My '90 302 5 speed manuel transmission balks and hesitates between 1200 and 2300 rpm. In the past the computer was replaced but I don't know if the replacement came out of an automatic or standard. I was told that they are the same but he wanted to sell the thing to me. Are the computers different for standard and for manuel? If so, how do you tell the difference? Does anyone know of a chip or tune source that I can contact for a overhaul of my computer. I have added a comp cam that comp recomends for truck applications and I hope this is not my problem. Any help is appreciated.

 

Yes, the computers are completely different. Especially if the computer is from a truck that is supposed to have an E4OD in it. The ECA's (main EEC-IV computers) are programmed with software that optimizes engine performance based on shift patterns and know operational parameters of the major dirveline components in the vehicle. If the computer has the wrong software for the driveline components in the vehicle its controlling, there is no way to reburn the correct information to the ROM chip. The part numbers on the computers themselves determine what vehicle, engine, and driveline it should be married with. Best bet is to look up the P/N on yours and cross-reference it against what SHOULD be in there.

As for the cam, is it speed density-ignition/injection-friendly? Truck applications are one thing but if its not recommended for speed density applications then your problem is right there.

 

Thanks for the helpful reply. I have rebuilt the engine. The cam is a comp cam 31-255-5 with lobe sep. of 114 degrees, which is said by comp to be designed for truck with speed density (MAP) application. I can't find any vacume leaks and the gauge shows high vacume at idle. I tried removing the egr vacume line thinking that was the problem - no difference. Oh, the only sensor not replaced was the MAP.
If I knew where to have the computer operation stress checked, I would send it and ask to have the thing optimized with a new chip or something, but I can't find anyone who does these models. A Canadian source told me he would have to have the truck as there are too many variables in these models to do this without it The dealer near me said he would do this and charged me for testing, left vacume lines open, then told me the a/c didn't work, astonishing in that the a/c gas lines, etc. were then currently spread all over my garage floor. Not confidence building. Does the computer come out or is there a part #. readable w/o removal? If I have to take it out, do you or the board know where can I send it for test and/or replacement. Thanks for reading my tale of woe and any reply.

 

The difficulty is that the computer is mounted behind the electronic shift control module unless your transfer case is also a manually shifted unit (manual shift means no control module). So to get at the computer you end up having to dig through the other wiring and electronics in that part of the truck. You may be able to clear the module and read the P/N but I just can't recall at the moment. Someone here may.

In truth, if the computer still allows the engine to run, its probably fine. The failure rate of the EEC computers is about one in every 150-200,000 units and its usually due to some other electrical problem shorting something vital to ground. The fault codes will pretty much indicate any issues with the system. You can pull the codes (which is most likley what the dealer did) with a Haynes manual and a paperclip if needs be. The dealer came back with the A/C issue moreover because the KOER test cannot be administered unless the A/C compressor clutch circuit can be monitored by the computer. The KOEO and KOER tests are the two in-car diagnostics tests available when delaing with EEC-IV-equipped vehicles. I would administer BOTH tests beofre making the assumption that the ECA has gone south on you. KOEO is a static test and KOER is a dynamic test.

 

Thanks for the suggestion. The hesitation comes on a slow to moderate accleration - not wot. I will pull the codes and go from there. I've enjoyed working on the truck but don't know anything about the computer stuff. Guess I am too old to want to learn but glad I am not too old to be able to. I am more concerned that the current computer may not be correct, not that its not working as designed. Thanks for the suggestion. A friend with the tool to pull the codes will help me do this tomorrow. Thanks again.

 

check out www.fordfuelinjection.com also if there had been an E4od ecu installed in your bronco it would for sure store some codes missing the tranny but should not affect the driveability of the motor. Check the codes like Grey mentioned and let us know what comes up. you can also cross reference the id of that ecu under your kick panel on that site to see which one you have

 

A friend and I tested for trouble codes. None on either KOEO or KOER. The problem does show up more under the added strain of the A/C compressor - I noticed that the hesitation is worse when the A/C is on. I thought mabe the compressor was cycling and that was the cause of the hesitation/balking on slow accleration - it feels kind of like that. However, the compressor doen't cycle off and on. The compressor is new, not rebuilt, and has about 1000 miles on it. Its smooth, quiet and cold.
The timing is advanced 10 degrees at idle as the cam manufactor suggested. I suppose I could have a damaged plug wire but wouldn't that show up more on wop accleration? The injectors are ford parts and new, so I rule that out as a source. Also, it is more noticeable when the engine is hot. It seems to do better when the engine is not completely up to full temp. The air charge and coolant temp. sensors are new and they are ford parts. I hope the headers, high flow cat and 3" exhaust system isn't causing the computer to overcompensate with rich/lean adjustments.
Any suggestions where to look next? It's almost certianly got to be something small, but I am out of ideas for the time being. Help is appreciated.

 

when you set the timing you did remove the spout connector correct.

 

Yes. I disconnected the spout before I timed it. I don't know if I can safely push the timing to 12.5 or so. I don't know if that will help or not. If anything, it might make the problem worse.