I have an 06 GT 5-speed with JLT CAI and 93 Octane Brenspeed tune. The car runs great, but when idling at a stop it drops from 1500 rpm down to 500 like it's going to stall and then shoots back up again. It'll do it 3 or 4 times before it smoothes out. It seems to do it even worse on damp rainy days. Anyone else have this problem? Maybe the MAF sensor on the CAI?
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06 Black Mustang GT 5-speed, Charcoal GT350 stripes, JLT CAI, SCT II w/Brenspeed Tune, Steeda Axle Back Exhaust, 3.55s, 18" polished Fanblade wheels, Qtr. louvers, Ductail spoiler
I haven't checked anything yet. I was going to see what kind of responses I got here first. I've had the intake and tune installed about 3 months now and it has just gotten worse lately. I did notice that it is worse when I have the defroster on too.
I had the same issue, it would drop then bounce up and and down a few times.. also when I would sit for a while at idle it would move between 800 and 1000 rpms constantly like the needle had a case of the shakes. Nothing severe, but noticable if you look at the gauge. I have a c&l racer and a gt500 tb, I think there may have been a leak near the tb. I never received the right hardware because of the twin 65mm tb, and the clamps the intake came with didn't fit so I "engineered" it temporarily.. I just fixed that issue on friday with some serious hardware and the problem seems to have gone away. I would definitely check for leaks as the primary problem.
Yea, check for leaks. Simple installs get taken for granted, but a small leak can throw the entire system off.
It could also be the tune. Tunes are a long, complicated seuquence of codes and if one is off, it could throw the car off. Those custom tunes are great, but they have to be perfect. I would try putting the stock tune back in, and re-installing the tune (after checking for leaks and tightening everything up). That will re-set the computer, and if there were any leaks, it can re-train itself.
Since you paid for a BrenSpeed tune, I'd call them up and make it their problem.
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Jav
05 Mustang GT 5-speed, Steeda CAI, ceramic headers, o/r h-pipe, FlowMasters, Steeda Diablo tuner, UCA & LCAs, 3.73s, GT500 front end conversion.
Thanks for the advice. I was going to change the tune to the 89 octane anyway, so I'll check for leaks first and then change the tune and let you know if that does anything.
Checked for air leaks. Everything seemed to be tight. Changed the tune back to the 87 octane tune. No difference in idle fluctuation. E-mailed Brenspeed for advice on the subject, and they told me to check for air leaks. I must be missing something.
Weird.....my car started doing that after I installed my headers two weekends ago. After a few days, the car seemed to train itself to deal with it and it runs just fine now.
If it started acting that way after doing any particular mod, I suggest you trace it back to that. You said it's been getting worse; worse since you installed the CAI & tune? Check for hair-line cracks in the tuning or rubber pieces of the CAI. Maybe a tear in the actual filter. If those pieces are intact, I'd ask BrenSpeed to send you some new tunes. It has to be that.......
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Jav
05 Mustang GT 5-speed, Steeda CAI, ceramic headers, o/r h-pipe, FlowMasters, Steeda Diablo tuner, UCA & LCAs, 3.73s, GT500 front end conversion.
Posts: 138
Joined: 9/10/2007 From: Fredericksburg, Virginia Status: offline
BTOWSE, this is a common problem with CAI (or any "oiled" air filter) and tunes. Just clean your throttle body and MAF (do not touch the wire just spray it) and the issue will go away. My car did this the first time after a header install on the stock tune, which went away by itself after a couple of days (like RUGEDRAW) and also after installing the a Predator and BamaChips tune. I wrote Doug at BamaChips about this issue and the response I give above is what he told me. Cleared up my issue right away and quite a few others here on this forum. Hope it helps you.
