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Discussion Starter · #1 ·
well you guys ive been having problems with my start up and idle it first started when my car started up it would hang around 2 grand then drop to about 1200 rpm and then hang a little bit longer for about 1 minute or so then back to normal replaced iac still no change then i was told to clean maf did that with the quick dry electronics cleaner then it started having trouble starting up for the first time or when ever the engine is cold it would take 3-5 times to get it started and when im trying to crank the engine it will half ass start and it will idle very rough around 400-500 rpm then die like i said i will do this a couple more times and then it will start and shoot up to 2000 rpm and then quickly drop down to the normal idle 800 rpm it wont even idle up to warm the car the only time it does is when the engine is already warmed up and thats when it hangs i replaced the maf with a new oem maf still no change i was thinking of replaceing the sensor that sits behind the maf i have no idea what its called can someone tell me and if you can help me please thx
 

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IAT (intake air temp) sensor? This sensor could be out of range yet not trigger a MIL. I believe there is even a TSB on it as well. Check the sensor per service manual and if out of range then replace. Also even the smallest vacuum leak could cause bad idle conditions and check the air inlet tube for cracks as well.
 

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Info....

Ok first what mods do you have done. I had the same problem and mine is fixed now but I have a heavily modded motor. I dont want to have you do alot of things you dont have to. A vaccum leak may be the answer to your poblems though. Its amazing what a simple vaccum leak can cause.
 

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At the beginning of the 4.6L tech forum there is a discussion about stumbling and rough idle.
Read through it. It helped me.
Just remember to disconect the battery to refresh the computer.
 

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Discussion Starter · #5 ·
i have no mods bone stock you guys i did not have this problem with the cranking part until i sprayed the cleaner on the maf checked vac leaks none of those and i can still smell the cleaner on the first start every single time and its been months ago since i cleaned it
 

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i have no mods bone stock you guys i did not have this problem with the cranking part until i sprayed the cleaner on the maf checked vac leaks none of those and i can still smell the cleaner on the first start every single time and its been months ago since i cleaned it
Thats why I recommended checking the intake boot for cracks because you had to remove it to clean the MAF and even small spider web cracks can cause the MAF to not read the correct flow and when cold the rubber is stiff and after warming up the intake boot gets softer and could seal better. Its just a guess but worth checking. Did you say that you already replaced the IAC and MAF? I may have read that wrong as why clean a new MAF. If you didn't replace the MAF and your symptoms changed upon cleaning is why I either suspect a bad MAF or the boot problem mentioned. Let us know what you find out. If you have a friend with another Mustang see if he will let you swap the sensor to test. Good Luck!
 
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