GT Performance Mods 2005+ Mustang GT Performance and Technical Information

hesitation at higher speeds

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Old Jun 29, 2005 | 06:59 PM
  #1  
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So I'm driving back to Maryland from Pittsburgh today, I find a nice long straight away on the PA turnpike, drop it into 4th, and step on it. Right when I stepped on it the car choked for a second then took off. I was doing about 77mph in 5th when I dropped it into 4th. This same thing happened to me on my way out to Pittsburgh. I can not reproduce the problem after it happens the first time; seems like it only happens once. Also, I did some drag racing a week ago with the same tune and gas and did not have this problem while launching. It seems this only happens from a rolling start. I am running the C&L 93 octane tune with 93 octane BP gas.

Has anyone else experienced this problem? It's rather annoying.
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Old Jun 29, 2005 | 08:03 PM
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Not having that problem. What version are you using? R12-R16?
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Old Jun 30, 2005 | 07:55 AM
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ski
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Originally posted by pittperson@June 29, 2005, 9:02 PM
So I'm driving back to Maryland from Pittsburgh today, I find a nice long straight away on the PA turnpike, drop it into 4th, and step on it. Right when I stepped on it the car choked for a second then took off. I was doing about 77mph in 5th when I dropped it into 4th. This same thing happened to me on my way out to Pittsburgh. I can not reproduce the problem after it happens the first time; seems like it only happens once. Also, I did some drag racing a week ago with the same tune and gas and did not have this problem while launching. It seems this only happens from a rolling start. I am running the C&L 93 octane tune with 93 octane BP gas.

Has anyone else experienced this problem? It's rather annoying.
If you're using version r21, then see if reflashing with the same tune fixes things.
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Old Jun 30, 2005 | 07:57 AM
  #4  
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Not a problem here... In fact, it actually cured some hesitation I was getting with the stock tune/air intake.
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Old Jun 30, 2005 | 09:00 AM
  #5  
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From: Waddington, NY (waaaay up north)
I don't have a tune yet, but have experienced this problem several times. Both times I was getting on it pretty hard and it happened shifting from 1st to 2nd.
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Old Jun 30, 2005 | 04:07 PM
  #6  
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Originally posted by outdoorstom@June 30, 2005, 9:03 AM
I don't have a tune yet, but have experienced this problem several times. Both times I was getting on it pretty hard and it happened shifting from 1st to 2nd.

Thats your traction control. Its a different kind of cut-off that keeps your tires from spinning. That's not a problem. The issue here is in high speed and high gears .
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Old Jun 30, 2005 | 05:03 PM
  #7  
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Originally posted by GhostGT@June 30, 2005, 5:10 PM
Thats your traction control. Its a different kind of cut-off that keeps your tires from spinning. That's not a problem. The issue here is in high speed and high gears .
I have had this same problem 7 or 8 times. It's not the traction control as I thought it was at first. It's been doing it when I stop at a stop or almost stop at a stop light and then take back off. It's done it a few times when I take off pretty slowly. I am fairly worried. I don't remember it doing it before I installed the JET performance chip and started running 93 octane fuel. Last night I took the JET chip out but I still have a tank of 93 gas and it did it twice on one take off today and it was a slow take off. Could the 93 gas choke the motor up sometimes? I'm going to leave the chip out and run 87 in it for a while and see if the problem occurs again.
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Old Jul 1, 2005 | 03:33 PM
  #8  
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Originally posted by 38special@June 29, 2005, 10:06 PM
Not having that problem. What version are you using? R12-R16?
I am using r21 and just reloaded the tune to see if that will help anything. I guess I should just get find a dino somewhere and get a custom tune.
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Old Jul 1, 2005 | 09:09 PM
  #9  
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Originally posted by pittperson@June 29, 2005, 9:02 PM
So I'm driving back to Maryland from Pittsburgh today, I find a nice long straight away on the PA turnpike, drop it into 4th, and step on it. Right when I stepped on it the car choked for a second then took off. I was doing about 77mph in 5th when I dropped it into 4th. This same thing happened to me on my way out to Pittsburgh. I can not reproduce the problem after it happens the first time; seems like it only happens once. Also, I did some drag racing a week ago with the same tune and gas and did not have this problem while launching. It seems this only happens from a rolling start. I am running the C&L 93 octane tune with 93 octane BP gas.

Has anyone else experienced this problem? It's rather annoying.
I have the C&L/93 octane predator tune as well, and I was JUST remarking to my son about hesitation appearing now and then. When first flashed it never did this. The only thing I can think of is the tune's parameters knocking some thresholds in the computer's number tables, and the computer is "adapting". I know NOTHING about the 05's computer management system so it's just a theory. I'm going to reflash it tomorrow. One thing I do notice is that the hesitation in in normal everyday driving. If I get down and dirty it's clean in every gear. Just got home a bit ago and proving I could chirp the first 3 gears to my son.

By the way, I found BP to run like crap (detonation) in my car so I tried Shell, and it's been fine.

I'm also in Maryland in Carroll County. We have a Cruise In every Saturday this way (alternates weekly between a spot in Eldersburg and Mt. Airy). While I can't make tomorrow's, I should be at most of the rest this season. Head on over some time--I have a Torch Red too, but just ordered $800 worth of exterior and underhood mods for the car. Can't wait.

John
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Old Oct 3, 2005 | 10:22 AM
  #10  
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Man, I was on my way back from Pittsburgh this morning, cruising at 75 (had held that speed for about 1.5 hours), dropped to 4th and stepped on it. The darn car bucked and hesitated again. I am stumped on why it is doing this.

As we mentioned earlier in the thread, the car seems to be flat out choking; not getting enough fuel. To give you an idea of what it feels like, just imagine being in first gear, stepping on it from a stop, letting your foot off the gas right away, and stepping on it again.

I'm running the C&L 93 octane tune with retarded timing. Anyone have any insight into this yet? Anyone else out there experience this same problem?
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Old Oct 3, 2005 | 10:43 AM
  #11  
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My wife and I had the same thing happen a couple times (2 or 3) when we were on our long road trip. It has never happened on my daily commutes or errand running.

It happened when we were running 70-80 MPH for long distances on open highway. When I would need to slow down a bit out of highway speed range then put the gas back on, not necessarily hard, there would be a hesitation and almost cut out like the gas shut down before it would kick in and go like nothing happened.

It definitely was not the throttle by wire delay or anything like that. The entire engine acted like it wanted to stop for a second.

I took it to the dealer for some other things and asked them to check it out and they ran all the computer diagnostics and couldn't find a thing or duplicate the problem.

This was all before I did any mods also.
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Old Oct 3, 2005 | 11:09 AM
  #12  
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This has happened to me once when downshifting from 5th to 3rd on the highway. I do not have a tune.
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Old Oct 3, 2005 | 12:28 PM
  #13  
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Ok, that makes me feel a little bit better that this has happend to unmodded cars.

6505Pony: I also never have the problem running around town, only after holding a constant speed for a good amount of time. I don't think I'd count the TBW out just yet. It's almost like the computer has to "wake up" and realize that it's not holding that constant speed anymore. The reason I say this is because it will only happen if I step on the gas hard, if I downshift to 4th and gradually give it gas, I don't get the hesitation.
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