Car can't drive when cold. only once warmed up. Misfiring when Warm....

[JakeP]

Doesn't really make sense if it only does the crappy idle when the motor is cold. If it was in intake leak, it would cause a crappy idle all the time.

why would leaks cause issues only when cold though...?

I think we're on the same wavelength...

[dkbmxer002]

why would leaks cause issues only when cold though...?

[fiftytakedowns]

As suggested above, I think you've got a vacuum leak somewhere. Find it. Check all hoses and gaskets that connect to the intake manifolds AFTER the throttle body. Also, injector o-rings.

HMM injector O-rings. I do have the mustang Injectors in there.

[Ryann]

As suggested above, I think you've got a vacuum leak somewhere. Find it. Check all hoses and gaskets that connect to the intake manifolds AFTER the throttle body. Also, injector o-rings.

[JakeP]

lol. don't commit suicide yet. Maybe try checking the ohms on the DME temp sensor? unplug the ICV? Have you thought about posting this on m42club.com?

[fiftytakedowns]

fml

[fiftytakedowns]

I get a 1271 engine code, which means coil 1 I believe, but I replaced with a coil on plug conversion. same code spit out.

brand new 02 sensor less than 5000 miles.

ICV is working, you can see it flip open and closed.

[dkbmxer002]

i have the same exact issue and have for about as long as you.. i have tried quite a few different things as well with no luck...


one symptom that may or may not be related that i also see is after driving on the highway for a while (and i believe only in cold weather) the car will sputter when i floor it on the highway cruising.

[immajackuup]

o2 and idle control valve is bad.

[JakeP]

Does it ever bring up a check engine light? if so, what code?

[fiftytakedowns]

I'm having the EXACT same problem as you on my 91 318i. Thought it might be the ICV so I swapped a junkyard part in and it was even worse.


Doesn't really make sense if it only does the crappy idle when the motor is cold. If it was in intake leak, it would cause a crappy idle all the time.




I'm really leaning toward this. OP, where does your temp needle sit when the car is fully warmed up and running well? Lowest quarter of the gauge?

when fully warmed up it sits SMACK dab in the middle of the gauge.


IS there any way to isolate whether this is a Fuel issue, a Spark Issue, or an electrical Issue?

Im planning to attack this in a couple ways this weekend:

- I am going to replace the ground strap between the block and the Chassis, because it looks very rough, and the wires are exposed.

-Additional ground between head and block for sensors.

-check all other grounds for contacts specifically the one from the DME to the shock tower or battery tray. (for some reason my hood has a ground strap on it) Any other grounds to check?

For Fuel:
I will jumper the Fuel Pump relay and see if for some reason something is telling the fuel pump to stop working maybe?? causing agressive Bogging, or no running whatsoever.

Check to see if any return fuel lines under the car have been Kinked cuasing fuel pressure against the flow.

I ahve no Idea how to test if it is not getting spark. or anything. Im really confused what would cause such an aggressive failure.


Here are some Videos of how it runs:

http://www.youtube.com/watch?v=Eu5npniUyl4

http://www.youtube.com/watch?v=NF3NEp_dnX4

[JakeP]

I'm having the EXACT same problem as you on my 91 318i. Thought it might be the ICV so I swapped a junkyard part in and it was even worse.

The most common cause of that is intake leaks. A smoke test of the intake is the best diagnostic for intake leaks.

Doesn't really make sense if it only does the crappy idle when the motor is cold. If it was in intake leak, it would cause a crappy idle all the time.

Another common issue causing hard starts and poor running when cold is a bad DME coolant temp sensor.

I'm really leaning toward this. OP, where does your temp needle sit when the car is fully warmed up and running well? Lowest quarter of the gauge?

[xwill112x]

Put a m50 in it, problem solved.

edit: my m42 knocks like crazy when i first start it up...has for years too. I dont really mind, as i have a m50 waiting in my basement :)

[fiftytakedowns]

I tried swapping out with different AFms to no avail.

[vpilarrt]

Mkae sure the AFM barn door is moving freely/not gummed up. I've had that on really cold mornings (<20°F). Sprayed the inside of the AFM with Carb/Choke cleaner - problem solved.