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. I've got one. I'll take some readings the next time I've got the Jeep out.

    Judging by the build of the Jeep, I am confident that the guy who built it knew exactly what he was doing. As far as I'm concerned he must have been an automotive genius to get everything to work together like he did. He didn't cut any corners either. He used the best of everything, even when it came to little details like the rubber fuel line. The custom fabrication he did is outstanding as well.

    Unfortunately his brother (who I bought the Jeep from) was an idiot and didn't know much about the Jeep's build. He could only brag about all of the trails he had done in Moab with the Jeep.

    Keep in mind that the Jeep has likely been built like this for well over 20 years, so any issues with incompatible parts would have been dealt with long ago. I was told that back in the day the Jeep had been magazine featured as one of the first CJ-7 builds to use a 5.0 with the EFI setup. That may or may not be true, but it's cool to think about.

    Crap! I had the upper intake manifold off several days ago when I was fixing vacuum leaks. I didn't even think about writing down any part numbers.
    #41 5.0 CJ-7, Feb 28, 2014
    Last edited: Feb 28, 2014
  2. I just took some pictures of the engine. I'll attempt to get them uploaded somewhere and linked into this thread.
  3. Update 2/28/14

    Despite knowing that the ignition control module was already bad, I opted to take the Jeep out for a little test run through a desert wash this afternoon. Expecting that the engine would quite likely die on me, I took along a very large bag of ice and had a friend follow me with his Jeep. Sure enough, after about 20 minutes of driving the engine died.

    To address Mustang5L5's question about the temperature of the ignition control module, I took several readings that ranged from 135 degrees up to 158 degrees. Obviously that's a large variation, but given the location of the distributor I expected there to be a sizeable range of error anyway. For comparison, the radiator and several spots on the engine block consistently showed between 192 degrees and 200 degrees, so all seemed right there. After checking temperatures I placed the large bag of ice against the ignition control module and waited roughly 15 minutes before the engine would start again.

    Do those temperatures seem typical for an ignition control module?

    This evening I picked up a new BWD Select ignition control module (under warranty) and a new BWD Select ignition coil to go with it. While I doubt that there is anything seriously wrong with the current ignition coil, I did witness it arching in the dark last week after spraying water on it and the spark plug wires. Now just about everything ignition related will be new, and I will also have more spare parts to carry on the trails.
  4. Since you probably have a few dead TFI modules laying around, you might consider tearing one up to use it to make a remote adapter for the TFI. Use the old module to make an adapter to mate the distributor connector to a 3 wire harness. Then you can us to move the TFI to a heatsink that is mounted is a cooler spot. The whole business should cost less than $30

    Or see http://www.mccullyracingmotors.com/index_files/tfikits.htm - $55.
  5. I am curious about something. According to the results of the class action lawsuit against Ford (CLICK HERE), the TFI modules are prone to failure (engine shutting off) at 257 degrees Fahrenheit. At what temperature do they typically begin to cause drivability issues (jerking, hesitating, backfiring, stumbling, etc.) without the engine actually dying?

    Also, I have been researching possible causes for repeated TFI failures. Information available seems sketchy at best, but this is what I've come up with so far:
    • heat (obviously the most common cause of failure)
    • ground problem (often mentioned but not confirmed)
    • wear/slop in the distributor shaft (no mention of what is considered to be normal and allowable movement)
    • weak/leaking ignition coil (a few mentions but no confirmation)
    • faulty EEC
    • faulty relay
    What am I missing? The new TFI and ignition coil are installed, but I haven't wanted to start the engine yet in case there is something else that might be causing the problem.
  6. Try this link for testing the modules you have to determine if they are bad. I would test a new one, record the values and then run it.

    Also, try and grab a motorcraft module. I'd even trust a new one from a boneyard over the new chinese electronics these days.

    The 94-95 use a remote mounted TFI. There are links on relocating the TFI on a fox body off the distributor.

    Sorry if i've seen quite lately as i'm traveling for business and my internet is sporadic

    EDIT: Would help if i put useful link

  7. This is already on my list of future modifications. :)

  8. I do want to go check out a couple of local junkyards. I rarely see Mustangs around here, but I know that TFI modules can be sourced from other vehicles as well.

    Also, please don't apologize for any delayed responses while you are traveling. You (and the others who have responded in this thread) are absolutely awesome! I will probably never get the opportunity to shake your hand and thank you in person, but I do hope you know how much I appreciate your help.

  9. I've never seen a TFI fail so easily before on a 5.0. Yes, i've seen the cheap ones fail, but they usually last a bit of time. To have yours failing so readily makes me wonder if they are the cause, or the result of other issues.

    Any way you can get some pics uploaded to a photobucket account? WOuld just like to see what's under the hood to see if anything jumps out as "Hey, that shouldn't be there" or "that doesn't look right" if you know what i mean.

    Also, Ford engineering part numbers would help out greatly in identifying the motor. Basically, on a 5.0, you will see a bunch of parts start with E part numbers. The E stands for decade, in this case 80's. So a part that starts as E7 was designed in 1987 and usually comes on 87-later Mustangs. If you were to find F1 part numbers on the car, that would suggest a 1991 designed parts, and usually signifys a later motor. This could be quite helpful in determining what it is you have. For instance, right behind the distributor should be a part number cast on the lower. It might start RFK-E6ZE or something like that. The E6 tells us it's a 1986-later designed part. However in this case, the lower isn;t that important. The upper intake is better as an E6 part would suggest to us a 1986 Mustang intake, OR a 87+ standard output 5.0 intake, while a part number with E7 would suggest an 87-93 5.0 HO mustang intake. This isn't critical so don't go ripping stuff apart, but good to know to start to ID stuff on the engine.

