Rover V8 auto gearbox issue

[Harleyboy]

Hi,
I have a 91 Range Rover V8 auto with a ZF 4HP22 auto box. The whole car feels very sluggish to accelerate as if it’s pulling away in 2nd or 3rd. Kickdown does work and then it pulls well but with normal throttle pressure it is very slow. I’m having have my foot planted almost the whole time until it reaches a crushing speed.

Engine power is fine evidenced by the performance on kick down and and it is not running oversize tyres. Am oil changed helped improve things but there is still an issue that I’m struggling with.

Anyone got any suggestions? Don’t want to spring for a new box until I can get a definitive

Thanks

[E-bmw]

Many years ago I had an early 90's Senator & it had a winter setting, in this mode it did pull away in 2nd assuming it was on ice/snow.

Does yours have this?

[Harleyboy]

Hi, no there isn’t a winter setting. Locking the car into first gear doesn’t actually help much either

[Steve_D]

Have you messed with the kickdown cable?
This cable has to be set up correctly using a pressure gauge attached to the 'box.

Steve

[GreenV8S]

Harleyboy said:

The whole car feels very sluggish to accelerate as if it’s pulling away in 2nd or 3rd.

Locking the car into first gear doesn’t actually help much either

If you know the 'box is in the correct gear and the transmission is not slipping, this feels more like an engine performance problem than a transmission problem. Does it have the older distributor based ignition? If so I wonder whether either the vacuum advance cannister or the 'slow return' valve could be faulty. The cannisters are notoriously unreliable and often removed from the system. Does the vac line to the cannister hold vacuum?

[Harleyboy]

Hello,

I haven’t messed with the kickdown cable and I’m pretty sure the guy who did the oil change didn’t either but it’s worth checking out - thanks

I’m not sure about the vacuum stuff but will check it out in a bit if I can figure it out!

Thanks for the pointers!

[Harleyboy]

GreenV8S said:

If you know the 'box is in the correct gear and the transmission is not slipping, this feels more like an engine performance problem than a transmission problem. Does it have the older distributor based ignition? If so I wonder whether either the vacuum advance cannister or the 'slow return' valve could be faulty. The cannisters are notoriously unreliable and often removed from the system. Does the vac line to the cannister hold vacuum?

It does still have a distributor so will go and have a look under the bonnet with the aid of a Haynes manual. As you can tell I’m not very mechanically adept!

[anonymous-user]

Harleyboy said:

.... the guy who did the oil change ....

Aha! Did he actually know what he was doing or was he just "bloke with spanner"? Auto's can be very sensitive to fluid level in the transmission and some have specific procedures/temperatures for correct filling. Best to keep them well away from anyone except genuine auto specialists. That sounds to me like your next port of call - a genuine auto specialist.

[Harleyboy]

Well, he was more than a bloke with a spanner but not a specialist. He knew about bleeding the fluid through (or something like that). The issues predate the oil change and changing it helped.

The engine is strong and pulls well when it hits the right spot. Don’t think the box is slipping as the revs aren’t increasing

[anonymous-user]

Agreed, nothing you've described sounds like "wear". It's something in the control system. If not fluid then, as others have already suggested, you'll be looking at cables etc and/or engine torque. I'd go to an auto specialist.