P code expert?? What's the trim "system"?

[80stech]

Idle control valve usually won't cause rough idle, more so not proper idle speed.

[kevinkay]

Originally Posted by 80stech

Kevin, If you have proper rail pressure and the regulator changes the pressure with engine vacuum(or better yet vacuum pump) then you have the lines on correctly.

In park when I accelerate the pressure drops 1 or 2 Psi then back to 49psi
If the lines were mixed up could that be my issue of not holding pressure or would the car not run?

I am thinking something I did yesterday in replacing the CCV I caused my shaky idle. I pulled out everything in the intake upto and including the throttle body. New throttle body gasket, new intake boot with the accordion offset. I was in the engine all day yesterday and need a rest (mental) before diving into it again.

LOVE/HATE relationship with my X!

[80stech]

It would be better if you could pull the vacuum line(at the manifold) to the fuel pressure regulator and observe the rail pressure to be sure. And of course check the vacuum line to the regulator as well for leaks. Think you did that already but not sure ??

As far as the rough idle I would agree that is probably something to do with what you did when changing the CCCV. Did you replace vacuum hoses as well? maybe one of the hoses to the vacuum distribution manifold broke or cracked or doesn't fit properly?

[80stech]

Maybe read up a bit on how the fuel pressure regulator works, interesting and very useful to know.

[upallnight]

Originally Posted by kevinkay

In park when I accelerate the pressure drops 1 or 2 Psi then back to 49psi
If the lines were mixed up could that be my issue of not holding pressure or would the car not run?

I am thinking something I did yesterday in replacing the CCV I caused my shaky idle. I pulled out everything in the intake upto and including the throttle body. New throttle body gasket, new intake boot with the accordion offset. I was in the engine all day yesterday and need a rest (mental) before diving into it again.

LOVE/HATE relationship with my X!

We saw this with another X member on this forum. He installed a new gas filter but he mixed up the return line at the filter. I think he took off his Youtube video of the fuel pressure when the line was installed backward. At the back of the filter where there are two hoses, the blue line is the return line and the feeds is the black line. The return is attached to the hose barb that is in the center of the fule filter. The single hose and vacuum line is at the front of the filter. Hope this help. If you saw my video that I posted it was a leaky injector that was the cause of the loss of fuel pressure.

[kevinkay]

I pulled out everything up to and including the throttle body again, cleaned up that little rubber hose that the idle control vales pushes into. Put it all back together and still have that change in my idle - very slight, only in drive with my foot on the brake I feel a little roughness/jump in the idle. I conclude that I have made the intake "tighter" and less leaks which is making my trim code more focused and felt with the idle???
I am starting to suspect my MAF.
There is an after market new MAF for $18, might be worth it to use it as a tester.

YES - I am "throwing parts" at my issue..... a new car one pice at a time!!

Thanks for all the input

[80stech]

It might be just coincidence that the shaky idle started after you did the work on the CCCV but sounds suspicious. A MAF problem can be really hard (almost impossible) to diagnose without replacing with a known good unit to try. I wouldn't put any faith at all in a $18 MAF though. Any chance you can swap with somebody?

[upallnight]

A bad MAF will not account for the drop in fuel pressure when the engine is off. You said you replaced the fuel pump, but you only replaced the pump itself. From that, I'm going to assume it wasn't a BMW oe pump from a BMW dealer, but an aftermarket pump.

The video that I posted for you showed three locations that you could be losing fuel pressure when the engine is off. You stated that you took the injectors out and turned on the ignition and didn't see any fuel leaking out of the injectors. Did you have the fuel gauge attached to the rail? If you did have the fuel gauge attached to the rail and you didn't observe any fuel leaking than the leak must either be in the fuel pressure regulator or the check valve at the fuel pump.

You stated that you replace the fuel filter twice so unless you connected something backward, I'm going to say that it isn't the fuel regulator.

That leave us with the fuel pump. Unless you performed the pinch off test as described in the video I'm going to say that you could have a bad check valve in the fuel pump.

[bcredliner]

All the stuff you are trying should cause codes on both banks. Per your first post the codes were only for bank two. I would be focusing on troubleshooting potential causes of a problem that would impact just bank two.

[kevinkay]

Originally Posted by bcredliner

All the stuff you are trying should cause codes on both banks. Per your first post the codes were only for bank two. I would be focusing on troubleshooting potential causes of a problem that would impact just bank two.

Yes, I agree. Its not plugs/coils or injectors because I switched them between banks. It's not my valve gasket, smoke tested it. I did a valve compression test - all within 200-205 psi.
Maybe I need to look at the exhaust manifold? (yuck- everything burnt on stuck) leak in the exhaust manifold gasket??

UPALLNIGHT- I have had my fuel pressure drop issue and searching for its cause much before this issue popped up. I suspected the issue when I would have a more difficult start on a warm engine. I started with changing the O-rings on the injectors and checking for leaks. Following instructions- when I went to "relieve the pressure on the rail" at the schrader valve I didn't get much if any fuel release. Did my reading and research and since my fuel pump was old/original and on my "list" - I changed it. I used OEM Pierburg pump. As far as I can tell the check valve has to be part of the pump?? and thus I have replaced it. I watched that video several time and MUCH appreciate your suggestions AND your commitment to me (and a lot others on this forum). i think I next need to separate the fuel line from the rail and test to see if pressure falls there.

Today I did a Freeze frame when the "service eng. soon" came on. looks like my short term in back 2 is WAY off???