3.9 EFI and auto problems

[wee_arthur]

Hi all,

I put a 3.9 EFI auto from a rangie into my defender and having some trouble with it, i thought the range rover section was the best place to put this.

1. The auto box seems to be making the engine stall, really have to hold the brake and rev the engine to keep it running.

2. The auto box wont select some gears, for example sitting still and idling, select reverse and accelerate and the motor wont move until the engine revs come back to idle. ? the same happens with drive but not to the same degree.

The box was working fine in the rangie. The only thing we have done to this in the conversion is removed the oil cooler to try it out, we only do trials so the gearbox doesn't get a chance to get too hot. But in the removal of this could enough oil have been lost to cause all of these problems? if so what oil should i use and should i do a complete flush?

Thanks for reading and any help in advance,

William

[SteveRK]

I think you might have two problems, first is a weak mixture on idle so the natural torque converter load on the engine is stalling it.

The second is a guess but should there be either a vacuuming pipe from the gearbox to the inlet manifold used for determining how much 'clutch band ' drag is exerted on the gearbox, and/or is the 'kick-down' cable fitted correctly?

[wee_arthur]

The kick down cable i would presume is correctly fitted as the kickdown does work.

How do you richen the mixture on an injection engine?

unsure about the vacuum pipe but i shall do some research.

Thanks for the fast response.

William

[Bowie69]

Have you checked the oil level in the box? Should be done cold, when idling, run up and down the gears in order then leave it in neutral -check dipstick.

[FridgeFreezer]

The kick down cable i would presume is correctly fitted as the kickdown does work.

I thought they had adjustment in them to change the kickdown point, and that the cable also controls the behaviour of the box under normal loads to some degree (tells it the driver's demands, if you like).

How do you richen the mixture on an injection engine?

If it's not Megasquirted then you don't - it it's running too lean or rich then it's because of a fault, usually a temperature sensor.

unsure about the vacuum pipe but i shall do some research.

Fairly sure there isn't a vacuum pipe on the 4HP22, see comments about the kickdown cable above.

[Bowie69]

Yes, the kickdown cable controls the box pressure, which controls the tension placed on the gearbox brake bands, if it is disconnected then the pressure is too little allowing the bands to permanently slip, and burn out very very quickly.

Well that is my simpletons version of how it works

[Range Rover Blues]

If it's not Megasquirted then you don't - it it's running too lean or rich then it's because of a fault, usually a temperature sensor.

Not true. Depending on how the EFi is set up the MAF can be adjusted to control idle mixture. If the EFi has the correct TSR and the lambdas work then above idle it will set a base figure for mixture within somehting like 15 seconds then modify the fuel map. Without lambdas or with the other TSR then it runs open loop and relies on the MAF sensor only.

At idle the idle speed is controlled by a stepper motor, the ECU should see an input from the inhibitor switch so that is can raise the idle speed. It should do the same with the airconn and heated screen.

It sounds like the idle speed it too low though, check the stepper is working and the pipes are all connected.

The gearbox sounds lke it's short of oil and piossibly the oil is too cold. The oil cooler also assists in heating cold oil when you start up. The oil cooler is quite necessary in fact.

Also check the shifter is correctly adjusted, this is quite critical.

I've found you can loose a lot of oil from the gearbox via the cooler pipes because it syphons out. I lost a couple of litres just disconnecting the oil cooler once (one of my oil coolers is below the radiator).

[Fett]

no bands in a 4hp22

[vougese39]

did you split the engine from the auto box?

if you did did you ensure the torque convertor was pushed back?

if no is applicable to the above then oil level is one start the car when cold move though the gears then pull dip stick out and check level top up with dextron 2 atf will be fine.

you may need to reset the base idle which is causing the idle fault

[Range Rover Blues]

P.S. you adjust the idle mixture on the EFi with an allen key on the back of the MAF sensor, if the system runs closed loop (with lambdas fitted) it will ignore the maf soon after starting anyway.

[Dave W]

For the specific gearbox problem(s) I'd start by checking the oil level as previously suggested.

An oil pressure problem inside the box would/could cause both your problems as it does sound as if the torque convertor is stalling your engine.

How exactly did you remove the oil cooler ? Did you loop the pipes together to bypass the cooler or have you blanked the outputs ? Blocking the oil flow through the cooler circuit would cause all sorts of strange problems.

I wouldn't run a ZF without an oil cooler for trialling, they very quickly heat up with low speed work and heat is a real enemy for the gearbox.