M30 dies when stopping periodically

[Asamaan]

Hi All,

Been a while since I posted after getting rid of my shimmy after only 8 years of owning the car.:p

So I was driving the other day, I get off the highway and pull up to a traffic light and I notice a slight engine hiccup and as I come to a stop at the light the car dies. I try starting it, but it won't fire up. I keep trying and it catches then dies right away. Wait another 30 sec, and it fires up. I pull into the parking lot and as I am parking, it dies again. Left it for 15 min and came back and fired right up. I drive it back to work and as I am stopping at a traffic light, I notice the same hiccup as before and it dies again. This time it won't start for another 10 minutes. Any thoughts?

I am thinking maybe a vacuum leak, but not exactly sure what to look for. Any other thoughts? I drove it home after it fired up and parked it since (4 days now). I just can't reliably drive it now, so I need to try something before I take it out again.

Its a 91 535iA w/ 140K on it.

Thanks,
Al

[Tiger]

If you splash cold water on the CPS, it should start up... if yes, your CPS is dying.

[shogun]

check the voltage, maybe the fusable link has a haircrack
http://www.bmwe34.net/Wiki/tiki-index.php?page=Fusible+link

[Kibokojoe]

Fuel filter plugged ?

[Asamaan]

If you splash cold water on the CPS, it should start up... if yes, your CPS is dying.
CPS=? Cylinder Position Sensor? is that the round wire on the spark plug wires? I had that break a while ago and I replaced it a few month later, but I believe all it does is manage how fuel gets delivered, 3 cyl at a time or all at once.


check the voltage, maybe the fusable link has a haircrack
http://www.bmwe34.net/Wiki/tiki-inde...e=Fusible+link
Haven't looked at this, but I'll check it out.


Fuel filter plugged ?
I was thinking about this, but my question would be, why would it work for the most part but then all of a sudden stops and then after waiting for it, it would fire up again?

Thanks All for your suggestions, I'll do some investigating tonight or maybe tomorrow and get back here with what I found.

Thanks,
Al

[Kibokojoe]

I had this happen on my Honda. It would start but stall in a few minutes. After a few minutes enough fuel would squeeze by to start again but it would stall again. Changed the filter and wahlaa.

[Kibokojoe]

Oh forgot how many fuel filters are on these beasts?

[BMW4LIFE]

change the fuel filter anyways...its cheap and takes 15 min to change

I was going to say fuel pump but that is just a guess

[Asamaan]

So I finally got around to replacing the filter and drove it around for a few days and on Friday I was running and errand and coming off the ramp again and the car dies again, but this time it never fired up again. So I had to get it towed which was the first time in 10 yrs, oh well.

I had someone turning the ignition on and off to feel if the fuel pump is working or not but never heard it buzz or anything. I had a volt meter laying around in the trunk so I decided to check the voltage coming to the fuel pump and there were 12 volts on 2 pins which I confirmed one of them was the fuel pump voltage from the Bentley.

What's next? Is it possible that the pump has pressured the system and wouldn't work till the pressure is lower? or the pump died for sure? Also is it possible that a wire got corroded and can be fixed without having to replace the whole pump?

Again this happened only going up a ramp of the highway which is turning to the right, so I am guessing something got shaken loose with the high speed turn.

Thanks for all the advice.

Al
91 535iA

[Tiger]

Crank Position sensor should be by the main pulley/crank of the engine.

There are two thing common in BMW to die... CPS and fuel pump. Take your pick.

[Asamaan]

I have re-tightened the CPS a while ago when I noticed it was loose, I guess I'll check that first, but from the diagnostics I did, it looks like a fuel pump. If it is, any suggestions on repairing it or finding a replacement that doesn't break the bank?



Crank Position sensor should be by the main pulley/crank of the engine.

There are two thing common in BMW to die... CPS and fuel pump. Take your pick.


Thanks,
Al

[Tiger]

Lots of cheap fuel pump on ebay. do a quick search.

