Code P30FF and loss of boost

[mmilkov]

I'd like to share with you the symptoms hoping that a knowledgeable and helpful soul might direct me how to diagnose the problem.

There is a slight rattle, especially at idle (as if you pass your fingers over wheel spokes), which wasn't there before. I've read this could be wastegate noise. In addition, when I drive the car, it makes a guttural sound and there is a loss of power. If I floor it, the computer displays the half-engine icon and puts it in limp mode. Before the car goes into limp mode, I hooked up my AccessPort and measured a maximum of 6.8 psi of boost, while I normally get about 13.5 psi (with Cobb v4.01 sport map). Is the measured boost the combined value of both turbochargers? If so, then getting 6.8 psi might mean that only one turbo is producing boost? Accessport reports engine code P30FF (boost leak from pressure line of turbocharger 2).

So what could it be? Is the wastegate stuck open? Is it the wastegate actuator?

Thanks in advance!

[ilikebmxbikes]

Check all of your vacuum lines and charge pipe first.

[Cozy]

Boost that low sounds like 'limp mode'. As above, check your vacuum hoses and boost pipes.

[patsfan313]

Same exact thing happened to me yesterday! I just drove her to BMW and they are looking at her now. Will report back once they let me know whats up

[mmilkov]

Originally Posted by Cozy

Boost that low sounds like 'limp mode'.

When the half-engine icon is illuminated, I hardly get any boost: 1-2 psi max. So I assume that this is limp mode indeed. However, when I restart the engine, the half-engine icon disappears (so I am no longer in limp mode?) and on full-throttle acceleration I get about 6.5 psi. This is still low but I attribute it to an actual boost leak or malfunction rather than limp mode.

[mmilkov]

The boost (intake pressure) reported by AccessPort is about -8.5 psi while the engine is idling. Does someone know if this is the expected reading or does it indicate insufficient vacuum?

My gut feeling is that I may have a vacuum leak and poor vacuum will prevent the wastegate from closing. I am thinking of pulling the vacuum hose off the wastegate and measuring the vacuum with a gauge while the engine is idling. Any idea what reading I should get? For that matter, since all vacuum lines are interconnected, can I measure it at any other place, such as the vacuum line to the exhaust butterfly valve, for example?

The reason I supect a vacuum leak is because the exhaust flap (which is vacuum controlled) appears to be acting strangely. The flap is open when the engine is off (I suspect this is normal), then it closes for the first few minutes while the engine is warming up, and then it opens again when the idle speed goes down. Does yours do that, too? I though the exhaust flap should open only above 3000 rpm?

[Dmacc]

Originally Posted by mmilkov

The boost (intake pressure) reported by AccessPort is about -8.5 psi while the engine is idling. Does someone know if this is the expected reading or does it indicate insufficient vacuum?

My gut feeling is that I may have a vacuum leak and poor vacuum will prevent the wastegate from closing. I am thinking of pulling the vacuum hose off the wastegate and measuring the vacuum with a gauge while the engine is idling. Any idea what reading I should get? For that matter, since all vacuum lines are interconnected, can I measure it at any other place, such as the vacuum line to the exhaust butterfly valve, for example?

The reason I supect a vacuum leak is because the exhaust flap (which is vacuum controlled) appears to be acting strangely. The flap is open when the engine is off (I suspect this is normal), then it closes for the first few minutes while the engine is warming up, and then it opens again when the idle speed goes down. Does yours do that, too? I though the exhaust flap should open only above 3000 rpm?

I believe the exhaust flap should do that, I've only heard it happen on cold starts, never really paid attention to it on a warm start. It is part of the start up procedure I believe.

[WPG D33Z]

That code is for a boost leak. Check your charge pipe and diverter valves, makes sure everything is plugged in tight.

[mmilkov]

Originally Posted by WPG D33Z

That code is for a boost leak. Check your charge pipe and diverter valves, makes sure everything is plugged in tight.

Thanks for the reply. One of the diverter hoses seems a little loose compared to the other one. I don't know if it leaks though.
So is there a separate code for a vacuum leak? I thought that the wastegate relies on vacuum for actuation, so if there is a vacuum leak, then the wastegate will not close properly and hence you may get code 30FF?

[mmilkov]

Here is an update.
I disconnected the vaccum line that goes to the top of the canister and connected it to a vacuum gauge. I read 10-14 in Hg. I put the vacuum line back and did a similar measurement for the line going to the other canister. The reading was the same. Is 10-14 in. Hg normal? Also, while measuring the vacuum, should I plug the vacuum opening on the canister and does it affect the reading? I left it unplugged. I can also measure the vacuum at other end of the hose, i.e. where it connects to the solenoid. Does it matter?
According to this post http://www.n54tech.com/forums/showthread.php?t=13114
the vacuum should be about 26". However, he measures it by disconnecting the hose from the solenoid and connecting it to a gauge. I assume he leaves the solenoid vacuum opening unplugged while doing the measurement.

[mmilkov]

Originally Posted by mmilkov

Here is an update.
I disconnected the vaccum line that goes to the top of the canister and connected it to a vacuum gauge. I read 10-14 in Hg. I put the vacuum line back and did a similar measurement for the line going to the other canister. The reading was the same. Is 10-14 in. Hg normal? Also, while measuring the vacuum, should I plug the vacuum opening on the canister and does it affect the reading? I left it unplugged. I can also measure the vacuum at other end of the hose, i.e. where it connects to the solenoid. Does it matter?
According to this post http://www.n54tech.com/forums/showthread.php?t=13114
the vacuum should be about 26". However, he measures it by disconnecting the hose from the solenoid and connecting it to a gauge. I assume he leaves the solenoid vacuum opening unplugged while doing the measurement.

I measured the vacuum by disconnecting the hose from the solenoid and connecting it to a vacuum gauge. The reading was 26" Hg at idle. So it does make a difference on which end of the hose you measure the vacuum. Since 26" is exactly the value I was supposed to obtain (see link above), I conclude that I don't have a vacuum leak. What else can it be? Bad solenoid or a bad wastegate actuator? I am afraid this is beyond my diagnosing skills. Time to see the mechanic...

[135i OREO]

Any update?

[rushbmw]

Any update on this? I currently having the same issue. Under normal throttle the car is driving fine. Once you give full throttle I get low power and the half yellow check engine light come on. I have a Sears OBD11 reader but, it tells me I have no error codes. Not sure if the Sears tool can read BMW codes If I restart the car the check engine light goes away until I go full throttle again. I've had all the fuel pumps, injectors and sensors replaced about a two years ago. It so strange just happen out of the blue.

[fboutlaw]

Also curious about this thread. The past 2 years I've had 30FF pop up, but only at the track over 15 minutes into a session. Whenever I took it to a dealer they said that I had no active codes and when I took it to Dinan, the codes were't popping up either, so I've never fully had this diagnosed.

Curious to see if anyone has resolved this cleanly.

[rushbmw]

I can easily get the check engine light to come on. Just go full throttle and it will pop up. If the dealer doesn't see any codes I will drive the tech and show them. I just find it strange that no codes are showing up. But then again, I'm not sure if my Sears Tool work with our cars.