Computer 101 please
 

Fellow enthusiasts,
My car has had a rolling idle problem, actually it sometimes just goes to 2500 and stays there. First I cleaned the IAC, then replaced it (from Ford), the TPS, and TB. Nothing seemed to work for more than about a week or so. Then I realized that it's a complete random problem. If I disconnect the IAC it runs fine.
If I disconnect the battery for an hour, it'll run good for about a week. Then the problem comes back.

So now the dealership says I need a new computer. The problem, they say, is they aren't in the inventory any more. Is that BS?

Will any computer from the junkyard work? Do any of you have a computer sitting on a shelf you don't need anymore?

Thanks,
Rob

Yeah it is pretty stupid. Ford only has to keep parts for so many years. I would think that they would keep the computer though. Being that your mustang is an 89, I dont think your computer is any different from a 90-93. As long as its for a mass air setup. Of course you need an eec-iv for an auto or 5 speed. I would go on ebay and get something from there. Take a look at this one, its from an 89 5-speed. http://cgi.ebay.com/ebaymotors/ws/eB...category=33596

Good luck

Got it, thanks for pulling that link up for me. I called around and OReilly's has one for 118.99, what do you think? Does is sound like the computer? The codes it pulled up were for a clutch sensor and A/C compressor sensor. Neither one of them would cause the idle to go to 2500. So I'm thinking computer.....

Any other opinions?
Rob

If you have already pulled codes up, then I would fix whatever is causing the codes before I spent the money on a new computer.

Also, the A/C compressor code may cause some weird idle problems. When the compressor is running, it is loading the engine. At idle, the computer will make adjustments to keep the engine idling high enough since their is a load on the engine caused by the compressor. It may or may not be causing the exact problem you are speaking about, but I would get those codes cleared and fixed before I bought a new computer.

What codes do you get off your computer. I agree with what Hethj7 says. I have a Ford Fuel Injection & Electronic Engine Control book that does refer to A/C causing idle problems under certain situations.

Thanks for your votes, I'm just going to take this one as it comes, sometimes you win and sometimes you don't. This is a "didn't win" situation. I'm just going to take it to Ford and drop it off and let them deal with it to chase it out. I hate to do that, but this problem has been plagueing me for awhile now. I'll post an update next week, it goes in on Monday. Thanks anyway though-
Rob