IronOutlaw

Ok, Im trying to help my buddy get his car fixed. He brought it to a mechanic and they cant seem to find out whats wrong with it but "fixed" some other things that ended up being over $400.

Its a 99 GT automatic. Sometimes for no apparent reason the car decides not to crank. Starter turns over fine, fuel pump kicks on (I havent checked fuel pressure yet), but I think its getting fuel due to the smoke it pumps out after it finally cranks.
Its not throwing any codes. I assume its not getting spark.

When the car finally cranks, which sometimes you have to wait for over an hour for it to, it revs up to 1500 rpms and then back down over and over (The AC is not on when it does this). Then if you put it into reverse it dies and doesnt want to crank again...put it in drive it will pull away and run fine. It runs perfect going down the road and is as fast as a stock 4.6 can be.

Mechanic wants to replace the PCM and the coil pack which is gonna be big money. Anyone have any ideas or had something like this happen before?


Also, another problem he has is sometime when going down the road in OD it will just start revving freely like in neautral, he has to put it in neutral and then back into drive to make it go again. Sound like a linkage problem?

Any help appreciated.

reznap

That sounds like a vacuum leak... other stuff sounds like no spark. Could be a huge number of things interfering with spark. Don't start throwing parts at it, get someone who knows what they're doing to look at it. The shop you mentioned sounds iffy, but I'm not the best person to judge that. I'd get some stuff checked out before you put new coils on there, that's pricey stuff.

IronOutlaw

I figure a vacuum leak would make it idle high all the time, but I will check around. Im not wanting to throw parts at it, the "mechanic" wants to. I think the guy is good with older carberated stuff but not so up to date with computer controlled engines.

someone told me the idle air control valve may need cleaning/replaced. Im gonna pull it and clean it and see if that helps get things rolling.

I just hate to see him throw any more money at this thing. He paid 7000 for it which was way to much and has spent over 1000 on it at the mechanic.

mustangman03

dont waste ur time cleaning it if it is the IAC try tapping on it and see if it cahnges if it does try puting 1 of those on it also try taking it by auto zone or advance to get the codes pulled and see what they are to see if they can lead you in the right direction

devongarver

Well he already said it wasn't throwing any codes, and it takes 15 mins to clean the IAC, so might as well give it a try. BUT, it sounds to me like a PCM issue. If its not the PCM, it could be related to a faulty/failing gear position sensor(i dunno the real name for this part lol) cliffyk would be the guy to ask about this for sure.