Car runs great until suddenly it dies completely....????

[Iridebikesalot]

Hey everyone!

I'm in need of some advice....I'll try to make it short!

I have a 1995 BMW 318ti and it's been great for the past two years. Until now. Ugh. A few months ago the idle was all crazy and would randomly die at stoplights... finally I took it in and they replaced the camshaft sensor. Ran great for a month.

Then it started running SUPER rich and everywhere I went I smelled like gas, so I replaced the 02 sensor. Ran like a dream.

About a week later, I would be driving around town and the car would run/idle better than it ever has and then all of the sudden would die completely. Everything electrical shuts down, tac goes to zero and all the check engine lights come on.

I pulled the car over and tried to start it again, no luck. Engine hardly turns over. Wait about 15 min (while trying to politely decline every guy that drives by offering to jump my battery- dudes really love using that one huh) and it runs again and runs good until 5 min later and the exact same thing happens again.

Soooo... I thought maybe it would be the ignition coil. Bought a new one- nope. Did the same thing after driving it for 10 minutes. It doesn't matter if I'm coasting along or if I have it floored with the RPMs up- it still happens. Just Boom. Dead. Everything to zero.

Anyone have ANY clue what it could be? I'm a poor grad student and this lil car has been draining my bank account lately trying to fix reoccurring problem after the next. Most of the fixes I have been doing myself to save money on labor charges, so if I can do it myself that would be awesome

My guesses - 1. Crankshaft sensor? 2. Fuel Pump ? 3. Is there a chance the Camshaft sensor that was installed was a bad one?

Any and all advice is appreciated! Hopefully I gave you enough details about what's going on and didn't bore you to death.
Thanks for reading!

Sara

[Romak]

I don't have an exact answer for you but from your description whatever is failing seems to be heat related. It'll fail while you're driving because whatever it is heats up and a seal expands or an electrical component maybe is getting too hot. Then when it dies it sits for a while and cool, then reverting to its original state and you're able to fire it back up again. I would look at things that can be damaged or influenced by heat. A bad sensor or fuel pump would be random and sporadic not always failing after driving. Does the problem ever occur on start up in the mornings? (or whenever you try to start it afters its sat for hours and is completely cold) The hardly turning over issue after the car dies, does it seem like a dead battery? as if there isn't enough power to crank it over? Or does it seem like something is stopping it from turning over?

The more details you can give us here the better and we can try to diagnose it. Since its a '95 and that means obd1, do a stomp test:

http://www.318ti.org/forum/showthread.php?t=7211

See if that shows any codes and report back what it says.

[Iridebikesalot]

Thanks for your reply, Romak!

I actually had no idea that you could do a code test on an obd1 car, so that's exciting- I'll give it a try this afternoon.

As far as the rest of the car goes... it ALWAYS starts up right away, even if I haven't driven it for a week and it's been out in the cold. Which is one of the reasons I love this car so much!

When it dies on me and I try to get it started again it's more like spitting and popping like it's <<this close>> to getting started but then dies again.

I agree with you on the heat related idea. Except one day after this had happened and I magically made it home after the car died on me four times I let it idle in the driveway to see how long it would go before it would die.... it kept running...idling fine... and maybe 15 min passed or so and I hopped inside to look at the gauges and the temp gauge was almost all the way in the red! I shut it down right away of course but then I thought... If the whole engine was about to overheat, how was it still running??? (If the problem was heat related)

Argh. I'll try out the stomp test and see what it says!

Thanks again for your advice!

[Iridebikesalot]

Dang... I tried the stomp test. Got excited that maybe I would finally get an answer and I did it three times just to make sure, each time it read "1444" which is the code for all faults fixed.

I'm lost haha

[Den]

Originally Posted by Iridebikesalot

Dang. . .I'm lost haha

What, no OBD on your bike?

A bad sensor should throw a fault code, but it ain't always so. . .

Glitchy DME is another possibility. Maybe stalk one of the Ti's in your town and ask to swap DME's. . .
or maybe someone on here has an extra that they will let you borrow.

http://www.pelicanparts.com/bmw/tech...DME-Repair.htm

Sorry you're having so much trouble pinning down the problem. FWIW, my '95 has been very good to me, no guessing games so far. Great cars and well worth the price of routine maintenance, like replacing sensors and hoses. Good luck.

[Iridebikesalot]

haha luckily bikes are much easier to work on than cars :-)

And thanks for your response, Den. I hadn't thought about the DME ....so I'll look into that more. Unfortunately I live in a town with only two other known Ti's, but it's worth a try if that's the problem!

I'm glad yours runs so well! I bought mine used three years ago and it ran like a stinkin' dream for two years. Not one problem. So I guess this is my payback :-/ Once I figure out the problem I'm sure it will be better than ever.

Thanks again!

Oh also- I thought of one more thing.... when I ran the stomp code it was when the car was running "good" so I was thinking of driving it around the neighborhood, letting it die again and then trying the stomp code again? Right after the problem occurs?

[Den]

OBD should store any fault code(s) in memory until cleared/reset.

[Iridebikesalot]

Curses. Well I have some free time tomorrow anyways so maybe I'll give it a shot just for kicks. Who doesn't love a driving adventure around town when you know your car's about to die anyways ?!

[Iridebikesalot]

Ok well my experiment gave me different results! Drove the car til it died like expected... did the stomp test immediately and it gave the code "1226" which corresponds to Knock Sensor #2.

Not familiar at all with knock sensors... does this make sense to anyone? Could this really be my problem? Are they related to the crankshaft sensor in any way?

[Den]

I've never had to mess with the knock sensors. They basically tell the DME if your engine knocks, usually due to fuel not meeting the octane requirement, and the DME retards the spark timing. Not directly related to the crank sensor. I don't think a bad knock sensor would cause your car to stop running, but who knows. . .

Random info:
http://www.m3forum.net/m3forum/showthread.php?t=280320

http://www.318ti.org/forum/showthread.php?t=25602

Looks like a bit of a PITA to get to the knock sensors, but you know you've been itching to pull the intake manifold and replace all the plumbing under there anyhow. Rubber hoses don't last forever.

This is for an M44, but you get the idea.
http://www.318ti.org/forum/showthread.php?t=18066