4.6L stalling at cruising speeds and stumbeling idle???

kylebgt · Jul 24, 2007

I am a long time member of mf.com and just recently stumbeled upon this site, to be honest I love it and may be abandoning mf.com.
There has been one problem that has plagued my car ever since I bought it and the general concensus at mf.com is that it is the IAC (Idle air control valve) I replaced that but the prob still happens at least once a month. It seems like this happens to lots of 4.6 gt owners.
:The scenario:
you are cruising at highway speeds (50-70mph) you approach an off ramp, push the clutch in, shift it into nuetral and let the clutch out. Normally the rpms will drop from 2-2.5k rpms down to 900rpm's or so but in this case the needle just keeps dropping until it hits 0 the result is a stalled engine while the car is rolling at 40 or 50mph..pretty scarry. This has happend to me twice already.
Another scenario is the rpm's bouncing between 900-500rpm's rapidly. Has anyone ever had these problems??
The IAC replacement certainly helped but didnt fix it entirely.
http://www.mustangforums.com/m_587901/tm.htm

thomas91169 · Jul 24, 2007

you dont happen to have some sort of rigged ducting that is forcing air into your filter/intake by any chance do you?

knew a guy who rigged a sort of ram ducting into his CAI and it worked well getting fresh air to the filter, but if he was moving, there was enough air coming into the intake that when he went into neutral at higher speeds the maf would sense all this airflow and zero throttle input and basically not know what to do but shut down the motor.

hows your TPS? have you cleaned your MAF lately? Give yourself a nice Seafoamin? Tune-Up(Plugs, fuel filter, etc)?

gotchopsticks · Jul 24, 2007

i have heard that it is a problem with the fuel filter. my car did that a few times and i came on here for advice, but since then it hasnt done it. i still have not replaced the filter, and my car does the surging at idle when its cold. i put a restricter plate in the IAC, a DIY job i heard about on here, and i assume thats why mine does it. so try replacing the fuel filter and see if there are any changes.

kylebgt · Jul 24, 2007

thats pretty intresting, never heard of that before. I cleaned my maf a short while ago. I know that I should seafoam it but I am a little clueless about seafoam, I am not sure if i should really trust it.

kylebgt · Jul 24, 2007

This is what I have planned to replace soon;
fuel filter
plug wires
seafoam it
new air filter
possibly set the idle lower
tps
clean throtlle body
Hopefully one of these will fix the prob. Thanks for the input guys!

1badsuv · Aug 27, 2007

Could someone please tell me the location of the fuel filter on a 2004 gt?

Thankyewverymuch!

the98stang · Aug 27, 2007

It seems this problem occurs A LOT with 2000 GTs in particular. I think it might have to do with a PCM update that Ford did. You can take your car to the dealership, and they will scan the PCM for any updates. I have been battling this problem for almost 2 years. And I've tried tons of things to fix it, with no luck.

BTW- seafoam is AMAZING. Just use it before you put the new plugs in, because it will foul spark plugs. But your car will run SO much smoother!

the98stang · Aug 27, 2007

1badsuv said:
Could someone please tell me the location of the fuel filter on a 2004 gt?

Thankyewverymuch!

Get under the car, and look towards the top of the fuel tank. It's looks like a little pepsi can kinda.

CobraRed_96_GT · Aug 27, 2007

sounds like a vacuum problem to me

the98stang · Aug 27, 2007

CobraRed_96_GT said:
sounds like a vacuum problem to me

I think he would see high idle and notice a vac leak right off the bat

BennyBlown2v · Aug 27, 2007

the98stang said:
I think he would see high idle and notice a vac leak right off the bat

Yeah but he is having IAC issues...which is a vacuum problem. Nobody ever said leak

I have this problem on my blown car, it's more than likely do to IAC and tuning in most all cases like this

cooper · Aug 28, 2007

Im on my 3rd iac now, all from oriley. car bucks and has no power and then varooom its ok. my cars a 2000 , but the iac in the books and computer at the part store , past 2 times it from a 1998?

the98stang · Aug 28, 2007

cooper said:
Im on my 3rd iac now, all from oriley.

That's when happens when you buy non-Ford electrical parts

thomas91169 · Aug 28, 2007

its the same piece from 96 up to 04 likely.

HoustonGT · Aug 28, 2007

Go buy a real Motorcraft IAC and not one from Oreillys and it will fix the issue.

97Vicious281 · Aug 28, 2007

Yeah mine would die before I changed the idle air control it would crank but unless I had my foot on the gas it wouldn't stay on fuel filter is in the back up under the bumper.

cooper · Aug 30, 2007

the iac in the book did not have the tube hookup to the intake. this one has the hookup within the uppre plen. aka v6 iac.

4.6L stalling at cruising speeds and stumbeling idle???

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