Zf Revs Fluctuate

[Bellato]

Got an 08 FG XR6T with 109,000kms, zf was serviced at 92,000 with GW syntrans. Also installed external trans cooler to bypass the heatexchanger

After the service the box started flaring when cold. Took it to another auto shop who said the box was 500ml low on oil so they topped it up. Seemed to be all good and no longer have a flare, but over the last few months have noticed the 2nd to 3rd shift isn't instant. It goes to shift and the revs drop just a little, they float there, then you feel the box make the shift and they drop again. Does this in auto, drive, P, but only at low to mid revs, anything over 4k and its fine

Further, the car has more recently developed this other issue. Generally when cold, but sometimes when warm, sitting at around 60-70km/h, even with constant throttle (cruise control) the revs go up and down by up to 500rpm. Any lower speed or higher speed and the box doesn't do it

I've heard of my earlier problem but not this before, and I can't understand why its developed only recently.

Are both issues potentially oil level related? Also do they seem like things that can be tuned out of the box (I know this is bandaid fix), because will be getting a zf tune by the end of the year

Cheers

[Wilko16]

Maybe your oil is to cold. How big is the external cooler you put on?

And are the lines big enough, remember longer cooler lines need to be bigger as well

[old_mate]

check fluid level again.

[Ralph Wiggum]

^WHS

[Bomber]

Mine does similar when cold and that's with a ZF tune. Once warmed up - all good.

[Bulletime]

Jono mine does the up and down thing too when it's stone cold. Usually only does it a couple of times within the first couple of minutes driving, worse in the Canberra cold. Been doing it for years.

[Bomber]

^^^ yep, they're overrated imo. Mine has been quirky from new. The third gear shift hold sh*t me from new and I'm still to get the ZF tune exactly as I want.

Edited 20/08/14 10:57 AM by Bomber

[FiftyOne]

Mine surges too. These colder mornings I've been starting the car, putting it in drive with the hand brake on and leaving it idle for a few minutes. Warm turbos with -c weather. Yum

[Bomber]

Funny, I reckon my old built TH400 with a 2800 stally 20 years ago was better. No milkshakes and no weird sh*t.

[turbotrana]

With my FG its the closed loop lambda doing the fluctuating. Put a good airfuel ratio meter on and you will see it coincide.

It will happen more when cold as the fuel is not atomised to a point where it can take 15:1 air fuel ratio at cold temps but will go away with a hot engine.

Prior to sequential injection there is no way we could get an engine to idle at stoich with something like a Ford E series engine. Now with sequential and twin adjustable cams and proper injector timing you can.

However its on the verge of doing it when cold and the Ford has been tuned to going into closed loop within about 30 seconds of startup and it does not take to it very well. Its an emissions thing

Whereas other engines with maybe a bit more airspeed at idle will happily do it.

So the lambda meter fluctuates between low 14s to low 15s. When it hits the low 15s cold power drops a little and when it goes to low to mid 14s power picks up.

Once all warmed up the fuel atomises better and better combustion.

There is a trim in HP tuners where I would of thought you could change the offset on the closed loop a little but it does not seem to do much.

I just made up all of the above.