CPS can be cheap at rockauto.com. Standard Parts is the manufacturer... u might be able to get cheaper one if you keep searching... don't know why it cost more than M60 CPS.

[genphreak]

You need to check the fuel tank return valve, $15 from bmaparts.com.

If you elect to do the Fuel pump, be sure to also do this at the same time. If you suspect electronics, or the Crank Positon Sensor, carry some 15A wire with you for next time... once it dies, pull the Fuel Pump Relay and directly jumper the FP feed pole/crimp in the socket to a powerful 12V feed. If the car runs again, the FPR or the ECU controlling it is turning the fuel off. That would probably be the CPS.

[Asamaan]

I finally got around to pulling the pump out of the tank. I took the actual pump out of its holder and tried to put a 9 volt battery to the two terminals in order to test it and I got nothing. Is it because the 9 volt battery is too weak and do I need to try to get the power from the Car Battery or a 12V DC power supply?

I was hoping to at least hear it hum when I put the 9v battery too it , but got nothing.

Thanks,
Al

[Asamaan]

Has anyone ordered from partlex.com? I found a replacement pump that's fairly cheap and I just wanted to make sure they are legit.

Here's the website to the pump in case someone else needs one

http://partlex.com/index.php?main_page=product_info&cPath=14&products_id=58

Thanks,
Al

[Warren N.CA]

Your distributor rotor may never have been replaced, and they do not last forever, and can cause weirdness when worn out. Cheap part. Replace the bitch, and even if it doesn't solve it, bet it will run better.


Hi All,

Been a while since I posted after getting rid of my shimmy after only 8 years of owning the car.:p

So I was driving the other day, I get off the highway and pull up to a traffic light and I notice a slight engine hiccup and as I come to a stop at the light the car dies. I try starting it, but it won't fire up. I keep trying and it catches then dies right away. Wait another 30 sec, and it fires up. I pull into the parking lot and as I am parking, it dies again. Left it for 15 min and came back and fired right up. I drive it back to work and as I am stopping at a traffic light, I notice the same hiccup as before and it dies again. This time it won't start for another 10 minutes. Any thoughts?

I am thinking maybe a vacuum leak, but not exactly sure what to look for. Any other thoughts? I drove it home after it fired up and parked it since (4 days now). I just can't reliably drive it now, so I need to try something before I take it out again.

Its a 91 535iA w/ 140K on it.

Thanks,
Al

[Asamaan]

Well I got the part that I ordered yesterday, I installed it and the car fired up. I decided to rewire the old pump in and it also worked, which got me a little confused, but again the car did stop before and then it worked and then stopped again.

I think I will also replace the distributor rotor to be on the safe side. I noticed a few hiccups today when I was driving it, so I still have something, but it is not a fuel issue for now.

I think I might replace the plugs, only been about 10K or so, but maybe 3-4 yrs. Air filter is good, just replaced 2 month ago. What else? (don't want to replace the wires yet)

Thanks,
Al

[Asamaan]

Well, it stalled on me again today twice. The first time for 5 min and then right next to the house and it won't start. I noticed when I am coming to a stop that it is trying to stall, but when I give it gas it keeps going. I noticed in traffic that if I am not stepping on the gas and it is rolling slowly, it is stalling and then catching and so on. It finally died when I came to a stop sign and pressed the brakes hard.

Please advice on what to look for?:(

Thanks
Al

[Jeff N.]

It sounds to me like your car is having problems running on the idle circuit. It's dying only when it's at idle, correct?

I'd check the following:

- throttle position sensor. Make sure the idle circuit is triggering.
- idle control valve. Make sure it's plugged in and is correctly turning on at idle.
- check your air flow meter and make sure that the "barn door" is not sticky. It should swing open freely when closed. They can get sticky when they get old.

A loose CPS can cause the problem you describe but it will tend to happen at any speed, not just at idle.

