Dunno if it's been mentioned yet, but I had this problem about a month ago...... wound up being a collapsed PCV hose with a leaky PCV o ring that left oil in my valve cover bolt housings.
The transport delay function setting in your tune is probably wrong due to the long tube headers relocating the O2 sensor further down stream.You need to take it to a true pro and have it looked at.
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2003 Mach 1, Automatic Transmission,4:10 gears
Preditor Tune
13.148 @ 106.3
1986 SVOSaved from the scrap yard,currently under reconstruction
I have an 2001 gt and have the same symptoms but I also feel a miss at low rpms up to like 2500 rpms wide open throttle is good but it misses its ass of and i cant figure it out i put new plugs in it, did a fuel pressure tests and i had 26 lbs at idle and had good compression across cylinders i dont under stand wat else it could be and i dont want to start guess and checking. The car is almost stock has k&n intake, 75mm throtttle body and plenum, x pipe with cats and slp cat back, and custom diablo tune. SOMEONE HELP PLEASE
I have a very very similar problem with my 01 gt auto(125k) totally stock 'cept for a k+n filter ....changed plugs and a supposed bad coil + fuel filter.... seeing im not a shadetree... mine is in the dealer shop for a third time in two weeks...car misses /hesitates at 30-40 mph at moderate throttle.....tech says torque converter could be a posible issue....what do you guys think ...total dummy here when it comes to this stuff....just a driver ... and not into putting that kinda money into my baby if i dont have to...all reply will be greatly appreciated.......A.MICK
Last edited by ANGRYMICK; 07-30-2008 at 08:05 PM.
Reason: grammar
To all the rough idle guys talking about cleaning the maf and plugs and all.......the best thing you can do is if you change anything to you car....ex changing parts or cleaning parts... pull the negative battery terminal off while you complete whatever it is your doing ...all the fuel/air settings the computer learns from what the sensors are reading so there for if the maf is dirty the computer learns to compensate... if you clean it ... the computer is going to act screwy for a while but if you reset it by leaving the batt term off it will go through a relearn stage when you start your car up again.... also look for cracks or burnt spots on your coil packs the love to arc the spark if the littlest crack exists... hope this helps...
thanks for the info!...i cleaned it but it was short lived,got dirty by time i got to autozone where i bought the part for$55 and some change. thanx again
I was having issues with stalling and such. Did alot of the usuall fix's but forgot about one of the most basic ones. Took off the throttle body and cleaned it with throttle body cleaner. Stang was great now, their was alot of build up on the back of the throttle body butterflies.
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2001 Mustang GT: Cams, Bullit Intake, twin throttle body, Long tube headers, Off road X pipe, Magna packs, Eiback springs, Maximum motorsports full length subframe connectors, caster/camber plates, bumpsteer, upper and lower control arms, Kingcobra clutch, Saleen chrome 18x9/18x10 replica rims, Autometer Cobalt watertemp, oil pressure, & fuel pressure gauges.
i have a 2000 GT that had a prochamber on it and i put my friends old slp xpipe on and after a day my car started to stumble and idle bad and turn off at red lights dose anyone know why it would do that after i put a diff exshaust system on there?
i have a 2000 GT that had a prochamber on it and i put my friends old slp xpipe on and after a day my car started to stumble and idle bad and turn off at red lights dose anyone know why it would do that after i put a diff exshaust system on there?
Bad O2 sensors?
John
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'03 Mustang GT, Maximum Motorsports Max Grip Box, Wilwood SL6 front/DL4 rear Big Brake Kit, Corbeau F1X Racing Seats, MGW Short Shifter, MAC Long Tube Headers/Prochamber mid pipes/Flowmaster 40, FRPP 4.10 gears, TrickFlow Diff Cover/ 75mm TB/Plenum, Moser 31 spline Axles, UDP
my 99 cobra idled rough after i installed my twin 62mm throttlebody...i adjusted it and it idles fine but now lately after running for maybe 30 miles in one day it will stumble bad at 4000-4500 rpm....it stumbles so hard that the car feels like it is completely out of gas and sucking for air....what could this be?
mine did that i changed the egr valve cleaned the iac and throttlebody and it seems fine now
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As of now: 97 gt, 373's, k&n cai, FR aluminum drive shaft, borla exhaust, pi heads, spec clutch, 5.0 short shifter, steeda ss long tubes, steeda H pipe, Dynotune nitrous 75 shot, granatelli fuego tuner
Hi all,
seems that all the problems on here are related to a bad idle, my problem is a slight hesitation when setting off from idle it kinda bogs (dies), for a split second and the only way to overcome it is to slip the clutch also when you floor it in first as it gets to the higher rev range it acts like a bucking bronco, surges then pulls back, surges then pulls back untill you change in to second, also when coasting down hills with your foot of the loud pedal it does the same, surges then backs off as if you are applying the brakes slightly then letting off obviously not as bad as you are not touching the gas pedal. anyone any ideas on that one?
My 2000's IAC started going bad right around 48k miles (last fall) and the best way to check is very simple:
When you're having that problem with it idling rough, stumbling or whatever, just take a wrench or what-have-you and give a few sharp taps on the outside of the IAC where it goes into the throttle body.
If the problem instantly clears up, that's your problem. This won't last of course, but in my case (being very lazy) it got me through the 2 or 3 weeks until I got around to replacing it.
iac valve 
