Engine Please Help Me Diagnose Issues With My 5.0...

Discussion in 'Fox 5.0 Mustang Tech' started by 5.0 CJ-7, Feb 24, 2014.

  1. This tells me the EEC is for a manual mustang. Still, i'd find it and runthe numbers to confirm.

    On the Mustang, there is a harness that connects to the top of the transmission to indicate neutral, as well as to the clutch pedal. usually to run the codes requires the clutch to be pressed in, and the trans in nuetral.

    Who knows if this was wired correctly in this case. This is rumored to cause idle surge issues, but hasn't been confirmed. Worth investigating how this circuit was plumbed up.
  2. Thank you very much for your posts, Mustang5L5. There is a lot of great information in them. I'll reply to a few of your comments and questions below.

    This is good to know. The EGR vacuum regulator is long gone like most of the other emissions stuff (giving code 84), and that is why there is no vacuum connected to the EGR. I will leave the electrical connector plugged in though.

    I think part of your post got cut off here. What sensors could possibly be faulty? In other words, if I unplug the O2 sensor harness, does the computer start ignoring signals from other sensors like the ECT in addition to the O2 sensors? Knowing what sensors get ignored could certainly help me narrow down the problem. Also, I will see what information I can get from the EEC. The transmission is a manual, so hopefully the computer is from a manual transmission car. Likewise I would hope that the computer is from a speed density car since there is no mass air flow sensor.
  3. This is very interesting. I will try to get a picture posted soon. For the moment I can tell you that the intake plaque looks similar to the 1986 plaque you posted, but it reads "FORD 5.0 LITER EFI".
  4. I have been using the ignition control modules that can be purchased with lifetime warranties from O'Reilly and AutoZone. Last night I picked up another new one from AutoZone, and I will install it this afternoon. I have always used generous amounts of the white heat sink compound. I have never used the clear dielectric grease even though that is what some parts suppliers and most parts store counter guys seem to think is correct for the application.
  5. Might not even be a Mustang engine. It could be a 5.0 standard output engine that came on various town cars and crown vics, thunderbirds etc. There are some differences. #1 being the firing order.

    Using a mustang computer with a standard output 5.0 firing order could cause some issue. You def want to dig out the computer and identify it, and then focus on identifying the engine
  6. I was told that the engine came from a Mustang GT, but obviously I'm not going to take that as fact. The firing order has always been arranged in the HO order, however, so that leads me to believe the engine is from a Mustang. For the sake of argument, how would the engine run if it was a non-HO with the firing order arranged incorrectly? Also, how do I identify the engine to be sure?

    Pulling the computer is going to be a nightmare. It is tucked up behind the dash of the Jeep and only partially visible by opening the glove box door. The wires are facing the glove box door, so if there is a way to identify the computer by just looking at the end with the wires I would love to know.
  7. You just need the part number located on a sticker on the end of the computer. Can you see that?
  8. Update 2/27/14

    After spending way too many days working on the engine, I finally felt the Jeep was ready to take out for a short drive. This morning I installed the new ignition control module, reset the timing again, bumped the base idle up a half turn, and then left the battery disconnected for half an hour. After that I cruised the Jeep around my neighborhood a little bit before parking it on the street. I never dipped into the throttle while driving around. This was meant to be just a very slow, easy cruise.

    When I came back to the Jeep half an hour later, it wouldn't restart. Suspecting a heat soak issue, I propped the hood up and let the Jeep sit for another 20 minutes. After that the Jeep restarted, and it continued to run with the hood up with no issues other than a backfire out the intake when I stabbed the accelerator hard. After about 15 minutes of running the engine at varying speeds I pulled these codes:

    KOEO: 81, 85, 82, 84, 10, 14
    KOER: 12, 94, 44, 33
    Cylinder Balance Test: 90

    Codes 12 and 14 are new. The others are always there. Code 12 (high idle) comes as no surprise since I had tweaked the base idle. I'll turn the idle screw out a quarter turn, reset the computer, and test it again later. Code 14 (ignition profile pickup circuit failure) makes me mad. The distributor was just rebuilt with a new pickup sensor and ignition control module. What the heck is going on here?
  9. Of course not...

