ryan_89_mustang

I have a shudder at around 1500rpms which is most noticeable in first and second, also at idle theres a shake at idle as well sometimes. Does anyone know what this could be or what I should do to find out??

brentloftis

It sounds like a vacuum leak to me, possibly timing but I doubt it. There are several ways to check a vacuum leak, sound being common but a little difficult if revving at 1500 RPM. My favorite way is with a propane plumbers torch (not lit of course) and a run of rubber hose. You turn the propane on and move the hose end all around your vacuum ports and hoses and listen for the engine to even out, telling you where the leak is. Others use aerosol cleaners like carb or brake cleaner and give each suspected location a quick spray to check. Both can be dangerous but work pretty well, I just prefer propane.

Edit: Oh and a common area I have found is under the upper intake plenum.

ryan_89_mustang

hmm, that sounds like it could be it I may try that I have a couple propane tourches in the basement. I was just thinking it couldn't be my plugs could it?, would it miss all the time if that was so? Also is there another way to cheack for vacuum leaks other then flamable stuff like could I feel the air?

brentloftis

http://www.harborfreight.com/cpi/cta...emnumber=41966

ryan_89_mustang

Update, I couldn't manage to find a vac leak, but now once the car has been started from cold it doesn't want to start when warm. It with start and wants to do its usual surge but goes to low and dies. I can prevent this by holding her at like 1800rpms for a couple seconds but still this is very annoying.

nseoi

i got the saaaaaaame problem, i just raise the idle a bit and it made it better, i know thats not a fix but hey i cant afford anything right now

ryan_89_mustang

Nice to know I'm not the only one haha. Was yours stalling without giving it gas? how much did you turn the idle up?

nseoi

yea like in the morning i would start it and this:

the idle would go to like 1100 for a few secs then drop to 800, then begin to surge between 1300 and 400 for a few times until it went too low and would shut off. so what i do now is let it idle, but then when the surging begins i keep my foot on the pedal just enough for it to 'catch', a few seconds like that and i can drive off. and yea it shudders in 1st if i let off the clutch too fast, sometimes even in 2nd and 3rd. as long as the RPMS are high the car is a dream. whatever, until i can fix it im ok, its just one of those things...

i have the idle at like 850 now

ryan_89_mustang

Okay, Thats simalar to what mine is doing but I only get one surge and it cuts out but this only happens when warm. On cold starts it will start perfect. My idle is pretty high too its idle close to 900 when warm.