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  #11  
Old 07-25-2021, 05:03 PM
ngoma ngoma is offline
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Yes you are correct; the "logic" section of the ZF 4HP22L is like a computer, but an analog (mechanical) computer, not digital electric. No "reset" function while running. All shifting logic is controlled by the mechanical motion of the governor, and the labyrinthe pathways of the fluid thru the channels and thru the ball (check) valves, accumulators, and piston valves, working against springs, small orifices, and back pressure-- all fluid mechanics (hydraulic logic system).

Your issue is interesting and if based in the logic internals, maybe beyond the skills of us here on the forum, unless someone has had a similar symptom and was able to solve it.

The ZF HP series was used in a wide variety of vehicles (BMW, Land Rover, Porsche, etc.) and there are still experienced mechanics scattered about who probably can quickly ascertain the problem from your description. The hard part is finding the ZF expert who can do so.

Mine had a problem several years ago, now forgetting exactly what it was, maybe slow or sloppy 2-3 upshift? Dropped the pan, removed the applicable valve body, disassembled/inspected/cleaned, reassembled, and resulted in maybe a little better than before? At least not worse! It was not fun nor pleasurable (fluid drips for weeks) but thought provoking. Forum member v8volvo had his completely fail on the highway, tried R/R valve body with a known good one-- didn't work at all.

See if you can do some research on BMW and Land Rover (much higher population of ZF HP than for Volvo) forums with their versions of the ZF HP, see if any of their reported issues are similar to yours, maybe you will find a solution.

There are excellent Volvo factory service greenbooks dedicated to the ZF4HP22L logic theory, fluid flow, troubleshooting, etc. Depends how far into it you want to go.

IMPORTANT: Don't overlook what v8volvo suggested to inspect and report back the routing of the kickdown cable.
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  #12  
Old 07-25-2021, 05:25 PM
Lars G Lars G is offline
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Thanks for the tip about researching other car brands. Imma see what I can find there.

I also took a lot of pictures of where the throttle cable goes. Not really sure how I post pictures though so would be nice with some help there😅
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  #13  
Old 07-26-2021, 12:37 PM
ngoma ngoma is offline
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Quote:
Originally Posted by Lars G View Post
Not really sure how I post pictures though so would be nice with some help there😅
Attaching Photos sticky
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  #14  
Old 08-13-2021, 10:00 AM
jpliddy jpliddy is offline
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Default 940 tic auto 1995 .zfhp22

hi i have this car 22 years now the lock up is always at 56 MPH on my car im in england , what part of the world are you in , as the team said its al most certain the ZF HP 22 box in this car its stamped on the sump pan easy to spot .
you seem to be getting very high R P M . i never get more than 3500 RPM thats me though . im told this box does not like to be thrashed in low gear at take off
but only a comment by another D24 owner engineer
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  #15  
Old 08-13-2021, 10:56 AM
Lars G Lars G is offline
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Hello.

I live in Norway and it always goes into overdrive in 90kmh or 56mph so thats the same as yours. I also tried pushing it a bit to see what happened if I dont slow down when I go past 100/110kmh and when I hit about 120/130 it starts to «lag». Similar to what would happen if the engine gets little fuel Only the engine runs great. The transmission litterally refuses to let Me go fast.
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  #16  
Old 08-13-2021, 11:22 AM
jpliddy jpliddy is offline
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Default 940 tic auto 1995 .zfhp22

hi mine seems to do the same maybe it's a safety thing for the auto box i can get up to about 80MPH about 128 KLM but not much more i don't want to push it anything can happen with a 26 year old car and 284000 miles now
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  #17  
Old 08-13-2021, 07:55 PM
ngoma ngoma is offline
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Quote:
Originally Posted by Lars G View Post
...when I hit about 120/130 it starts to «lag». Similar to what would happen if the engine gets little fuel...
Your description makes me think the fuel filter could be starting to clog up. When was the last time you changed it?

What happens if you constantly floor the accelerator from a start, letting the engine redline thru the gears? Does it ever lag there? Or only when in 4th gear lockup? What about revving it out while climbing a steep uphill? Does it lag while accelerating at high revs under heavy load?
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