one went out. Has maybe 2,000 miles on it and the pressure seemed fine when I pulled the line off and fuel shot across my garage haha. None the less, I'll check it as well.

It sounds as if the ECU is missing some sensory input regarding engine speed.
I would look into the cam position sensor, and double check that the VSS is hooked up.
If that stuff checks out, I'd swap ECUs.

m

That's my thought as well. As far as the cam sensor goes, my DME threw a code for a bad cam sensor last week so I replaced it with a brand new one and haven't seen the code since. Doesn't mean there's not something wrong with it though....

Hoping to grab another DME in the next couple days and I will report back with what I find.

Does any of this sound like it could be related to the crank position sensor? This sensor I thought I purchased new but now that I think about it, I'm not sure I did.

[Bimmian89]

You might think im crazy but dude get a walboro fuel pump. Ebay 95$ shipped and im 99.9% sure your problem will be solved. I know it idles and revs fine but when you put a load on it the fuel pump cant hang( i'd say its on its last leg). My dads 318 had this issue, it would rev fine idle fine but with a load it wouldnt hit a lick over 2500 rpms. It actually felt like it was redlining. We exhausted every thing possible to figure it out and it was just a defectove VDO fuel pump. Pump was 2 months old brand new. So if you havent tried it, atleast just swap in a known good pump and im certain it will run like a champ again. Good luck bud.

EDIT: After reading your full post in the OP, im 100% its your fuel pump.

[Bimmian89]

http://www.youtube.com/watch?v=MNF7GRzX4f0

Driving with fuel pressure gauge..

http://www.youtube.com/watch?v=AHrhHLXcP38

This is one of how it acted.. NOTE, 4k was on a good day sometimes it wouldnt get over 1500.

[JCarp90]

Thank you for the tips, Bimmian.

I actually found that my cams were out of timing. After fixing that, it runs amazing.