Who else knows A LOT about cars?

[yamihoe]

It isn't FZ related but I am down to pulling ideas from anywhere at this point.

1993 32v Ford 4.6
Ran normal then randomly cuts off in the middle of the street and is towed home. Checked all fuses and relays (of course)

I have ohm'd out: Cam and Crank position sensor, both coil packs all 8 injectors as well as put a noid set on them and the TPS, all are within specs.

I have Replaced the ccrm, fuel pump, ECU, plugs/ wires, pulled the valve covers off and the timing chains are still under tension and dont appear to have jumped a tooth.

It gets spark, and it gets fuel but will barely give me a putter and occasionally a backfire, so it feels like a timing issue in my gut, but the ecu adjusts timing from the (cam?) sensor that I tested good... I feel like beating my head against a wall with this car, no wonder the shop sent it to me...

Am I missing anything obvious?

 

[FinalImpact]

I put money on the waste spark coil packs! :thumbup: That is if I understood this correct: 4.6L is a V8 and it has two coil packs each with 4 wires?

Unfortunately - ohming them out will tell you little other than "They MAY WORK" UNLESS all of the high energy is leaking through the bodies and going to the wrong places. i.e should be going down the wires and too the plugs but instead are jumping internally.

Simple test is to expose them completely and wait for dark. Have a helper crank the key and watch closely for arc-over between the towers of the outgoing wires.

If it idles - mist them with water. If it kills the engine, its very likely the coils dielectric withstand is so low its easier to jump through the coil body than down the wires to the spark plugs. The hotter the engine and coil, the more likely it is to fail.

- Compression test should give a clue about cam timing. Do a compression test.
- Cam timing. 1993, does that have VVT or just Cam sensors?
- It predates OBDII so there is no info to gain from the ECM.

- If it has compression, and the coils are not leaking, ADD some fuel and see what it does. As in a spray bottle to an open throttle plate OR Open the throttle plate and hit it with starter fluid.
BE CAREFUL THO!!! Bad coils and STARTER FLUID can have catastrophic results! Arc over along a wire can lead to fires in the engine bay as well as trying to start it backwards (acrs to the wrong plug that should NOT be FIRED at this time)....

* Lastly, some sanity checks:
- Connect a Volt Meter to the CPS. Crank the engine. You should see ~ 5V DC pulses w/leads straight into sensor.
- pull the covers off and check the cam timing marks. Verify TDC, #1 Cylinder has all valves closed and it has compression.

That's what comes to mind...

No, I don't work on cars either!

 

[TownsendsFJR1300]

Do you have a ECU plug on the car under the dash you can plug into the computer and look for any faults?

You may want to put a compression tester on some of thse cylinders and verify timing is indeed on. If its jumped a tooth, compression should be off...

If you can get a clip over timing light, slip it over the plug wires and confirm spark as well.

 

[Hellgate]

Good luck and save that rare Yamaha motor.

 

[FZ09Bandit]

Should have attempted a fuel pressure test before just replacing the pump, anyways.

Will it stay running under load like if you keep your foot on the gas? You also need to check for vacuum leaks as well.

Some OBDI Vehicles will have a spot for a plug, but most scanners now days don't like to read them.

Fords do have issues with the coil packs going bad but usually not both, but course it would be so much easier to look at a misfire counter OBDII FTW!!!!!

 

[Project84]

Check the ECU harnesses or ICM harness for bent pins/burn pins.

I have a '94 Z28 that I have been chasing the same random stall issue for years... finally found the issue by wiggling the ECU harnesses while the engine was running. The awesome GM engineers put the ECU's in these cars right under the drip rail for the wiper/cowl.... so it gets a water bath and eventually these harnesses, despite being the weathertite kind, fail. Major PITA.

Hope yours isn't so bad.

 

[FZ09Bandit]

Why does my post go into the weird zone!?!?!

 

[yamihoe]

I did a fuel pressure test which is why I replaced the pump, it was sitting at 11psi with the key on, compression is surprisingly great, within 6psi across all 8cylinders.
I tried carb cleaner and starter fluid, both yielded just a putter. Still will not so much as idle, and every time I try and start it the plugs get soaked in fuel, so I believe plenty of fuel is getting to it, and it is a spark issue at this point.

obd1 is pretty much useless because the codes clear everytime you turn the key off, not that any codes are even being thrown. I can force a code by unplugging a sensor, and it recognizes the open circuit but nothing other then what I unplug.

no vvt for that thur ferd, just 4 o' them fancy bump sticks :thumbup:

I think I will just throw coils on it just to see what happens.

 

[yamihoe]

Should have attempted a fuel pressure test before just replacing the pump, anyways.

Will it stay running under load like if you keep your foot on the gas? You also need to check for vacuum leaks as well.

Some OBDI Vehicles will have a spot for a plug, but most scanners now days don't like to read them.

Fords do have issues with the coil packs going bad but usually not both, but course it would be so much easier to look at a misfire counter OBDII FTW!!!!!

The only way I get the putter out of it is with my foot on the floor.

the ford coil issues are more known for the COP's from the 2v and 3v motors. the bricks are generally more reliable.


I forgot to thank everyone for their inputs!!!

 

[FZ09Bandit]

I have replaced many a brick, your right about the COP.

Hope you find it, it's hard to fix anything without fiddling with it lol.