2000 4.4 Problems Starting

[supersteve]

Found out some more info.

The BMW comupter system monitors all of the vehicle computer systems. It; however, only converts OBDII codes on emissions related codes as required by US Regs. So if there is a non-emissions related cause to this problem it will never throw an OBDII code. The only way to find out if another system (EWS) is causing this is to read the main computer with a BMW capable code reader. I have one on the way.

I also now suspect a heat failure of the crank position sensor could be the cause. My non start seems to be happening after the entire truck has warmed up. It will not happen if I just drive 15 minutes to work and let it site 12 hours. It happens if I drive a long time (an hour) then try to restart wether it sits for 10 mins or 12 hours. It also becomes difficult to start when running erands. Start, stop, start, stop, no start kind of thing.

I have not replaced it only tried to start with it disconnected. It wouldn't start. I have found out that after the engine is running, if the CPS fails the computer will convert to the signal from the Cam Shaft Position Sensors for Ign and FI. Setting a "pending" code. The computer will not start off the cam sensors.

The next attempts to start may not generate a code because the engine hasn't started (not emissions related). After the engine starts the code is eased because everything is fine.

Also in a discussion with the BMW parts guy I found out the current Crank Position sensor has been replaced with a new part number. The price has also gone from $36 on the OEM parts site to $108 at the dealer. I also have one of those on the way.

I'll let you know what happens.

[HellzMindPlaya]

Well i haven't done anything special to the X5 lately, but I haven't had any problems starting... I wonder if it has anything to do with the lovely weather we have been having... It is supposed to rain 3 inches in the next 3 hours.

[HellzMindPlaya]

So can anyone think of a good reason my X5 would like crappy weather and dislike nice weather? It has been behaving really well lately. Now that I think about it when I bought the X it was crappy weather for a good while, then it dried out a bit and we had a pretty dry summer and the car proceeded to run like crap. Winter is here again and we are back to lots of rain and a good running X5.

Has anyone else had a car, truck, or suv/sav do anything similar

[supersteve]

It adds weight to my suspicion of the Crank Position Sensor failing because of heat. The engine won't start off the cam positon sensors. The computer will however, switch over to them for a reference if the CPS fails while it is running. The wet weather may be keeping your bell housing cool enough so that the CPS is not failing in the time you are driving.

As I said above, I have been having problems only after long trips. I now have a Peake Research reader. The next time, If it does, I will read the computer with it and see whay it says.

[texmln]

You guys need to invest in a Davis CarChip. Plugs into your OBDII port and records multipe data points from your vehicle. There are several versions with different recording capacities. I think mine was something like $180 and records 300 hours of data, plus any OBDII codes. This way you can leave it in all the time and pull it after you have several "incidents" to see if they all have something in common in the data.

[supersteve]

Problem is The systems are built by Bosch to BMW's specs. They only report the required emissions related codes to the OBDII. If this is not emissions related it won't show. In order to read BMW's codes you must have a BMW capable reader IE...Peake research tool, which I now have.

[texmln]

I agree, but the cool thing about the CarChip is it collects more than OBDII codes. (By the way, I don't work for or have any interest in the company.) It collects the following data:

• RPM
• Throttle position
• Engine load
• Fuel pressure
• Fuel system status
• Short- and long-term-fuel trim
• Battery voltage
• Timing advance
• Coolant temperature
• Air flow rate
• Intake air temperature
• Intake manifold pressure
• Oxygen sensor voltage

Seems like just the kind of data that would help everyone figure the starting/stalling problem out.

It keeps both a data table AND graph, making it really easy to see how the car is operating over time. 300 driving hours worth before it starts to overwrite!

[supersteve]

The problem, as I see it is that BMW's computers will not give out the info you listed.

You have to think about this as a language barrier. The computers on the cars are thinking in BMWeese. If they find a problem it then throws a code in BMWeese. If it is a required ODBII code (required by US regs since 1996) it translates it into OBDIIeese so an OBDII reader can read it.

I was messing around the other day with both of the readers (Actron OBDII and Peake Research) I was able to find a code with the Peake tool after I had "erased all codes" with the Actron. I was also able to find transmission codes with the Actron that the Peake didn't find. I think unless your willing to spend several $K for a reader there is no one reader that covers all the bases on a BMW.

[HellzMindPlaya]

The Carsoft setup that I have will read codes from all systems, it even reads that I have a few problems with my instrument cluster. It only cost me about $150 from some company in Hong Kong... Something like www.one-stop-factory.com they sell the interface, all you have to do is find the software to make the interface work. Use you favorite file sharing software to do that.

I am guessing that it is just my problem is just tied to the fact that it is wet outside... Electrical components get better continuity when it is wet outside. Mine used to have problems starting when it was dry, but since it started raining very heavily my X has not acted up. This is the longest I have seen the thing go without having any problems. When I bought the car it was winter and it ran fine... Summer came and it had problems starting. It doesn't do it only when the car is warm, mine has had troubles many times starting in the morning where the car has sat for a good 8 hours at least.

Thanks Texmin for the idea, it sounds to me like it may be worth looking into. Even if it doesn't work with our X5s it should work with a lot of other vehicles, which would make it worth the cost down the road somewhere. Sounds like a cool little toy at least!

[supersteve]

Hellzmindplaya,
Do me a favor? Open up your engine electronics box and look for any moisture in there. I was digging around in mine and I found water stains in the connectors (by the pins on the box) for the AGS. It's the silver box (transmission controller) with blue plugs. After digging around in there I got caugh in a down poor and my trans went into "fail safe" mode. I went back in and pulled the box out opened it up and found more water. I used a hair dryer to dry it out. I closed it up, put it back in and she has been running like a top.

I plan on going back in and sealing the rubber grommets and the lid with silicon.