Mark D 93 chip in my m42 lacking power up top

[bimmerm42]

I just put in the Mark D 93 oct chip in my m42 and also a green performance air filter in the airbox the same day. well the car seems to have improved noticably in midrange  2.5k-4k  but 4.5k up seems to die down. Does anyone know what could be the problem? sometimes the car takes longer to start then usual and hesitates when you hit the gas. don't know if these things have anything to do with it (but existed before the chip) any ideas to what the problems could be would be greatly appreaciated thanks

[bmwman91]

Hmmm, could potentially be a junked up fuel filter.  Does it run rough at all?

[bimmerm42]

No not really, but I'll check it out thanks

[Febi Guibo]

is it RPM related or throttle related? eg: motronic (and our AFM) are on three separate tracks, idle, part-throttle, and full throttle.

If you issue turns out to be only happening at full throttle --regardless of RPMs-- (eg, gas pedal quickly and firmly pressed to the floor), it might be your AFM.

[bimmerm42]

Do you know where I can find the values of resistance to see if my AFM is on the right track. Or do I have to swap it with another?

[RED IS 91]

[D. Clay]

Do these chips change the emissions at idle and at 2500 RPM?

[bimmerm42]

Thanks Red Is 91...  very helpful

[e9nine]

Do these chips change the emissions at idle and at 2500 RPM?

Mine didn't

[e9nine]

I just put in the Mark D 93 oct chip in my m42 and also a green performance air filter in the airbox the same day. well the car seems to have improved noticably in midrange  2.5k-4k  but 4.5k up seems to die down. Does anyone know what could be the problem? sometimes the car takes longer to start then usual and hesitates when you hit the gas. don't know if these things have anything to do with it (but existed before the chip) any ideas to what the problems could be would be greatly appreaciated thanks

If the problem existed prior, it's def. not your chip.
I'd go back to the stock chip and sort the issue out if I was you. I like to make sure a car is running 100% stock before adding certain components.
However, if you want to stay with the Mark D chip - when was the last time you did a tune up? What spark plugs do you have in the car, how old are they? What kind of gas do you put in the car? Have you tried some injector cleaner? When did you last change your ignition wires?

[bimmerm42]

I use 93 octane gas ever since I bought it, I have NGK's with two electrodes they look to be in good condition but they look a little reddish. what could cause that (lean mixture,hot plugs etc). I bought the car a few months ago. I wanted to find out what exactly caused the hesitation before I spend a hole lot of money guessing what it could be. Umm  the wires seem to look in good condition and the car idles fine but I don't know what they are doing at high rpm's. I ran lucas injector cleaner when I first got it on the road. I'm planning on throwing in an air/fuel gauge to get some kind of idea what the mixture ratio is at wot. Sometimes when I pull the clutch in and the rpm's come down past idle and the car almost stalls, this is once every few days or so. would a vacuum leak cause this random problem?? wouldn't it be all the time?

[MarkD]

I use 93 octane gas ever since I bought it, I have NGK's with two electrodes they look to be in good condition but they look a little reddish. what could cause that (lean mixture,hot plugs etc). I bought the car a few months ago. I wanted to find out what exactly caused the hesitation before I spend a hole lot of money guessing what it could be. Umm  the wires seem to look in good condition and the car idles fine but I don't know what they are doing at high rpm's. I ran lucas injector cleaner when I first got it on the road. I'm planning on throwing in an air/fuel gauge to get some kind of idea what the mixture ratio is at wot. Sometimes when I pull the clutch in and the rpm's come down past idle and the car almost stalls, this is once every few days or so. would a vacuum leak cause this random problem?? wouldn't it be all the time?

You should check the following:

- fuel filter (just replace it)

- fuel pump  (low delivery can cause low power/stumbling at WOT as more fuel is required then.  Last week a car I was tuning had this same problem and the pump was faulty.

- it may be your ignition coils.  Try swapping in another one, that's the easiest way to check it.

The topic of your original post seems to indicate the problem is with my chip, but then you go on to say that the problem occurred with the stock chip also...   You should have fixed the problem before installing the chip.


Mark

[bimmerm42]

You should check the following:

- fuel filter (just replace it)

- fuel pump  (low delivery can cause low power/stumbling at WOT as more fuel is required then.  Last week a car I was tuning had this same problem and the pump was faulty.

- it may be your ignition coils.  Try swapping in another one, that's the easiest way to check it.

The topic of your original post seems to indicate the problem is with my chip, but then you go on to say that the problem occurred with the stock chip also...   You should have fixed the problem before installing the chip.


Mark

No I never once thought it was the chip, I have faith in you  But yes that is something I'm going to check out (the fuel filter and pump) Thanks for the reply.