2000 4.4 Problems Starting

[HellzMindPlaya]

I only run premium from shel and chevron. Mostly Shell because I have a company gas card from there.

[noncom23]

Techron made a big difference for me. Do you all rec. a gas treatment in mine at current 7000 miles?

[HellzMindPlaya]

The Fuel system flush that I had may have been an underlying reason that my cats got clogged up. I ended up cutting them down and hollowing them out and am working on getting an O2 sensor simulator that will get rid of my SES light. (keep getting an after cat O2 sensor aging errors, sim is to slow.) Cats are just too expensive and since there are two it is even worse.

If you are having the starting problem like I am having, but you only have 7000 miles on your X5 I would make the dealer or BMW NA fix it. Not worth throwing your own money at.

[The Cleaner]

I am starting to think you have a fuel line check valve problem. The fuel filter has the pressure regulator built in and when the one way valve is leaking it allows the pressurized fuel line to get air in it The fuel in the lines runs back into the tank and delay or even make difficult starting. That situation is not monitored by OBD so that would explain the lack of SES. If you can, stick a fuel pressure gauge on the fuel rail and let it sit overnight and see if the pressure holds.

[HellzMindPlaya]

Is the one way valve you are talking about inside of the fuel filter? When I had a service 2 done at about 98k they replaced the fuel filter.

[supersteve]

I had previously posted on this.

I haven't had the problem come back since using the fuel injector cleaner for about 60 gallons running Mobil premium and cleaning the power lug on the firewall.

Just for Sh^ts and giggles I tried going back for a tank full on Hess premium. I'll let you know if it comes back.

[vinuneuro]

The SES is not an end-all method of catching problems. We had misfires with our X5 a couple years ago at idle right after start-up, W/O any SES codes..the problem was ignition coils. SES will only be triggered past a certain threshhold. The fact that that it starts(ed) on the second try means that the it is igntion/electric/electronic related. It is NOT a fuel pressure problem.

Make sure all your grounds are alright. You'd be surprised at the kind of problems they can create. Then look into the ignition switch, ignition coils, starter and then the ECU.

[supersteve]

I agree about the grounds. I cleaned all the battery connections and other connections under the spare tire. Problem continued.

I then cleaned the power lug under the hood on the fire wall. The problem seems to have stopped.

I was doing all of this while running Lucas FI cleaner in the fuel tank with Mobil gas (Again about 60 gallosn of gas). The only reason I went back to Hess gas was to in fact, rule out the brand or particular station as the cause.

I do; however, disagree that this could not be caused by fuel system.

If the FI system leaks down the pump may not be able to make enough pressure on start up to atomize the fuel. It only runs for a short time during the start. It then waits for a signal that the engine is running to start pumping full time. It's a safety to stop from pumping gas all over the place if there is a leak in the fuel system.

After a second or third try @ starting, the pump will be able to "catch up". This is why there is a leak down test. Once it's running the pump will run nonstop maintaining the pressure.

Neither a fuel leak down problem or bad connections will give a OBDII code. At least not an accurate one.

[supersteve]

I think I can say the problem is resolved. After sitting at the airport for a week, she started on the first try.

Just a reminder, I had run about 60 gallons of gas through with Lucas FI cleaner. I also cleaned the positive power lug under the hood on the drivers side fire wall. This power lug supplies battery power for everything but the starter.

It took fifteen mintutes to disassembly, clean and reassemble the power lug. It didn't look corroded; but, it looked glazed and the problem stopped as soon as I cleaned it.

Anyone else try it with good results?

[HellzMindPlaya]

I Disassembled it and cleaned in with a rag because i couldn't find a wire brush and it didn't help at all. You are saying to clean it with a wire brush or something right? I need to try the fuel injection cleaner also. Thanks for the input.