Quick Shifting, Throttle Irreg on decell...help

[ff43sc]

>I have a 95 gmc k2500 4x4, w/6.5L L65 engine,187k miles, injection pump and
>computer were replaced in feb 2003, recently the shifts have become stacked,
>very quickly moving through 1st to 3rd gear....along with this when i let off
>the throttle slightly the rpms drop quickly several hundred rpm, same with
>cruise control on, I can pull up a hill at 70mph with no problems but as
soon as
>i come over the grade and start back down the throttle(on cruise control)
>drops very choppy , then accels, then drops(within a second or two...) and
will
>keep doing this until it needs to accel regularly again....
>took it to a tranny shop, then said they were getting bad data from the
>throttle(electronic) and couldn't diagnose it further until that was
corrected, i
>replaced the APP($300) but it still does it... paper clip to check codes only shows 12, no service engine or service throttle lights have come on at all, rpms are 2500 at 65mph, 4.10 gears, 245-75-16 tires,. This summer I had the timing reset and had it on a tech 2 scanner and it was indicating low range
>engaged in the various data screens, but no computer codes were recorded.....could a sensor indicating low range
change the
>throttle response and shifting?? the engine sounds much louder at 65-70mph also...still plenty of power snowplowing, pulling etc. for any help you can give me or refer
>me to, thanks, steve
>ff43sc@aol.com

[ 01-01-2004, 06:51 AM: Message edited by: ff43sc ]

[SHEIDEN9]

i recently had the same thing happen checked everything couldnt find anything wrong, no codes all inputs ok finally took it to chevy they couldnt find anything wrong. drove it home 2 miles down the highway the truck quit wouldnt restart they put a pump in it after i chewed them for about an hour, runs great now

[ff43sc]

can anyone give me any more help/opinions on this problem?? from reading numerous posts, It sounds like maybe my torque convertor isn't locking up in overdrive(i know nothing about how the 4l80e works) but some of the other posts i have read sound like the torque convertor not locking up is to blame. The computer isn't showing any codes, no service engine light...if it's not locking(torque convertor), can this be remedied with a new module/controller? or does torque convertor need to be replaced?? or does the tranny have to be rebuilt..how does this work? any help would be appreciated...thanks

[rustypig]

Sounds like maybe there may be something going on with the overdrive clutch selenoid (torque converter clutch selenoid...TCC), engaging/disengaging which could cause symptoms similar to yours. I'm not as experienced in this area as I'd like to be, but it may help to clean all the connections to the tranny "cannon plugs". I've fixed intermittants and other various oddities more than once by disconnecting every electrical connection I can find and blowing them out with dielectric (electrical connection) cleaner. Then I'd check every vehicle ground I can find and clean them as well. May be worth a try and see happens.
Sorry...it's not much of a help though.

[Chris Hinds]

I've written with this issue too, and nobody seems to know. My truck is a stick, but behavior is similar. I get good power, but it takes minimal pedal to cruise down the road, and lifting on a downhill causes abrupt decel. Cruise hammers on and off on anything but level or uphill, and is harsh to say the least.

My throttle is very hard to modulate at low RPM. You move the pedal at all and the engine wants to flare... If yours is similar, I think your transmission shift problems might be a result of the extremely low throttle setting that the truck is now operating at... Shifts are based of throttle position, with less throttle getting shifts to happen at lower RPM...

My ideas so far... The resistor that goes in the FSD connector is missing and resulting in excessive fuel for a given throttle position or the the IP is somehow screwing up and overfueling for a given command. I'm still learning how this all works.

Haven't checked the resistor yet, and if it's the IP, I'll just live with it, since my truck is a stick. BTW, the truck has been this way since I bought it 15k miles ago, and has 208k on it.
Good luck!