[mustangdrvr2019]

ok it doesnt matter whether its hot or cold outside but when i start it up the car idle like shit. the rpms will bounce from 1500 down 500 almost to the point where it sounds like it gunna stall but then jumps back up 2000. i will do this for about 25 seconds before settling at 1000 and then runs fine. does anyone have any ideas on what the problem could be? all i have on my car is a CAI, underdrive pulley, and predator diablo performance tune.


thank you
david

[AtlanticBlue99]

could be the tune, but what brand and type of u/d pulley? i had a 42% motoblue crank pulley warp with engine heat and crack my harmonic balancer, ultimately throwing off my timing and causing a roush idle that fluctuated from 1200-700 and back.

also, you may have a leak in a seal on the engine from either of the intake manifolds.

are you throwing a CEL?

[mustangdrvr2019]

yes i also have the motoblue 42% reduced underdrive pulle. i dont think it has anything to do with the tune because it has been doing this long before the tune and pulleys were installed

[AtlanticBlue99]

Well hate to break your heart, but you too have fallen victim to motoblue products. I wasted a couple hundred bucks with new fuel filter, air filter, spark plugs, etc. befor taking my sluggy car to the lincoln/mercury dealership to get the new 1 piece ford crank pulley/harmonic balancer, longer belt, and new intake manifold gaskets.

I guarentee you have a leak somewhere be it vaccuum or seal for the intake

[einod]

Agreed.

[00SoSlow]

IAC? possibly

[mustangdrvr2019]

why have i been a victum to motoblue? i stated that i was having problems before installing the pulleys and tune. how long did it take to your underdrive pulley to warp. i have never heard of anyone else having problems till now. im not saying you wrong its just that why do all these forums tell us that we should buy the motoblue underdrive pulley if we are gunna have problems down the road.

also how do i check to see if i have a leak in either the intake manifold or the vacuum line

thanks
david

[AtlanticBlue99]

Originally Posted by mustangdrvr2019 why have i been a victum to motoblue? i stated that i was having problems before installing the pulleys and tune. how long did it take to your underdrive pulley to warp. i have never heard of anyone else having problems till now. im not saying you wrong its just that why do all these forums tell us that we should buy the motoblue underdrive pulley if we are gunna have problems down the road. also how do i check to see if i have a leak in either the intake manifold or the vacuum line thanks david

You could have had a minor problem until you got the pulley- then the pulley could have warped with engine heat in no time if it was a hot season, or a few months if it was a cold season. Mine warped from Jan 05- Mar 05.

If you had a minor leak somewhere, it could have nothing to do with the pulley, but I would rule out checking your harmonic balancer to see if it looks like mine did when I took it off...

The diagnosis is either to your idle air control, intake manifold gaskets, any other air/fuel component, or possibly comething simple like the problem I had but wasted a couple hundred dollars diagnosing...

You can spray some carb cleaner around the block to see if your rpms surge. If it surges from the outside of the block, you have narrowed down the location of a leak.

[ben1380]

Originally Posted by AtlanticBlue99 Well hate to break your heart, but you too have fallen victim to motoblue products. I wasted a couple hundred bucks with new fuel filter, air filter, spark plugs, etc. befor taking my sluggy car to the lincoln/mercury dealership to get the new 1 piece ford crank pulley/harmonic balancer, longer belt, and new intake manifold gaskets. I guarentee you have a leak somewhere be it vaccuum or seal for the intake

How can you say he has fallen victim? He had the symptoms prior to installing the parts...Then you go one to say that it's a vaccuum leak????? Please explain.

If it was a vacuum leak, I think the symptoms would occur more often. It could be the IAC or something else.

Try running some seafoam through it.

[99mustang232]

a high or erratic idle is consistant with a intake gasket leak, what type of CAI do you have, because you might also want to inspect your air intake tube... if you have a k&n filter sometimes excessive oiling can cause issues, doesn't hurt to properly clean your MAF sensor and check your IAT sensor or even clean your IAC.

[AtlanticBlue99]

Originally Posted by ben1380 Originally Posted by AtlanticBlue99 Well hate to break your heart, but you too have fallen victim to motoblue products. I wasted a couple hundred bucks with new fuel filter, air filter, spark plugs, etc. befor taking my sluggy car to the lincoln/mercury dealership to get the new 1 piece ford crank pulley/harmonic balancer, longer belt, and new intake manifold gaskets. I guarentee you have a leak somewhere be it vaccuum or seal for the intake How can you say he has fallen victim? He had the symptoms prior to installing the parts...Then you go one to say that it's a vaccuum leak????? Please explain. If it was a vacuum leak, I think the symptoms would occur more often. It could be the IAC or something else. Try running some seafoam through it.

I had the exact same problem and brought up the brand issue before he posted about what exactly he had. I am trying to help with diagnostics...

It is air/fuel related for sure, as I said in both posts. Seafoam won't fix a leak.

Also, any leak like this will grow worse over time.

[ben1380]

Not sure it's definitely a leak. If it were a leak I think it would happen more often than just 25 seconds after starting up. It would happen every time he was sitting at idle...at stop lights, etc...don't you think?

Anyway...run seafoam through it...easiest thing to do first. If that doesn't fix it, at least it'll clean it out.

[Twist 2 Go]

Originally Posted by ben1380 Not sure it's definitely a leak. If it were a leak I think it would happen more often than just 25 seconds after starting up. It would happen every time he was sitting at idle...at stop lights, etc...don't you think? Anyway...run seafoam through it...easiest thing to do first. If that doesn't fix it, at least it'll clean it out.

usually yes, but some of the o-ring type gaskets shrink when cold and then expand after a little engine heat has occured. 3.8's in Windstars are bad about the intake o-rings shrinking. I've never seen it happen in a mustang though. Usually, you'll get a mil light w/ a vacuum leak though. I'd ck the iac and throttle body personally as well as all the tubing connections at the cai. If using a oil-type air filter, also might try cleaning the maf as over-oiling a filter will contaminate it.