Another no start.... Not the DME relay

[porsche4life]

Bypassed the alarm....

[Grun_RS]

Is the 36psi fuel pressure specifically for a 944; even still that seems low? The 56psi I mentioned earlier is right out of the 968 spec. book.
If it cuts-off quickly I'd suspect either the ignition switch or a faulty coil...

[John_AZ]

Numbers may have different meaning:

Clarks does show fuel pressure at the rail to be 36psi.
Fuel Pressure - Checking

Bosch PDF shows the fuel pump will put out 56psi +- or 4 bar for the universal fuel pump 0 580 464 069 that is an interchange for our cars (OEM 0580 464 021)

http://www.cannell.co.uk/Bosch_Technical/Bosch-fuelpumps.pdf

John

[porsche4life]

I don't think its the pump.... It wouldn't have been that sudden of a death from the pump...

I'm still suspicious of the injectors.... I'll get them in bottles next weekend and check.

[cauzomb]

Pull the fuel injector plugs and test the resistance of each injector, they should be right around 2.4 Ohms. If they don't have any resistance, or the resistance is too high, 4+ Ohms, the injectors probly won't fire, even if the noid signal checks out.

Try making a couple wire connector pig-tails that you can slip over the injector connection stabs, then stuff the multimeter probes into the wire ends, or strip the ends of the wire, then wrap the wires around the probes for a good reading..

If there is NO resistance, or "open" circuit between the two pins, the coils are probly bad....

Before you go out and replace the injectors if they look bad, trouble shoot the cooling fan issue, make sure that you don't have any shorted wires and that all the relays are good and working..

A short could have caused an over current situation that may have burned out the injector coils, this is unlikely but possible..

Check all your fuses.. Try spinning the fuses in their holders to "clean" the contact area.

If they fall apart while you spin them, put in a new fuse. .. clean the battery terminals and connectors, disconnect the 10mm bolts that hold the main power wires that lead to the fuse box and dme relay, then clean the eye's and bolts with a wire brush, or scrape them clean with a pocket knife..

If you have good resistance readings on the injectors, pull the fuel rail up with everything still connected.. Clean the whole area real well prior to removing the rail bolts.. That way there is little chance of dirt or grit getting into the injector holes in the manifold, then lift the fuel rail and carefully check the injectors for fuel spray..

The bottle method mentioned above is a good idea..

If they don't spray any fuel, check the pintle valves, they could be stuck closed.

You can carfully press them upwards with a finger nail, or the little plastic pocket clip end of a cheapo ball-point pen cap.. If they do not move, don't force them, they should move up relatively easy.

I though I had posted here about the fuel pressure maybe too high, and to unplug one of the injectors to see if the car would start like that/per clarks-garage fuel 07

and remember seeing another suggestion about checking if the AC knob is in the on or off position for a reason that the cooling fans come on.... Dunno what else would cause a no start, maybe a bad DME temp sensor/plug?

[cauzomb]

Also, if the bottle test doesn't work for you, no fuel spray, and the injectors have resistance within spec, you can use a small 12volt power source and the pigtail wires to manually fire the injectors.. Just a quick tap on and off the power source should fire the injector open and closed.. Watch for fuel spray and listen for the injectors.. There should be enough residual pressure in the rail to squirt some fuel with the manual test, use the bottles to catch the fuel... Carefull cause the wires might make a spark and you'll have fuel vapors in the area.. Use longer wires and like a 12volt cordless drill pack, or 12 volt DC power supply.. Or the cars battery.. They should be able to handle the power if you don't just leave them connected, they are connected straight to the battery via the DME relay.. The DME provides the short to ground to fire the injectors, via triacs or similar transistors..

A quick tap to the power source should fire the injector open and closed, this will tell you if there is a problem with the injector harness being dirty/loose somewhere down the line. Alternatively, you can ommit the direct power test to the injectors..

Disconnect the battery possitive cable.. then probe the injector harness for resistance, make sure that your ohmeter is connected securely to each end of the circuit from the DME plug, to the fuel injector plug, then wiggle the harness in different spots, near the DME plug, and out in the engine bay.. Watch for fluctuations in the resistance readings as you wiggle the harnesses.. A bad connection or partially broken injector harness in the engine bay will not provide enough current to fire the injectors, but would allow small voltages to pass if one wire strand is still left connected "noid light will still work"

Something like this could be caused by a bad engine mount, allowing extra engine movement "like when you are shifting/ adding/removing load to the engine quickly with a bad mount would cause repetitive flexing of the injection harness.

[kfray]

Have you tested the AFM
http://www.clarks-garage.com/pdf-manual/elect-22.pdf

[cauzomb]

I think the car will start, then die if there's a problem with the AFM, or disconnected AFM plug.

looks like the problem is that it won't start at all.

[John_AZ]

Originally Posted by cauzomb

Pull the fuel injector plugs and test the resistance of each injector, they should be right around 2.4 Ohms. If they don't have any resistance, or the resistance is too high, 4+ Ohms, the injectors probly won't fire, even if the noid signal checks out.

Try making a couple wire connector pig-tails that you can slip over the injector connection stabs, then stuff the multimeter probes into the wire ends, or strip the ends of the wire, then wrap the wires around the probes for a good reading..

If there is NO resistance, or "open" circuit between the two pins, the coils are probly bad....

Before you go out and replace the injectors if they look bad, trouble shoot the cooling fan issue, make sure that you don't have any shorted wires and that all the relays are good and working..

A short could have caused an over current situation that may have burned out the injector coils, this is unlikely but possible..

Check all your fuses.. Try spinning the fuses in their holders to "clean" the contact area.