    This is important to me, so I just pulled the dash apart and retrieved the computer. The "engine control computer" sticker (which also indicates "remanufactured original equipment") has the following information on it:

    Number: 8-4331
    Calibration Code: 1100MG
  10. Any other numbers? Starting with E7 or E9 or anything along the lines? Pretty much post anything you find on there. The more info the better.
  11. This is the way it goes when working on this Jeep. Nothing is ever easy. The only other number on the sticker is 91-1088-77, but that looks like a label number or something like that. I can see E4AB-14A297-AB on the red gasket in with the pin connectors. E4LB-14A459-B and SMB-2C can be seen on the plastic around the pins by moving the foam gasket out of the way.
  12. That makes things tough. The computer is probably not a OEM computer than an is an aftermarket reman perhaps. Hard to ID what its in this case.

    The other two part numbers are just PN for the components that make up the EEC...and don't tell the programming.

    You are basically looking for a sticker like this

    In this case U4P0 would tell us it's a 94-95 Mustang computer.
  13. That figures. It is definitely a remanufactured OEM computer, but any factory stickers must have been removed. I spent multiple hours on the Internet yesterday trying to ID it based on the limited information I do have. All I found were a few obscure threads on other forums with guys having the same problem of not being able to identify their remanufactured computers.
  14. So moving on...

    I reinstalled the computer and took the Jeep for another short drive. This time I went outside of the neighborhood. The engine is definitely stumbling and hesitating, likely because of whatever is causing code 14. As soon as I returned home and parked the Jeep, I propped the hood open. After about 20 minutes I went back to the Jeep and felt the distributor behind the ignition control module. It was still HOT!

    I think it is safe to assume that this new ignition control module was either questionable to begin with or cooked itself very quickly. I'll go to AutoZone this morning to swap it out for another one. Regardless, something needs to be done to help control the heat on these things or they will surely continue to fail on me. Are there any other ignition components and/or ground/wiring issues that could possibly be causing the ignition control module to generate so much heat?

    A remote mounted ignition control module (something like THIS) may be a future project for me, but for now I need to deal with what I've got.
  15. Can you determine the firing order currently being used?

    Standard 5.0 firing order is 1-5-4-2-6-3-7-8
    5.0 High Output firing order is 1-3-7-2-6-5-4-8

    The cylinders are numbered 1-4 on the passenger side front to back, and 5-8 drivers side front ot back. Start at cyl 1 on the dist and go anti-clockwise
  16. I wonder if there is a wiring issue or something causing the module to overheat?

    Is the unit hot from heat soak of nearby components...or is it overheating internally?
  17. The engine has always had the HO firing order, which is a big part of the reason I assume it came from a Mustang (see post #26).
  18. I am wondering the same thing, but I don't know what to look for. I always thought the ignition control module was heat soaking from the distributor, but now that I'm examining things more closely it seems that the flat surface on the distributor that the ignition control module mounts to is much hotter than any other area of the distributor.
  19. Do you have an IR temp gun? Or can you get one? I def think this needs to be investigated as there is no way you should be going through TFI modules that quickly. I'm still running the original ford module from 1988 on my car. It's never been changed.

    As for the engine, it is possible the intake plate is just swapped onto a Mustang 5.0 engine, but it would be nice to know for sure. Can you see the injectors? What color are they? Are they orange?

    What i'm getting at with the engine/EEC is that if that engine is not a Mustang 5.0 HO engine, and is a standard output 5.0 from a cougar, t-bird, crown-vic, then it has some physical differences between it and the HO engine. The firing order is a main issue, and the non-HO computers were mostly batch fire. Swapping in an HO cam would work, but required an ECM change to run properly.

    This thread seems to hint at what I'm trying to explain

    Basically, i'm trying to identify your parts and see what the person did. It's quite possible a part or two is incorrect causing your issues. We are making a lot of assumptions here based on the previous owner doing the conversion correctly. But hard to know.

    Also, if oyu notice in the above link, it shows an intake manifold with a part number on the underside. Can you use a mirror to see this part number to identify the intake?