Brand new to this forum and I'm hoping someone here might be able to help alleviate the want to merge my head with a solid object.

1991 Jeep Wrangler Renegade ( bare with me )

With a "90's" LT1 ( 90's is in quotations for a reason, bare with me )

Paperwork on this vehicle states motor came from a 96 z28, and that the ECU/PCM was flashed with a (insert unknown year obd1 flash here) caprice to circumvent a programed in limiter? (that's the story) injected, but not direct injected, uses the coil for and 86 caprice, all married together as what i can only describe visually as a baby between the flying spaghetti monster and a painless wiring harness (P/N 60502). It "looks" like it was installed by a professional shop according to the paperwork.... Had to preface all of this in prep for: There are two OBD ports in the jeep, 1 obd1 that looks to be a part of the original jeep harness ( doubt it will give me crap all ) and the other is an obd2 port, with three wires in it, directly connected to the jeep obd1 port. I have a cel light but no way to read it. Jumpering the wires as if it was an obd1 leads me to believe one of two things; 1- its obd2, or more likely. 2 it goes nowhere as its plugged into a dead harness.

Runs absolutely fantastic, scalded dog and what not for about an hour or at least until you shut it off. (give or take 30 min) Then when attempting to start back up will only run on 4 cylinders (sounds like it) let it cool off and fires right up for about another hour. OR it may die on you while driving. Initially though was a fuel issue.

New:
FP
FP harness back to relay
FP relay
Fuel Filter
1 new injector 7 cleaned injectors
ICM
Coil

Potential problems i suspect:
#1 Opti
#2 injector control relays (PWH)
#3 Fuel pump

Potential problems my friend suspects:
Fuel delivery
Pump circut

 

The only F-Body LT1 year you can “jumper” the ADL pins and flash the codes on the CEL (if that’s what you meant) is 1993. Totally different ECM from 94-97. 94/95 OBD-1 needs an OBD-1 scanner, or software like Scan9495. 96/97 were OBD-2 and require OBD-2 scanner. Never heard of anyone putting an OBD-1 program in a 96/97 PCM. 96/97 owners who want to avoid the invasive emissions diagnostics embedded in OBD-2 simply install a 94/95 PCM. All years references are for the F-Body (Camaro/Firebird) PCM's. B-Body (Caprice/SS/Roadmaster/Fleetwood) are slightly different. Then there's the Y-Body (Corvette) 92-96 variations.

Just to add to the confusion - 94 F-Body was OBD-1 with a 12-pin ADL, 95 F-Body was OBD-1 with a 16-pin ADL. To use an OBD-1 scanner on the 95 16-pin you need to jumper the wires (courtesy of Shoebox):

http://shbox.com/1/xraycable.jpg

F-Body ADL/DLC connector wiring, all years (Shoebox):

http://shbox.com/1/DLC_wiring.jpg

Would need more info/photo on using the “(ignition) coil for the 86 Caprice”. Not an LT1 modification I've ever heard of. Also unclear what the reference to “direct injected” is.

 

Hook up a fuel pressure gauge and monitor it while driving. That’ll at least rule that in/out as a cause.

I imagine a part number from the PCM would help Fred and any other LT1 experts identify what we’re working with.

 

Could he open the PCM to find either EEPROMS or the soldered chip too? The presence of removable PROMS would indicate what...93?

 

93 has the removable chip, at least in the F-Body. Not sure about the 92/93 Corvette.

I'm not familiar with the PCM part numbers. Appears they have additional alpha-numeric coding on the label that indicates the program that was in them when they left the factory. Not familiar with those details either. I replaced my 94’s PCM in 2000 with an aftermarket engine management system from MoTeC. It was capable of running a complex system consisting of normally aspirated ~500 HP plus two stages of dry nitrous bringing the total flywheel HP to 762. Also capable of running 8 coil near plug ignition like the LSx cars. User programmable, built in data logging, diagnostic codes, etc. Only kept the factory PCM to feed the speedometer, and manage idle air control.

 

Sorry for the delayed response, DI - Everyone keeps asking me if its direct injected like they expect me to have a Gen-V in the jeep, so was just a clarification.

As for photos i will do my best to get something uploaded in the am.

 

45-47PSI under load, 43psi at idle.

I will grab from ecu in am, though i believe it has that removable chip that you have to take with you to the new ecu? But i will double check.

 

43.5 PSI (3 bar) at idle, with the vacuum compensation like disconnected from the fuel pressure regulator. GM tolerance spec is 41-47 PSI. When you reconnect the vacuum line the pressure will drop proportional to intake manifold vacuum. Typical drop with a stock cam is 8-10 PSI below the “no vacuum” pressure. Less drop with a more aggressive cam.

Best test is tape gauge to windshield. Take it out n the road, WOT @5,000+ RPM, should hold at least 40 PSI (small pressure drop due to remaining intake manifold vacuum due to air flow pressure drop across air filter and through ducting).

 

Without going to the airport, the only places near me that i could get to WOT and be able to get out of first gear are over an hour from where i live ( tourist town and the police are akin to **** Germany gestapo)

 

You can do it in 1st gear.

 

Sorry for the delay in photos things keep popping up, problems with incoming parts as well as existing ones.

 

Super sorry for the delayed response.

So Motor has been changed due to excessive magnetic material in the pan. Which includes NEW:
MSD opti
Plugs
Wires
Knock's
CTS
VC's (old ones cracked and leaking)
grounds and straps

RUNS like a top for LITERALLY 13 mins and dies, suspects, fuel and ecm atm, restarts immediately since the CTS has been replaced (ecm signal not gauge)

 

Go back to post #2 and answer question regarding “(ignition) coil for an 86 Caprice”. The coil from a 1986 Caprice would not be compatible with the LT1 ignition system. Could you possibly mean 1996 Caprice, which used a version of the LT1 engine.

Have you had the ignition control module (ICM) tested by an auto shop? The ICM is susceptible to heat soak, which can prevent the engine from starting. When testing the ICM make sure it gets heated up by repeated testing.

 

Yes i did mean 96, Well the icm was replaced. I finally tracked the problem down to a series of shorts in the 20yo(guesstimate) painless wiring harness. located directly under the fuse box, cut out 6 inches of harness and completely re did the fuse box. Daily driver now, still working out some of the aftermarket lighting that was on it. However i wanted to give you all an update. Doubtful but someone may run into something similar?

 

Always good to hear how you worked it out.