Dharn55

Yars ago when the crank position sensor went bad on my car it would turn over, but the fuel supply would shut off. Once I replaced the CPS it ran again.

Porschenstein

Thanks, I already replaced it, no luck.

Porschetech3

Did you check for 12v power at the injectors, colis, MAF, change-over valves, purge valve ect.??

Porschenstein

Yes, thanks for all of your advice. Although I only checked injectors 3 & 6 since my hand fits enough to reach those two.
I think my next tasks will be putting noids on 3 & 6 to see if they’re pulsing. Also to pull the seat back out an figure out why I can tone ground on C3 fuse. I also thought maybe I need an assistant to turn the key to see voltage on all that while the starter is running.

Thanks again, really appreciate your help.

Porschetech3

OK, since you have 12v at all the injectors,coils,Maf, change-over valves, purge valve, ect, and the starter spins good, and you have good fuel pressure(?) and good compression (?)

Then go back and triple check this..

Porschenstein

It was actually fuel injector 3 & 5 that I could get at, haven't checked the other 4. At this point I'm assuming one on each side is good so maybe all 6 have power.

Not sure about fuel pressure, since the pump doesn't come on. Should I jump it or turn on via Durametric so the fuel pump runs and check pressure? Haven't bothered since the pump won't run without being forced.
Can it detect low compression, and not turn on the fuel pump for that reason? I can check compression, but not sure how many rotations before stopping to look at the gauge?

I will, but it'll be a quadruple check... and I do see plug 3 spark when turning over. Haven't checked all 6 for spark.

Thanks again, really appreciate the help.

hardtailer

ECU cannot check for low compression.
You crank until the needle on the compression tester no longer moves. Ideally you find a way to record the pressure achieved on the first compression stroke and count how many strokes pass until the pressure no longer increases. Do this for every cilinder.
If you can, open the throttle body fully during all your measurements.

Porschetech3

Ok, then lets back up even further to the BASICS

Three most improtant things an engine needs to run..

1 Compression

2 Fuel ( and air)

3 Spark

More in depth things and engine may need to run

1 proper timing of spark

2 proper timing of valves ( this can also effect compression readings)

3 proper fuel


So ;
1 Test compression on all cylinders, three compression strokes is enough to max out readings

2 Test fuel pressure with gauge ( a substitute fuel can be used as a test ie, starting fluid/propane/ just to see if the engine will run and verify that the other two necessary basics are OK )

3. Test for healthy spark once every compression stroke on every coil...


So go back and verify these three things to see which one is missing, because if they are all there, THE ENGINE WILL RUN ...

Porschenstein

I understand all that and will verify what I can, but at this point I know for sure the fuel pump isn't coming on. That's why it's my main focus at the moment.
Since I can jump the relay and it comes on and I can put the relay back in and turn it on with Durametric, it appears that the pump, fuse, relay and wiring is all good for the pump.
I have confirmed when the key is turned on, FP relay pin 86 gets 12+ v. So I want to determine why the DME isn't sending ground to pin 85 on the FP relay when the key is turned.

Until the pump runs when the key is turned, nothing else matters, it's not going to run.

Please don't take this as argumentative, I do appreciate all input, just explaining why the fuel pump is my main concern at the moment.

wdb

It certainly sounds as though you have it narrowed down. If you bypass the DME to activate the pump does the car start and run?

Porschenstein

No, I’m thinking the DME is not activating any fuel/air components for some reason. Probably one or more bad wires that I haven’t found yet. Wishing the Durametric could show realtime log data from the DME to maybe give a clue as to what’s missing. I ordered a Foxwell NT530 yesterday, hoping it may see something the Durametric can’t see. I’ve read Durametric is limited on the gen 1 DME 5.2 cars.

Currently removing plastic covers in the driver door sill so I can un-tape the harness. Haven’t looked for weld points in there, it was under water so maybe something in there burnt in half while grounded in water.

dcdrechsel

I would be inclined to check the subsystems that signal the dme to block engine run .Three come to mind- airbags -rollover -burglar alarm .Manny years ago a renlister had a no start issue that turned out to be the steering wheel was not installed and tripped the airbag fault. Since the dme checked out as good by ecu doctors and you can activate the fuel pump via durametric but can't activate with the key seems like dme has a no run condition set .Another question would be the key and imobilizer compatibility -don't know if ecu doctors checked that .

Porschenstein

ECU Docs did confirm that, I sent the key as well and they said they tested on bench and installed in a 996 & it ran. Plug & play they said.
The no start due to Airbag module is a prime candidate since mine was toast. I was thinking if the donor module had deployed the bags maybe it can tell DME no start until it’s reset. Also seen some say it has to be married to the car by VIN. You would think Duramtric would report that though, it sees the Airbag module & claims it’s error free.
I’ve seen Airbag module cloning services & am considering it just to rule it out. Hoping the Foxwell device does a better job of diagnosing than Duramtric.

If anyone can confirm the Airbag module can create a No Start condition on the DME that would be great. I would definitely have it cloned or reprogrammed if mine is too far gone to clone.

Porschenstein

dcdrechsel

Pin 12 at dme is where airbag module connects -don't know characteristics when activated it's either ground or voltage .Quick call to ecu doctors might get an answer .