Pulling away slowly

[998automan]

Hi, seem to be plagued with problems at the moment so thanks to everyone who has taken the trouble to reply to them, much appreciated . I noticed over the last couple of days that there is a significant lag when pulling away from stationary almost as if pulling away in the wrong gear (quite dangerous at times!) . Otherwise engine running well, all gears seem to be working, any ideas welcome? 

[(minisniper)]

My first suspect would be fuel

[998automan]

Thanks, interesting. I did install an in-line fuel filter just before the carb & wondered if that could be causing an issue so have removed it and will test tomorrow. Also wondered about oil level affecting gear selection/clutches, usually check mine is on full when cold but have read that this is not how its done, any tips? 

[kalkat]

To check the oil level:

Run engine 'til warm

Turn off engine

Check oil level within 1 minute

.......... I think it's the only vehicle that you do this with!

[wimfournier]

Maybe Minisniper is looking in the right direction. When the engine is turning with the box in neutral, everything seems all right.
When you put the box in Drive, the engine has to produce power. That needs more fuel.
There is one thing with our Mini's. The fuel line from the tank to the pump is iron. And iron rusts when there is water. And there eis always water inside this fuel line. Because. Because, when driving the fuel surface in the tank is lowering, so, air from outside is entering the tank
I have a question, how 'damp' is the air where you live. Overhere it is about 50%.
So every time water is entering the tank and overnight it becomes cooler. That means that waterdamp is condensation against the inner wall of the tank. And water seeks th lowest point in the fuel system. That is, the fuel line under the car.
Rust is building up there, very slowly. But, after ten, twenty, thirty years, there is a lot of dust.
Pull off the little tube from the 'bottom-line' before the pump. Apply a long tube so that you can put the other end in your mouth and blow.
So you can feel how 'open' the fuel line is.
The pump is working with a spiral spring. After all those years, the spring is not any more that strong. May be you need a new pump.
The fuel we have in these days is not more the fuel from the old days. They put additives in it that eat up slowly the flexible fuel lines in the system. The remainders stick in the rust in the fuel line.

[kalkat]

You may well have crud in the float chamber/blocking the needle valve. This could easily cause fuel starvation

[Stu]

I would agree with the others, sounds like a fueling issue somewhere. I'd also suspect a vacuum leak from the carb to manifold gaskets.

I don't know if you've had the carb off recently but a vac leak could be the cause and worth checking. Are the bolts good and tight?

Does the engine lag when rising the revs in neutral?

Try spraying some WD40 around the carb manifold to seal any leaks and go for a drive. If it still does it then clearly its not a vac leak from the carb and you need to investigate elsewhere.

Could be an issue with the float bowl as Kalkat said, but I'd start with the easy stuff and go through it bit by bit.

Let us know how you get on  

[jockduck]

Hi, I have read the replies and they are all full of good stuff however I am unclear as to the exact nature of the fault, is the engine bogging down on take off or even stalling or is the gearbox slipping and the engine revs but the car is sluggish in take off?
Jock

[notamini]

In his opening statement, Automan says "Otherwise engine running well, all gears seem to be working"
You might need to play with the dashpot oil, lighter/heavier.

[998automan]

Thanks to everyone, loads of great advice. Yes the car is `bogging down` on initial pull away. If it was a manual you would simply dip the clutch and give it more revs, obviously not an option!! Once you have gained some momentum it is fine, however I have noticed some fairly significant flaring in the change from 1st to 2nd that has coincided with this problem so I am  beginning to suspect transmission rather than engine fault? Have just replaced oil and no difference to how it was before. Can anyone offer a method to check if it is a clutch/brake band issue? Cheers all. 

[jockduck]

Hi, Well it certainly sounds different to the "normal" autobox faults, I did think of 1st and 2nd "tying up" both gears engaged at the same time, I guess its possible, the car would tend to stand on its nose when it happens, flaring between 1st and 2nd I have not heard of, suggests sluggish operation of some of the valve block and/or band servos. How do things go if you use the gears manually? that would bypass the box decision making process, also try taking off in 2nd again this may bypass the problem area.
Jock

[998automan]

Thanks Jock, good advice. I will try tomorrow & let you know!

[998automan]

Hi Jock

I have tried selecting the gears manually and all seems fine. Unfortunately still have the same problem with initial pulling away even in 2nd. Fuel line and pump working fine, did discover that one of the plugs is black (other 3 nice brown colour) Changed HT leads but no difference, any other ideas what this could be & could this be the cause of the power loss?   

[Stu]

Have you checked for a vac leak?

[jockduck]

Good Morning, Just had an idea, how about a compression test on the engine?
Jock

[998automan]

Hi, thanks guys. Manifold and carb nuts all seem fully tight. Did a compression test a few months ago and all was ok then, will test again if it`s not dirt in the carb. Is it worth tweaking the timing? (currently 8 degrees at TDC 1500rpm vac disconnected).

[Stu]

Have you checked the choke and throttle cables are set correctly?

[69hcode]

Might be a bad torque converter. You'll need a tachometer to check it.


Warm up the engine then set park brake. Put left foot on the brake. Push accelerator and see how high rpm's go. Should be 1400-1500 rpm's. Significantly lower, like 1000 rpm or less and you need a new torque converter. A little lower might just be a tuning issue.

[998automan]

Thanks for the advice. I am a little unclear as to what you mean, am I right in thinking that this is a stall test so revving the engine in Drive until it stalls?

Cheers Mike. 

[Stu]

Yes Mike, 69hcode is refering to a stall test to check the condition / performance of the convertor. The convertor only provides torque transfer at lower revs. Once it reaches higher revs its not providing any more torque and is just acting as a fluid coupling between the crank and box. This is why doing a stall test will check the torque capability of the convertor. If stall occurs way below the minimum it would suggest its not performing. I would only consider changing one if all other possible causes have been considered / checked.

I have the test guidance figures if you need them, just let me know.

Sorry to hear you're still having problems. Have you checked everything else?

[998automan]

Hi Stu

Thanks, that would be great. Still experimenting with timing but no real improvement so it would be good to rule converter in/out.   

[wimfournier]

The staal test should be done by 80 degrees C or 176 F engine oil temp, to be mesured in the dipstick hole in the sump.
Find 1000 engine rpm stationery and apply the handbrake and footbrake wth your left foot.
An 850 should reach 1300 / 1400 rpm in 2nd or 'drive' with the accelerator on the floor.
An 1000 1400 - 1500 rpm.
If you only reach 1000 or less; stator wheel in the converter is slipping, get a new converter.
If the revs go over 1500, the transmission slips, you have to deal with that.
If th erevs do not go over 1300, your engine's lacking power, the engine is your concern.

Beware that the temp is all right and you have 10W40 in the sump.

[Stu]

Thanks Wimfounier.

[69hcode]

More timing might help. Check your mechanical and vacuum advance.