2007 GT Throttle Issue

[StockishS197]

Hi,

I have been chasing an odd throttle issue with my 2007 Mustang GT. Under very specific situations (low speed cornering/turning), the PCM is commanding less throttle input, despite the same pedal input. While at higher speeds, in neutral/clutch in, issue doesn’t arise.

The car has ~55k miles, manual, long tube headers, catted x pipe, hot rod cams, CMDPs. The car has done it prior to mods, through multiple tuners and revisions, TCS off/on. Also replaced the TB with a new Ford Performance stock replacement and issue still persists.

I had a prior 2006 that didn’t have this issue, but this one is puzzling. I have been working with Lito and the logs look good, car otherwise drives great, but cannot figure out why the PCM is pulling commanded throttle.

Did something change in the PCM/Strategy in 07+ PCMs or has anyone else seen this issue? Screenshots of the throttle both when the pedal input and PCM commanded throttle match, and when the PCM is pulling throttle.

Any help is appreciated.

 

[Laga]

I was have throttle problems with my 05 and this PCM reset procedure for throttle helped. It worked for me. It’s worth a try.

 

[StockishS197]

I was have throttle problems with my 05 and this PCM reset procedure for throttle helped. It worked for me. It’s worth a try.

Have done this, KAM reset, and tune revisions and it still persists.

 

[Midlife Crises]

I was having similar problems with the twin 65 throttle body I’m running and this procedure did not solve it. I loosened the four mounting bolts and very carefully tightened them again in stages. Haven’t had throttle issues sense.

 

[07 Boss]

Seems like as far fetch but have you examined your actual throttle pedal? The pedal assembly is just a potentiometer with brushes that rub across metal plates. Could be while you are turning the angle that you are depressing the pedal may shift a bit. If there is any side to side movement of the pedal arm it might be getting inconsistent contact with the metal plates. Maybe take the time and open her up to see what it looks like on the inside. It's a reach but it looks like you have exhausted most other troubleshooting ideas. The only other think I can think of is maybe you have a broken wire with an intermittent connection when your turning.

 

[StockishS197]

I was having similar problems with the twin 65 throttle body I’m running and this procedure did not solve it. I loosened the four mounting bolts and very carefully tightened them again in stages. Haven’t had throttle issues sense.

Yeah this a good call, but have taken off the TB a few times to ensure it’s seated well and even replaced the TB, still happens.

 

[StockishS197]

Seems like as far fetch but have you examined your actual throttle pedal? The pedal assembly is just a potentiometer with brushes that rub across metal plates. Could be while you are turning the angle that you are depressing the pedal may shift a bit. If there is any side to side movement of the pedal arm it might be getting inconsistent contact with the metal plates. Maybe take the time and open her up to see what it looks like on the inside. It's a reach but it looks like you have exhausted most other troubleshooting ideas. The only other think I can think of is maybe you have a broken wire with an intermittent connection when your turning.

Yeah another good thought. In the datalog, pedal position is logged and consistent. The only variable I have seen is the ETC commanded throttle being lower.

Very odd that it only happens while turning at low speeds lol

 

[GriffX]

Turning at low speed means additional load to the engine from the power steering.

 

[StockishS197]

Turning at low speed means additional load to the engine from the power steering.

So perhaps increased load, PCM sees the increased load from the PS pump and decreases commanded throttle as it’s seeing the increased load?

 

[GriffX]

So perhaps increased load, PCM sees the increased load from the PS pump and decreases commanded throttle as it’s seeing the increased load?

No real idea what is going on, but I would guess it is a tune problem.

 

[StockishS197]

No real idea what is going on, but I would guess it is a tune problem.

I wish it was that easy. Lito has looked over the logs and all looks good. When I bought the car, it had an old SCT X2 Brenspeed tune and had the same issue, so thinking it either a PCM issue or mechanical.

 

[86GT351]

Understanding you state that Lito is helping, have you datat logged the fuel? Maybe in turns the car is going lean reducing power?

 

[StockishS197]

O2 voltage, STFTs, pump DC and fuel pressure drop across injectors all look normal and similar to when it doesn’t occur.

Also, car runs great at WOT and doesn’t show any issues of being lean.

 

[GriffX]

Here is a good list which parameters to record

https://support.bamaperformance.com/hc/en-us/articles/201797909-What-Parameters-Do-I-need-to-Datalog-05-10-ALL

 

[StockishS197]

Here is a good list which parameters to record

https://support.bamaperformance.com/hc/en-us/articles/201797909-What-Parameters-Do-I-need-to-Datalog-05-10-ALL

Great resource.

Going to log torque source and see if that shows why the PCM is reducing throttle input.

 

[StockishS197]

We have a result!

During the free revs when the PCM is limiting commanded throttle, torque source goes to 1, whereas normal is at 0.

Based on my googling, torque source of 1 means Transmission Torque Truncation, or limiting torque so that makes sense, but why on the manual?

 

[JC SSP]

Does it do it with traction control on or off?

 

[StockishS197]

Does it do it with traction control on or off?

Happens regardless of TCS on or off.

 

[StockishS197]

Final update here. Lito updated the tune to remove transmission truncation manually, which solved the initial issue. Sounds like this isn’t normally an issue.

Is truncation built into the manual cars too from factory?

 

[GlassTop09]

Final update here. Lito updated the tune to remove transmission truncation manually, which solved the initial issue. Sounds like this isn’t normally an issue.

Is truncation built into the manual cars too from factory?

Hi StockishS197,

This is interesting..........

Do you happen to know the '07 MY Spanish Oaks ECU OS\Strategy code of the OS being used in your car's ECU (7-digit code)?

The only Ford OEM Spanish Oaks ECU OS\Strategy code I know of that has TM Manual Transmission Truncation (engine TQ output by gear control) enabled is FPAN054 (specifically run in Spanish Oaks ECUs fitted to the Ford 05-10 S197 FR500 class series factory race cars). I have a copy of all manual OEM GT Spanish Oaks tune calibrations from 05 thru 10 MY's & a couple of Spanish Oaks based GT500 tune calibrations (1 '07 MY & 1 '10 MY), but the Spanish Oaks OEM OS strategy I've listed here was the only 1 I've seen to date that has this feature enabled from Ford for a manual trans...........autos have this feature by default (use engine TQ output among other parameters to determine gear shift logic\points).

This feature, as I understand it, was intended to be used primarily instead of ABS to control engine TQ output by gear for competitive racing purposes (road racing, HPDE, drag racing, etc.)......that I've noted in the 2 copies I have in hand, this feature was disabled thru the tune calibration by default (engine TQ output was set to some ridiculously high number that the engines would not achieve for all gears thus "disables" it thru the tune), but at least the feature was available\enabled in the OS\Strategy (or firmware if preferred) to be used.

Just curious to know...........