Won't Fire....

[TNRanger]

ok, so I put the tranny on and bolt up the starter. Turn it over and get 1 code a 552. So I go tracing clutch switch wiring and find a blue/yellow and grey red not matching up at the ECM. Fix those, scan again and get a 1 1 1. So now I try to start it with all systems go... still no fire. I pulled the #4 plug wire to check for spark. I don't see any, but it backfires with that plug undone. Now I'm cornfrused(read drank too much or not paying attention)....... Fuel is being delivered cause the smell of raw petrol coming outta the collector is sickening. Missing spark would make sense, but why in the world would it backfire with one plug undone when it never did with it hooked up. I am left with the conclusion that when rewiring injectors I've managed to screw up the firing order. Due to the fact that I'm not getting a single code now other than a 111 and fire must be present in order for it to backfire.

Tell me what yas thinks.

James

[Digger]

In a DIS system like the 4.0 uses, the plugs are paired together to complete the circut. If you pull one, it will effect the other.

I don't know what you have all taken apart on your truck, but check the injector wiring. I don't know about the newer 4.0's, but mine (93) is MPI which means that there are only two channels to the injectors and they are fired in groups of three. This makes it harder to mix up the injectors, but if you have SFI, each injector has it's own channel coming out of the computer and it is crucial to get the wires on correctly.

Edit: Just saw one of your other posts. Did you do any research on the 95 4.0 to make sure it was MPI? I know the '92 computer would be unless it was from Cali.

[TNRanger]

Did plenty of research. I cleaned the 95 4.0 completely and rewired it MPI. It was of course SFI. I've determined that it is the computer and I'm gonna order a reman from NAPA as soon as I get my 4-link finished. I kept getting a NSS/Clutch sw error. Hooked up a 91 x computer and didn't get the error (the computer was looking for a map it didn't find, but it didn't have the clutch switch error until I unplugged the clutch switch. sooo I assume that's the prob.

[Digger]

:cool: :toast:

[Mustang]

You are not using the firing order from a haynes or chiltons manual are you?One of them is wrong,haynes I think.Hook everything up and won't fire a bit,Check to see if you have power at the coil pac,also check for proper ground.

[TNRanger]

Yah, I believe it was the haynes manual that is wrong. I used the Mitchells Electrical to do the wiring. I have DOUBLE checked continuity to every single wire from it's connector to it's origin(ground, EEC module, Gauge, etc...) The wiring should be in perfect order. As soon as I get my 4 link finished i'm gonna order the computer from NAPA and we'll know the problem for sure :) Thanks for the suggestions.

James