Repzard

Hi Forum, I have a 99 Mustang Gt for starters.
I just replaced the intake manifold yesterday do to which i thought was a crack in intake but ended up being a bad intake gasket on driver side need thermostat inlet.

Well car got put back together after insatll of intake and it ran awesome.

Drove car around for a few so computer could relearn after battery was unplugged for a while install.
Still ran well.

Parked car at my house for about a hour then took it out to grab a bite to eat,about a hour there.

After that came out drove car home and about half way home the car started to miss fire really bad and idle crappy.
Miss fires in rpm range 1000-2000 rpm then smooth out a little but I can still feel the power lost.

Now what I think it maybe is a bad COP or Fuel Injector.
Also was reading it could be a stuck open or close EGR valve or IAC could be dirty or malfuctioning.

Anyone have this same problem after install of new intake manifold that might be able to shed some light on the problem.

Ps..I dont see any leaks(coolant) after install of manifold. and dont have a steady SES light but it did flash a few time when problem started but didnt stay on.

Hope some can help

Thank You

fausty

Try cleaning the IAC with carb cleaner. Do you have to hit the gas to keep the car running? Any codes?

Repzard

No dont have to gas it to keep it running.
But it does idle roughly.

Havent check yet to see if there is codes stored.
have to find my ODBII scanner or take it to autozone for free scan

Thing that gets me is it ran so good after install of intake manifold for a while then all of a sudden out of the blue it started missing.

Anyone think it could be a loose spark plug or coil?
I even replace all the boot on COP's with new one while it was apart.

I heard also egr valve could be stuck open/closed?

Just gets me

Repzard

No one has any other ideas to check?

Repzard

Well I got home from work and figured what heck I will start up the Stang and see how she runs, Double check all wires, coils and vac lines and everything seems ok except coils kinda wiggle a little on bolts,not side to side but rides on bolt (should the coils(Cop) do that or should they be nice and tight no movement).
Well the Stang ran pretty good and no miss at idle or throttle.

does anyone think it the way the coils ride on bolt with movement?
they all seem seated in channel pretty good.

I thank you all for your replies so far.Fords are new to me but I do know Chevys pretty well

Repzard

BTW no codes

Repzard

I cleaned the IAC and I really think that help smooth out idle, wasnt to carbon up because I cleaned plenum when it was off car for intake job and didnt remove the IAC or TPS when I cleaned it.

I think I fixed the misfiring issue.
I believe the problem was to do with COP not tight enough and they where wiggling around back and forth on bolt that hold them down,so I tighten them up so there was no movement at all.
I believe there was some spark leak going on or theyre losing connection here and there with movement

Took stang to work today 53 miles one way and she drove awesome.


Thank You everyone for all your help and input on this matter.
Hope i can help someone down the road with problems of the same nature.

denice25

Try to clean your IAC....