Thread: Swapping transmission ECU's

Not sure if it was swapping over the EAT ECU or if the transmission is getting worse, but it was getting some violent gear changes this afternoon. One a couple of occassions, I heard the rear wheels "chirp" while accelerating.

Put the original EAT ECU back in tonight. Will see how it goes tomorrow. Maybe tomorrow night I'll change over the Selector Position Switch to see what difference it makes.

I've almost resigned myself to this being an internal problem in the transmission but figure I'll try to change over the "easy" things first.

So, any thoughts on why I should or shouldn't swap over from a ZF4HP22 tansmission to a ZF4HP24 transmission?

Originally Posted by PaulP38a

So, any thoughts on why I should or shouldn't swap over from a ZF4HP22 tansmission to a ZF4HP24 transmission?

You should, because i dont have an ZF4HP22.

"...I heard the rear wheels "chirp" while accelerating" ...

I'm impressed!

Is this accelerating under full throttle or accelerating as if a blue striped Commodore/Falcon was following you as the lights turned "green" ?

Many engine/AT ECU communication setups are designed to momentarily retard the ignition timing at the instant of changing gears in order to reduce power sufficiently to ensure a smoother change. You seem to be getting full power delivery, hence the "chirp"...

If you slightly ease off the loud peddle to prompt a gear change, then continue accelerating? does it "clunk" as badly?

Do you have a faultmate you can use to check on AT specs?

cheers
hoges

Originally Posted by Hoges

"...I heard the rear wheels "chirp" while accelerating" ...

I'm impressed!

Is this accelerating under full throttle or accelerating as if a blue striped Commodore/Falcon was following you as the lights turned "green" ?

Somehwere in between. I was giving it a fair bit of boot at the time, but not foot-to-the-floor.

Originally Posted by Hoges

Many engine/AT ECU communication setups are designed to momentarily retard the ignition timing at the instant of changing gears in order to reduce power sufficiently to ensure a smoother change. You seem to be getting full power delivery, hence the "chirp"...

If you slightly ease off the loud peddle to prompt a gear change, then continue accelerating? does it "clunk" as badly?

It's all over the place at the moment. Sometimes I can feel it backing off, wanting to change, and then sometimes it does or doesn't change. Much worse when it is from a cold start. Not as bad when it warms up.

Had it happen again today while warm - the "chirp" and violent change - it didn't back off for that change of gear.

Originally Posted by Hoges

Do you have a faultmate you can use to check on AT specs?

Not yet unfortunately, but one is on my wish list. Mechanic had his Testbook on it a couple of weeks ago and it was reporting no faults. He thinks it is a mechanical problem but we both know it is going to be an expensive exercise to drop the AT out to check it properly. If I'm going to drop the AT out of the car, might as well use the opportunity to put a stronger box in (i.e. HP24).

Cheers
Paul.

This might sound dumb but does it have the right amount of oil in it? You haven't said if you have check that. These boxes are different to check then most autos. You have to check the oil level when its cold not hot as you do with most autos. I had a trimatic with a shift kit on a few other bits done to it and unless it had the right amount of oil in it the thing wouldn't change gears when it should.

You changed the computer for the box and its pretty much still the same so my bet its the oil that actually does all the work not the computer that is telling it what to do.

Also if you pull the dipstick and smell a sort of "dirty or burnt" your oil is stuff and needs to be changed!! It should be a nice red. When i got mine the auto box oil was stuffed! It was brown colour and had been serviced by a so called "good" rover workshop in sydney.

This has just reminded me its due for another oil, filter change and diff oils aswell. has any one used the filter kit thats been selling on ebay the last few months?

Originally Posted by 2door grover

This might sound dumb but does it have the right amount of oil in it? You haven't said if you have check that. These boxes are different to check then most autos. You have to check the oil level when its cold not hot as you do with most autos. I had a trimatic with a shift kit on a few other bits done to it and unless it had the right amount of oil in it the thing wouldn't change gears when it should.

Fair comment. I had it serviced at CMW a few weeks ago and they did change the filter and the oil. Didn't make much difference to driving at the time. I assume they put the right amount of fluid in but will check again myself.

In the 99 model, there is no dipstick for the AT. You've got to get under the car and unscrew the filler plug.

I'd be getting under your car and checking, wouldn't be hard on yours

most auto shops will check the box when warm because "thats how you do it for holden and ford so every other car must be the same" as i was told when 1st asking question about my car.

Originally Posted by 2door grover

I'd be getting under your car and checking, wouldn't be hard on yours

Took your advice and checked it. Far from being underfilled - it spewed a fair bit of fluid out of the filler hole. Colour was bright red and clean, with the odd metallic sparkle (guessing that's from bits of gears breaking off inside). Got my son to work through the gears while I collected fluid in a tray underneath.
Approx 600ml came out before it slowed to a trickle.
Took it for a run up the road and not much difference... still hunting between changes, but it did go up the 3rd and then 4th without as much complaining as yesterday. Will take it to work tomorrow and see how it goes.