Loss of power with WOT, interesting problem.

[gmannino]

Recently, my car has been experiencing a huge loss of power during WOT. It doesnt always do it but it seems to do it more often with a larger load. Like going uphill or with passengers in the car. It runs great otherwise but when I floor it, I notice a dramatic loss of power and the check engine light will come on. Everything going back to normal power when I left off of WOT. I've heard a few times on the forum that it might be a weak fuel pump.

I'm thinking it might be the fuel pump because my car has a hard time starting when its cold. I changed the check valve and filter already. What do you guys think it could be? Anyone else had a similar problem with the M20?
thanks

[repenttokyo]

fuel pump / clogged fuel filter? that's what it sounds like to me. if you've changed the filter, check the pump next.

rarer would be a loss of spark due to alternator not putting out enough power, but like i said, that's a long shot.

[BillionPa]

ignition coil perhaps.

[gmannino]

I dont have ignition coils, its the M20 motor.

[billb]

I dont have ignition coils, its the M20 motor.

The M50 has six coils, one on each spark plug. I wonder if you've got a Throttle Position Sensor issue. What code do you get when you do the stomp test (assuming a US-based car?)

[Bellicose Right Winger]

Driveability problems that get worse with increasing load are often ignition related. Pull the distributor cap and check for moisture and corrosion. Also make sure the carbon brush that contacts the center of the rotor is in place and not broken.

Paul Shovestul



Recently, my car has been experiencing a huge loss of power during WOT. It doesnt always do it but it seems to do it more often with a larger load. Like going uphill or with passengers in the car. It runs great otherwise but when I floor it, I notice a dramatic loss of power and the check engine light will come on. Everything going back to normal power when I left off of WOT. I've heard a few times on the forum that it might be a weak fuel pump.

I'm thinking it might be the fuel pump because my car has a hard time starting when its cold. I changed the check valve and filter already. What do you guys think it could be? Anyone else had a similar problem with the M20?
thanks

[gmannino]

brand new distributor cap and rotor. the m20 doesnt have ignition coils. i can try to verify the cap and rotor but most of the time those are in good condition.

[BillionPa]

the M20 does have a single ignition coil.... trace back from the distributor and you will find it.

[billb]

brand new distributor cap and rotor. the m20 doesnt have ignition coils. i can try to verify the cap and rotor but most of the time those are in good condition.

There are two styles: rod and ring type, depending on year. Yours should be the rod type, as shown on the attached page. Can, and do, go bad.

http://www.realoem.com/bmw/showparts.do?model=HC13&mospid=47402&btnr=12_0014&hg=12&fg=05

Edit: Do you own a Bentley manual? Section 120, Ignition.

[billb]

Curious how you're coming along with this problem.

[gmannino]

I've tested the coil before very recently, i replaced it with another 5 series coil and tested it for results, both were good. i will try to replace the fuel pump and see how that works. I think it might fix my hard starting problem.
Also I was thinking about sonicating my fuel injectors to see if that might be the problem.