[97mustanggt]

i just finished installing a intake spacerf on my cobra, it idles good, but while driving my rpms hang high then drop quickly and it jumps up and down from 1000 and 1100rpms, it sounds like a lion calling for its cubs like a huff pause huff, then it goes a way...wats going on here any ideas

[97mustanggt]

so today i disconected tha i.a.c from my gt while it was on and it turned off rite away, on my cobra i disconnected it and notthing happned i drove it around like that and tha rpms seem normal now and it dosnet huff pause huff pause at stops....is it ok to run with ur iac disconnected?

[bitemark46]

The iac tells the computer how much fuel to add based on the air flow. I'd put it back in. It was probably idling funny cause you increased the plenum volume. Let it re-learn and adapt to the increase. Either that or you may have a vacuum line that you didn't put back on.

[97mustanggt]

hmm well its weird how on tha gt it totally turns tha car off, but on tha cobra it stays on and when disconnected it seems to ride good, but i hope ur rite that tha car need to learn and accept tha more plenum space

[Mach Boy]

Originally Posted by bitemark46 The iac tells the computer how much fuel to add based on the air flow. I'd put it back in. It was probably idling funny cause you increased the plenum volume. Let it re-learn and adapt to the increase. Either that or you may have a vacuum line that you didn't put back on.

+1 the computer has to get used to the increased volume. It will even out over time.

[97mustanggt]

so tha huffing sound should go away, how long should it take, cause idle is perfect it just driving around and then putting it in neurtreul and then rpms go down and up huffing

[Mach Boy]

I'd say within a week depending on how much you drive it. If it doesn't get better you need to look for a leak.

[97mustanggt]

ok, yea i was thinking a air leak but since it idles good idk, but hopefully that huffing stops, my friend says drive it for like half an hour or 45 min straight so that tha computer can reset and learn it.

[97mustanggt]

today drove it for about 35min straight, still having tha same problem, idle is still good, but while driving and i hit a stop tha idle drops down and from 1000rpms to 1200rpms its bouncing up and down huffing...i sprayed carb cleaner around spacer to c if idel changed and nothing

['97'Cobra]

check for the vaccum hoses, mine were cracked and broken when Primo and I took of my intake. Just a suggestion. Mine kinda does the same thing, i had it tuned to drop the idle tho but it still jumps around just a hair.

[97mustanggt]

which ones are tha vacume hoses, i wouldnt mind it jumping but tha noise it makes is so noticable and annoying, can it be a bad tps?

[97mustanggt]

found out my egr gasket was torn to shreds i changed it and i still have tha problem, i think my car is sayin fuck you spacer, i disconnect my iac car stays on and problem seems fixed, i disconncet my tps and car still stays on...im missing a screw on my fuel rail im sure that aint cauzing tha problems

['97'Cobra]

well it sounds like your IAC is the problem kind sir.

As long as the fuel rails arent shifting and the injectors O-Rings are snugged in, it shouldnt be a problem

[97mustanggt]

problem seems to be fading away it dosent bounce up and down no more but it does stay at 1100 till i come to a complete stop then it goes down to 900rpms...hopefully it only gets better, but im going to buy another iac, just replaced last year but ehh ill replace it again.

[tbird88tbo]

if you have access to a scan tool, plug it in and look at desired idle. That will tell you if it is ideling at the rpm the computer is comanding it to. the other way you can check your iac is, crimp off the hose going to the iac with some pliers and see if it stalls or changes rpm. If no, make sure your tbody is clean and not open a hair. You can check for vac. leaks by misting the engine with an alternetive fuel ie. propane, carb cleaner, brake clean, ect... (just dont be stupid and spray it on the exhaust) and look at short term fuel trim on your scanner (after engine is running in closed loop mode).

[97mustanggt]

thanx, probly seems to be goin away, reps for everyone

[M.P. Cobra Fan]

Stupid question, but did you ever disconnect the battery. I never had that problem when I installed my intake spacer, but I disconnected the battery for 5 minutes before startup.

[97mustanggt]

yea i did after i created a spark with tha alternator lol