Fellow Fordsters,
My 1985 F150, 302/5.0L, AOD, EFI truck is giving me heartburn with foul running issues. The truck starts well, but is running very rich, and has very rough idle. All codes have been reconciled, all sensors replaced, fuel injectors cleaned, fuel pressure tested and ECU and wiring checked for defects, new spark plugs and high tension wires together with a new distributor cap and rotor and TFI module. Yesterday, after giving up in despair I took it to a "computerized diagnostic" center. The tech said the computer reported trouble code 18, problem in the IDM circuit This code was stored and I retrieved during KOEO test, this morning. I cleared the codes and during another system test (KOER), with my code reader, the engine will pour out billows of black smoke during the WOT- goose test, returning to idle and running very rough and hunting and eventually stalling from running so rich. Plug readings, as can be imagined, are BLACK and sooty. The computer did not repeat the code 18 problem after clearing it and running the engine through the KOER tests, and no KOER codes are being reported! The engine has good balance between cylinders and very good compression. Engine vacuum, is in the "normal" range, except when the engine begins to stumble, which causes the needle on the gage to report erratically.

Timing chain has been replaced and the upper intake manifold has a new gasket, and is properly sealed. Vacuum connections/plumbing have been thoroughly tested for vacuum leaks, including the brake booster. Timing has been set according to specs. The electrical system is running at over 13.4 to 13.8 volts.

Today I checked resistance in the IDM circuit and found to be 22K ohms (pin 4 to corresponding pin on TFI connector) at the distributor, which is what is specified in the manual. Wiggling wires and all of that found no defects. A new catalytic converter was installed less than 300 miles ago. I've replaced the ECU with one known to be working, no did not observe any difference in the way the engine runs. After wringing out the wiring again, for the N-th time, I started it up and, as usual, it ran good for a few minutes and then after warming up a tad, began to stumble. Yes, O2, ECT and ACT sensors have been replaced, and so has the MAP sensor, TPS, EGR valve and position sensor, TFI module and just about everything but the wiring harness which, again, has been throughly wrung out. One observation, is that the engine smooths out when going from neutral to drive/low/rev, and when shifting back to neutral it begins to run very rough and, in some instances, stalls. Is there somthing on the transmission I may be overlooking??? The idle speed control bypass is tested and working properly, and the upper intake manifold completely cleaned of sludge. I have no idea what to do next! PLEASE HELP!!!

I have read just about every book and information on the web regarding this subject. One would think I'd have a clue, by now!

As usual, any advice or shared knowledge is greatly appreciated.

Norman C

 

Maybe have the fuel pressure regulator replaced or change the fuel filter that is located in the cannister on the driverside frame. Im not talking about the silver inline filter, this one is in a round black canister that unscrews like a jar lid. Good Luck

 

Thanks for your input. However, the fuel filter (main) and the fuel pressure regulator have already been replaced. When this problem started, one of the first things I checked for was proper fuel delivery to the system. On suspicion, I replaced the fuel pressure rgulator. No change in operation was noted.

Regards,
Norman

 

A few questions are in order....What model and year did you take the ECU from? Did also match the code that is on it (sometimes its a paper tag- these has to match the same as the one you replaced) Was it the same year and model and the same engine as yours (The ECU that you replaced/ swapped)??

The other solution is the convertor or a sensor thats in the transmission. (which I doubt if you had no prior problems before you swapped the ECU (IF its the same code as before)

Lastly, the ONE thing that you did not mention is the KNOCK Sensor. These do go bad and act just like what you described.

Did you REBOOT Properly? Meaning disconned the ground cable from the battery for a min of 30 min, then do the 10 mile road test? Then do the KOKO tests and the KOER tests. Notice the WOT test is quick, to the floor one time at the time the tester is ON and you are in test mode, Engine running, normal operating conditions. Code 77 will come up if its not done right, but it shouldn't keep the engine from missing.

Black smoke could mean a injector is leaking slightly, but after a while, your cal. convertor will clog up and the oxygen sensor would create a fault condition.

These are some ideas you haven't mentioned but need to correct if you haven't done so already.

 

18 (rc): Loss of TACH signal from TFI (Thick Film Integration- the module on the side of the distributor) module to the PCM. There is an open in the SPOUT circuit. Suspect SPOUT connector.

 

Code 77 (r): No goose detected during Dynamic Respose test. Rerun test, goose it harder. If this code is received during cylinder balance test, then a TP change was detected- rerun test, making sure not to disturb the throttle as it is running.

 

Code 98 (r): Hard fault present. The PCM is running in FMEM (Failure Effects Management Mode), so something is royally screwed up that the KOEO test should have told you about. Rerun KOEO and fix whatever you find there.

 

Last but not least, Don't forget to REBOOT EVERytime you replace a sensor. And do the road test....These 302 EFI engine depends on the sensors to work properly before the computer will.

 

Thanks for all of the responses.
First off, the borrowed ECU was identical to the one installed at the Ford factory. It was only used to see if there was any difference in the way the system performed. Once that was establishshed, the original ECU was reinstalled. NO changes/improvements, whatsoever, were observed.

