idle problem

fordtech28 · Sep 15, 2007

My cobra started to idle at 1,800 rpm for some reason.I changed the idle motor tps sensor (I had spares) with the same result.The other thing I did notice the intake sounds louder I mean the sucking air noise is really noticible at idle something it didnt do before.As a trouble shooting step I disconnected the mass air flow sensor and the idle went down but the car ran like crap but its idleling where its supposed to but the air sucking noise is still there.I'm thinking its the mass air flow sensor but any input from you guys is great before I just go start buying stuff. Thanks guys

toyman · Sep 15, 2007

So try cleaning the MAF sensor. Quick and easy and doesn't cost a dime.

DarkStallion095 · Sep 15, 2007

IAC

The same thing happened to me. Exactly about a week ago. Im almost positive its your IAC valve. Its the other thing bolted onto your TB besides your TPS. Get a new one. I got mine at Kragen Auto Parts. It wasn't a Ford part but it said Ford on it nonetheless. From Ford its like a 125 bucks. I paid about 80 for mine. So yeah get a new IAC. Should solve your idle issue. My car even ran a little better once I changed this. Let me know if this is your problem. I have a GT but I think your cobra has an IAC too. Oh when it happened to me I disconnected the Mass air sensor and it idled back down but sounded like it was bout to die. I reconnected it then the RPMs went back up. So yeah bud, IAC.

HISSIN50 · Sep 15, 2007

Check for a vacuum hose that came loose (crankcase ventillation, etc). The RPM difference and noise you noted lead to this being the cause.

Good luck.

fordtech28 · Sep 16, 2007

toyman said:
So try cleaning the MAF sensor. Quick and easy and doesn't cost a dime.

I cleaned the maf twice I had a spare working tps and idle motor sitting in my garage its not a vacuum leak I checked all the hoses and spayed brake cleaner to see if the idle changed and nothing I belive its a fuel issue since the mass air controls the fuel also and there was a strong smell of fuel .Also I did notice that since a week ago everything I turned the car off it made a noise coming out of the intake kind of like a horn I will try to get another idle motor since I also believe thats the cause of the noise when I shut off the car. Thanks for all the input I will kept you posted.

Bosko5.0 · Sep 16, 2007

This just happened to me like 5 times today! I started it up for like 5-10 secs idled ok then It rose to 1800 or so. turned car off started it back up it was fine???? luckly the check engine light came on when this happened so I have to pull the codes today.

HISSIN50 · Sep 16, 2007

If you dont think you have a vac leak (which you don't seem to think you do), try disconnecting the IAC and see if your idle drops way back down.

Bosko, if normal things don't work, swap another TPS on. When the wiper degrades, it can cause a hanging idle which is fixed by replacing the TPS (even disconnecting the IAC in said situations won't lower the idle back down).

Blackened302 · Sep 16, 2007

also might wanna try checking out your PCV valve..

Fopar · Sep 16, 2007

HISSIN50 said:
If you dont think you have a vac leak (which you don't seem to think you do), try disconnecting the IAC and see if your idle drops way back down.

Bosko, if normal things don't work, swap another TPS on. When the wiper degrades, it can cause a hanging idle which is fixed by replacing the TPS (even disconnecting the IAC in said situations won't lower the idle back down).

ya it does , a bad TPS (reading high) will cause the IAC to open more through the throttle follower function...

Listen to HISSIN though you likely have a vacuum leak, there's some hoses under the upper intake plenum too... start looking for vacuum leaks...

fordtech28 · Sep 16, 2007

DarkStallion095 said:
The same thing happened to me. Exactly about a week ago. Im almost positive its your IAC valve. Its the other thing bolted onto your TB besides your TPS. Get a new one. I got mine at Kragen Auto Parts. It wasn't a Ford part but it said Ford on it nonetheless. From Ford its like a 125 bucks. I paid about 80 for mine. So yeah get a new IAC. Should solve your idle issue. My car even ran a little better once I changed this. Let me know if this is your problem. I have a GT but I think your cobra has an IAC too. Oh when it happened to me I disconnected the Mass air sensor and it idled back down but sounded like it was bout to die. I reconnected it then the RPMs went back up. So yeah bud, IAC.

Hey man you nailed it it WAS the stupid IAC valve I bought another one and bam the air noise went back to nornal and its idleing where its supposed to before I bought it.I took the intake off and blocked off the hole for the idle motor at the front of the inner throttle body and it idled normal with no intake noise but what I dont get was why did the other IAC didnt fix it i had it as a spare I bought evrything new when the car hit 100,000 miles just for peace of mind. Thanks again to every one

fordtech28 · Sep 16, 2007

DarkStallion095 said:
The same thing happened to me. Exactly about a week ago. Im almost positive its your IAC valve. Its the other thing bolted onto your TB besides your TPS. Get a new one. I got mine at Kragen Auto Parts. It wasn't a Ford part but it said Ford on it nonetheless. From Ford its like a 125 bucks. I paid about 80 for mine. So yeah get a new IAC. Should solve your idle issue. My car even ran a little better once I changed this. Let me know if this is your problem. I have a GT but I think your cobra has an IAC too. Oh when it happened to me I disconnected the Mass air sensor and it idled back down but sounded like it was bout to die. I reconnected it then the RPMs went back up. So yeah bud, IAC.

FYI For anybody who lives in Cali Pepboys has the idle motor valve for 59.99 and it works like oem

Blackened302 · Sep 17, 2007

for the sake of not starting another thread, i'd like to resurect this one:

i'm having some idle troubles myself. everything was fine until i messed w/ making my own CAI.

the problem is the car will not sit at 850 like i set it. instead, it's sticking at about 1300rpm.

i checked for vacuum leaks w/ the CAI, no dice. i threaded in the ACT sensor and siliconed it for extra measure, and did the same w/ the breather tube fitting.

i also checked for leaks at the vacuum lines under and around the upper intake--nothing. all that aren't in use have good plugs on them, and the lines that are in use are not cracked or anything.

what leads me to believe it's still a leak, though, is that i don't get a sucking noise from the dipstick (when i pull it out) like i did a few days ago before this problem.

btw, IAC and TPS are both new OEM equivalent parts and are only a few (3 to 4) months old.

thanks, gents.

EDIT: tps voltage was at 1.10. it wasn't adjustable (running the explorer tb), so my buddy opened up the holes to make it so. setting it under a volt did the trick!

idle problem

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