Cold Start

[kringer]

I've read lots of threads about hard to start BMW's.

I still have some questions.

My 325iC will not idle (until warmed up) if the outside temp is below 50F or so. It might idle but I have to keep the rpm's at 2k until the temp gauge gets out of the blue. If the car dies before then it will not start and will be flooded. I know this becace of all the black smoke out of the pipe tring to restart. Also if I pull the fuel relay and clear the cylinders the put the relay back in it will start. I still must keep the rpms up.

Now my questions.

1: where is the cold start injector so I can test it?

2: I see alot of people talking about the fuel pressur regulator. What would that have to do with it?

3: is there someting else it could be?

Once it is warmed up it runs great.

Thank you in advance.

Kevin
352iC 160k

 

[jrt67ss350]

Since you have a 325i, you do NOT have a cold start injector. My guess is that you have a bad coolant temperature switch that is resulting in the computer thinking the engine is warmer on start up than it actually is. In other words, the computer is going into closed loop mode immediately upon startup, and the engine is not getting the richer mixture it needs to run when cold.

Here's another way to think about it: the behavior you describe is EXACTLY what happens if you try to start a carbureted car in cold weather if the choke is not set. The open loop mode that the engine computer runs the car in when cold accomplishes the same kind of result as setting the choke on a carbureted car. If the computer thinks the engine is warm when you start it when it's actually cold, it's not going to choke the engine, and it won't idle.

Since the car runs great when warm, I bet it's not the fuel pressure regulator that is bad.

 

[kringer]

I guess I'll stop looking for the injector. thanks for the quick response. I'll check the colant sensor. where is the sensor located abd what should the resistance be?
I think I found 2 sensors one 1 wire and one 2 wire. wich one is it?
Kevin

 

[kringer]

ok. I checked the two wired temp sensor. It reads abour 2150 ohms resistanse cold and 1400 slightly warm. I havn't checked it hot. I replaced the one wire sensor. Same issue. I can not drive the car until the temp gauge gets out of the blue zone.

Any more suggestions?

 

[ldzpstnr]

Hmm I thought it was the coolant temp sensor too. I dont know what the OHM readings should be on your car's temp sensor. A bentley might say, but check it whens its hot and compare the numbers. I still think its that temp sensor.

But if its not the temp sensor, maybe try checking the fuel pressure. Maybe the fuel pressure regulator is not supplying enough fuel pressure when the engine is cold. Cold engines require more fuel to run and idle properly until they are warmed up. But I doubt its this also.

Sure you dont have another sensor thats gone bad??? Your car should have the seld diagnosis ability, do that and see if it spits out any trouble codes.

 

[epj3]

Which sensor did you check/replace? There is a siemens/bosch/some other random sensor, and then a VDO or Siemens sensor. Confusing, yes, but one sensor controls your temperature gauge, and the other tells the ECU engine temperature.

 

[ldzpstnr]

I think those two coolant sensors are right next to each other. I remember my 85 318i's coolant sensor(also called the thermo time switch) was brown in color. There was a white one right next to it, and that sensor ran the temp guage in the dashpod. Remember, this was my old 318i though.... your newer car may have it some other color or other location.

Do you have a repair manual? If not, maybe just drive by an auto shop and ask them if they could look at it for you or atleast tell you wich one to check.

 

[jrt67ss350]

The thermo time switch runs the cold-start fuel injector - nothing more. Since the 325i doesn't have a cold-start fuel injector, I doubt it has a thermo time switch.

My 325e has about 4 different coolant sensors up in the thermostat housing.

 

[jt88488]

Re: Idle problem at cold starts & stalls
1999 328i (e46 - automatic), 108,000 miles

Let me share a similar situation and hope someone puts this information to good use. When I start my car first thing in the morning, it starts fine, then after several seconds the idle problems starts, the rpm’s drops from 1000 down to 500, goes back up then drops down again before eventually stalling. Start it up again and once the car warms up the problem goes away for the rest of the day. I recently purchased this car and looks as though its been this way for a while. A week later, the ses triggered and after taking it to the shop, they identified fault code 1-activation, ignition, cyl 2. They explained that the crankcase vent valve + hoses needed to be replaced.
Crankcase vent valve (pressure regulating valve) #11617501566 part $43.50; vent pipe #11611432559 part $22.00 ; vent hose #11157532649 part $9.70 ; connecting line #11611440317 part $28.75; labor $300

After putting out $450, it didn’t fix my original idle problem. I took it back to have them look at it again, then they came back with Idle air valve (t-shape idle regulating valve) #13411744713 part $180. I wasn’t going to fall for it twice so I got a second opinion. This time I had honest guy really diagnose the problem by ruling out everything from vacuum hose leaks #51731470035, idle air valve, throttle body (throttle housing assembly) #13541433414. The guy explained that he was puzzled since it wasn’t throwing out any codes. But, eventually, the answer surfaced, it’s the VANOS.

VANOS assembly (RMFD Adjustment Unit) or variable camshaft control (Variable Nocken-Steuerung or Variable Nockenwellen-Steuerung) #11361440142 part $475/labor $500.

Now, I forked out $1000, and the idle problem is finally fixed. Mornings start-up are great. Looks like in 99 the manufacturers switched from a single vanos to a double vanos and there must be a faulty part incased in the unit. I’ve heard this being the problem on more current models with lower mileage as well. Hope this information helps.

Regards,

JT

ps: I also read in another thread that someone resolved this with a solution on BMW bulletin, with a software upgrade. Didn't try this since I read it after replacing the vanos.

 

[jrt67ss350]

That's great, but it doesn't help with e30 BMWs since VANOS wasn't even thought of yet when these cars were new.

 

[epj3]

That's great, but it doesn't help with e30 BMWs since VANOS wasn't even thought of yet when these cars were new.

ROFL What a moron