Irregular idle on Deceleration
06-19-2010, 02:06 AM
#51
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Thread Starter
Join Date: Oct 2007
Location: FL
Posts: 1,533
Just an FYI update.. I fixed my problem with idle and surging by putting an air dam around the intake filter.. My filter was exposed, however, and the air blowing directly on it was causing turbulence in the MAF housing, which was causing the problems.. When I would push in the clutch at just about any speed and let it go to idle, the idle would be erratic, sometimes even stalling. Now the idle is perfect, even if I clutch in at 80 mph..
I realize it probably doesn't relate to your problem, but I figured since I posted that I was having similar issues, I would post my solution.
I still question what changed for you that caused the issue? While the MAF housing in the CAI can affect the tune, the change is a static one based on the diameter of the housing.. since that doesn't change, either the MAF sensor is faulty or something else changed to cause the erratic idle. You mentioned that Ford flashed your PCM even though they were told not to.. did they happen to do that prior to this problem coming up? Just curious as to what the real problem is.. the more we know, the better advice we can give.
I realize it probably doesn't relate to your problem, but I figured since I posted that I was having similar issues, I would post my solution.
I still question what changed for you that caused the issue? While the MAF housing in the CAI can affect the tune, the change is a static one based on the diameter of the housing.. since that doesn't change, either the MAF sensor is faulty or something else changed to cause the erratic idle. You mentioned that Ford flashed your PCM even though they were told not to.. did they happen to do that prior to this problem coming up? Just curious as to what the real problem is.. the more we know, the better advice we can give.
As of right now I have only driven the car maybe 100 miles and I honestly think that ford reflashing the pcm masked the problem and the computer is just correcting/adapting to it. I still havent heard from brenspeed and its been about two weeks now so I am kinda unhappy with their response to the tune most likely causing the problem. I plan on putting the intake back on and taking it to a performance shop for them to look at it but am currently in the process of moving and holding off on finding a new shop until I move.
Thanks for all the info I am actually going to try what you suggested with the air dam when I put my filter back on.
06-19-2010, 08:06 AM
#52
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Join Date: Aug 2008
Location: Mississippi
Posts: 1,679
IS that a real vent on your hood? Maybe turbulence under the hood is causing the problem. I am looking into closing the vent on my hood. The more I think about it that vent can only do more harm than good - causing turbulence at the CAI and allowing more moisture on my coil packs.
It might let the engine run a little cooler, but without the vented hood I know I wouldn't have a cooling problem anyway.
It might let the engine run a little cooler, but without the vented hood I know I wouldn't have a cooling problem anyway.
06-19-2010, 09:26 PM
#53
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Join Date: Dec 2006
Location: Redding, CA
Posts: 4,552
I have a very similar problem that started when I added my supercharger. I use the same tune that works with identical equipment on literally thousands of identical mustangs, so Kenne Bell insists that it isn't the tune (and I am inclined to believe them on that). However, two of the biggest symptoms I have are an erratic idle, particularly when moving fast (only happens when moving), and a very slight surging when cruising.. I have an aeroforce and an AF gauge, and I recently took the car out on the highway to troubleshoot, and noticed the gauge was bouncing back and forth from about 13.1 to about 15.6 AF ratio. I switched the Aeroforce gauge to watch the MAF sensor and it was bouncing between ~3.9 to ~5.1 lb/m in tune with the AF ratio. This was in 3rd gear at 60 mph, so RPM was around 3k. It did the same in 4th gear but was more subtle.
In troubleshooting, I have replaced the MAF, the TB, the plugs, found any vacuum leaks and fixed them, replaced the fuel pump, monitored fuel pressure, changed the injectors, double, triple, quadruple checked wiring, and in general have torn my hair out in frustration over this. Since none of this happens in boost, the supercharger is not the factor here. However, the intake IS a factor, and the MAF and MAF housing are different than stock.
So I take an interest in this thread, since a real solution might point me in a direction that leads to the actual problem rather than a "band aid". I am starting to wonder if the fact that the MAF rests up against the headlight in my case is transferring vibration and causing a fluctuation..
To the OP's solution (restoring to stock), the question is, did the reset to factory tune cure it, or did replacing the factory MAF housing? Obviously one won't work without the other, but you did change 2 factors to solve the problem, and chances are it was only one of them that actually caused the problem. If you come up with anything else, please post it. Thanks!
In troubleshooting, I have replaced the MAF, the TB, the plugs, found any vacuum leaks and fixed them, replaced the fuel pump, monitored fuel pressure, changed the injectors, double, triple, quadruple checked wiring, and in general have torn my hair out in frustration over this. Since none of this happens in boost, the supercharger is not the factor here. However, the intake IS a factor, and the MAF and MAF housing are different than stock.
So I take an interest in this thread, since a real solution might point me in a direction that leads to the actual problem rather than a "band aid". I am starting to wonder if the fact that the MAF rests up against the headlight in my case is transferring vibration and causing a fluctuation..
To the OP's solution (restoring to stock), the question is, did the reset to factory tune cure it, or did replacing the factory MAF housing? Obviously one won't work without the other, but you did change 2 factors to solve the problem, and chances are it was only one of them that actually caused the problem. If you come up with anything else, please post it. Thanks!
Your issue could have been solved with some data logging and tuning. The MAF location, wiggling or not, turbulant air or not, diameter of the pipe, length, are all very critical and included in the tunes from KB.
Variations in mileage, quality of the sensors, vacuum leaks, fuel, driving style and other motor related parts and pieces have a huge impact on the way a tune runs in a car. No two are exactly alike and KB knows it. They also they can create a tune that will work pretty good in 90% (just a guess) of the cars.
I hope you didn't buy those parts you replaced. You wasted your money and time.
Custom tuning is amust for any FI system. Until you have expereinced it, you can't appreciate it.
06-20-2010, 01:29 AM
#54
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Thread Starter
Join Date: Oct 2007
Location: FL
Posts: 1,533
IS that a real vent on your hood? Maybe turbulence under the hood is causing the problem. I am looking into closing the vent on my hood. The more I think about it that vent can only do more harm than good - causing turbulence at the CAI and allowing more moisture on my coil packs.
It might let the engine run a little cooler, but without the vented hood I know I wouldn't have a cooling problem anyway.
It might let the engine run a little cooler, but without the vented hood I know I wouldn't have a cooling problem anyway.
Yes it is real and was on the car for a while before the problem started but I may try closing off the vents to see if it helps
06-20-2010, 03:23 AM
#55
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Join Date: Oct 2008
Location: Henry County, Georgia
Posts: 1,636
my car is 100% stock aside from headers and it does the same thing sometimes. When i back out of my driveway or a parking lot and let off the gas it jumps from 500 to 1000 rpm and back and forth so i would rule out the turbulence idea