91 surging with mind of it's own

[Rythymaxe]

My 1991+ just got back from the shop after almost $1500 worth of needed maintenance, but now it surges,gains and loses power, and the tach won't stay on one spot, even in low idle. I took it back to my friend's shop and he's diagnosing it, but has anyone else had this problem? I had an 89, but other than a clutch someone else did, an on the road surpentine belt, and a camshaft pos. sensor I did it about half an hour, I haven't had much experience in the Yamahauler engine these things have. I know my friend will make it right, but let's have some educated guesses and see who comes up right. I heard that the computer side of the temp control sensor gives it these symptoms, but I don't know. Any experience with power loss and tach ghosts? Thanks all.

 

[randy'sho]

did you have the crank sensor replace when you spent $1500? sounds like the possible problem too me!

 

[itwonder]

The tach issue may be as simple as correctly performing the idle reset procedure. Check for vacuum leaks and loose clamps on air tube between MAF and TB. Run KOER and KOEO tests. Pull codes. Check IAC and MAF.

 

[Rythymaxe]

Randy:

The crank sensor done the day before I bought the car. Checking data today, but the car's not throwing any codes. Thanks for taking the time to suggest that. I was wondering about vacuum leaks also...we'll see.

 

[Rythymaxe]

Mechanic says the Ignition Control Module is bad or going bad. Has anyone else had an ICM go out during the course of doing routine maintenance? The car was running fine when I took it to the shop to find out the condition of the car as I had just bought it. The entire cooling system was replaced and flushed, cam, crank, cam sensor housing seal, and seal at the timing chain were redone. The timing belt itself was new, but the cover was leaking oil, new valve cover gaskets, intake gasket, replaced climate control unit with hard buttons and new pos. battery terminal. Has anyone had an ICM go out and if so, what were the symtoms? I have an aftermarket ICM waiting for me, but was told the motorcraft at $391 would last so much longer than the after market. My mechanic is also a friend, and I don't want to jeopardize this or tell him how to do his job as he's always treated me right in the past. I know the Yamaha is a different animal, therein lies my concerns. I do have someone else who works on SHOs inclusively, and he's given me some other issues I might have, like the grease on the ICM being bad and throwing mixed signals. I don't know how to handle this as I just spent a lot of money on maintenance right after buying the car far from home without the ability to take it somewhere to see if it was worth the sale or not. Confusion reigns supreme.

 

[Kens1992mtxSHO]

If you're talking about the DIS (which it sounds like you are) I have a used spare one. PM if interested. It is a motorcraft DIS.

I had one go out on me and had the same symptoms.

*EDIT*

They can act up when the bolts are not tightened or the grounds are not properly seated. Also make sure there is sufficient heat sink compound on the back of the DIS

 

[Rythymaxe]

Thank you Ken, but I already have one on the way from SHOSource here in Washington State. They have used ones at a fraction of the price of a new one they pull from cars.
Again, thanks and everyone here have a very Merry Christmas and Happy New Year! I hope this DIS takes care of the way it runs. I have faith...(holding crossed fingers behind back).

 

[93rev2sev]

Thank you Ken, but I already have one on the way from SHOSource here in Washington State. They have used ones at a fraction of the price of a new one they pull from cars.
Again, thanks and everyone here have a very Merry Christmas and Happy New Year! I hope this DIS takes care of the way it runs. I have faith...(holding crossed fingers behind back).

It won't. You have a vacuum leak.

 

[Rythymaxe]

The DIS came in the mail two days ago. I took it to the shop, it was installed and now it runs like a new car. This part, along with the 120,000 mile overhaul done 20,000 miles too late, did the trick. I'd like to thank everyone who wrote in to help, thank you for your time and some great advice. I'd like to especially thank Ken for the offer of his spare DIS. It's a truly giving person who would do that for another he doesn't even know personally. I'd also like the thank Mike, the mechanic at SHO Source for all the phone advice and letters he sent trying to get my problem solved. After what my friend and mechanic did to get my car in excellent shape, I feel I can go anywhere now and not have to worry. Again, thanks a bunch guys, I feel very lucky to have people like all of you who help just because.

 

[38SHO]

welcome to the SHO world

 

[Devin]

The probably damaged the DIS. I've heard of very, very few failures just out of the blue.

 

[38SHO]

yeah I never really read the OP I guess...

u paid a shop 1500 bucks to fix your car up and they gave it back to you running like crap?

I would never go back to that place

and the fact that a different DIS fixed the problem, thats awfully suspicous that they harmed it.... if they were in the timing cover u gotta remove the crossover tube with the DIS mounted to it... so they probably whacked it on something or hit it with something....