LoOp

Hey guys, Having trouble with a 92 rs i just bought. Has a 5.0l TBI / 5spd trans. When i got it, the car would idle itself up and down really fast, so i pulled the iac and cleaned it. This didnt help. Then i put a new map sensor on it, which helped a little, but not much. Heres something odd, If i unplug the map sensor, car idles fine. It wont take the gas when i try to drive it, but in nuetral it runs awesome. The guy claims the car ran perfect until it sat untouched for 6 months (maybey a lie?). He says they put a stage 2 chip in the computer also (possibly screwed it up?) . This is my first time around on a "computer controlled" v8 and im lost. Any help would be highly apreciated.

transxtreme

Try getting the stock chip back and start by elimination. Get back with the results.

Token

oxygen sensor.

LoOp

Put a stock computer back in the car with the same results. Wont take the gas but no check engine light. Tried to read the codes anyway, got code 12. What usualy goes bad from sitting on Tbi engines? Guess ill just go piece by piece putting new sensors on it until i fix it. Sooner or later im bound to improve something lol. I caught up with the previous owners of the car, they said it ran perfect when it was parked. Then when it was cranked up again to sell, it wouldnt take the gas and revs up/down at an idle.

transxtreme

Take off your air cleaner, start engine look at the injectors and watch the gas as it goes into the TB, Rev it and see if your getting enuff gas. Not enough gas try the fuel filter, prolly clogged from sitting, which is a possiblity.
If that doesnt work try the relay and pump.

slimdawson

If the pump comes on at all, the relay is good. Technically, it could cut off and on sporadically but more than likely, it won't.

Injectors could be clogged or stuck. Everyone of my injectors(LT1) got stuck after months of sitting. I tapped on them with a wrench to get them working again.

You may have water in the gas from condensation that could have formed in the gas tank. Run some gas drier in it as well as an injector cleaner.

LoOp

I watched the gas from the injectors at an idle. It has a very good spray, but starts spitting and it tries to cut off. Both injectors do this at the same time, so im guessing its something else. I did try tapping on them just in case but it didnt help . I was told the IAC on the throttle body should be able to move in/out with little pressure, but it takes me beating on it to get it to go in. Should i be able to push the shaft in by hand on this sensor? I also noticed a wire which has been replaced going to a relay on the firewall. Im guessing its the fuelpump relay, but i dunno for sure yet. The wire is run to a switched 12v+ on the fuse box (very profesional huh). I figure it may be running on a low power source so ill try running it to the batt directly to see if that changes anything. Thanks for all the help guys, any suggestions are much apreciated.

anthony714

yeah the worse thing you can see when buying a used car is mods........new chips and wires coming from nowherea bad sign,but not the end of world...first try to undo someones elses screw up...relace the crappy chippy with stock first..u dont need it anyways,,then figure out his wiring job..then look at the trouble code..dont discount it..i dont have the codes for your year but in earlier yars thats a signal code usually associated with the distributor connector.....but research it first..this thing u have call the internet very powerful...a bad sensor or other problem can wreak havoc on a computer controlled engione since it will do all kinds of funky things to try to adjust to the faulty signasl its receiving..also the sporatic squirting u saw could be the ecm trying to adjust to that trouble code since those injector pulses or squirts are controlled by an electrical signal from the ecm..but one word of advice and take it...diagnosing is tough period especially in a chat room...do your homework first,use the tools u have including the net,befopre you start replacing parts,you can replace 99 out of 100 parts and still not fix it,doing that is just guess work,you may guess right or u may guess wrong,and even if you do guess right eventually,what did it cost you???if you feel above your head spend a few bucks and had an experienced tech diagnose it and decide if you can do the fix yourself or have him fix it...it may very well end up costing you much less........i know we all kinda like to do our own thing,but you said it best in your message..somethign on the lines that this is your first computer controlled car an u know nothing of it...then why guess or pretend u do..let someone who does know