gatkins94

OK...here's MY update. I took the throttle body off again last night and decided to REALLY clean it. I used an ENTIRE can on that thing, along with rags and even a sharp scraper to make sure I got the areas around the butterfly hinge points.

That did it. This thing is running like a new car today, all the way to work, through lunch, and hopefully on the way home. I'll update if that changes, but I think that's what my problem was.....a dirty throttle body.

DM-SC

Well...at least one person found some relief!

I've had two vehicles (carb equipped) exhibit the same erratic idle on decel, over the years. Replacing the EGR value fixed both of them.

I have no idea if a bad EGR would cause the same symptoms on an EFI vehicle...

TypeS

My 06 has been doing this for 8+ months, mods are JLT intake and Brenspeed 93 oct tune. I have tried cleaning the TB as stated on the spray can along with disconnecting the battery and reloading the tune. I have not fully removed it so I will try what was stated above and see if the more thorough cleaning will do the trick.

gatkins94

TypeS, you've tried cleaning it on the car? Yea, I had to take it off and really polish the runners. I had the thing completely carbon free when I put it back on and it's like driving a new car now! I will re-post if it starts again soon, but I think this did it. My car had gotten to the point that I could barely drive it...it would surge to about 2k, then drop back to about 3 hundred rpms...and it did it at every idle, so this was a dramatic improvement. I did buy another TB off of EBAY that has the TPS switch on it, and I was planning on just putting it on a shelf, but if you, or anyone else wants it, I'll put it on my car and test it out, then if it works sell it for what I paid for it.

bobbob

yeah i have a 2006 v6 and have the smae problem when im rrolling at any speed with the car in neutral the rmp rev up to 1000-2000, but as soon as i put in the clutch it drops down to normal 700, if i release the clutch while rolling still it goes right back up, as previously said it only was once and a while but now its every ******* time i drive its irritating, i also found that if i roll to a stop once im 100% stopped it drops to normal rpm, ive cleaned the MAF the tb is next, how can i check the voltage on the tps? i cant find any wires with the .98 volts, hahaha when it revs at stop light everybody (including mini vans) try to race me lol. any suggestions? clean the entire tb?

simplexdesign

So the latest update is that I went to ford earlier this week and had them reflash the pcm and I reinstalled my factory airbox and sure enough it seems like the problem is gone.

I called brenspeed and talked to dave and I was assured that the JLT intake and tune could not be the problem since they sell so many but with no other choice but to believe that it is I asked for them to work me out a deal on another tune and intake since this one seems to be the cause of the problem. I havent heard back from him yet so we will see if they actually give me a replacement

shanec

There is no way in the world the intake is the problem. It is completely passive. Unless there's an install mistake causing a leake, there is nothing there that chould cause problems.

The tune - different story. All kinds of possibilities in the tune.

But based on my recent experience my guess is your throttle body or tps. Ford programming your car only reset the car's attitude and expectations about that hardware. I think in time the problem will return and you end up replacing those parts.

Just my guess. I had similar issues that got.fixed with a new throttle body.

shanec

PS: I'm assuming you've already cleaned your throttle body and MAF. There is a cleaner for each. Throttle body is simple spray and wipe. MAF is spray and let dry. Never ever directly touch the MAF sensor.

dkersten

I tend to disagree there.. While I am not 100% sure on the JLT, I know that many CAI's use a different size MAF housing, which affects how the MAF sensor reads. This is why the tune change makes the difference, and while theory suggests that just adjusting the MAF tables should correct it, there are other factors that may be coming into play. Furthermore, either the "performance tune" could be causing the issue, or just the fact that the MAF sensor is in a different location. I am starting to question if it is a matter of "stability" of the sensor itself.. If the CAI is bouncing around on decel, is that causing inaccurate readings from the MAF sensor? After all, it is just a wire that the air flowing past the sensor pushes on. This would be why turbulence would also cause a problem like this.

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!

dkersten

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.