Replacing the DISA caused many more problems

[zMarih0e]

Hi guys

So I recently got the brake pads on my 2002 BMW X5 3.0L changed. Everything seemed normal for about a day or so.

The next day, the check engine light came on, and the car seemed to be running very poorly. I had very low MPG in the city (approximately 11 mpg), and I stopped by Autozone, and it was a P0171 and P0174 error (Lean fuel bank 1 and 2).

So, I decided to check the mass air flow sensor (MAF). It seemed kind of dirty, so I bought the MAF sensor cleaner (not brake cleaner or anything like that). It seemed like I cleaned it, so I reinstalled it. Problem did not go away.

So I moved on to the DISA. I took out the DISA, and lo and behold, it was literally destroyed. The flap was completely loose, and useless.

So I ordered a new one, and hoped that would solve the problem. I installed it, and well now I have some new problems.

The car will run very well on the highway, and in the city, at very good mpg (what I was used to getting). However, the car has a VERY rough idle. And, the car, if sitting at a stoplight, for a mere 5 seconds, dies.

If I am decelerating, the car will drop normally to 1500 rpm, and then suddenly/swiftly drop from 1500 and will try to hit zero. It will go to about zero, bounce up a few times, and then fall back to zero and die (unless I put some throttle into the engine -- so at stoplights if I put the car in neutral, and put on the brakes and accelerate, I can keep the car alive).

I have no idea what is going on, and how this makes any sense. Previous to installing the new DISA, the car operated fine. (As in, low mpg, but drivable).

Additionally, if my RPM is below 1000, the brakes sort of tighten and stop working. If I have a highish RPM (2000 or above) and I try to use the brakes, they work normally. It seems like the car is losing power under 1000 RPM because the lights indicating mileage and temperature on the dashboard start flickering slightly.

Even if I am turning into a parking lot, if I let go of the pedal, the car is near dying. So it isn't a matter of being idle for 2-3 minutes, but rather being idle for almost 2-3 seconds, that causes the issue.

The DISA was purchased from a BMW dealership parts section, and I believe it to be an OEM.

Additionally, the DISA makes a lot of noise at 1000 rpm. And the entire intake shakes.

I have checked the lower intake boot, and there are no cracks whatsoever. (I believe it was replaced two years ago)

I was able to travel 150 miles with this car, with these problems, by just using cruise control at 70 mph -- no issues, had a fuel consumption of 19.2 mpg.

I just checked the latest error codes at Autozone, and this is what I got:

P0300
P0171 (had before)
P0174 (had before)
P1349
P1345
P1347
P1352
P1351
P1342

So in summary:

Before installing new DISA: Vehicle was not powerful at low to medium RPM -- average mpg ~11. But car did not shut down at idle, no rough idle -- just poor city driving performance. Could go up to 85 mph potentially.

After installing new DISA: Vehicle is powerful at low to medium RPM (as it used to be) -- average mpg~19-20. But car shuts down at idle, very rough idle.

What is going on?

[upallnight]

Check the rubber boot for the throttle and the ICV, bet you it's torn or ripped.

[zMarih0e]

Nope, it was replaced last year. That was my initial thought as well, but I checked it and there are no cracks / tears. Any other ideas?

[ArmyX5]

You have an air leak some where. Go back and check all your MAF and DISA connections. Also, did you make sure that no parts from the old DISA went into the air intake?

[upallnight]

When you pulled the DISA Valve out was the metal pin still holding the flap at the top? Was there still a metal pin? If you didn't have a metal pin don't start the engine until you find that pin. Contrary to some people on this forum that pin can work its way into the engine and you will be looking at either an engine rebuild or a new engine.

[zMarih0e]

No parts from the DISA went into the airtake -- the DISA was destroyed, but the pin was still intact when I removed it.

Just to prove the point.... I drove 150 miles on the highway after replacing the DISA. Car runs completely fine, just if I stop at a stoplight or stopsign and don't rev the engine... car dies.

So I don't think anything fell in the intake. I will recheck the connections and try to find the airleak somewhere somehow. (if that is the case -- I do feel that there is an airleak, but I just can't find it!)

[ArmyX5]

I am not sure what kind of engine you have, but here is a good reading site that can give you some ideas of what to look for. Look at the video.

General diagnostic procedure for a single or multi-cylinder E39 intermittent misfire? - Bimmerfest - BMW Forums