I have been chasing an idling problem in my 89 and I now think I have a bad computer. The down side to this is I can't get a new computer. Autozone and Murray's don't list one and Ford said it was discontinued.

Heres the number: E9TF-12A650-Z1B

What can I do? Can I swap in a different model in without any problems? There are something like 10 different models to choose from.

This truck is turning into a nightmare.

 

You should be able to locate one at a junkyard..

 

I just got done searching on line for one and there are a couple of yards that have them. I just hope the computer will fix my problem.

I would still like to know if I can swap in a different computer and is there a place to send mine to have it repaired?

 

How did you determine it is your computer?

 

Someone sent me this link for computer testing/repair: http://www.fulllogic.com/

 

Well first thanks or the link.

I have two pages typed up of the things I have done to the truck to try and solve this idling problem. Every sensor has been changed and the voltage meassured on the TP and the EGR sensor. Some sensors changed twice.

I had a post about my flashing check engine light that gave a little detail as to what I have done but not in detail like my typed up pages.

I understand that computers don't normally go bad but I have no clue as to why I have a some what random idling problem. All the grounds are good so what else can cause a code 35? I don't know what else can cause a code 35 so I think I am having trouble with the 5V supply voltage or something from the computer to the EGR sensor. So it's really a guess or should I say I hope that it's bad. It's the only thing that hasn't been changed other than the little valves on the intake with vacuum lines.

I don't know what else to do. What can someone tell me if I take it in and have it checked? They will say the sensor on the EGR valve is bad. I know it's not. I've had three of them on there and replaced the EGR valve itself.

Is there a way to check the computer out of the truck? Does any one suggest something else?

If someone thinks they may be able to help I would be glad to email you the typed up document I have of my jorney.

thanks bob

 

I had a idle porblem (hunting for idle) on a 90 5.0 It was a bad engine, lack of compression on 2 cyl. It would not build enough vacuum. hook a vac pump to the map sensor while engine is running. Then pump up to 17 - 18 inches of vacuum and see if idle smoothes out.

 

I should do that but heres the kicker. The truck will pur like a kitten and then it won't. It just doesn't run bad all of the time only when it wants to.

The plugs look great with no signs of burning oil and the truck has great power.

Most of the time a bad MAP will run rich? When I unplug the vacuum line to the MAP the truck runs real rough and rich.

I will go buy some tools after work to perform what you speak off.

 

Have you checked all the wiring? It sounds like an intermittent short of some kind. It will be hard to find since it's intermittent like that but I think it's more in the wiring than anything else. If a computer goes bad, it will stay bad, and not run good one minute and bad the next.

 

I have looked at the wiring but I have not checked each wire back to the connector with a meter yet. I need a drawing to do that in a timely manner.

Heres why I think its the computer. It seems to be more of a problem cold than after I drive the truck and get it warmed up. I also have swapped out the new ERG sensor with the old one and I had different reactions from both of them.

With the truck warm some one said that it appears to be running fine in the closed loop but not the open loop. I am no expert but I am searching or hoping for anything to show up now and or get the problem fixed. I don't care how at this point.

If some one could answer me why I get code 35 or should I say the things that can cause a code 35 then I would look for them.

Code 35 means the voltage is above 4.8 on the EGR sensor. Now I can't think of a reason why a bad wire or how a bad wire could give me a higher voltage reading so I move to the next best thing, the computer since I have bought two EGR valve sensors already and gotten the same results from both. Not that the above couldn't happen I just don't have the experience to give a good reason how or why it could be.

So it isn't so much that it's bad one minute and not the next. It's more so when I first start the thing up in the morning is when I am having the real problems.

Don't get me wrong. it does seem like things have went one way then the other but I can not put my finger on any of it because I have changed everything so I can not compare the begining problems with what I have now.

I can say that the truck does run smoother than it ever has so I know the tune up things have improved the performance of the motor.

So I will ask to see if anyone out there has the drawings for an 89 4X4 with a 5.8 and C6 so I can check the wires the correct way? Can anyone explain any other related conditions that could apply to a code 35?

By the way, I have a computer on it's way. I am hoping it will be here by this coming Tuesday.

in the morning I plan on checking things when the problems are happening to see if I can see anything different than I have been.