2001 GT40 misfire when hot

[Ray]

2001 GT40 misfire when hot have replaced spark plugs ,HT leads ,rotor ,distributor cap, coil , & ignition module only has problem when engine warmed up have replaced low pressure fuel pump & fuel pump relays no change was thinking it felt more like ignition problem can you just change PIP in distributor any thoughts

[Peter6000]

Looks like the sensor in the distributor is the only thing that's left besides the ECU.
A oscilloscope would be the tool to troubleshoot this instead of throwing parts at it.
Under what conditions and rpm does it misfire (idle, under load, full throttle)?
You can pull the spout connector this will set the timing to fixed 10 deg. But it eliminates the ECU for timing control. If it still misfires it's not the ECU.
Check the fuel pressure on the rail you can get a tester for some $40 at harbor freight.


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[SilentSeven]

I had run problems with my GT-40 and it was a problematic hall sensor in the distributor. A remanufactured Ford truck distributor was the cheapest solution. The part numbers below should work. The top number is the original Ford part number that was on my factory PCM distributor and the bottom two numbers are from US based remanufacturing firms.

Replacing the hall sensor is possible but you need a means to remove the distributor drive gear which is pinned on. It was simpler and cheaper to purchase the remanuafactured unit. < $100 USD.



Ford / F1TZ12127C / No longer available
Cardone Part number (remanufactured Ford Part) - 302891
NAPA Part number (remanufactured) - 48-2891

[Peter6000]

I had run problems with my GT-40 and it was a problematic hall sensor in the distributor. A remanufactured Ford truck distributor was the cheapest solution. This part numbers below should work. The top number is the orginal Ford part number that was on my factory distributor and the bottom two numbers are from US based remanufacturing firms.

Replacing the hall sensor is possible but you need a means to remove the distributor drive gear which is pinned on. It was simpler and cheaper to purchase the remanuafactured unit. < $100 USD.



Ford / F1TZ12127C / No longer available
Cardone Part number (remanufactured Ford Part) - 302891
NAPA Part number (remanufactured) - 48-2891

If you do feel like taking the distributor apart I have a sensor you can have it if you pay shipping guess $7 or so.
Came off a working engine.

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[Ray]

Thanks for reply misfire is only under load as you take off the faster you go it seems to come right as soon as you slow down it starts to miss if you stop put it in neutral rev engine it sounds good that's why i feel its more electrical than fuel where is the spout connector you are talking about to disconnect Peter Thanks

[Peter6000]

I'm on the road take a look in the ProBoss manual if you dont have it's under manuals in this forum.
It's a must have.
I agree does not sound like fuel.
Could also be a ground or +12V issue.
Put a voltmeter on the + and - on the ignition coil should not drop below 12v

Peter

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[Peter6000]

That's the spout connector if you remove it the ECU is disconnected from ignition control this is also used to set base timing.
With it removed the engine loses power but should not misfire.

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[Ray]

Thanks have tracked down fuel injection test kit so am going to test fuel pressure and rule fuel pumps out

[THE HECKLER]

check the water temp and oil temp sensor switches. may be bad and running in limp mode...

[Ray]

Hi Peter did some testing over weekend have very low fuel pressure 12psi at 3000rpm & 20 at idle however still think my problem is distributor as i disconnected the spout you showed me misfire went away plugged back in straight back so yes i if i could have your sensor would be great and i'll pay freight

[Peter6000]

Hi Peter did some testing over weekend have very low fuel pressure 12psi at 3000rpm & 20 at idle however still think my problem is distributor as i disconnected the spout you showed me misfire went away plugged back in straight back so yes i if i could have your sensor would be great and i'll pay freight

I would fix the fuel pressure issue first could be the high pressure pump or the regulator, you can test regulator by blocking the return line. Turn ignition on with blocked line pressure should go up way above 40 psi dont start the engine.
Could also be a leaking injector this would explain the missfire.
The fuel pressure should stay up for at least a few minutes after turning ignition off. If not you have a leak.


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[Ray]

Just checked that all good realized I'd put pressure gauge on wrong side of pump has 40psi at idle doesn't drop with key off at all

[Peter6000]

Just checked that all good realized I'd put pressure gauge on wrong side of pump has 40psi at idle doesn't drop with key off at all

Good, now you have to find out what happens do you loos spark or is the timing running of.
Start with checking sensors
MAP, ECT, Air intake temp, TPS, Knock
MAP if frequency all other are dc/ohm
Details are in the manual.
If no success connect a ignition test strobe light check base timing then try to make the misfire happen and watch the timing. You may have to add a few extra marks on the crank pulley.
Still would be nice to have oscilloscope to see what's coming out of the ECU..



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[Peter6000]

Just checked that all good realized I'd put pressure gauge on wrong side of pump has 40psi at idle doesn't drop with key off at all

Where are you located?

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