[ddog46]

my mate did a exhaust swap for me and now for some reason when ever i apply pressure to the brake when accelerating it’s cuts of the revs? really lost could be a fuse in the ebox or maf sensor or 02 but no idea.. any suggestions much appreciated

 

[markusmarkus]

The first step in diagnosing a problem is to scan the engine computer (DME in BMWspeak) for codes. The Service Engine Soon light is on only when an emissions related code is present.

 

[Effduration]

Check vacuum hose that goes to brake booster… and while your at it, check whether booster still holds a vacuum.
‘the brake booster is a potential source of a big vacuum leak.

 

[vtwagon]

my mate did a exhaust swap for me and now for some reason when ever i apply pressure to the brake when accelerating it’s cuts of the revs? really lost could be a fuse in the ebox or maf sensor or 02 but no idea.. any suggestions much appreciated

That sounds totally normal to me. Lots of cars do this. I think it gives you a few seconds of both pedals applied, then cuts accelerator pedal input.

 

[Sapote]

i apply pressure to the brake when accelerating it’s cuts of the revs?

Because the smart engineers thought nobody would do this together, unless it’s in neutral during toe/heel shifting

 

[ddog46]

The first step in diagnosing a problem is to scan the engine computer (DME in BMWspeak) for codes. The Service Engine Soon light is on only when an emissions related code is present.

Yes it has 2 codes showing: P0102 P1620

 

[ddog46]

Because the smart engineers thought nobody would do this together, unless it’s in neutral during toe/heel shifting

but it used to? i have to use my handbrake on hills when stopping now kind of annoying since i park on a steep hill

 

[ddog46]

That sounds totally normal to me. Lots of cars do this. I think it gives you a few seconds of both pedals applied, then cuts accelerator pedal input.

nah a few days ago it worked perfectly, now has no input so sucks to start on hills

 

[TobyB]

Nah, the engine should respond to the throttle even when you're on the brake.

At least, 5 of 5 of our cars do. Even the E39 and the E36. And the Ferd.

SOMETHING has gone squiffy in yours, and it ought to be possible to fix it.
What do those codes mean?

t

 

[M.Blacktree]

My E46 will rev when I hold the brake pedal and give it throttle. That's what I do at the drag strip, to launch harder.

 

[Bali]

Yes it has 2 codes showing: P0102 P1620

Always provide the descriptions with the codes so we do not have to look them up. 👍
P0102 Mass Air Flow MAF Circuit Low
P1620: Map Cooling Thermostat Control Circuit Signal High

 

[Sapote]

but it used to? i have to use my handbrake on hills when stopping now kind of annoying since i park on a steep hill

Yours is an automatic?

 

[TobyB]

Hmmm,
do I remember some threads from not long ago
about MAF circuit problems messing with how the throttle responds?

t

 

[broome9000_]

I'm fairly certain that this is MAF related (judging by codes too). When the MAF is unplugged/faulty, you cannot have the foot on the brake and rev the engine.

 

[Dedlotus]

I'm fairly certain that this is MAF related (judging by codes too). When the MAF is unplugged/faulty, you cannot have the foot on the brake and rev the engine.

THIS^^^