Pronounced Driving Mode Differences?

[pilotgore]

Then you must have the Grimmspeed eliminators or something like it installed. The GT350 ECU considers the muffler valves an integral part of the engine airflow management system and it gets pretty grumpy when the valves aren't working. So, if your car is working okay but the valves aren't moving with the switch or the start-up sequence, then something is convincing the ECU that all's well. That's what the eliminators do, for people who want the valves stuck open or closed all the time.

I believe the eliminators completely cut the valves out of the system and are no longer connected. If he’s seeing movement at startup, then I don’t think it has the eliminators installed.

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[BierGut]

I believe the eliminators completely cut the valves out of the system and are no longer connected. If he’s seeing movement at startup, then I don’t think it has the eliminators installed.

I am not seeing movement at start up.

 

[BierGut]

Then you must have the Grimmspeed eliminators or something like it installed. The GT350 ECU considers the muffler valves an integral part of the engine airflow management system and it gets pretty grumpy when the valves aren't working. So, if your car is working okay but the valves aren't moving with the switch or the start-up sequence, then something is convincing the ECU that all's well. That's what the eliminators do. They're for people who want the valves stuck open or closed all the time.

Someone with a GT can correct me, but AFAIK, the Mustang GT muffler valves are decorative and the ECU might not care whether they're working or not. But the GT350 ECU will throw a code and it might even go to limp mode - that I'm not sure of.

This will be the first line of questioning at the dealer. They sold it this way, so they need to figure it out. I do have the previous owners number, however, I ended up with it in some mistakenly passed on paperwork. I am shy about calling (at least at this point) because, well, while I would welcome calls from new owners of my previous cars, I am not sure who else might.

Also, I checked all drive modes with the rocking on the threshold. The car does stiffen up from normal to sport to track -- so we're good there.

Thanks to all of you guys -- I really appreciate the help and consideration!

-BierGut

 

[pilotgore]

I am not seeing movement at start up.

Whoops... I definitely read that wrong.

 

[Point45]

Presumptive comment ... If one has never heard the different GT350 settings, one wouldn't necessarily know. The car is loud and raspy, is it the loud mode? How would I know? This is my very first experience with a GT350.

If it was a Z/28 or Porsche with their sport exhaust I would have some experience.

So again -- I'm working on determining whether they are open or closed. I'll know later with luck.

Glad you found out if theres a problem but its not really presumptive. If the noise difference from all accounts is significant and like an on off switch.

Everyone is just overthinking the initial question of if the valves are working properly.

There is a TSB about the valves sticking, its not an uncommon issue with the mustangs. Something you can ask the dealer about.

 

[sox3]

I just went out and checked mine. My valves are open a small amount. If you take a bight light and look thru the honeycomb on the right side you can see if the harness is plugged into the valve assembly. On the left side you look up thru the exhaust pipe with the valve and can see the plug on that side. If it has a grimmspeed module there will be no harness connected to the valves. Dont know if this will help any.

 

[BierGut]

I just went out and checked mine. My valves are open a small amount. If you take a bight light and look thru the honeycomb on the right side you can see if the harness is plugged into the valve assembly. On the left side you look up thru the exhaust pipe with the valve and can see the plug on that side. If it has a grimmspeed module there will be no harness connected to the valves. Dont know if this will help any.

Cool -- I'll be looking in a few minutes.

 

[sox3]

Now, not to throw more wood on the fire. could it have an AWE Switchpath that allows you to open the valves anytime by remote? Wonder if it could have that but no remote included to operate it??

 

[BierGut]

Cool -- I'll be looking in a few minutes.

BINGO! We have a winner!

The harnesses are not plugged into the actuators. They are looped over something and held tight with a wire tie. There looks to be just the open plug port so what was done to deactivate the valves is still a big mystery.

Great call man. Now the process begins of identifying what product is where?

Maybe I will be rude and call the previous owner.

 

[pilotgore]

I just went out and checked mine. My valves are open a small amount. If you take a bight light and look thru the honeycomb on the right side you can see if the harness is plugged into the valve assembly. On the left side you look up thru the exhaust pipe with the valve and can see the plug on that side. If it has a grimmspeed module there will be no harness connected to the valves. Dont know if this will help any.

The real hero!

 

[sox3]

Glad you got it solved. So now do you return to dealer for fixing? Or If you have room you can drop the lower cover and plug them back in. Its not a difficult job if you can get under it to remove the two forward bolts.

 

[BierGut]

Glad you got it solved. So now do you return to dealer for fixing? Or If you have room you can drop the lower cover and plug them back in. Its not a difficult job if you can get under it to remove the two forward bolts.

I'll definitely go back to the dealer... they are 4 miles away and I just bought the car Saturday.

The question remains... with the valves just slightly open, is the car making normal, loud or in between exhaust noise?

Are do the valves open 90 degrees when in loud mode?

 

[sox3]

They should be wide open I beleive in loud mode.

 

[BierGut]

They should be wide open I beleive in loud mode.

Then I have a problem that they need to address.

 

[sox3]

The valves have to be set in either open or closed mode , then disconnect the harness and install grimmspeed plugs. Whoever installed them may not of had the car running and valves open prior to disconnecting the harness from the valves.

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