17 replies to this topic

[natnek]

 I've searched for an answer to my problem on this forum,but couln't find the answer.

Also excuse me for my spelling..)

 

 

I've got an automatic gearbox in a 1990 mini.

Completly standard.

 

My problem :

When engine reaches normal temprature and i want to select a gear [any gear] the engine stalls inmediatly.

Rev's go down so much the engine just dies. 

I need to rev up to 1500/2000 rpm to keep the engine running.

Also when i stop and don/t floor the pedal the engine stalls and dies..rev's go so low the engine just don't want to keep running.

When it stops, i need to put it in neutral and start the engine again..make some rev's up to 1500 rpm and bang it back in gear [i can feel the gearbox doesn't like this ..there is a big kloink than coming from the gearbox]

 

When engine is cold there is no problem .. i can select any gear and drive off without any problems.

Also the stopping and driving off again is no problem than.

Rev's go down around 100/150 rpm (wich is normal for an auto box) but no problem's here.

 

I've already replaced:

-coil (replaced by correct one..see ignition)

-ingnition (used to had pionts ignition when problem started,now elctronic ignition)

-spark plugs and leads

-carb + gaskets

-inlet/exhaust manifold.+gasket

-made sure everything is gastight.

-checked compression (cold and hot test done,all 4 are ok )

 

I've had mini's for around 15 years..never had an auto gearbox..so i just clueless now..

 

Any advice welcome.

 

Thanks in advance.

[RedRuby]

Not an expert particularly with auto's, sure someone will come along soon, but I have a thought in my mind that the oil could be causing this so an oil change may be required. Hope someone can confirm this and it ends up being a quick and simple fix.


By the way there is nothing wrong with your spelling, it's better than mine and I'm English

[Guess-Works.com]

Initial thought would be lack of oil, closely followed by torque converter failure.

[natnek]

Forgat to add ..ghanged the oil and filter already.

 

My thought's right now are indeed the torque converter wich might be causing the problem's.

Maybe if the oil (and so the gearbox) is getting up to temprature there might be something (like a bearing or so) causing to much friction because it expands to much due to temprature?

 

Build quite a few engine's and manual gearboxes in the past,but never opened an auto box,so don't exactly know what to find /look for if i do.

 

The converter is it repear eble?

or do i need to replace it as a unit?

 

Auto boxes (in mini's) are not a common thing overhere..quite rare.

So are parts and people with experiance on ato boxes.

 

Thanks for replies.

[Stu.]

Is this something thats just started to happen or has it got worse over time? Does it only happen when drive is selected or does it occur on manual selection too? Have you checked the idle speed is not set too low? You could carry out a stall test to confirm whether the stator in the torque convertor is slipping, or whether it is operating correctly. If it is at fault they can be sent off for overhaul.

Have you checked that the gear selector rod is correctly adjusted?

The correct engine idle speed for an auto is 800 rpm.

Edited by Stu., 04 September 2015 - 11:05 PM.

[peter-b]

Any automatic specialist shop should be able to tell you if its a transmission/convertor problem. They might not know how to fix it but at least you'll know where the problem lies. If it ends up being an engine out problem, can you do that? I was thinking you might be able to box it up and send it to a repairer, just the trans i mean.

[Spider]

I know little about them Autos, but if you suspect the Torque Converter, do a speed stall test, while not 100% conclusive, it may show a fault. To do this, get the engine Oil up to temp (very important) then pull over somewhere, where there is a good bit of space in front of you (in case!). While the Car is in D, hold the foot brake HARD and while doing that, open the throttle all the way (put the other foot down). Don't do it for longer than 10 seconds though. The engine should only be able to rev to 1300 - 1500 RPM.

 

It could also be in the Valve Block Assy, that essentially put in in to the various gears while driving. If one of the Valves is gummed up, it can hold or not fully release that Band, so it can in some gears, end up selecting two gears at once, though one gear will not 'lock' but drag. This is also why it's super important to change the Oil often, use best quality Oil and never cook the Oil in Autos.

 

For part of proper diagnosis, the Oil Pressure needs to be checked, be aware though that there are two Oil Circuits in these Power Units, a High Pressure System and a Low Pressure system. Both need to be checked, and there is a recommended procedure for this (if I get time, I'll post it up).

[Stu.]

It might not be gearbox related either. Could be something else like a vacuum leak, or as I said before idle speed. I'd have thought that if it was the convertor it'd occur when the oil is cold as well as hot, so for me I'd be looking elseware first. It's probarbly something simple. These auto boxes are pretty robust so dont 'automatically' assume thats were the fault lies.

If you have the choke out when starting and it runs ok when cold, does the issue start when you put the choke in after the engines warmed up?

[natnek]

The problem occurs when the engine gets up to temprature. Say after 5/7 Miles. By that time the choke is already closed a fair amount of time.

Did the stall test. Engine isn't reving more than 1500 rpm while foto brake is pressed firm to keep standing still.

Problem occurs in al gears.. As soon as i stop in any gear i need to rev the engine.(almost full throttle) to keep engine going.
As soon as i put in back in neutral the engine the rev's go up again.

[New game mini]

I am definitely no expert but when I got my auto it used to cut out like this when warm (after closing the choke). I adjusted the idle speed so it sits at about 800rpm in D which will be a little higher when the car is in N as the idle drops a fair bit when going from N to D. Mine idles around 1000 rpm in N and 800 in D I believe. As I said above I'm no expert but it worked for me!

[Zacherius (again!)]

I'be had a few autos ( got a sprite SPi auto at the moment ).
I've had this on various ones and always pointed to three things, either timing, mixture or idle.
The torque bar thing ( can't remember it's name ) that comes up to the carb or injector needs to be set right as well, as that will mess with your idle speed.
You can turn the idle up slightly ( mine sits at about 900 at the moment ) but if it's dropping so much it cuts out, yet runs fine when cold ( is the choke being used ?! ), I'd say get the bar and your idle right first as may just be that, then look at timing or mixture. (The first time I had it, it was starving of fuel when warm, but ok when cold and choke on ). Nothing to do with the auto box.
Not sure if that helps. Good luck...

[Guess-Works.com]

its called the kick down linkage, and relates throttle position to the transmission. There is a specific procedure for setting up the kick down rod length.

Edited by Guess-Works.com, 07 September 2015 - 12:24 PM.

[natnek]

Kickdown bar is already adjusted correct as described in factory manuals. (but that's only for throttle respons for gearbox)

Milled a small tiny bar to factory spec measurments to set that up correct..

 

I need to set idle at around 1700 rpm to keep engine (just) running when i stop the car in gear. (people think your crazy when they see the mini reving at the lights.)

If correct idle is used (around 900 rpm as it should be in normal conditions) when i re-start the car after it stalled it runs/idles fine in neutral.. only when i select any gear (r,1,2,3 or D) the engine inmediatly stalls..

 

As described already choke is not used any more (engine is on temprature already when problems occur,so choke is closed already)

When engine is hot and problems start not even choke can hold engine up to rev's and still engine stalls.

 

Mixture.. I can't believe that to be honest.. car used to run fine in the past..untill this problem came up.

Also i've switched the carb from one of my other mini's wich drove perfect with this carb,and the carb from the automatic is now on my other mini and that one drives fine aswell..only the automatic min still has got the same problem.. so it isn't carb related. (imo)

[Spider]

Given your descriptions and what you've done, it does sound to me to be gearbox rather than engine related.

 

I am also wondering if it maybe the Primary Gear, only a guess as I don't know much at all about the Autos.

Edited by Moke Spider, 07 September 2015 - 06:46 PM.

[silve1999]

Torque converter I think