Strange loss of power at high speed - Please help

[Gordon-Glasgow]

Hi there everybody, I'm new here and really hoping someone can give me some advice.

I just recently bought an e24o elegance automatic, 1999. I really love the look and feel of the car and in normal driving conditions around town etc it is fine. But tonight I wanted to really test the gearbox because I had trouble with an automatic gearbox on a bmw before.

When I got the car up to almost 100 mph it was as if it just suddenly lost power and started slowing down. I had to get off the motorway fast. It seemed like when I put my foot down on the accelerator it actually slowed it down if anything. It wouldn't even let me reverse so I took the key out of the ignition and waited a couple of seconds before restarting. That seemed to work and I drove home ok.

I tried counting up the gears but had some trouble.. I know it gets into gears 1,2,3, and 4 ok but was thinking maybe the problem is getting into 5 which is to say the gearbox is broken?

To tell the truth, I know very little about cars so I would appreciate any advice and ideas. I am worried that it might get worse if it is a gearbox problem and maybe I should sell it now while it will pass as an ok enough car. I'd much rather fix it but I know a new gearbox is just too expensive.

Gordon

 

[BlackC55]

Sounds unlikely to be a gearbox problem.

You may have the famous air mass fault. A diagnosic test can show this up. Try driving it at full throttle and see how it performs. If is hesitates and the gear changes are poor it is likely to be an air mass problem.

It need some looking by someone who knows what they are doing.

Start with a diagnostic check and go from there.

 

[Gordon-Glasgow]

Thanks a lot, BlacKC55... Although I don't understand much about what you say it seems you are suggesting it might not be a gearbox problem and that means I can hope to keep the car. Is this famous air mass fault expensive to repair? Can you give any more information on that for someone that understands almost nothing about cars?

Cheers again.

 

[BlackC55]

An air mass sensor is not expensive.

My advice is to take it to a specialist near you and get them to drive it.

 

[television]

The next time you do this test, use the rev counter, that will tell you if anything is slipping or loosing drive, if the revs go up and the car speed does not increase, then its the box, if the engine will not rev up faster than the road speed of the car then it is not the box.

Mass from Bosch = ½MB price

 

[Gordon-Glasgow]

cheers

Hi Television and thanks. When the car reached about 95 it just started to slow down as if there was no acceleration at all. It was as if I had taken my foot off the accelerator but I hadn't, I was pressing it down almost to the floor.

The accelerator didn't work again until I had switched the engine off and back on. If it had happened on the outside lane of a busy motorway it could have been very dangerous and I was lucky enough to be quite close to an exist ramp.

I think I will take BlackC55's advice and get a specialist to look at it. I'll keep you all posted with results.

Gordon

 

[Dieselman]

I concur, this isn't a gearbox problem as that wouldn't restrict the engine power output, just cause the box to lock into one gear.

Have the fault codes read but it sounds like an MAF sensor problem.

The MAF sensor senses how much air is being injested by the engine so the ECU adds fuel accordingly.
If the sensor goes faulty the ECU doesn't know how much fuel to squirt in and usually goes weak mixture.