TurboDiverArt
12-11-2016, 10:35
Hi All,
I’ve searched the forms for threads on hard shifting and delayed shifting and I didn’t find a response that addresses my situation so decided to start a new thread.
I have a 1999 Suburban K2500 with an 4L80e and 250,000+ miles, I have run Redline Hi-Temp synthetic trans fluid. I change the fluid and filter regularly about every 10,000 miles. The trucks been great and still runs and tows strong. The past few years I have been using a car as a daily driver so only using the truck during the summer to tow my trailer. I think from sitting most of the winters it’s developed a problem. I notice when dropping into drive from either neutral or park it takes about 2 seconds to go into gear, reverse is immediate and normal. In addition, seems more often when cold that under light throttle (shifting below 2000 RPM) that it’s delayed shifting from first into second gear. It almost feels like it’s partially in both gears as it feels like acceleration has slowed while shifting. When it does go into second it shifts harder than normal. If when it’s in this in-between state I give it more throttle it’ll bang hard into second. The problem does not happen on the 2-3 or 3-4 shift or on lock-up. Occasionally when slowing and then accelerating, like at a light that’s just turned green the truck will be in second gear and delay downshifting feeling like it’s staying in second gear and then drop into first with a hard bang. I’m aware of the issue so I try to baby the truck to minimize the bangs. When accelerating at low to normal acceleration if I feel this in-between state I’ll usually slightly lift from the throttle to allow time and a smooth shift into second and I assume cause no damage. If I take off hard in first the shift into second is normal and firm. Seems that if I’m accelerating and RPM is above say 2200 RPM the 1-2 shirt is normal. Below 2000 RPM it happens almost all the time when cold and maybe half the time when warm. I just changed the fluid expecting to find clutch material in the pan but it was very clean which was a little puzzling if in fact first and second gear clutches are fighting against each other. The fluid was a little burnt I think but I had a lot of hard towing on the fluid where the converter wasn’t locked up so the trans temp went higher. I changed race tracks 2 years ago and the newer one although closer is more local roads so the converter doesn’t lockup since I’m below 50 MPH most of the time so temps are higher.
I have a B&M Transpak installed that I put in maybe 10 years ago and has worked great since. I do have a Heath Max-e-Tork ECM that I installed years ago. Bill knew about the transpak so programmed for it so I didn’t get harsh shifts with the ECM, it’s worked beautifully. I’m thinking maybe a sticking valve? Seems strange that it only seems to give me problems between 1-2. Since the drop into drive is slow I’m assuming the problem is probably into first or out of first. At idle in neutral/park if I up the RPM’s a bit it’ll drop faster into first. Never bangs into first from neutral/park.
I do have Car Code but I think the cable is bad as I can no longer communicate with any GM vehicle from any of my laptops. I’ve reached out to Car Code recently but have yet to hear from them.
Any help or suggestions would be appreciated. If anyone is in the Central Jersey area and has an ODBII reader that can read trans codes I’d love to meet up and maybe look for codes. I know the trans has a pressure sensor/regulator that sometimes goes bad but I don’t know if you can read actual pressure thru a scan tool.
Thanks,
Art.
I’ve searched the forms for threads on hard shifting and delayed shifting and I didn’t find a response that addresses my situation so decided to start a new thread.
I have a 1999 Suburban K2500 with an 4L80e and 250,000+ miles, I have run Redline Hi-Temp synthetic trans fluid. I change the fluid and filter regularly about every 10,000 miles. The trucks been great and still runs and tows strong. The past few years I have been using a car as a daily driver so only using the truck during the summer to tow my trailer. I think from sitting most of the winters it’s developed a problem. I notice when dropping into drive from either neutral or park it takes about 2 seconds to go into gear, reverse is immediate and normal. In addition, seems more often when cold that under light throttle (shifting below 2000 RPM) that it’s delayed shifting from first into second gear. It almost feels like it’s partially in both gears as it feels like acceleration has slowed while shifting. When it does go into second it shifts harder than normal. If when it’s in this in-between state I give it more throttle it’ll bang hard into second. The problem does not happen on the 2-3 or 3-4 shift or on lock-up. Occasionally when slowing and then accelerating, like at a light that’s just turned green the truck will be in second gear and delay downshifting feeling like it’s staying in second gear and then drop into first with a hard bang. I’m aware of the issue so I try to baby the truck to minimize the bangs. When accelerating at low to normal acceleration if I feel this in-between state I’ll usually slightly lift from the throttle to allow time and a smooth shift into second and I assume cause no damage. If I take off hard in first the shift into second is normal and firm. Seems that if I’m accelerating and RPM is above say 2200 RPM the 1-2 shirt is normal. Below 2000 RPM it happens almost all the time when cold and maybe half the time when warm. I just changed the fluid expecting to find clutch material in the pan but it was very clean which was a little puzzling if in fact first and second gear clutches are fighting against each other. The fluid was a little burnt I think but I had a lot of hard towing on the fluid where the converter wasn’t locked up so the trans temp went higher. I changed race tracks 2 years ago and the newer one although closer is more local roads so the converter doesn’t lockup since I’m below 50 MPH most of the time so temps are higher.
I have a B&M Transpak installed that I put in maybe 10 years ago and has worked great since. I do have a Heath Max-e-Tork ECM that I installed years ago. Bill knew about the transpak so programmed for it so I didn’t get harsh shifts with the ECM, it’s worked beautifully. I’m thinking maybe a sticking valve? Seems strange that it only seems to give me problems between 1-2. Since the drop into drive is slow I’m assuming the problem is probably into first or out of first. At idle in neutral/park if I up the RPM’s a bit it’ll drop faster into first. Never bangs into first from neutral/park.
I do have Car Code but I think the cable is bad as I can no longer communicate with any GM vehicle from any of my laptops. I’ve reached out to Car Code recently but have yet to hear from them.
Any help or suggestions would be appreciated. If anyone is in the Central Jersey area and has an ODBII reader that can read trans codes I’d love to meet up and maybe look for codes. I know the trans has a pressure sensor/regulator that sometimes goes bad but I don’t know if you can read actual pressure thru a scan tool.
Thanks,
Art.