Engine Engine Surge

[timjimmy]

I just installed a 2800 stall Performance Automatic torque converter in my '06 GT. It idles and drives great, but the problem is that the engine surges while coasting in gear. It will drop down to 500 RPM then back up to 750. Sometimes it will drop to 500 and jump all the way up to 1500. It seems like there is drag on the engine, which drags down the engine, which then compensates and boosts the RPM back up. On cold starts, sometimes it will die when dropped into gear. Any ideas?

 

[Noobz347]

It sounds like maybe there's something that wasn't reconnected during your converter swap? Perhaps the 05+ equivalent of the VSS.

I'm sure that someone will be along shortly that know a lot more about your model year than I do.

In the meantime, have to checked to see if there are any codes present?

 

[timjimmy]

No codes and I checked everything several times.

 

[timjimmy]

That's what stumped me. It isn't throwing any codes and will just rip the tires of under throttle, shifts fine, downshifts fine, and idles fine. Only while coasting does it have a problem.

 

[racerraj]

I wonder if it needs a tune to compensate for the load change under those conditions? I assume it is safe to say that problem did not exist before the converter was installed. Seems the 05 and up V8s need a tune for just about any change (not all, but most).

 

[timjimmy]

That's correct, it only appeared after the install and I did no engine mods at the same time. I checked with Brenspeed, who I purchased it through, and they said it wasn't necessary. I'll double check today.

 

[timjimmy]

I have yet to hear from Brenspeed's torque converter guy, which is very unlike them, but the problem disappeared until this morning, when I drove the car a mile, parked for two minutes, and jumped back in. The second time I started it it died when I placed it in drive. The car even ran fine this Saturday when I took it on a 300 mile drive to a Mustang show in Oregon.