car still idles like poo

the98stang · Sep 17, 2006

So here's what I have done to try and fix the problem:

New spark plugs
New fuel filter
Cleaned MAF and intake filter
New IAC
New PCV and grommet

She STILL dies every once and a while when braking at a stop sign/light. The idle will sometimes drop to 500 and recover to 700 too. Maybe it's the IAC? I was a cheap bas_ard and bought one from Autozone, instead of buying a motorcraft one . Also, my COP plugs look a little old so maybe that's the issue (70k miles)? I checked all vac lines and they seem to be fine. No check engine light either. It seems the problem happens on a cold and hot engine. Any ideas? Thanks..

Tanner

Stang|ess · Sep 17, 2006

Clean the MAF? I see you have a k&n, maybe you have oil residue on the MAF

the98stang · Sep 17, 2006

Stang|ess said:
Clean the MAF? I see you have a k&n, maybe you have oil residue on the MAF

No I cleaned it

Pennywise2 · Sep 17, 2006

Sorry to hear you are having a problem with your mustang.
Tanner it is possible one or more of your fuel injectors could be
clogged.Also your EGR valve could have tooken a dump on you.
IAC and EGR valves I would never go cheap on always buy Motorcraft
replacements it's worth the few extra bucks.
Next have all of your fuel injectors cleaned by hand to see if it helps
you never know.Good luck Tanner and let us know what happens.
Fix your car before you spray your Nitrous Express kit.

twogts4us · Sep 17, 2006

Have AutoZone check your battery...for free.

billfisher · Sep 17, 2006

remove the iac connector and it should idle low. if not, you need to adjust your throttle stop until it does. then reconnect the iac and it should run better. forget the old "adjust your voltage" crap.

get a hose long enough to reach from your IAC to the intake hose.

insert it into the intake hose, removing the pcv. you will now have a direct connection from the IAC to your maf.

if it idles fine, you need to look into a pcv leak or excessive blow fooling the pcm. idle quality relies on reading idle air from the maf. if it thinks there is no air used by the IAC it stops it. in other words positive pressure inside the pcv system feeds back ito the intake tubing thereby giving an incorrect maf reading and loss of idle quality.

connect the IAC directly is simply assuring that's not the case. if it idle well, fix it. if you have a bazillion miles with blowby, good luck. mine was having idle issues with 146,000. i use a seperate PCV vacuum source and have my IAC connected directly to the intake hose.

the98stang · Sep 17, 2006

billfisher said:
remove the iac connector and it should idle low. if not, you need to adjust your throttle stop until it does. then reconnect the iac and it should run better. forget the old "adjust your voltage" crap.

Should I start up the car and then remove the IAC connector? I remember one time I was working on my car and left the connector unplugged. When I tried to start the car, it would start for a split second and then die. So if it doesn't idle low with out the connector, will the idle run high, or not change at all? Is the "throttle stop" that black circular piece on the IAC? How do I adjust it? Thanks for the replies guys!

Tanner

the98stang · Sep 17, 2006

twogts4us said:
Have AutoZone check your battery...for free.

The battery took a poo recently...so it was replaced....

I don't think this is battery related though. I've had this problem for months now.

madmatt · Sep 17, 2006

Without the IAC, the car will start and just die. I say thats the only thing left it could be.

billfisher · Sep 17, 2006

1. disconnect the iac.

2. adjust your throttle stop for a 500rpm idle and...

3. shut off car

4. reconnect the IAC.

just try it.
IAC is not the sole source of idle air. the slight throttle blade opening is the rest.

Give Me TP · Sep 23, 2006

twogts4us said:
Have AutoZone check your battery...for free.

What a friggin idiot

MBDiagMan · Sep 23, 2006

When an engine has idle problems, but otherwise runs normally, the problem is more often than not, a vacuum leak of some description. This could be a rubber hose, intake manifold gasket, PCV valve, EGR problems or any other thing that can allow air to enter the intake, past the throttle body.

stangGT97 · Sep 23, 2006

A Wells IAC from Autozone is a fine replacement for the Motorcraft one... after all, isn't the OEM Ford part prone to failure? why would you even consider paying dealership prices for a piece of junk part? That being said, I've had the Wells IAC for over a year with no problems. I would definitely do exactly as Bill says though, to rule the IAC out as a possibility... was the car stalling before the IAC was replaced? If so, then I doubt that was your problem from the start. Excessive EGR flow can cause rough idle and poor part-throttle quality, just something to consider... Good luck man!

the98stang · Sep 30, 2006

stangGT97 said:
A Wells IAC from Autozone is a fine replacement for the Motorcraft one... after all, isn't the OEM Ford part prone to failure? why would you even consider paying dealership prices for a piece of junk part? That being said, I've had the Wells IAC for over a year with no problems. I would definitely do exactly as Bill says though, to rule the IAC out as a possibility... was the car stalling before the IAC was replaced? If so, then I doubt that was your problem from the start. Excessive EGR flow can cause rough idle and poor part-throttle quality, just something to consider... Good luck man!

Yes the car was stalling before I replaced the IAC. I replaced the IAC BECAUSE it was stalling lol. BUT come to think of it, I didn't clean the MAF using electrical cleaner. It's a long shot, but maybe it will help?

stangGT97 · Sep 30, 2006

the98stang said:
Yes the car was stalling before I replaced the IAC. I replaced the IAC BECAUSE it was stalling lol. BUT come to think of it, I didn't clean the MAF using electrical cleaner. It's a long shot, but maybe it will help?

Sure why not, it only takes a couple minutes at most. Have you checked for vacuum leaks? Especially check the vacuum line coming off the back of the plenum. If you have a big enough leak, the car will sputter and die

bluestreak_96gt · Sep 30, 2006

the98stang said:
So here's what I have done to try and fix the problem:

New spark plugs
New fuel filter
Cleaned MAF and intake filter
New IAC
New PCV and grommet

She STILL dies every once and a while when braking at a stop sign/light. The idle will sometimes drop to 500 and recover to 700 too. Maybe it's the IAC? I was a cheap bas_ard and bought one from Autozone, instead of buying a motorcraft one . Also, my COP plugs look a little old so maybe that's the issue (70k miles)? I checked all vac lines and they seem to be fine. No check engine light either. It seems the problem happens on a cold and hot engine. Any ideas? Thanks..

Tanner

I was just curious if you found your problem yet, because I feel your pain. My f-ing ride was doing the exact same shat. Now I was told to check my TPS. So I did, and I ended up getting new TPS and all my headaches were no more. Just a suggestion though.... good luck!!

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