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Username Post: 98 Tahoe with a hard 1-2 upshift        (Topic#350630)
BOTTLEDZ28 
Member
Posts: 29

Reg: 04-02-06
04-15-18 11:53 AM - Post#2731041    

I have a 1998 tahoe with a 4L60E with 160K miles on it. It has a very hard and firm 1-2 upshift. I think it started after I did the GEN3 (0411) ECM swap but Ive had Lextech mess with the tune and nothing changes. Ive even tried a spare ECM and it does the same thing. The only way to get it to shift easy it to time the shift just right and let off the throttle just before its about to shift.

The converter also unlocks once in a while when its raining out and wont even get into lock up on rare occasions once I get to a cruising speed on the highway.I have to let off the throttle for a second and then get back into it and the converter will lock.

I had a buddy scan and log the ecm with EFI Live and he didnt notice anything wrong. TPS voltage looks normal. Line pressure is normal and he even added torque management back into the tune and that didnt change anything.
Im thinking there is something going on in the pan. Can anyone offer me any advice and info on what might be causing this?

1991 z28,sebring silver metallic, 383 HSR, AFR 190's, F.A.S.T,T56, 4th gen rear ,30 lb injectors,, 3.73's, slp headers. MSD 6AL,holley fuel pump,Harland sharp 1.5RR


Edited by BOTTLEDZ28 on 04-15-18 12:05 PM. Reason for edit: No reason given.

 
65_Impala 
Very Senior Member
Posts: 3990

Reg: 12-29-02
04-15-18 02:13 PM - Post#2731060    
    In response to BOTTLEDZ28

Did you put a pressure gauge on it and check the line pressure, or just look at the "line pressure" in the OBDII data? If you haven't used a gauge yet then try it first.

Otherwise, it might be accumulator for the 1-2 shift.



 
rain_man_rich 
Contributor
Posts: 138

Loc: Grants Pass, OR
Reg: 02-09-14
04-15-18 03:27 PM - Post#2731076    
    In response to BOTTLEDZ28

Here's a pretty good read.

http://twincharlotte.com/blog/30-common-4l60e- tran...

and this:

https://ls1tech.com/forums/automatic-tran smission/...





Edited by rain_man_rich on 04-15-18 03:30 PM. Reason for edit: No reason given.

 
BOTTLEDZ28 
Member
Posts: 29

Reg: 04-02-06
04-16-18 04:34 PM - Post#2731206    
    In response to 65_Impala

I did not put a gauge on the trans to read line pressure. I will look into that. Right now, I am having trouble finding the correct 1-2 accumulator parts for my truck. Apparently, GM used quite a lot of different setups for the 4l60E

1991 z28,sebring silver metallic, 383 HSR, AFR 190's, F.A.S.T,T56, 4th gen rear ,30 lb injectors,, 3.73's, slp headers. MSD 6AL,holley fuel pump,Harland sharp 1.5RR


 
BOTTLEDZ28 
Member
Posts: 29

Reg: 04-02-06
04-17-18 06:14 AM - Post#2731270    
    In response to BOTTLEDZ28

Ive read through countless forums over the last two days and have decided to replace the 1-2 accumulator piston and spring and see what happens. If that does not fix the issue then I will most likely replace the valve body with a new one.

Ill update this thread with my findings

1991 z28,sebring silver metallic, 383 HSR, AFR 190's, F.A.S.T,T56, 4th gen rear ,30 lb injectors,, 3.73's, slp headers. MSD 6AL,holley fuel pump,Harland sharp 1.5RR


 
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