Hello,

I am owner of 2005 Ford Mustang GT from czech republic, so please sorry for my bad english...

I have problem with engine/throttle body or PCM. My car is self revving or shuts off the engine while driving.. I heard, that it could be TPS/throttle body problem, so i changed it. Now I have BBK TB, new TPS sensor and new gas pedal, but the probem is still there.
Yesterday I measured TP1 and TP2 voltage, and it is correct (I found how it could be in ford service manual)
I captured video of measuring (via SCT and LiveLink) and as you can see, its okay, but at the end there is a short down-peak in TP voltages (to 0.6V from 1.2V)


Then I started engine and measured RPM, TP1 and TP2 voltage, TB position and pedal position.. And as you can see, accelerator pedal is in the same position, but the engine is still revving hard and then again and more. (and I am also not really sure of 5000RPM by less then 25% gas).



I also have graph of this:
(The green curve is acc pedal in the same position, oscilating between two values 4.5 and 5.0, others are TP1 and TP2, RPM and throttle plate position, it's from second video, in third video acc pedal value is not oscilating, but the problem is the same...)

So if I changed TB, TPS, gas pedal, I also think it is not an electrical or TB step-motor problem, it could be only problem with my car's PCM... or any other idea???

 

Throw a few questions at you first.
Do you have a Tuner and a Tune?
Do you have a Cold Air Intake?
Have you disconnected the -battery cable to re-set the PCM?
Why did you not just clean the TB first?
IIRC the BBK TB needs a different tune.
Any other Mods?

 

Well, yes, I have SCT Tuner and Steeda CAI (tuned for this by SCT)
I've tried disconnecting battery, no change..
I also cleaned my old TB, but the BBK TB was on my wish list for a long time, so I bought it.. no change
BBK TB doesn't need different tune (it says BBK, I know, it will be better with tune, but the problem was there before too)

This is the only engine mod, I have then only different spark plugs and exhaust (borla)

I should also say, that there will be no DTC trouble code within this testing. But if the engine stops when driving, or if these problems occur when driving, there are many DTS trouble codes like: P2104 - throttle actuator control system - forced idle
P2106 - throttle actuator control system - forced limited P2111 - throttle actuator control system - stuck open P2135 - throttle / pedal position sensor / switch a/b voltage correlation P0223 - throttle pedal position sensor/switch B (tp-b) ckt high input

 

More questions.......
Was the tune a Generic tune or one made by say Breenspeed or others?
Was the Borla considered when ordering the tune?
What kind of plugs did you use?
Did you get colder plugs by chance??or stock replacements?
I'm sittin here thinkin you changed something, and the PCM is workin overtime to correct it and it's not working.

 

It is only generic tune by SCT (for Steeda CAI) and it's not considering Borla exhaust.. but I have to say, that the problem was there before CAI and SW upgrade.

Plugs are stock replacement, but again, the problem was before them too.

The only thing which was on the car before I bought it, is the Borla exhaust, so only O2 sensor or something could be wrong as upgrade..

 

well, there is only 2 things I can suggest at this point.
Send off to e reputable tuner, and get a tune specifically for your stock strategy, including all of the upgrades.
Check the fuse junction box in the passenger well, to see if it has been water damaged.it should not mees with your engine, tho stranger thing have happened when it gets water on it.
Good luck.

 

OK, tomorrow I will check the fuse junction box and all fuses and I will see.. And then I could order some specific tune from Brenspeed for example.

And is there any possibility to check if PCM is not damaged without diagnostic module?

 

That was my tuner. It's a good choice, Bamatunes I hear are good also.Make sure to go back to stock before uploading anything. Now, no-one has ever upgraded your tune from stock like the dealer correct? It still has the strategy code on the PCM? and it checks out? Check it to make sure. I have no idea how to check a PCM for errors.The only other thought is what kinda Gas do you have there? 87 octane? That's what it prefers unless the tune is for something else.

 

Thanks for tuners.. How do you think to go back? Only with software?
I hope, it will be no problem to get stock Mustang GT 05 software for my PCM strategy code.. or is it problematic to get it? Maybe from tuner, because I am not really sure if Ford sends it to me, and the SW version I downloaded and backuped in my SCT tuner could be damaged.

I run 95 octane fuel (EU octane, I heard it's about 91 US octane - tuned for it via SCT)..

I'll rather check also the PCM strategy code printed on PCM and the code loaded with SCT, good idea

 

There "Should" be a menu item that says load stock tune in your SCT. That is what I would do if the strategy in the tuner corresponds with what the PCM tag reads. If not, you have found your problem and it is hard as hell to correct if it is possible. Then you start callin long distance to tuners telling them your woes.

 

Heh.. now I only hope, it is the same code I will check it in a few hours and I will post it here, I also check fuses.. thank you for advice

 

Today I realized, that this would probably be only software problem..

I loaded Stock tune and after starting engine it worked quite good. Its only stock tune, so after a while I stopped engine and closed garage. Now its time to get Brenspeed tune exactly for my stang, so I hope, it will work fine!

But today no more problems with self-revving and so on, maybe this helped.. thanks

 

Then "I" would just put your stock Air Box on until you get the good tune from whomever you choose. The Steeda CAI's all need a tune to run right. So i'm **** glad you found the problem.

 

Me too, but I haven't stock air box, I bought it with some crappy cheap "CAI" and throwed it out.. But its very snowy here in these days, I wont drive until May, so there is a plenty of time to make it okay.. I only hope now, the problem is solved

Thank You very much!