Please Help : Stalling issue

[Ans]

Hi Guys, I reallllllly need your help!!! My 89' model 318i (M40 engine) just stalls now and then. I try to start again but it just swings and on the 5th/6th try, it starts. The car idles perfectly and starts perfectly. Especially when the engine gets hot, it either stalls or missfires - the revs don't go past about 4000rpm - it surges between 800rpm and 4000rpm whilst holding the accelerator flat down. I have changed - fuel pump, fuel filter, spark plugs, checked the ICV, checked all electrical wiring and now I'm thinking of changing the crankshaft sensor....I don't know if that could be the problem, I found that on the cable to the sensor, there is a bit of damage but the wire is not cut. Could that be the problem? Anyone experienced something similar?

[Ans]

This forum just doesn't help a brother...................Or maybe everyone is as confused as me, or my explanation is not good enough.................I don't know. Nevermind, I'll search for help elsewhere.....................................................Thanks anyway!!!

[charlE30]

I've not experienced these exact sysmptons... but have you checked you've not got any air leaks in any of the hoses/breathers, if there is visible damage to the wire on the crank sensor try swapping it for a known good one.

My girlfriends 325 once developed some strange habits similiar to yours and it turned out to be the AFM, fitted a good second hand one and it sorted it.

[Ans]

Wow, a reply..........Thanks man!!!! Was thinking about that also, but its difficult to get proper second hand spares in SA. I always have to go to the dealers and their prices are ridiculous! I could end up spending fortunes only to find that was not the problem........Does anyone know how to test the AFM?

Thanks again charlE30.......at least I know someone out there cares..........Enjoy

[Grrrmachine]

Don't just change parts until you fix it; get a multimeter and test all the parts. It's least likely to be the AFM; more likely to be the CPS or blue temp sensor. Put either CPS or BLUE TEMP into the search box on this forum, and you'll find all the answers you need.

And please, use the ENTER key; "...................." doesn't really mean anything.

[Ans]

"..................."Thanks man................Will search now.........by the way ".........................." not suppose to mean anything, its just something I'm use to doing but for your sake

I'll use the ENTER key.Its amazing how people from other parts of the world react to minor things. Anyway, thanks again and let me get searching!

[charlE30]

Hopefully repairing the cable will work but they are very sensitive to the resistance throught the cable. You need to check it with a multimeter.

The below is a quote on how to check the crank pulse sensor..

Using an ohmmeter, check resistance
between terminal 1 (yellow wire) and terminal
2 (black wire) on the sensor side of each
connector. The resistance
should be 500 to 600 ohms.
If the reading is incorrect, renew the sensor.

Just found this on checking the AFM

The sensor's electrical operation is checked by measuring
resistance across the potentiometer's electrical terminals. Disconnect
the harness connector from the sensor AFM and connect
an ohmmeter between terminals 7 and 8 of the sensor. The resistance between the terminals
should increase steadily without any flat spots as the
sensor flap is moved to the full open position. If any faults are
found, the air flow sensor is faulty and should be replaced.

Check the intake air temperature sensor by connecting an
ohmmeter between terminals 8 and 9. At approximately 68°F
(20°C) , the resistance should be between 2200 and 2700
ohms.
Throttle Basic

This is to check your engine temp sensor (blue one)

To test the switching function, disconnect the White wire
from the switch. Using an . ohmmeter, check for continuity
between the switch terminal corresponding to the white wire
and g round. At coolant temperatures below 86°F (30°C), there
should be no continuity (switch open). At coolant temperatures
above 1 1 8°F (45°C), there should be continuity (switch closed ).
If any faults are found, the switch should be replaced .
Replacing the switch will require d raining and replacing some
of the engine coolant. See COOLING SYSTEM . Use a thread
sealant when installing the new switch/sender, and torque it to
25 to 30 Nm ( 1 8 to 22 ft. l b.)

Do you have a copy of the haynes manual? I've got it electronic and could email you a copy if you want, I've also got the Bentley electonically but it doesn't cover the 318

If I can help in any other way mate I will

Charlie

[Ans]

Hi Charlie, thanks man. I have a haynes manual and I tsested the resistance in the crank sensor. I found the resistance to be 540 ohms but then I twisted the wire on the point where it rubbed and resistance started to jump around. After repairing the cable, the resistance now remains the same. Hope that was the problem. Will put back today and check.

Thanks for the advice on the AFM and temp sensor...will check those also. Will let u know what happens.

Ans

[charlE30]

Hopefully it'll be resolved, the CPS is paramount for the engine to run correctly.

Charlie

[Ans]

Hi, I put back the CPS, started the car up, let her idle for about 30 minutes and then drove around the block for a few times and she's still hesitating and "missing" a little, the revs dropped to almost zero twice. Got back to my garage, opened the hood and was blown away by the tremendous amount of heat from the engine bay (I don't think thats normal). I switched off the car and opened the filler cap to the radiator immediately - isn't it suppose to boil/bubble up? How do I check if water is circulating through the radiator? And could this also be a cause to my problem?

[charlE30]

Is your viscous fan working properly? What was your temperature needle doing? the excess heat may have just built up from idling with no air flow through the bonnet area. If water is flowing through the rad the top hose will be hot too touch when it's reached temperature.

Blocked water circulation (if that is a problem) wouldn't effect the way the engine runs unless it was just about to boil.. I do stand to be corrected on that one, I'm trying to think logically

Have you done the checks on the AFM and blue sensor? maybe worth checking the injectors aswell.

I sent you a very useful link

[Ans]

Found my problem and it only cost me 80 bucks!!! I was busy checking the Immobiliser wiring and found 2 wires were lose, I sorted that out and I wanted to test the car so I went to close the hood. I had the wiring harness cover under the hood opened so I first went to close it with the car idling. I tapped the cover to ensure it clips in and my car dies. I start her up again and start to play with the relays and "VOILA!!!" I found the problem. The Damn DME relay was faulty. Bought a new one and the car now runs fine for about a month now.

Thanks for all your help Charlie, really appreciate it.

[charlE30]

Pleased you got it sorted in the end