stalling at the lights an idling low ... ideas ???

[NickBrighton]

i have recently purchased a 1990 318is for the first couple of days its been running fine now it stalls when you pull up at the lights and seem to idle very low around 600 and sounds rather lumpy, ideas for a fix would be much appreciated
cheers

[Brianmoooore]

Since you say it worked OK at first, I'd look for a split in the big convoluted air hose between the air filter assembly and the throttle body, or other air leak in the area.
Chances are the previous owner did a quick bodge with some tape for the sale, and this has now failed.

[NickBrighton]

thanks for the advice, much appreciated. the only thing though i was told by the owner that the air pipe had been replaced and it does look very new if theres no air leaks can i assume that the filter is ruined or do you have anymore ideas ????

[NickBrighton]

you're a genius buddy, i popped the bonnet inspected and removed my air feed/air box and filter and surprise surprise the first part of the pipe coming from the front bummer has a huge split in it problem solved cheers

[Speedtouch]

Your 318is has a "front bummer"?

[Grrrmachine]

If you're talking about the pipe from behind the headlight to the air flow meter, then a split there means nothing. The hose between the air filter and the actual engine is the important one, and a split there will ruin the engine's performance. But it's hard to see how a massive split would form a few days after buying the car...

[NickBrighton]

on the way home from buying the car the tick over when pulled up at the lights was going between 1000 and 1500 on its own, but it only did it once after a 60 mile drive. yesterday after having done over 100 miles in a couple of days the car was stalling when stopped in traffic so i stopped driving came home and looked on here for some advice. having been told that it was most likely related to air flow as mentioned above i took everything off and the cold air feed ??? ( if thats what its called ) was so perished that bits of it fell of in my hand the rest of the system is clean and the filter an the pipe that connects to the throttle body (Im assuming) is brand new done at the last m.o.t only 2 months ago. if you think that the first pipe is not gonna cause any issues then ive got a problem else where . any ideas ????

[Grrrmachine]

Well, it's the air pipe between the air filter and the throttle body that needs to be sealed. If that's new and fitted properly, then your problem is elsewhere. If the crumbly pipe is on the other side of the air filter, then it doesn't make a blind bit of difference to the running of the engine.

Other vacuum hoses may be an issue, such as those feeding the brake servo and under the inlet manifold, so check them out thoroughly too.

Speedtouch is the ECU expert, but I have a funny feeling this will be engine management related, with the blue temp sensor most likely at fault, although I'm not familiar with the Motronic 1.7 setup in the iS. What happens is that the sensor (or its wiring) fails, so the engine doesn't know its proper temperature and can't fuel accordingly. If the car has had a new battery recently (such as the day you bought it) then it'll be in "learn mode" and will run rich to start with, but the more you drive it the worse the problem gets, which is why it's now cutting out.

Did the previous owner say anything about a new battery recently, or is the car slow to crank in the mornings?

[NickBrighton]

nope the battery definitely isnt new and the terminals look like they haven't been disturbed in a while. having driven the car on a 50 miles round trip stopping an starting isn't the issue, all of a sudden the idle will drop an if you dont rev the engine it will stall. it has done this twice in the past couple of days and ive noticed that the car only seems to do this when the fuel garage is around 1/4 or just above could this make a difference or is it more likely the gauge is no longer accurate ??? and is much lower on fuel than displayed

[Speedtouch]

Possibly a duff gauge, or some gunge in the bottom of the tank that's blocking the fuel flow. When was the fuel filter last changed?

[NickBrighton]

i havent a clue to be honest, im going to be working on the car on the weekend changing a few bits. would you recommend using injector cleaners im going to change the fuel filter but i used these in the past, in modern cars and they've been great is there any reason not to put some red-ex in the BMW????/

[Grrrmachine]

Don't bother, it's snake oil. If your injectors are causing the stalling then a bit of fuel additive won't make a blind bit of difference.

Don't just swap parts over either, as you're more likely to disturb things that were previously fine, and introduce new problems. Follow the guide:

http://www.e30zone.net/e30zonewiki/inde ... ake#Idling

[Brianmoooore]

The performance of the injectors are fundamental to the performance of most E30s. Most do not have a lambda sensor controlled feedback loop controlling the air/fuel mixture, so no compensation is applied to correct ageing injectors. Even on those with a lambda sensor, it can only apply an averaged correction, taking no account of differences between individual injectors.
If your injectors are 50,000 miles old or older, then their performance will have dropped off in spray pattern, flow and leakage, and they will benefit greatly from a rebuild.
If you look in our traders' section, you will find someone offering a full rebuild service for £10 per injector.