iamgod

well, day after she crispified we undid the cat back and punched her out...clogged as hell. then we pulled her outta the garage and tried to start her up again...same thing pops off then chugs. we pulled the spark plugs and #2 injector wasn't firing, perfectly clean...looked new...#'s 1, 3 &4 were covered in a black goo. i cleaned off the plugs, reinstalled and she popped off again but still couldn't idle.

we pulled the fuel rail off and put 2 liter bottles over the injectors to see how and what was coming out. the fuel is coming out black. we tested #2 with voltmeter and all signals were good so we swapped it with #1 and both started firing..yay no new injectors.

we are gonna grab a new fuel filter and drain the tank...replace fuel filter and flush with new gas. otherwise spark and everything look good.


So close yet so far away...

Calmchaos

Nice detective work though!

iamgod

everything looks fine. just runs uber pig rich. idle smooths out in higher rpms 5k+ enough to move onto a trailer under her own power. thinking maybe AFM is fubar...sensor is fubar. dunno

Calmchaos

*being stupid*
Are you sure they are the right injectors for the car?

BTW, why is it taking you so long to work on it?

jpk

You might have a short in the #2 injector wires, probably right at the connector end. When you switched injectors, you likely moved it enough to temporarilly fix itself.

The poor running is likely due to a bad refrence sensor - without it, the DME can't time the ignition correctly, nor advace/retard the timing according to engine speed.

PeteL

It sounds to me like the fuel pressure regulator.

harrisonrick

+1...makes it black, sooty and gooey...

iamgod

its an early 944 i have replaced one of the FPR's

also it has 2 new ref/speed sensors aswell as lindsey harness kit (both tested fine

to date i have replaced:
-speed + ref sensors
-speed + ref sensor harness
-dme
-dme relay
-fuel filter
- 1 fpr
- cap
-plugs
-wires
-rotor
-coil
-ignition switch

all started after a no start condition that i couldn't diagnose...all work was done in my brothers garage and as finances could afford.

i figured out the no start as a dead dme...and a dead replacement dme...third times a charm.
then she almost started on fire after the cat glowed to hot because of this rich condition.
all injectors are firing we just did the one fpr but no change.

jpk

I stand by my theory of refrence sensor, that's EXACTLY how my car was running when the refrence sensor was bad. Since you've replaced the sensor and the harness, you need to go a bit deeper. You need to get the sensors hooked up to an oscilloscope to see the waveform they're generating, that's the only way to confirm they're doing what they need to be doing. The specs are in the sevice manual.
It could be a number of things; inproper gap which results in a weak signal; maybee the grub screw that triggers the pulse fell out of the flywheel; or maybee that part of the DME is no good.

iamgod

hmm...interesting. i'll check it out

jpk

This is the best refrence I've found on the Bosch Motronic DME; Start at the blue button labeled "The DME (ECU)" and go on down through the rest of those buttons...

http://frwilk.com/944dme/hfm.htm

teamking

Any update on this?

My 951 was running rich until I fixed the fuel level sender...

...seriously. The fuel return goes through the fuel level sender and was clogged. Thus leading to too much fuel pressure. Thus leading to running rich.

So I unclogged it and fixed the problem with running rich. But my fuel gauge still doesn't work properly!