It's almost for sure not fuel related. Car needs more fuel at speed than at idle and your running fine at speed, correct? Here's a simple check for fuel - when driving at about 25 mph on the flat, keep the throttle constant watch the MPG gauge in the speedo. If the MPG gauge cycles up/down on about a half second cycle, your fuel is too rich or too lean. (You're seen the Motronic closed loop function try to correct the AFR) It's typical for older cars to do this a little but if you have big swings, then you might have some sort of problem in the fueling system or measuring system (AFM, FRP, O2 sensor, etc). Still I very much doubt this would cause the car to stall.

Hope this helps...good luck!

[Asamaan]

Jeff,

Thanks, for the things to check.

the car is a 91 535i M30 Auto.

I grabbed my bentley manual this morning and did some testing.

The throttle position sensor is working fine according to the bentley.

Idle control valve. It is plugged in, and is buzzing when the ignition is turned on. I noticed that the resistance is higher than listed in the Bentley. Bentley states 20 +/- 2 across 1 & 2, and 2 &3 and 40 +/- 2 across 1 & 3. I am getting 30 across 1&2, and 2&3 , and 60 across 1&3. Also I noticed by tapping on the valve with socket extension, I managed to drop it to 25 and 50.

The air flow meter and temp sensor are working properly so is the water temp sensor.

The CPS was filthy, so I took the screw off and cleaned it and re-installed it. I haven't checked it for proper measurements since I had to get to work at some point.

Based on the idle valve values, is it the Idle valve that is causing the problem?

The car is still not starting though.

I took the car for emissions testing yesterday during the day and its readings were way below the requirements, so it passed with flying colors, so this is not making any sense.

Thanks,
Al



It sounds to me like your car is having problems running on the idle circuit. It's dying only when it's at idle, correct?

I'd check the following:

- throttle position sensor. Make sure the idle circuit is triggering.
- idle control valve. Make sure it's plugged in and is correctly turning on at idle.
- check your air flow meter and make sure that the "barn door" is not sticky. It should swing open freely when closed. They can get sticky when they get old.

A loose CPS can cause the problem you describe but it will tend to happen at any speed, not just at idle.

It's almost for sure not fuel related. Car needs more fuel at speed than at idle and your running fine at speed, correct? Here's a simple check for fuel - when driving at about 25 mph on the flat, keep the throttle constant watch the MPG gauge in the speedo. If the MPG gauge cycles up/down on about a half second cycle, your fuel is too rich or too lean. (You're seen the Motronic closed loop function try to correct the AFR) It's typical for older cars to do this a little but if you have big swings, then you might have some sort of problem in the fueling system or measuring system (AFM, FRP, O2 sensor, etc). Still I very much doubt this would cause the car to stall.

Hope this helps...good luck!

[Tiger]

You just solved your problem.

Emission test revealed that you don't have fuel problem.

CPS... without proper measurement will cause problem.
ICV is out of spec... computer is sensing 'out of spec' situation. Simply tapping it brings it closer to spec is still out os spec and will be back to way way out of spec the moment you start engine again.

Distributor cap is a good possibility causing problem since same thing happens in older MB... these distributor caps are rarely changed because it is durable but 10+ years is really pushing the limit.

[Jeff N.]

Well, could be the ICV. I could understand how that could make it stall, not as clear how that would prevent a restart. Car typically runs with a bad ICV, just doesn't idle well.

I should have also suggested a stomp test to pull the fault codes. You may want to clear out the codes, drive it for a bit until it fails, and then pull the codes. If the ICV is flagged, that's some damning evidence.

Here's what I might try with the ICV in the short run:

- pull it and blast the throat of it with carb cleaner; they tend to gunk up with higher mileage cars. Make sure the little valve thing is not binding, etc.
- try swapping out for a bit with another car if you can.

I'd also make a point to correctly gap your CPS. 1mm IIR. Check the nose to make sure it hasn't been ground off on the triggering wheel. If they collide with the wheel, they can be toast. A flaky CPS would definately cause all sorts of trouble. I'd also check the plug harness to make sure it's clean...dry.

