Check Engine Light comes on at the weirdest times

[RebelScum]

OK so I just got my 1994 E36 318is home today. On the way (highway) the check engine light came on. I made a stop and shut off the car fora few mins...when I restarted it it was still on. Then I accidentally stalled the thing, and it went off. It didn;t reappear until later on on the drive home; when I got to my garage, I intentionally stalled it and it went off again. Under the hood I noticed the cold air intake tube is cracked all to hel, but otherwise the hoses are solid.

The car has been sitting for 7-8 months with fuel and oil in it. The oil has been changed but I need to get a few hundred KMs under the car before I can rule out standing fluids. The car did fail an emissions test yesterday, but the tech felt like the standing fluids were the cause.

Could that, combined with my ratty CAI tube, be the cause of this (hopefully minor) problem?

Your insights are greatly appreciated.

Cheers

r

[BMWMPow3r]

could be air leak. Is your e36 a obd1, you can check the stored engine code yourself if you have a bently manual.

[justaddwada]

Originally Posted by BMWMPow3r

could be air leak. Is your e36 a obd1, you can check the stored engine code yourself if you have a bently manual.

a check engine light for manifold pressure shouldn't turn on when the car
is going down the freeway. and he would have noticed shitty idle.

[BMWMPow3r]

If its a large enough air leak on the boot(which is after the MAF), it will go on will driving too.

a tiny air leak within the manifold would more than likely trigger the light when at idle, because the vaccum pressure is higher due to the throttle plate being closed.

anyways, the codes should be stored, so try to pull them. you need a bently.

[justaddwada]

OP there is a key on sequence for checking your diagnostic codes. Search
for "OBD 1 e36 code check" or similar. I think it is key position 1, immediately
press gas pedal 5 times. wait. the check light will stay on for a few seconds
to show that it worked, then it will flash a 4 digit code. morse code style so
count carefully.

[RebelScum]

Hey all, thanks for the replies

I need to clarify one thing: I misspoke. It's not a "cold air intake tube", is the standard air intake boot. I've replaced it.

I've put new plugs in and cleaned the intake manifold. I filled it with premium with some injector cleaner and took it on a 400km drive today. The engine light came on and off intermittently, and then finally went off (seemingly for good) for the last 200km of the (all highway) drive.

When I got into town I made a stop and shut off the car for 15 mins. When I restarted it there was no problem, but going from 1st to 2nd up a hill I revved it hard and the light came back on.

At this point I'm fairly sure it's a dirty or faulty sensor. The engine and tranny have been functioning perfectly (it's a very very smooth car). There are no unusual engine sounds, no sputters (though it struggles to get up to idle on startup now and then), and no performance issues. RPMs are bang on, running at around 3300 in 5th at 125 km/h.

I don;t have a Bently, but I do have this: http://www.bimmerzone.com/fcodes.htm

Of course I don;t know which code corresponds to my car, if any :P

[mmke36]

When I first got my 318 (OBD II) I had a similar CEL problem; it happened for a few days or a week. The only corolation I could draw was between the CEL and the fuel level being around or below quarter tank: fill the tank, two starts later, all clear. All fluids were changed that week too. Never a problem since (fuel is typically kept above half).

[thumperj20]

just to put in my tw0 cents check your o2 sensor they are wierd sometimes going off and coming on.

[heifetz17]

http://forums.bimmerforums.com/forum...ne+light+is+on

Pull your code, go back to your site and find that code, then let us know what it is.

Then we can tell you how to fix it