1997 k1500 Chevrolet Suburban shaking/shuddering/jerking at highway speeds
- Thread starter Fredje
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Having the transmission rebuilt and converter replaced should solve your transmission-specific problems irrespective of what the OP has done. If you have any concerns, discuss them with transmission builder or shop owner so they and you can align on a build profile, parts, procedures and any relevant drivability symptoms or other questions you have.
I was going to reply to my post but as it is not 100% solved I am still waiting. Long story short, I had the entire transmission completely rebuilt and upgraded, and the issues were gone the first days, however a very small shuddering at 2000 rpm, around 40-45mph became present again, during lockup. It originally went away using anti-shudder additive, however it has come back again. As the car is currently being used in France for home renovation I will bring it back to the TM builder here in Belgium before the end of the year to have the lockup converted to non-PWM (on/off only). I really don't like the idea of a modulating lockup being allowed to slip. Will keep you posted.
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Personally I would like to set the PWM signal to minimum 90% (for example), instead of modifying the transmission, but I do not know how to do this or someone who could do this for me. Anyone who could help me out with remote instructions? I have read that HPTuners software should be able to modify the tables?
I've considered a similar objective.
I looked just now, using JET's DST, and I see this option for my 1998 K1500 Suburban 4L60E L31 (see red arrow in image below).
There are MANY other parameters in the transmission configuration tables that might effect a change, but I would like to try this option shown below, first.
Right now my Suburban is on jackstands because I'm swapping a 9.5" rear for the 8.5". I hope to try this modification as soon as it's back on the road.
JET's DST can be used to tune 1996 and later ECUs.
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That should have been done via any one of several drop-in PWM-to-On/Off conversion valve kits available in the aftermarket. You shouldn't have any shuddering at all upon TCC application, regardless of whether the PWM system is active or been defeated. My guess is that you have a small leak in the TCC circuit somewhere...
Hey Nick thanks for your feedback, but I did not ask the TM builder to remove the PWM through any of the kits available (could tou recommend one?). So that leaves me with an overhauled transmission that is by design even in new condition already prone to PWM issues and it does not surprise me that minimal leakage even in a refurbished transmission leads to these issues, as probably some mating surfaces are not 100pct restored to new tolerances when doing an overhaul. Anyway I will head back to the TM builder but to get rid of this problem I think PWM elimination would be a good idea. Could you recommend one? Thanks again!
Have your builder install Fitzall's valve for the 1995-2000 model year units - he will know what part number and where to acquire it...It has o-rings, cost around $25 and is good to go. Seals off that circuit completely and I'd venture to guess would fix your shuddering in 4th gear upon TCC application (lock up). If you're curious, Google 'Fitzall 4L60E 1995-2000' and it should be the first or second results in your query.
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