Poor idle, dangerous kangerooing, stuttering, Please read

[rare]

Ok guys,

My alternator failed thursday so I bought and fitted a new one yesterday (had to remove AFM etc to get to it) everything was running fine but idle was a bit low so I messed around with the CO2 to try to get it to idle a bit stronger. Worked fine, for about an hour it drove perfectly. Then after that when I got to about 3-4K revs the car felt like it was hitting a brick wall and the power would die then come back on. Gradually got worse and worse, to the point that if I left it at idle it died by itself, or it was all over the place.

The MPG meter is also going crazy, all over the place.I cant even drive it because its impossible to do so. Had to tow it home last night:(

Any one got any ideas? Would it be to do with the AFM / CO2? Thats all I can think of right now, unless its something major major wrong (god hope not!)

[TouringMatt]

Would it be to do with the AFM / CO2

Pretty sure youre not suppose to mess with the CO2!

Did you disconnect the battery when changing your alt?

[rare]

Yep battery was taken off. I bet I have fcked the CO2 Settings up a treat. Great!

[TouringMatt]

ECU has to re-learn after you disconnect the battery and will run differently

Can you put the CO2 setting back to where it was?

Matt

[rare]

Damnit! I didnt realise that. After the alt was fitted it was running a little odd which is why i messed around with it. I should have left it to do its own thing from what you are saying.

I have no idea where the CO2 setting was orig I guess there is no such thing as a defualt on them (ie all the way to the left or something). I may have to try and get it running ok enough to drive it to an MOT station.

[buff]

the Co2 screw only make changes to the amount of air bypassing the AFM blade at idle - it makes a tiny differnce to the running mixture of the engine above idle speeds. It is most unlikely that this is your problem, even if you set to to either of the extremes.

[rare]

Hmm, ok cheers. Im having trouble thinking what it could be now:(

[Brianmoooore]

I would expect to find a nice big tear in the big rubber hose from the AFM to the throttle body.

[rare]

Its fucked now. I took the AFM off, cleaned it etc and the pipes. The car will hardly start now, backfires and missfires when it does and dies after 30 seconds.

Annoyed. No car. Again.

[billgatese30]

try unplugging the battery and leave it off for a good 30 mins or so, then reconnect and try and and start it again, if it starts and stays alive, leave it to idle for about 15-20mins or so (keep an eye on the temp gauge and switch the heater on full if it gets too hot) then go give it a little drive covering all types of driving and rev ranges and loads in different gears (i.e. some thrashing some gentle) to let the ecu to learn its settings

if it doesn't even wish to idle then i would look at fuel lines/filters and see if thers enough fuel getting there, if it is then i would check the spark on all plugs, then check for any air leaks around the throttle body and inlet manifold.

[Brianmoooore]

An E30 will start and idle quite happily with the AFM/air filter totaly disconnected and off the car.

[Jon_Bmw]

An E30 will start and idle quite happily with the AFM/air filter totaly disconnected and off the car.

Yes i can second that, it runs like a bag of shite but it runs none the less.

[WARLOCKM42]

Check the oil fumes hose that goes from the valve cover to the hose between the AFM and throtle body. If air goes in that it bypasses the AFM and the engine wont idle.Thats why it goes off when u remove the oil cap when the engine is running.

[Geoff]

Just a thought, and im sure you havent, but have you checked to make sure your AFM connector plug isnt left unattached. That could be a reason in the first place to why it was not running correctly.

Also i managed to flood my engine the other day by swapping over the inlet manifold. Ant told me to remove the iscv valve and start it that way. when it kicks in plug it back in.

This may have nothing to do with it, but give it a go!

[rare]

I will check all these things on Monday, cheers. Im starting to think it may be electric?

[rare]

Seems like the crank sensor was at fualt. Cheers guys.