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06 GT Vista Blue 64Ws Manual Sequentials 50F/35R Metallic Tint K&N Drop-in Air Filter JBA Shorty Headers JBA Exhaust BamaChips 87 Octane Tune
Btowse, did you ever get this issue fixed? I''m surprised no one has mentioned this, but apparently that is a common problem on 05-06 GT''s. I had this problem myself when I first got my 05 used in 07. It would do it occasionally for a few seconds then stop, and the problem became more and more frequent over the course of several months. Wasn''t real frequent, but every other week or so, it would show itself for a minute or so. It eventually got to the point where when the idle would begin to fluctuate, the idle would dip so low it would kill the car. A few weeks later, the problem started again and I immediately got a check engine light and the car went into failsafe mode.
Anyway, problem is the throttle body assembly. When I did a search for this, I found a number of people that had the same problem and it was usually the same culprit. Ford replaced it under warranty and haven''t had the problem a single time since. I have read that some members simply "clean" their throttle bodies to fix the problem. Since mine was under warranty and finally threw a code for the dealer to diagnose, I didn''t have to worry about all that. Hope this helps.
finally other people have this problem too.....my idle has been dropping down way too low then back to where it should be after a couple of secs only after i put it in nuetral coming to a stop....it has been on and off....but getting worse to where the car stalls..today it stalled as i was making a left turn and the powering steering died as i mwas watching a car almost t-bone me.......now what is bothering me is ive had my 05 since 7-05 with no problems...and now all of a sudden i hear more and more stories of this happening to others too....but nobody has a definite answer....i am giong to take the advice of the above post and clean my throttle body...hopefully that help....(i recently replaced my fuel filter, and cleaned my c&l....)
Posts: 138
Joined: 9/10/2007 From: Fredericksburg, Virginia Status: offline
O-5: Make sure that when you clean your air filter, or more importantly when you re-oil your air filter, that you do not get too much oil on it. That is were the problem (dirty throttle body) originates. The tunes just heighten this issue. Clean the throttle body and MAF and you are good to go (repeat in a couple of months if necessary).
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06 GT Vista Blue 64Ws Manual Sequentials 50F/35R Metallic Tint K&N Drop-in Air Filter JBA Shorty Headers JBA Exhaust BamaChips 87 Octane Tune
well this problem began last week BEFORE i cleaned the filter but now its getting worse..im gonna take a look at everything tom when i get home from work...i hope its the oil ....im just afraid of a bigger underlying problem.....but more pissed that i cant find the exact cause....
I''m sure the throttle body is the culprit. I did a couple of tests last week. I put the factory box and tune back and drove it for a week to see if it had the same problem. At first, I didn''t notice it but it did drop down to about 500 rpm but corrected itself quickly and stayed at around 800-900 rpm. Then I reinstalled the CAI and tune and got the same problem but instead of correcting itself, it bobs up and down like it''s going to stall. Turned on the air conditioning and that''s all it could take. It stalled at 2 different stop lights with the added strain of the A/C. Now I know it''s not an air leak. The CAI just seems to be more sensitive to the problem than stock.
Does anyone know of a good throttle body cleaner to recommend? Filter cleaner?
i set the idle at 1000 to overcorrect the problem .....but it did not help.....funny bc i turned on the a/c 3 weeks ago and got stuck in yet another intersection with a dead car while traffic was about to plow me...thats actually the first time i experienced the problem...i guess the a/c just brought out the problem more....tom i will clean out the throttle body...hopefully it is covered in crap and the culprit....i really dont want to bring my car to a shop for them to tell me they cant replicate the problem....
I cleaned the throttle body and MAF sensor and reinstalled my CAI and tune this morning. Didn''t realize it was so dirty until I saw how brown the run off was when I sprayed it. Now it runs and idles better than ever! Idle is a consistent 900 rpm. Thanks to those of you who suggested it. I should have tried it in the first place.
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06 Black Mustang GT 5-speed, Charcoal GT350 stripes, JLT CAI, SCT II w/Brenspeed Tune, Steeda Axle Back Exhaust, 3.55s, 18" polished Fanblade wheels, Qtr. louvers, Ductail spoiler
Printable Version
Fluctuating Idle - 
Since you paid for a BrenSpeed tune, I'd call them up and make it their problem. 
