SEFI Questions

[jeffdukovac]

My truck seems to run OK at 20-25psi on the fuel rail. If I kick the pressure up to were it should be - 37psi it will die if you pop the throttle.

Also experiencing hard start condition when warm (have to keep the starter on a little after the motor starts to fire (to keep it running))

Ran codes and it says I'm running rich and the O2 sensors aren't switching. Checked the O2's and they are switching.

I am going to try a computer off a 93 T-Bird tomorrow and swap in a different HP fuel pump.

Any suggestions to get it into closed loop?

Motor:
347 c.i.
92 T-Bird computer and harness
adjustable fuel pressure regulator (within 1 lb to a reference gauge)
24lb injectors
70mm MAF calibrated for 24's
65mm Ford throttle body
long tube headers

Jeff

 

[jeffdukovac]

? No one has an idea ?

 

[crawln68]

There could be other things going too, but you need to have your MAF, injectors AND the ECM all calibrated together. Running the 24 lb injectors you will need to run a X3Z ECM from a Cobra mustang or have a custom chip burned for your current ECM.

 

[Broncobowsher]

I will bet that it is a problem with compatable parts. The MAF probably tuned for 24lb injectors and a Mustang computer, not a t-bird.

I could (and have in the past) gone into great detail about how I hate aftermarket MAFs. How the calibration isn't just the MAF, but how the computer reads the signal from the MAF to determine things like load and spark tables.

Here is a table of 2 different Ford MAFs. Notice that they are not even scaled the same. Make a chart out of them and the lines cross.

Mustang speed parts are there to make mustangs go fast. Full throttle in a quarter mile. Drivability means that they can start, make it through inspection and idle good enough to go through the pits at the drag strip. Are you sure these are the parts you want on your bronco?

 

[jeffdukovac]

The 2 charts you show are for different size motors - one for a Lightening (351?) and a 3.8 V6.

They shouldn't be the same as the flow demands for the different motors would be different and the weight of the vehicles are grossly different.

I borrowed another computer from a T-bird that I am going to try out.
Found out that this computer is listed as a Mustang computer.

 

[mountain14er]

If you let it run till hot at high fuel pressure, shut it down for 15 min to an hour and then recheck the fuel pressure, will it drop at all? The hard warm engine restart almost sounds like leaky injectors and a loss in pressure after sitting could confirm that.

 

[SaddleUp]

Found out that this computer is listed as a Mustang computer.

That would be a problem. The wiring between the T-Bird and Mustang is different. They don't even use the same components. (The T-Bird doesn't even use the MAP/BP sensor) Other problems include at least one injector that wouldn't even be working. O2 sensors mixed up, and smog stuff all mixed up. (CANP and TAD reversed, etc.)

 

[jeffdukovac]

The new computer(s) both came out of T-birds (one a 93 and the other a 92) but I have seen them listed as used in Mustangs also.

The harness and efi components I am using are off a 92 t-Bird which is basically the same as a 94-95 Mustang with the curved upper plenum.

A complete cross reference list of all the computers would be really nice to find,
the only list that I have found is in the document:
Technical Notes on the EEC-IV MCU written by Tom Cloud.

 

[crawln68]

Look on www.fordfuelinjection.com. Ryan has a pretty complete list of ECM's and EEC codes for your viewing.

 

[SaddleUp]

The new computer(s) both came out of T-birds (one a 93 and the other a 92) but I have seen them listed as used in Mustangs also.

The harness and efi components I am using are off a 92 t-Bird which is basically the same as a 94-95 Mustang with the curved upper plenum.

A complete cross reference list of all the computers would be really nice to find,
the only list that I have found is in the document:
Technical Notes on the EEC-IV MCU written by Tom Cloud.

Yes, the 94/95 Mustang ECM is pretty close to the same wiring. Check the link in the post above. It has a chart to compare the pins between each of the particular systems. Actually here is a direct link to the page: http://fordfuelinjection.com/5.0Lpinouts.html

 

[jeffdukovac]

Found some interesting things this evening.

My code reader with the original computer would show that it was testing 6 cylinders and with the new computer it would test 8 cylinders.

I also found that #3 injector was not clicking, so I'll assume that it is open all the time, giving me a rich condition. Couldn't check the back 3 injectors on the left side due to the upper plenum.

Guess its time to pull all the injectors and try to clean them.