I've got a 1990 740 2.3 Auto. The Lambda light is on, on the dashboard, indicating a fault. The symptoms I have are as follows:

Car starts and ticks over perfectly and pulls away with no problems until I put my foot down and it reaches approximatley 3000rpm, this is where the engine dies, it's almost as though I've switched the ignition off but when I back off the throttle it comes back to life and carries on as normal until I try to boot it again. Any ideas?

Thankyou,
Paul.

 

Have you done any work on it lately?

 

Hi,

No, I've not touched it. I bought it like this. When I bought it the guy said that that very day the light came on. I wasn't too bothered as it drove ok until you booted it.
I'm not all that bothered about it as it's only a temporary car whilst I do some restoration work on my classic but it would be nice to sort it out as it is a bit of a pain in the **** when trying to overtake!

Cheers,
Paul.

 

Check and make sure he didn't have the rear main seal replaced.

 

Ok. Will do but for what reason? What are you thinking could be the problem?

Paul.

 

If the flywheel was installed wrong then it will act like that.

It could also be a bad Maf or speed sensor.

 

MAF sensor or speed sensor..... ok. By "speed sensor" do you mean engine speed sensor/crank sensor?
As for the flywheel, can't answer that but will bear it in mind if all else fails.

Many thanks,
Paul.

 

The fact that it happens at one particular throttle setting makes me think you have a bad place in the throttle position sensor. You can attach a voltmeter and with the key on you can slowly open the throttle voltage should slowly increase also. If you find a bad place you have found your problem. You can also unplug it an check it with a ohm meter. It should go up smoothly with no bad places.

 

Yes I mean the crank sensor for the speed sensor. Also if the flywheel is damaged it could do that as well.

 

How mutch fuel is in the tank? Tryed to fill it upp?

you have a Fuel pressure problem, check the pump in the fuel tank! or the pump under the car. That is the problem