High idel pls help!

lunchmeat

lunchmeat

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OK so I got a 97 MarkVIII LSC and just had a new motor with 50,000 miles on it put in like a week ago. Heres the problem. When I first start the car it idels at 2000 and if you wait awhile it drops to 1500 also when i shift it into drive or reverse it shifts real hard like the car is trying to take off(as in if I wasnt holding the break it would just drive off real quick)Oh and after I put in drive or reverse the RPMs drop to like 500. My dad thinks it will just fix its self after a couple weeks. I dont know. Any help???? :confused:
Thanks
 
What did the place say who did the engine swap. Didn't they do any drive qaulifications ? Have they got the correct MAF installed etc. ?
 
Can you do a vacuum test? Otherwise my first thought is IAC.

Next time try tapping it. Its located near the throttle body and is a small silver-ish canister. Not very big. If you tap it and the idle drops there is a good chance its the problem.
 
The guy that did it said it should work its way out. Also when I'm driving it I get to 30mph and let off the gas instead of slowing down it keeps gaining speed till about 40-45mph
 
Then there is something wrong. Something is causing a high idle. Either the throttle body is sticking open, the throttle cable is damage, vacuum leak, MAF is messed up, etc.

I put a new engine in my car and never had this problem. The only problem I had was with the tires not sticking to the road.
 
My first guess would be the IACV(Idle Air Control Valve). Give it a good rap with a wrench handle. ;)

At least on the Gen2 it's an easy fix. Inspect the harness and plug for any corrosion that may be adding false resistance to the circuit. You may also want to inspect the TPS(Throttle Position Sensor).
 
Read my above post. Its easy to see and find - but not on a 96 or earlier!
 
OK guys this is what I did. I bought a new IACV and put it on this morning and it helped lower the RPMs at start up a little(they seem to drop quicker) and it doesnt seem to keep accerlating from 30 to 40 like I said earlier. But it still shifts really hard out of park(like it wants to take off) So where is the throttle body positon sesor at??? Anyother suggestion??? Thanks for the help.
p.s. should I take back the new IACV to autozone??? It was $50?
 
OK. Starting to get mad now. I unplugged the throttle body control sensor and the RPMs droped to about 800-900 and it shiffted just fine. So I put on a new one. And everything was going good till I took it out for a test drive and it died on me at 3 stop lights. WTF??? Why is it doing this?? I guess I'll just take it to ford and let them hook it up to the machine and figure out whats wrong with it. Unless one of you guys know something els I dont??
 
while it is at a high idle, go under the hood and manually shut the throttle body. i think your cable is too tight or the bracket may be bent. try to manually shut it. if it idles down, then that is your problem.

Try it.
 
Were vacuum leaks ruled out yet? Throwing cheap parts to fix a problem is one thing, but replacing what you have adds up! A vacuum gauge is like $12.
 
Ok I did the manual shut off you suggested already and it just shut the car off. Honestly I have no idea where/what a vacuum gauge is/looks like. Any pics please?? My dad keeps telling me just to take it to ford and let them put it on the machine. but thats like $70+ I took off the parts I did put on there cause they didnt help.
 
you shut the throttle body manually and it died??? am i understading that one correctly???
 
Ok when I unplug the IACV it just dies. Now if I unplug the throttle body sensor it drops idle to about 800-900 and acts fine. I put a new sensor on it and it seemed like it fixed it accept it would die at stop lights(did it to me 3times in a row) So should I go out and get a vacuum guage?????
 
OK bring it back. I took the car to the guy that put the engine in. He hooked it up to his machine to see what it said the problem was. It came up with the TBS. So we put back on the new one and ran the test again. Still says the TBS but this time it reads a higher voltage(still idles high while in park) He didnt have time today to mess with it anymore so he suggested to goto autozone and have them test it so I did. Same thing! The TBS. Why? I just put a new one on. WTF?
 
Pull the harness at the main connection, locate the right pin (pain in the butt) and use a multi-meter at both ends I guess.

Are you sure your getting the correct TPS? Maybe try another, if its bad they should exchange it.
 
Its the one autozone pulled up on there computer. Its located on the throttle body. And it looks exactly like the one I pulled off.
 
Held on by screw not bolts, right?

At any time you did play with the idle screw on the TB, did you?
 
They are held on by screws yes. There is no idle screw. And if one is on there please tell me where?
 
No, cause it should not be touched :) Not sure though if you have one, the Gen 1s do.

Did you at least check vacuum yet?
 
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