Cold start engine shakes and sputters

[roundel318]

its worth testing, seeing it doesnt cost you much.

[bearsbmw]

So that tests whether or not an injector is leaking while the engine is off... never really thought about that... my idle issue is prevalent at more than just startup, though.

yes because your fuel system is spose to hold presure untill next startup and and leaky injector would flood the engine causing these symptoms

[AcSchnitzer318is]

OK I'll play...

1. ICV (replaced)
2. Vacuum Leaks (did TB heater delete and replaced hoses)
3. o2 Sensor (replaced)
4. Plugs & Wires (replaced as part of maintenance)
5. Fuel Injectors (mustang 19#)
6. Exhaust Header Gasket (had a leak)
7. AFM (replaced)
8. Engine Temp Sensor (replaced)
9. Throttle Position Sensor (replaced)
10. ECU swapped (known good unit)

Also had engine smoke tested (no leaks), fuel pressure tested (40-50psi)... no problems.  I am guessing this problem is completely external to the motor.  Reason for this conclusion is that I swapped in a rebuilt motor (20k miles) that didn't exhibit this behavior in the donor car.  Only after being put into this chassis did it start doing this.  The original motor in this chassis did this as well... so something external to the motor is causing this.  Rules out most sensors, vacuum leaks, or timing.  Any other ideas guys?  I was thinking maybe fuel pump... but fuel pressure tested ok.

[roundel318]

good food for thought.....
only thing that comes right to mind is a fuel pressure regulator?

[bearsbmw]

yes I would like to see if anybody has done the regulator because I think these can get stuck in the high presure postion and not leak fuel beyond the diafram

I'm going to redo my ground straps tomorow and open my fuel tank and look inside and look at the fuel pump

[roundel318]

We need a song "process of elimination".
It could be a fat breaks track

[bearsbmw]

I love BMW's and all there problems 'Boom De Ah Dah'  'Boom De Ah Dah'  'Boom De Ah Dah'  'Boom De Ah Dah' !!  

[roundel318]

I am not sure about others, but here is at least one fuel pressure regulator.
Item 6
http://www.realoem.com/bmw/showparts.do?model=AJ93&mospid=47318&btnr=13_0308&hg=13&fg=15
And it seems like it would come and go with an engine swap.
Perhaps there is another on the car somewhere?

[bearsbmw]

I remember reading somewhere that the e30 has a check valve at the fuel pump that can fail and cause these symptoms

http://www.m42club.com/forums/showthread.php?t=4688

[roundel318]

Good call, dig out the rear seat

[bearsbmw]

fuel pressure regulator could very well be the problem

[roundel318]

A Bentley manual should have some simple test procedure to check it out?

[bearsbmw]

No shrader valve on my fuel rail so Im going to remove the regulator and examine it visualy for corosion and rust I will then submerge the regulator in water and put 10psi to it and look for bubbles and then take my sandblasting gun and use the suction hose while under water on the vac nipple and see if the gun picks up water

[bearsbmw]

update: removed fuel regulator and there was alot of goldish color residue around the orings... I stuck a small screw driver in the middle hole of the regulator and pushed the spring back and forth and it seemed to be sticking and then started spraying wd40 into the housing and worked the plunger with the very small screw driver up and down and it became alot better ... will let everybody know how car starts on cold start soon

[roundel318]

It's the AN TI CI PA TION