Problem #1
To start with, I am unsure of the exact year of the engine. I was told that it was an earlier block ('85-ish) that had been upgraded with a later EFI system ('89-ish). Personally, I think the guy who I bought the Jeep from was on crack. I do know that his brother built it, but that is about the only thing he told me that I believe. If my research has been accurate, the EFI components appear to be from an '86 or '87 car as there is no mass air flow sensor. Also, I find it very difficult to believe that someone would go through the trouble of transplanting a Mustang GT engine into a Jeep only to come back a few years later and swap in an entire EFI system complete with the computer and wiring harnesses. I suspect that the entire engine (complete with EFI, computer, and all wiring harnesses) were pulled from a wrecked '86 or '87 Mustang GT, but how can I find out for sure?
Problem #2 (hopefully not really a problem...)
The catalytic converters and most of the emissions components are long gone. It was like that when I bought the Jeep back in 2010. I would have personally kept the stuff if I had done this conversion myself. Regardless, I'm not looking to reinstall any of the stuff at this time since I rarely drive the Jeep. Here are the codes that have always been present. They have never concerned me since I understand what they are and why they are there.
KOEO: 81, 85, 82, 84, 10, 11
KOER: 94, 44, 33
Interestingly enough, the EGR valve is still mounted on the intake. It has no vacuum to it (accounting for one of the codes), but I've never known if I should keep the electrical connector plugged in or not. I'm not sure what effects either option has on the computer, so for now it has been plugged in.
Problem #3
This thing loves to kill its distributor. I estimate that in the past four years I have rebuilt the distributor six or seven times. Since the Jeep is not a daily driver, that represents a lot of work for very few miles of enjoyment. I will expand more on the specifics of this at a later time.
Problem #4
What's up with these engines and the whole surging idle thing? I'm not sure that I have ever been able to get this engine to idle properly. Recently I've gone to work on this problem again, and this time around I'm determined to make it perfect. So far I have done the following:
base idle -- set to 600 RPMs
timing -- set to 10 degrees
IAB/IAC -- fairly new and very clean
TPS -- fairly new, passed all voltage tests, adjusted to .97 at idle
vacuum leaks -- all new hoses and/or plugs installed, new PCV grommet installed
10 pin connectors -- clean with dielectric grease
fuel filter -- brand new
fuel pressure -- 40-41 psi (KOEO), 35 psi (idle), 42 psi (idle with regulator disconnected)
EGR -- clean (but see notes under problem #2)
grounds -- primary grounds checked and cleaned
edit- spark plugs have only 1000 miles on them and the spark plug wires are brand new.
Problem #5
I have found that the engine seems to run well when it is cold. The idle is smooth, and I can stab the throttle with no hesitations or stumbles. I assume this is when the computer is in an "open loop". As the engine gets hot, the idle starts getting rougher with some surging, and any stabs at the throttle result in heavy hesitations and stumbles.
There have never been any O2 sensor codes present, but as part of my process of elimination I disconnected the O2 sensor harness to see what would happen. Much to my surprise the engine idled perfectly with great throttle response when it was both cold and hot. Unfortunately I am not sure what this means. By disconnecting the O2 sensor harness, did I force the computer to remain in an "open loop" where it is ignoring all inputs (including the ECT sensor, for example), or was the computer only ignoring input from the O2 sensors (which would seem to indicate that they are the problem)? I need to know what effect unplugging the O2 sensor harness had on the computer.
Problem #6
Last night I had the engine idling for quite a while. Quite unexpectedly it died and then wouldn't restart for almost half an hour. My gut tells me this is another ignition control module on its way out. (See problem #3.)
Problem #7
On rare occasions I get code 67 (neutral pressure switch or clutch switch circuit failure) when doing a KOEO test. This of course prevents me from doing a KOER test as well. The code usually goes away fairly quickly, but I read some discussions on how code 67 can cause a surging idle. The transmission in the Jeep is a manual with "granny low" from an older Ford F-150 or F-250. There don't appear to be any wires coming out of it, so I'm not sure what occasionally causes code 67 or how to troubleshoot it.
This Ford stuff frequently has me pulling my hair out.