If they fall apart while you spin them, put in a new fuse. .. clean the battery terminals and connectors, disconnect the 10mm bolts that hold the main power wires that lead to the fuse box and dme relay, then clean the eye's and bolts with a wire brush, or scrape them clean with a pocket knife..

If you have good resistance readings on the injectors, pull the fuel rail up with everything still connected.. Clean the whole area real well prior to removing the rail bolts.. That way there is little chance of dirt or grit getting into the injector holes in the manifold, then lift the fuel rail and carefully check the injectors for fuel spray..

The bottle method mentioned above is a good idea..

If they don't spray any fuel, check the pintle valves, they could be stuck closed.

You can carfully press them upwards with a finger nail, or the little plastic pocket clip end of a cheapo ball-point pen cap.. If they do not move, don't force them, they should move up relatively easy.

I though I had posted here about the fuel pressure maybe too high, and to unplug one of the injectors to see if the car would start like that/per clarks-garage fuel 07

and remember seeing another suggestion about checking if the AC knob is in the on or off position for a reason that the cooling fans come on.... Dunno what else would cause a no start, maybe a bad DME temp sensor/plug?

Originally Posted by cauzomb

Also, if the bottle test doesn't work for you, no fuel spray, and the injectors have resistance within spec, you can use a small 12volt power source and the pigtail wires to manually fire the injectors.. Just a quick tap on and off the power source should fire the injector open and closed.. Watch for fuel spray and listen for the injectors.. There should be enough residual pressure in the rail to squirt some fuel with the manual test, use the bottles to catch the fuel... Carefull cause the wires might make a spark and you'll have fuel vapors in the area.. Use longer wires and like a 12volt cordless drill pack, or 12 volt DC power supply.. Or the cars battery.. They should be able to handle the power if you don't just leave them connected, they are connected straight to the battery via the DME relay.. The DME provides the short to ground to fire the injectors, via triacs or similar transistors..

A quick tap to the power source should fire the injector open and closed, this will tell you if there is a problem with the injector harness being dirty/loose somewhere down the line. Alternatively, you can ommit the direct power test to the injectors..

Disconnect the battery possitive cable.. then probe the injector harness for resistance, make sure that your ohmeter is connected securely to each end of the circuit from the DME plug, to the fuel injector plug, then wiggle the harness in different spots, near the DME plug, and out in the engine bay.. Watch for fluctuations in the resistance readings as you wiggle the harnesses.. A bad connection or partially broken injector harness in the engine bay will not provide enough current to fire the injectors, but would allow small voltages to pass if one wire strand is still left connected "noid light will still work"

Something like this could be caused by a bad engine mount, allowing extra engine movement "like when you are shifting/ adding/removing load to the engine quickly with a bad mount would cause repetitive flexing of the injection harness.

Good knowledge.

A 9V radio battery works as well.

Pelican has a DIY Injector clean in the Tech Info Center above radio button.
Pelican Technical Article: 944 Fuel Injector Clean & Reseal

OR

WitchHunter Performance - Injector Cleaning & Flow Testing Services

Injector seal kit:
PorscheDoc says BorgWarner 274081 at Checker/Oreilly.
V2Rocket_aka944 says ask for set for a 2.3 Thunderbird turbo coupe at AutoZone
Stay away from the Bosch seal kits.
I got my aftermarket at a VW parts house.

John

[porsche4life]

I sent my injectors off to witchhunter about a year ago and they were beyond repair.... So I have rebuilt injectors from Pelican that are less than a year old. The fan thing was that the AC was turned on.... I just hadn't noticed it....

[cauzomb]

Sounds good, but who knows how old they were before they were cleaned and had new seals/caps put on.. They might have a replacement waranty from pelican if they don't spec out. check the resistance, see if they fire into the bottles via the stock harness/cranking over the engine.. Don't do the direct battery test if they are not firing from the stock harness, that might void the waranty.

[porsche4life]

They are out of warranty by a little over 2mos now... And they wouldn't all die at once... I unplugged one by one and tried starting.... Still nothing....

[cauzomb]

A couple months out, they might still exchange em? check the other stuff mentioned though.. to be certain if the injectors are working or not.. or if there's any trouble in the harness. Or a disloged ground wire somewhere.. are the engine mounts leaking fluid?

[porsche4life]

Don't think the mounts are leaking... They are less than 2yrs old so they better not be...

[cauzomb]

dunno man, check the above stuff; DME temperature sender is a two wire plug that looks like an injector plug, it's below the intake manifold, it's bolted into the cylinder head near the coolant temperature guage sender. Car might start with it unplugged if it's bad.

[porsche4life]

Drumroll please! I got it running....

Turns out the rear bolt on the rotor had come out... The first time I pulled the cap I didn't tug on the rotor and I couldn't see the rear bolt b/c of the dust cap... Put the bolt back and we are back in business! Time to order some delrin...



I got my new front struts assembled today too...

[cauzomb]

Congrats on finding the culprit, as well as those nice struts What kinda plug wires are those? they look nice, and mine are jumping spark on occassion..

[porsche4life]

Those are the Magnecor wires that pelican sells. I haven't had any problems with them in the last 3yrs....

[cauzomb]

Thanks, think they work ok with a perma tune and stock coil?

I'm having a bit of success in my wiring issues besides the rats nest of wiring repairs that I had to do to get things back to factory connections, before I could troubleshoot other wiring electrical problems. I'm thinking brownies on me

[porsche4life]

I would imagine they would work fine....

I don't want to hear about wiring issues... I've got to sort out the wires on the silver car... It was in the middle of being race prepped... Part of the harness has already been clipped... I still need to clip everything else unneeded and neaten it all up.....