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4T65E-HD -- shifting on highway and sudden shudder at 10mph on accel

G

GP1138

New member
So I got this car a few weeks ago and it had a weird issue where if I would kick down on the highway it would rev high and kick into gear. If I eased the throttle it'd shift normal. I wondered if it had anything to do with ETC.

I have been having random ground issues and today I came out and the car would not start - I had to tighten the battery cable where the ground connects. After fixing this, the car now has major issues when decelerating past 10mph and then giving throttle- it shudders and bangs into gear. If I start from a stop it's fine -- I don't think it's the rev and clunk issue. It's never done this particular thing before. If I engage TapShift it appears to not happen, but the downshift issue on the highway does happen.

Any insight on this? I think I will do a pan drop and shift kit and see if it goes away.
 


It seems to have come on all of a sudden though, the slowing down issue, that is. It's acting really odd for seemingly no reason.
 
Last edited:
rickisrad said:
sounds like converter lock up?????
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You may be on to something. The odd shuddering at low speeds has abated (TAPS relearn?) but the jump during downshifting remains. I tossed it into TAPShift tonight as it's easier to control the jumping and found that if I floor the throttle when it's in 4th and let the TCC disengage, when I manually tapshift down to 3rd, there is NO jump. If I'm cruising and then attempt to tapshift down to 3rd, it does the rev and jump. I'm wondering if this is a TCC issue.
 


Updating - did a pan drop and filter change and did the shift kit at the same time. Low speed issue is completely eliminated, shifts are much crisper. Still wants to jump up and overrev on the highway but kicks into gear much faster with just a shudder. Not terribly happy about that but it's better than slamming into gear like it was.

Not much of an update but just in case anyone searches this in the future.
 
How did the fluid look when you changed it? I have a 2004 Comp-G as well, and I know that it's suffering from the dreaded input clutch seal issue.
 
GeosGP said:
How did the fluid look when you changed it? I have a 2004 Comp-G as well, and I know that it's suffering from the dreaded input clutch seal issue.
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Brown, but very little if any metal shavings in the pan. I took it to a trans shop and they remarked how nicely it runs aside from the slip and clunk on the highway. It has done the low-speed thing once or twice but much less pronounced. Basically I'm going to drive it and keep my eyes out for a good used unit or simply get it rebuilt once tax time comes (or simply overhaul it myself). It doesn't have the normal rev-clunk a lot of these do.

What's yours doing? From what I'm reading, my issue is likely a channel plate gasket issue.
 
Mine will feel like it is slipping, then it will bang into gear and take off. The past few days it has been getting progressively worse, so I'm about to go outside and drop the pan and change the fluid. I'm certain that the trans filter is clogged something fierce. We'll see how it does after that.
 
Changed fluid, and maybe 25% better? Fluid was chocolate brown, has metal in it. Magnet in the pan had a good amount of metal chunks on it and was coated in a fine coating of material. Still slips at random, but when I stand on it from a 40 MPH roll, it'll drop to 2nd and take off. Sometimes it will not slip, sometimes it will. Call it 80/20 in favor of not slipping. Still like to bang-shift on the 1-2, and the 1-2 is definitely delayed longer than it should be. I have to lift to get it to shift.
 


Well a sort of update. All of a sudden last week I went to leave from a stop sign and it refused to go until I put it into TapShift. 1-2 slipped like crazy and once it got into 3rd it was fine. Later in the week it just stopped going at all - if I got it to roll over 15-20mph I could manually shift into 3rd and drive but yeah. From reading it appears my Forward Apply Band is shot. If I put it in gear and hit the gas I can hear whirring from outside the car. Got a line on a known good trans for cheap so I'll likely be grabbing that and finding someone to put it in. I like this car too much to kick it to the curb.
 
Having the same issue with my comp g. Floor it and it slips and kicks into gear. Sucks love the car but don't have money to replace transmission
 
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