View Full Version : Help!!! sound like a vacuume leak?

10-18-2006, 03:03 PM
when i start the mustang it instantly revs to about 3000rpm. im thinking vaccum leak, but im not 100% sure.

i didnt use any silicon or any sealer on the intake gaskets(from heads to lower intake) could that be a problem? i did last time but forgot to this time.

any other thoughts?

oh, and i just had the motor apart to swap headgaskets....

In The Zone
10-18-2006, 03:18 PM
A vacuum leak in to the valley would not cause it to rev @3000

DOH! got silicone..................

Sounds like somthin else does it come back to normal or stays there?
check your linkage on the tb im not sure how your efi works but i know the idle is not adjustable well easily

10-18-2006, 04:48 PM
should i pull the intake and silicone to rule that out? linkage is fine, and the idle does come back down, but no matter how much gas i give it it revs way too high, and when it idles it sounds like the cam is huge

10-18-2006, 04:49 PM
is the cam huge?

well is it

10-18-2006, 04:50 PM
no, i think its like 220 or 224 duration, 5.29 lift

In The Zone
10-18-2006, 05:01 PM
if it is coming back to normal then runnin rough like u got a big cam

could be the iac leaning it oout after it is warmed?
asssuming iac = incoming air temp.......

and yes i would personally re do the intake.... a lot o work but worht it and do not reuse your gaskets ..once torqued they should be tossed....

that aside efi is a real bear to daignose some times... good luck man

this is why i went with a tbi setup on my 302 for the BII

simplicity and the conveince of EFI

10-18-2006, 05:05 PM
ok im gonna pull the intake then and see if thats it

Always broke
10-18-2006, 05:24 PM
NO don't pull the intake just yet get a propane torch (not lit) put it near the common intake leak spots if the engine changes RPM then do it but do this first but it does sound like the iac if ya got more questions call 604-854-3699[cheers]

10-18-2006, 05:26 PM
its not iac i did nothing to any of the other stuff, gonna pull the intake anyhow just because, and i dont have a propane torch

10-18-2006, 05:28 PM
the torch works good unless its leeaking from the lifter vally id pull it better safe than sorry

10-18-2006, 08:02 PM
it was from the lifter valley, siliconed her up, runs like a champ, no detonating, now i just gotta get a light on this thing and its good to go

In The Zone
10-18-2006, 11:10 PM
power time it much better or if ya need i got a light.......bring it over...