    Parts I'd love to see...the distributor, and any associated wiring on it, the injectors, and the engine overall.
  10. Well, there are a few pictures that I didn't get around to posting the other day. As you can see the engine certainly isn't show worthy, but it is a thing of beauty nevertheless. LOL!
  11. Looks right at home in a Jeep if you ask me!
  12. So what's up with the intake manifold/TB facing the driver side?
  13. The intake manifold can mount either way. Certain ford's flipped it around for clearance.

    I don't know what engine is in the Jeep, but here's some observations


    Here's a 1986 Lincoln Town car 5.0 engine. I don't know what's in the Jeep yet, but if you look at the two engines, the intake manifold is the same. Now this engine is standard output 5.0 with about 150HP. There are some differencec between it and the 86 5.0 HO in the mustang.

    Looking at the engine, i think i see grey top injectors which suggest 14# injectors. Would need to see a closer shot

    I also see 1984-1985 Mustang valve covers designed for a carbed engine. When running EFI, this may cause an issue with vacuum leaks, idle hunting, surges, etc. Could also cause a lean or rich condition. It's not really appropriate for an EFI engine. They have a vacuum hose running from the TB down to the cap on the valve cover. This seal needs to be tight. I'm curious what they have on the other valve cover to block that port?

    Also, the accessory system has been changed to a Mustang setup. So who knows what else is changed.

    Now, if this is a 1986 town car engine, it does not have the HO firing order. If they are using a town car computer that's fine, but I just wonder what the cam is that's in the engine, what computer (if running the 14# injectors) and the spark plug wire firing order. I'm curious to if that all jives.

    To make a long story short, the engine looks like it has a mix of parts on it.

    Also, the EGR system doesn't work because the vacuum port is capped off and the EGR vacuum system is not present.
    #54 Mustang5L5, Mar 4, 2014
    Last edited: Mar 4, 2014
  14. The intake plaques look the same to me, but I see a lot of differences in the casting marks on the intakes. I'm not familiar enough with 5.0 engines to know if that means anything.

    To me the injectors in my Jeep look more white than grey. It's tough to say for sure though. If they are a grey, they are an extremely light grey. I can see what looks to be E67E-B(?) on the injectors (the last letter/number or two can't be seen). That could mean they are 19# injectors, right?

    I don't know if it helps, but on the injector harness tag I can read the following:

    I was told by someone else that the valve covers look like '85 Mustang valve covers too. That would seem to support the previous owner's notion that the block and EFI setup are not from the same vehicle.

    Or maybe it wasn't changed. I don't want to assume anything that could lead down the wrong path of diagnosis.

    I still want to know if a 5.0 engine would even run if the firing order (HO vs. non-HO) is wrong. Can anyone answer this for me?

  15. Update 3/4/14

    I finally started the Jeep today (new TFI module and ignition coil installed). It runs like total crap! It stumbled and jerked around when I attempted to drive it down the street. Even the smallest of stabs at the throttle kept resulting in backfires out the intake. It didn't even seem to idle well.

    Since the engine previously passed the cylinder balance test, I highly doubt there are any mechanical issues like a sticking valve or problems with fuel delivery at the individual injectors. My gut tells me this an ignition problem. I'm now wondering if the distributor is off. That wouldn't explain the engine running worse than it previously did, however, since the distributor has not been removed since the new pickup sensor was installed.

    I may go shopping for some chocolate bars, marshmallows, and graham crackers this evening. If I decide to torch the Jeep I might as well be ready to make s'mores while watching it burn.
  16. Only real way to know is to check the underside for the part number. E6 would suggest a Standard 5.0 intake, or a 1986 Mustang HO intake. E7 or F1 would be a 1987-93 5.0 mustang HO intake.

    19# injectors are orange. Those came on the 86-93 5.0 HO in the mustang and lincoln Mark 7. Light grey injectors are the 14# injectors that came on the non-HO 5.0 engine.

    Can't get much off the part number. Need a complete number off the injector. The harness tag just comes back as a harness

    They are. The issue here is there could be vacuum leaks. Need to see how the previous owner blocked off the hole on the passenger side cover. EFI needs to be completely sealed so this is prob a minor issue now, but you might want to swap to EFI covers in the future.

    It will. The non-HO engines use a computer that uses batch-fire. It means that all the injectors fire at once. So it will run fine with the HO firing order. The cam is what determines the firing order, so with an HO firing order, one should assume it has the HO cam inside it. Easy way to find out is to swap the firing order and see if it runs. The compouter (unknown at this point) could be a non-HO and just fires the injectors at once, so if you swapped the cam to a non-HO cam, it would still run.
  17. BTW, i see the a/C compressor hooked up but not actually connected

    If you want to remove the heavy compressor, this is what you need


    Relocates the power steering pump up slightly higher, so hopefeully you have some slack in your lines.
  18. Thank you for that information, but the A/C compressor will be staying right where it is at. Eventually I will be converting it for use as an onboard air compressor for airing up tires (off-roaders air their tires down at the start of a trail for better traction and a less jarring ride) and maybe running air tools.