I don't know what a KOKO test is. SORRY! I'm familiar with KOEO and KOER, only. I've searched the manuals and find no reference to it. The knock sensor is the only one in the lot that has not been replaced. I have one and will install it tomorrow. As you can tell, I've capitulated to this problem and no longer question anything.

THe codes have been, at various times, cleared by using the code reader, per the manufacturer's instructions AND by disconnecting the battery for an extended period of time. Either/both work in clearing the stored codes. I do this after each run, irrespective of the type of test performed. It is difficult to operate a car that stumbles and stalls on the public roads, so ten mile drives are out of the question, until it displays some semblance of civility and is able to operate for more than a couple of minutes without stalling. The catalytic converter may well get clogged up if I continue to run these fruitless tests. But, for now, not even the professional shops know what to do with it, nor do I, for that matter. This EFI system is a complete POS in my opinion, and that is putting it mildly! I do believe the system is confused, and emits an occasional ghost code. I've chased countless numbers of these and replaced the O2 sensors, ECT and ACT at least six times, to no avail. Three EGR valves, all of the vacuum solenoids, and three MAP sensors. The only thing left to replace is the purge canister and the knock sensor, which, I don't know what it has to do with a rough idle, I must admit.

The TFI module and the other part have been replaced and the one thing that is consistent is a fat healthy spark to the plugs. Failing that, with as rich a mixture as it is getting, the plugs would not be able to fire. I have tested the connectors to EVERY sensor and to the coil and ignition components. No amount of wiggling or pulling causes any loss of continuity. Each pin to the ECU, and its correponding wire/connectors, have been throughly checked for cleanliness and electro-mechanical condition.

The fuel system was completely cleaned, injectors cleaned with an ultrasonic cleaner, checked for spray pattern and new filters and Orings installed. The fuel rail was cleaned and pressure tested, together with the fuel pressure regulator and fuel pump.

I will, test the fuel return hoses for obstructions tomorrow, just in case there may be a kink in one of the hoses or something.

Thanks again!

Norman

 

Coresair---->I'm going thur the same issues. But I get backfire from the intake during stop and go driving. Also I noticed, that when I stand on the accelarator, the tranny doesn't "kick" down to 1st. By any chance that module in the tranny has a problem???? Let us know what you find.

 

Coresair, have you fixed your problem? Well, I kinda gotta "grip" with my issues. My original problem was, after the engine gets to operational temp and ONLY in stop and go driving, it will stall, backfire thur the intake and die. After waiting for about 15-20 mins it would run and it would stall, backfire and die. Well, after searching this forum, I found a forum member had the same issue. He found the distributer was at fault. So, I put in a dist from a 90 Lincoln Town Car. No backfire, stalling or dieing, yet. But a have misfire issues. I need to recheck my timing.

 

I was advised by a local smog repair station to take my car to a smog test only station and have it fail the the test. The reason for this is that the people's republic of California has a smog repair assistance program in place, for autos that fail their outrageous tests, as well as a limited buy-back program by where the State pays you 1K for the carcass. My registration was due for renewal and the idea had some validity, and so I did just that. The truck would not even get on the dyno long enough to produce a failed reading, so I was back to square one, another fifty bucks in the hole. I returned to my mechanic and informed him of what had occured. He took another look at it and could not figure out the problem, he checked everything. I was charged another sixty bucks for that viewing. Now, my tags are expired and the truck runs like s***. I am fresh out of ideas and have limited resources to fix the darn thing. The computer still puts out ghost codes which have been chased, ad nauseam, and no fewer than three of each sensor is in the box of parts, which have been replaced on suspicion, at one point or another. Someone suggested the transmission may be an issue, (failing to run on the dyno) but I can hardly see how the transmission would cause the engine to hunt and stall at idle, in neutral, under no load? Am I missing something here? My next step -- under consideration -- will be to buy an old truck (pre '75) so I can get away from these oppressive smog rules, and use a carburetor rather that that POS Ford F/I system. You may be able to tell, I've reached my limit of frustration with this.

 

Well I made it home. Damn, thing backfires, stalls and dies under load. Coresair I'm in the same boat. After major thought, because it only backfires, stalls in "stop n go" driving. On the highway, i have no problems. I replace the "cat" and distributor. I'm wondering, do I have some "bad wiring" somewhere? I know some forum members will say, "Stop poring parts into the vehicle and troubleshoot the problem." Well after following the recommended steps to fix the problem, you still have the problem!!!! I know if we put our heads together we will figure this out.

 

What codes are both of you getting? Have you replaced the computer with the same code thats on the computer (label sticker is on it)?

 

The codes i'm receiving i
31------>EGR, PFE or EVR circuit below minimum voltage.
44------>Thermactor air system inoperative.

I've pulled the plugs and they are "black". It looks like the engine is running rich. Some sensor is telling the computer to pour more fuel and make it run "crappy". TPS, O2, MAP? What other sensors could make the engine run so rich?