Engine accelerates when the brake pedal is pushed I take the vacuum line from the brake booster with my finger over the hose and still does the same thing with no vacuum at the booster parking brake light stays on anti-skid light stays on also has the light on with the gear and explanation mark anybody out there now what’s going on
Not based on your description, no. I’ll ask some questions with punctuation and let’s see if we can figure this out.
Engine accelerates when the brake pedal is pushed - Meaning the rpms increase when you press the brake pedal while the car is idling sitting still? Does it also do this while driving down the road?
I take the vacuum line from the brake booster with my finger over the hose and still does the same thing - Meaning you remove the big vacuum hose at the brake booster and blocking the line? Do the rpms still increase when the brake pedal is pushed?
parking brake light stays on anti-skid light stays on also has the light on with the gear and explanation mark - Ok the “P” light is on, the “ABS” light is on and the “Gear with exclamation point” light is on?
Please answer the questions I posted as well as adding the # of miles on the car and if it is an automatic or manual.
First things first - driving is optional, braking is not. All the warning lights indicate brake faults and the error codes need to be read, the problem repaired and the lights cleared. The car might not be safe to drive. Check the fluid level first, make sure the parking brake lever is all the way off. Have the codes scanned an post back with the actual error codes not just a description… we want the C1234 codes - chassis codes. Maybe the auto parts stores can read them, likely not.
I am not concerned about the rpm rise nearly as much as the brake error codes.
To the first question sitting in park engine runs fine put my foot on the brake pedal RPM goes up an engine revs up driving everything seems fine until I come to a complete stop and you can hear the engine rev and RPM bounces and then Settles
Yes pulling The big vacuum line from the brake booster with my finger blocking engine runs fine step on the brake pedal engine revs up RPMs go up
While in park the gear with! Beside the p stays on no ABS light no parking brake light just the gear with the !
Mileage is 251037
Just pull the codes and you will be able to solve the problems from there… You cannot mentally pull the codes however…I have tried, its a fools game. You need an OBDII scanner at the bare minimum to work on modern vehicles. Everyone who drives a vehicle should own one and with how cheap they can be obtained these days…they are a no brainer. A must have item…
You remove the vacuum hose from the brake booster, block it off, and the engine rpm still increases when you step on the brake pedal? Tom would be saying “doesn’t anybody screen these calls?”!! … lol … I have to say that is really an unusual and unexpected symptom.
so what could be happening … hmm … suggest to focus on the increased rpm while stepping on brakes , as figuring that out may fix the others …
-
maybe the vacuum hose your are removing isn’t really from the brake booster, but from a different part that looks like the brake booster. the brake booster you removed the hose from has the brake master cylinder attached to it, right?
-
mechanical interference between brake pedal linkages and accel pedal, which is causing the accel pedal to move slightly when you step on the brake pedal. get your head down in that area and take a close look at the accel pedal as you press on the brake pedal w/your hand
-
maybe this is just the way it is supposed to work. the computer bumps the idle rpm a little to avoid stalling the engine when stopped at stop lights. It increases the idle probably when you turn the AC on, or when you turn the headlights on, anything that loads the engine, so maybe it also does that when the brake pedal is depressed. You’d think this would only happen, if it did that at all, only when the brake pedal is depressed in gear, not in neutral or park. This idea seems very unlikely, but you could try another BMW of the same make/year as an experiment. This is happening idling in N and P, right?
-
maybe pressing the brake pedal is somehow shifting the throttle position sensor?
-
maybe its a software bug – the computer is increasing the rpm when it shouldn’t – and there’s revised software available to fix it
Thanks for the info guys I figured it out guess you can say by process of illuminations it was the mass air flow giving me the problem on the 325i wrapped it up and running fine thanks again