It seems like your problem is worse with heat right? That can be related to water in harness, distributor cap, etc. You didn't just clean your engine or something like that not too long ago, right?

There's really not much that can go wrong on the M30. Just need to be methodical and it should sort itself out.

[Asamaan]

I haven't replaced the distributer cap and rotor for as far as I can remember.

I did do a stomp test before I started measuring everything this morning and got 1444 which was no faults.

I cleaned the CPS and remounted it, but I couldn't figure how it can be gapped considering how it is mounted. I did check its connected and it looked good and I reseated it and didn't do anything. I will try to look at the Bentley for how to test it.

I Haven't washed the engine or anything like that.

I think what I am thinking of doing next is as follows:
1. I'll double check for spark (just in case)
2. I'll take off the ICV and clean it and measure the resistance on it again.
3. I'll try Shogun's Reseting the ECU method.
4. Not sure what next?

Thanks all for your replies.
Al

[Blitzkrieg Bob]

I haven't replaced the distributer cap and rotor for as far as I can remember.

I did do a stomp test before I started measuring everything this morning and got 1444 which was no faults.

I cleaned the CPS and remounted it, but I couldn't figure how it can be gapped considering how it is mounted. I did check its connected and it looked good and I reseated it and didn't do anything. I will try to look at the Bentley for how to test it.

I Haven't washed the engine or anything like that.

I think what I am thinking of doing next is as follows:
1. I'll double check for spark (just in case)
2. I'll take off the ICV and clean it and measure the resistance on it again.
3. I'll try Shogun's Reseting the ECU method.
4. Not sure what next?

Thanks all for your replies.
Al


I had something similar happen recently.

the ///M would start cold, run fine for the first 15 - 20 minutes then, start running like crap, stalling, dying and cough, weeze and fart its way to 1500 rpm.

Checked the cap and rotor, and they were the original 20 year old part, tested the coil and it was slightly out of spec and then the plug wires too.

ended up redoing the whole system and cured the problem

[Asamaan]

Well, I cleaned up the air flow meter and the idle control valve, and put it back in and still no start.

I checked the CPS and according to the Bentley, I should be getting 580 Ohms across any of its terminals, and I am not getting anything at all, so I guess that's my no start culprit, unless I am doing something wrong.


The one thing I tried was hooking up a spark plug to one of the connectors to check for spark and I got spark, so I am curious if the CPS is really bad or something else. I thought I wasn't suppose to get gas or spark if CPS is bad.

Thanks,
Al

[Blitzkrieg Bob]

you'll get spark, but the CPS failure will cause the DME to stop the fuel pump.

It's a safety thing...pump will turn off when the crank is not turning to avoid pumping fuel during a crash.

[Mordan]

maybe clean the Injectors with some cleaner you put in the gas. It solved bad hot starts and some idle stalling for me.

[Asamaan]

Thanks to all who replied. I got a new CPS after checking the old one and determined that it failed and the car fired right up after the new CPS was installed.

So lesson learned, before replacing the fuel pump because it is not working, check the CPS first. To check the CPS, all you have to do is get 560+/- 20 OHMS between the middle terminal and one of the outer ones. If you are not getting any or not in the range replace it.

Thanks again,
Al

[Kibokojoe]

Very good.... I love a happy ending

[Rus]

Thanks to all who replied. I got a new CPS after checking the old one and determined that it failed and the car fired right up after the new CPS was installed.

So lesson learned, before replacing the fuel pump because it is not working, check the CPS first. To check the CPS, all you have to do is get 560+/- 20 OHMS between the middle terminal and one of the outer ones. If you are not getting any or not in the range replace it.

Thanks again,
Al

I guess I'm a little late in the game, but glad you figured this one out. My CPS caused my bimmy to stall a couple of times in traffic before finally kicking the bucket. Multimeter diagnosis had me ordering a new CPS 10 minutes later. They seem to have an odd way of going out sometimes. Mine also caused hesitation when getting on the throttle until the engine warmed up. Just my $.02