surging idle sometimes

[White5.0]

sometimes when i start my car the idle surges up and down for a while and will eventually stall if i let it go....if i get in the car and rev it a little bit a few times it will idle perfect just below 1k.

other times it doesnt do this

and other times it doesnt do it right away but will do after idling perfectly fine for 5 minutes or so. then it will start surging up and down up and down...once again, if i get in the car and rev it a little bit it will stop doing it


what causes this??

[Smallville]

Sounds like a sticking IAC (Idle Air Control) motor:goodidea:

[97LaserRed]

x2! i see it all the time

[White5.0]

Sounds like a sticking IAC (Idle Air Control) motor:goodidea:


x2! i see it all the time


yeah i was thinking it might be that....my IAC valve it really old, i should probably buy a new one.

anything else that might cause this? in case a new IAC doesnt work...

would a bad TPS cause this maybe?

[John4cam]

Have you ckecked the tps voltage?? So many people have these issues with 5.0 liters.

I would start with the iac, try cleaning it first and make sure the plunger inside moves freely, then the tps voltage. After that I would guess a bad ground somewhere.

[jaa55]

what MAF are you using?

[jaa55]

when we did a trick flow swap and MAF to my friend scotts 87 we had the same problem. the thing would surge and stall, it ended up being the MAF sensor, bought a new one from summit and it fixed the problem

[White5.0]

Have you ckecked the tps voltage?? So many people have these issues with 5.0 liters.

I would start with the iac, try cleaning it first and make sure the plunger inside moves freely, then the tps voltage. After that I would guess a bad ground somewhere.

no i havent....any good write ups on how to do this? i wouldnt think it'd be hard...

[White5.0]

what MAF are you using?


when we did a trick flow swap and MAF to my friend scotts 87 we had the same problem. the thing would surge and stall, it ended up being the MAF sensor, bought a new one from summit and it fixed the problem



that is another thing i am worried about....i have a granatelli mass air meter :hide1: lol....i know their suspension products completely suck so that may be the problem as well

[jaa55]

yeah ryan i would try another one if you have one at your disposal. what your explaining his car was doing the exact same thing. got a new MAF meter and it works perfect now.
what way did you do you mass air swap? an entire harness or did you pin the computer yourself?

[White5.0]

yeah ryan i would try another one if you have one at your disposal. what your explaining his car was doing the exact same thing. got a new MAF meter and it works perfect now.
what way did you do you mass air swap? an entire harness or did you pin the computer yourself?

It was already done to the car when i bought it....i think its the entire harness cause i have an A9L computer

[jaa55]

you still run a A9l or P if you pin the harness yourself or use the entire harness from a MAF car. the reason why i asked is id check to make sure the MAF wires are in the right pins on the computer. someone could have pinned it wrong, heres a link to the info
http://mustangforums.com/forum/5-0-mustang/80121-mass-air-flow-conversion-from-black-snake-and-schwindty.html

[White5.0]

you still run a A9l or P if you pin the harness yourself or use the entire harness from a MAF car. the reason why i asked is id check to make sure the MAF wires are in the right pins on the computer. someone could have pinned it wrong, heres a link to the info
http://mustangforums.com/forum/5-0-mustang/80121-mass-air-flow-conversion-from-black-snake-and-schwindty.html


actually now that i think about it...the plug for the mass air meter goes through the firewall by itself...it is not tied into the rest of the harness so it is probably pinned

[jaa55]

id check that as a start, if thats good.......id test the car with another MAF. if you can find one soon, when i bring my car up to school ill plug my MAF into your car and see if it fixes the problem :thmbsup:

[White5.0]

id check that as a start, if thats good.......id test the car with another MAF. if you can find one soon, when i bring my car up to school ill plug my MAF into your car and see if it fixes the problem :thmbsup:

sounds cool...do you have 24lb injectors tho? thats what i got

[jaa55]

yes, i'm stealing the ones off my dads notch since he got that kenne bell

[White5.0]

yes, i'm stealing the ones off my dads notch since he got that kenne bell

haha nice

[Gray 5.0]

mine is doing the same thing ive been messing with the maf all day it runs ok but surges constantly this started about 2 days ago. its a new maf and everything wheres the iac located????

[White5.0]

mine is doing the same thing ive been messing with the maf all day it runs ok but surges constantly this started about 2 days ago. its a new maf and everything wheres the iac located????

its on the side of the throttle body. try cleaning it and try a base idle reset. that made my car run a LOT better

[Gray 5.0]

is it the bottle looking thing and if so i cleaned that like i was gunna sell it. the car just started surging a few days ago and like i said ive been moving the maf around but it just keeps going. its really getting annoying i dont know what else to try

[White5.0]

is it the bottle looking thing and if so i cleaned that like i was gunna sell it. the car just started surging a few days ago and like i said ive been moving the maf around but it just keeps going. its really getting annoying i dont know what else to try

clean the mass air meter and check everywhere for vacuum leaks. one of your vacuum hoses could have an opening. they are rubber and when they get old and dried out they crack and draw unmetered air into the engine and causes all sorts of problems. i would take off your upper intake manifold and just replace all the vacuum hoses