Overdrive shutter, can recreate

[kenjunior]

Got a question:

Run truck up to hiway speed, doesn't matter, if its 55 thru 75 mph, if its not shifted into OD and I hit the set cruise button tranny will shutter like its coming apart. If I let it shift into OD THEN set cruise its fine, if I let cruise (hitting resume) take truck to hiway speeds its fine.

No truck mods at all, Gryphon programmer with basic tune. I haven't tried much in tinkering, I just know how to get around the shutter.

Any thoughts???

KenJunior

[Jackpine]

The only questions I have are, "Does the truck do this when the OEM stock tune is loaded?". And, "Which tune are you using?"

It sounds like when you hit the cruise button, you let off on the gas to allow the cruise to take over, is that correct? And, it sounds like you are accelerating fairly hard when you do this, or the truck would already be shifted into overdrive, right? I've never felt the shudder you describe, but then I don't set the cruise the way you seem to be doing either.

- Jack

[kenjunior]

I only had the truck for less than 2 months before tuner. I never noticed it. I returned it to stock and no, the shift/shutter is not there.

Not hammering down but just a solid run up to hiway speed before and click the set button as I let off gas pedal.

Just a basic tune from the guys here. 87 Performance.

[Jackpine]

My advice is, don't set the cruise control that way. It appears the transmission is shifting into overdrive at the exact instant the PCM is attempting to set the fuel and torque converter to hold the current speed. My feeling is the PCM is getting conflicting signals from the speed sensor and engine load. I'd let the speed stabilize, and allow the transmission to shift into overdrive before "setting" the cruise speed.

It's possible that this is something Bill can fix in your tune, but I doubt it's really needed. Since a tune has less "slop" than the stock tune, it's possible the transmission is not fighting with the cruise control in the stock setting.

I'm doing a lot of guessing here though and Bill might have much better ideas. Still, it doesn't sound like what you are experiencing is dangerous to the transmission.

- Jack

[kenjunior]

If I don't let it do it's shifting before I actually set the cruise, it will continue to shutter for, well I don't know how long, I have let it be stupid for probably 10 seconds, at 70 MPH 10 seconds of shuttering seems like ETERNITY and I just tap the brake and shut the cruise off, let it shift and then set the CC again.

KJ

[Oliver]

This is not only your problem but this is a big problem actually some of shutters
are not compatible with your car and when you drive in fast speed then the
shutters are create problems and you may face the different problems
in your fast driving