just installed new motor and idles high

[Champ10187]

I just installed a compplete drivetrain and wiring harness (computer and everything) out of a wrecked mustang. Ran perfect and idled perfect before i yanked it and now when i start it up it idles from 1300-1400. lowest i could get it was 1100 and that was by turning the idle screw all the way. I dont think its a vacuum line cuz the boost/vac guage shows about 18" at idle but i dont know if that can rule out a leak. any possible suggestions??

 

[motrV8ed]

Could the the Idle Air Control solenoid...the long one on the side of the TB. Try takin it off and cleanin the hell outta it w/ some carb cleaner. Basic place to start, then I'd also keep my eye out for vacuum lines.

 

[Champ10187]

im almost positive thats not it cuz why would it be fine before the swap. i unplugged the selenoid and the idle dropped to about 1000, that means its working, right?

 

[motrV8ed]

I would take that as it being stuck or gunked up. You'd be amazed at how many times I've come across something that messes up that was working 2 minutes ago!

 

[bmo37]

could be a vaccum leak, does the idle sound eradic and lumpy, recheck all the vaccum lines and listen around your intake for leaks. Thats usually the case when removing the vaccum lines you sometimes end up ripping a small gash into the tubing and don't notice or feel the effects till the cars back together. The only other things that contribute to the idle setting are like stated the iac, the t-body screw which you should leave set so the flap is completely closed with no slack, or the eec where you can program the idle in.

 

[jrichker]

With 18 inches of vacuum, there probably aren't any leaks that would cause your problem. 18-20 inches of vacuum is excellent for just about any engine.

 

[Champ10187]

could be a vaccum leak, does the idle sound eradic and lumpy, recheck all the vaccum lines and listen around your intake for leaks. Thats usually the case when removing the vaccum lines you sometimes end up ripping a small gash into the tubing and don't notice or feel the effects till the cars back together. The only other things that contribute to the idle setting are like stated the iac, the t-body screw which you should leave set so the flap is completely closed with no slack, or the eec where you can program the idle in.

no the idle does not seem lumpy at all.

there is hissing noise coming from the back of the intake...right between the intake and the firewall. Are hissing sounds signs of a vacuum leak?

 

[bmo37]

no the idle does not seem lumpy at all.

there is hissing noise coming from the back of the intake...right between the intake and the firewall. Are hissing sounds signs of a vacuum leak?

yes sir hissing is not good. You can take carb cleaner or wd40 and spray it around where u think the intake is leaking you should hear the engine rev or make an different sound than usual if in fact it is leaking, Have to be careful cause I had a exhaust leak which sounded similar to and intake vaccum leak.

Question what exactly did you do I know you said drivetrain and harness but did you have the intake off?

also a few other things what kinda of eec did you intall, also do you have a bypass valve installed on your sc setup?

 

[Champ10187]

no i did not have to take off the intake. I changed everything basically, fuel fuel lines, all harnesses and computer. It is the stock computer but it has a chip in it tuned for the engine combo.

And yes i do have a bypass valve for the blower. i'll try the carb cleaner and let you know what happens.
thanks
Chris