RPM surge ?

[Power Hungry]

The shudder is not new and is generally related to the converter locking up too quickly after tip-in. That is easily remedied.

I suppose the unstable idle could be related to a lean condition, although it is quite uncommon to see lean conditions at idle. It may also come from too much timing at idle. Try adjusting the custom option for timing back about 2 degrees (-2 degrees) and see if that resolves the unstable idle. If so, we can fix that and the shudder at the same time.

Thanks.

[MercedesTech]

Cool. Can't thank ya enough Bill. Like I said, friday i should have time to tinker with it some. I will post back what I find.

And it seems fine at idle, while standing still. Its while in 4th gear that things start to seem really "off". Cruising at 52 MPH I found the rpms "hunt" some. They will shoot way up, then calm down, and bounce around a little. The converter will start locking and unlocking at slightly higher speeds. Also, converter will NOT stay locked. No matter what speed (took her up to 80 on the way home the other day to be sure) , if I remove my foot from the gas, the converter automatically unlocks.

If I turn OD off, truck drives almost completely fine. The issues are not any where near as pronounced.

[04FX4]

Mine has done this a few times as well. The difference is mine does it at low speeds, and in second gear. I notice mine when going through school zones. I have talked to Bill , but my problem is that I can not make it happen when I want, so it is hard for Bill to fix the problem. My RPMs jump about 200-400 and the TQ is not locked and it does not seem to be jumping in and out of gears.

[Power Hungry]

Originally Posted by MercedesTech

Also, converter will NOT stay locked. No matter what speed (took her up to 80 on the way home the other day to be sure) , if I remove my foot from the gas, the converter automatically unlocks.

Converter unlocking during decel (ie. foot off the pedal) or when quicly accelerating (pressing down quickly on the throttle) is normal. However if the converter keeps locking and unlocking while at a steady cruise, there is a problem.

Let me know if this is what's happening.

[Jackpine]

Originally Posted by Power Hungry

Converter unlocking during decel (ie. foot off the pedal) or when quicly accelerating (pressing down quickly on the throttle) is normal. However if the converter keeps locking and unlocking while at a steady cruise, there is a problem.

Let me know if this is what's happening.

Interestingly, at least to me, Bill, is how the converter tends to stay locked with the cruise control on when going downhill. At least it did on our trip to and from California. It's almost as though it's trying to maintain the speed in a coast situation (up to a point of course) instead of just letting the vehicle speed up.

Also, reducing the shift points and torque converter lockup points both for upshifts and downshifts does seem to have helped get rid of the "eagerness" to unlock under mild load that I complained about before.

I know this post is a bit of a hijack, but thought it might add something to the knowledge base.

- Jack

[Power Hungry]

Oddly, I've never really paid attention as to whether the converter unlocked on decel when in cruise. Since it uses an inferred throttle value, I'd assume it handled shifting in a relatively similar fashion. I do know that the throttle feed rates are much less aggressive than using your foot which may account for less frequent unlocks.

I'll have to throw something in the Expy and go for a ride this evening so I can take a closer look.

Thanks for pointing that out. Might be quite helpful!

[MercedesTech]

On cruise, the converter stays locked !

Converter unlocking during decel (ie. foot off the pedal) or when quicly accelerating (pressing down quickly on the throttle) is normal. However if the converter keeps locking and unlocking while at a steady cruise, there is a problem.

Hmm.... Because no matter what speed, it unlocks immediately. Doesn't feel right, but maybe just me looking for something wrong.

Anyways, yes, the converter will lock and unlock under steady acceleration. The RPMS also bounce around. when it first goes into 4th. I will feel the surge. While under steady pedal, I will feel the RPMs go up, and the truck pull (talking only a second) then drop right back down and feel slugish, then shoot back up and pull, etc. Maybe I should hook up a video camera on my guages so you can see whats happening. Sure is hard driving, and trying to stare at 8+ guages !


Jack&Janet: don't worry about hijack at all. The more the better ! Really.

[kokopellimotorsports]

Subscribed.

Ty

[88Racing]

Don't want to have to mention this, but have you tried it with the STOCK program?

Just trying to eliminate weather its the tune or the tq converter.

Lars