Stuttering At Part Throttle

Dirty Sanchez · September 13th, 2006, 03:56 PM

I have a 06 GT, made in late febuary. At part throttle (cruising on the highway maintaining speed) i get a slight jerking (not violent), if i give it more gas, its fine, let off the gas and its fine. Its right at the mark where you maintain speed. Mods are JLT2 CAI, Xcal 2 tuned from brenspeed, Steeda UDP and Steeda CMDP. After getting parts installed and flashed, ran GREAT. two weeks later took it to the dyno, everything looked great, lowered the timing from 26 to 21 and adjusted faul to maintain 12.5 ratio. Leave th4e dyno running HARD, not a single complaint. 2 months go by, i dont change anything, all of a suden one day i noticed this stuttering at part throttle. I do the normal, re-load tune, no diffrencce, laod Brenspeed tune, still no diffrence. CHanged gas companies and pump (92BP ive always used, 92 BP from a diffrent gas station, 91 Conoco, and 91 amaco), still no change. Checked Wires and plugs: nothing stands out (though not sure how to check these, plugs looked a normal worn plug (not singed, no rainbow effect, no tar like look, not black)).

I dont have a fuel pressure gauge or have an idea how to check this while the car is moving (at idle it seems fine). Can anyone help. I cant find a TSB that fits my description. I dont want to rip the mods off to take it to my anal delaership, as sson as they see one modded part, they will instantly blame it on mods and charge me 200 bucks to look at it.

i could really use some help right now. car has 2k miles on it, never raced, never did a burnout, just occasionally will wrap out a gear or two on a weekend.

Thanks,

DS

btw - very cool site, not sure how i never heard of it before now (been building up mustangs for 10 years now).

drgnracin72 · September 13th, 2006, 07:23 PM

its a pretty new site only been around a little over a year now. as for the tune, i would send the tune back to brenspeed and have them go over it to make sure everyhting is ok. ohter than something in the tune, i dont really know what it could be

mdvaldosta · September 13th, 2006, 07:39 PM

What kind of air filter? Maybe oil / dirt on the MAF, something loose around that area, vacuum leak maybe. Really sounds like it's something to do with air metering.

99mustang232 · September 13th, 2006, 11:27 PM

i would take that money that you would be spending at the dealership and put it on the dyno and get it tuned, they will be able to monitor the air/fuel and review and modify the settings as needed.

Dirty Sanchez · September 14th, 2006, 04:10 PM

i will check the MAF, what should i clean it with? I sprayed Carb cleaner around the intake and CAI seals to see if the idle changed, nothing. Dont think it is a leak anywhere. Air filter looks brand new (only used for about 1k miles). I thoguht it was the tune, but after loading 2 diffrent tunes, figured that should be fine. Like i said i had it on a dyno after installing the parts and loading the tune, everything was fine. Not sure how the tune woudl have changed itself 2 months after loading it and dyno testing it.

Thanks for the help, keep the suggestions comming.

Dirty Sanchez · September 18th, 2006, 03:36 PM

Turned out to be a fualty TPS, easy fix and im back on the road, no more issues. Thanks for the help guys. Hope this helps anyone having similiar issues.

September 13th, 2006, 03:56 PM	#1
Dirty Sanchez Newbie Join Date: Sep 2006 Posts: 4	Stuttering At Part Throttle I have a 06 GT, made in late febuary. At part throttle (cruising on the highway maintaining speed) i get a slight jerking (not violent), if i give it more gas, its fine, let off the gas and its fine. Its right at the mark where you maintain speed. Mods are JLT2 CAI, Xcal 2 tuned from brenspeed, Steeda UDP and Steeda CMDP. After getting parts installed and flashed, ran GREAT. two weeks later took it to the dyno, everything looked great, lowered the timing from 26 to 21 and adjusted faul to maintain 12.5 ratio. Leave th4e dyno running HARD, not a single complaint. 2 months go by, i dont change anything, all of a suden one day i noticed this stuttering at part throttle. I do the normal, re-load tune, no diffrencce, laod Brenspeed tune, still no diffrence. CHanged gas companies and pump (92BP ive always used, 92 BP from a diffrent gas station, 91 Conoco, and 91 amaco), still no change. Checked Wires and plugs: nothing stands out (though not sure how to check these, plugs looked a normal worn plug (not singed, no rainbow effect, no tar like look, not black)). I dont have a fuel pressure gauge or have an idea how to check this while the car is moving (at idle it seems fine). Can anyone help. I cant find a TSB that fits my description. I dont want to rip the mods off to take it to my anal delaership, as sson as they see one modded part, they will instantly blame it on mods and charge me 200 bucks to look at it. i could really use some help right now. car has 2k miles on it, never raced, never did a burnout, just occasionally will wrap out a gear or two on a weekend. Thanks, DS btw - very cool site, not sure how i never heard of it before now (been building up mustangs for 10 years now).

September 13th, 2006, 11:27 PM	#4
99mustang232 MM Fanatic 1999 Ford Mustang V6 Join Date: Sep 2005 Location: newport news, va Posts: 3,717	i would take that money that you would be spending at the dealership and put it on the dyno and get it tuned, they will be able to monitor the air/fuel and review and modify the settings as needed. __________________ ...even fire and single cammin

Threads Similar to: Stuttering At Part Throttle
Thread	Thread Starter	Forum	Replies	Last Post
And some more part 2!	JAY'SRED02	Pictures	3	October 7th, 2007 05:50 PM
NEED A PART	sn94	5.0 Mustangs	0	September 20th, 2007 05:21 PM
How Much Hp will these new Part get me..	Speedstang302	5.0 Mustangs	11	September 13th, 2007 11:41 PM
Engine Stuttering	Dallas01GT	99-04	11	August 3rd, 2007 02:27 AM
power loss at part throttle?	5litercobra	5.0 Mustangs	0	April 6th, 2006 01:21 PM

September 13th, 2006, 07:39 PM	#3
mdvaldosta Maintenance Man 2002 Mustang GT 11.47@120.58 Join Date: Aug 2005 Location: Valdosta, GA Posts: 3,928	What kind of air filter? Maybe oil / dirt on the MAF, something loose around that area, vacuum leak maybe. Really sounds like it's something to do with air metering.

September 14th, 2006, 04:10 PM	#5
Dirty Sanchez Newbie Join Date: Sep 2006 Posts: 4	i will check the MAF, what should i clean it with? I sprayed Carb cleaner around the intake and CAI seals to see if the idle changed, nothing. Dont think it is a leak anywhere. Air filter looks brand new (only used for about 1k miles). I thoguht it was the tune, but after loading 2 diffrent tunes, figured that should be fine. Like i said i had it on a dyno after installing the parts and loading the tune, everything was fine. Not sure how the tune woudl have changed itself 2 months after loading it and dyno testing it. Thanks for the help, keep the suggestions comming.

September 18th, 2006, 03:36 PM	#6
Dirty Sanchez Newbie Join Date: Sep 2006 Posts: 4	Turned out to be a fualty TPS, easy fix and im back on the road, no more issues. Thanks for the help guys. Hope this helps anyone having similiar issues.

All times are GMT -4. The time now is 10:59 PM.
Contact Us - Modded Mustangs - Top
Modded Mustangs is ©2005-2008, All Rights Reserved, And is Not Affiliated with Ford Motor Company. Forum is powered by vBulletin ©2000 - 2008, Jelsoft Ent. Ltd. & SEO by vBSEO 3.1.0 ©2007, Crawlability, Inc.