Bingo!! I may have solved the misfire and lean codes P0171, P0174, P0300

teklord69 · Sep 26, 2011

Below are my previous posts when I started experiencing rough idle:

http://www.bimmerfest.com/forums/showthread.php?t=568487&highlight=
http://www.bimmerfest.com/forums/showthread.php?t=570551&highlight=

Symptoms: Rough idle (cold or hot). Car runs fine but sometimes felt a tad sluggish probably due to misfiring. No smoke emitting from tail pipe.

The codes I was getting: (lean codes):

Not shown are also codes P0300, P0304, P0305 (misfire codes)

Things I ruled out:
Coilpacks -I switched them around to different cylinders. Made no diff in the codes.
Spark plugs - I installed fresh Bosch plugs. Still idles rough.
MAF - Cleaned it twice. Ran the car disconnected. Still idles rough.
Vacuum leaks from intake tube - No rips or tears that I could see.

Items I was going to do next:
New fuel filter, CCV Valve

Then I went to the E46 fanatics board and a lot of them were getting these lean codes. Also someone in this board mentioned DISA valve. So since it was easy enough to pull the valve out, I gave it a shot.

Comes out easy. Need to take out one electrical connector, then remove two T40 torx screws. You don't really need to take out the intake boot to remove the bottom torx screw but it makes it easier if you dont have the proper tools.

I pulled it out slowly.

I first noticed how much gunk it has. The gunk smells like fuel.

Upon close inspection. The darn intake flap is cracked. God knows where that cracked piece went into.Hopefully not my combustion chambers.

Also the metal pivot pin for the valve comes out easily. I don't think it should be loose like that:

Finally, the PLASTIC yellow pivot totally broke. This means the DISA valve doesn't work anymore. The pivot is no longer connected to the vacuum and the intake flap I assume remains closed all the time.

I need to get another DISA valve ASAP. Anyone can help me where to get the best price for this part? Also, I put the DISA valve back in the intake, but this time I removed the loose pieces (flap, metal and plastic pivot). So basically the valve is wide open. Will the car run like this until I get a replacement?

Final rant.. Whats up with these German plastic pieces? I used to own an Audi and it seems like plastic materials are the weakeness in German carts. They all eventually deteriorate and crack.. I dont recall Japanese cars have any weakness in their plastic parts..even on older models.

Anyway, once I get this new part I will clear the codes and drive around. I will report back on the results.

edjack · Sep 26, 2011

There is a BFD in Yurrip to design a car to be recycled. Perhaps the Krauts have selected a plastic that is easily recycled, and therefore, perhaps not terribly stable.

Just sayin'.

teklord69 · Sep 26, 2011

I just realized how lucky I was that I was able to take the DISA out before the metal pin fell into the cylinders..As far the the plastic piece that was chipped from the flap, it probably had burnt out long time ago and I am not too concerned about that. Like clockwork, this failed me at 100K miles. I now have 105K.

bluebee · Sep 26, 2011

I forget who said that, other than the cooling system, checking the DISA is the next most important thing to preserve the health of our engines!

- Why check the DISA at 85K miles to 90K miles or whenever the airbox is removed (1) (2) & how to repair a rattling DISA unit (1) (2) (3) & why the DIfferenzierte SAuganlage ("Differential Air Intake") valve flap breaks (1), sometimes with parts sucked into the intake manifold (1) (2) (3) (4) (5) (6) (7) (8) & how the disa valve o-ring fails (1) (2) & how it can cause all sorts of cold-engine rough idle problems (1) (2) & where to get just the DISA valve o-ring (1) & how the DISA valve operates (0) (1) (2) (3) (4) & an example of how a broken DISA valve can ruin your engine (1) & how to test DISA operation (1) (2) (3) (4).

Note: Your pictures are included below, at 640x48 pixels, so they stay with this thread for reference purposes.

uncmozo · Sep 26, 2011

DISA valve is a BMW only part, when I replced mine I got it from a local dealer about $200. BTW, the design hasn't changed, same crappy pin, same plastic flap.

agent15 · Sep 26, 2011

It carries a new part number, so perhaps something has changed (possibly internally)...?

cn90 · Sep 26, 2011

My 98 528i does not have the DISA Valve.

$1M question: what happens if you remove the "internals" and re-install just the shell?

Fudman · Sep 26, 2011

cn90 said:
$1M question: what happens if you remove the "internals" and re-install just the shell?

In theory, there should be some impact on overall engine performance, such as reduced power/torque during wide open throttle. The DISA valve changes the length of the intake manifold so that the velocity of the incoming air changes, which in turn changes the way the air fuel mixes and can also increase the inlet pressure (like mild supercharging). I don't know if the normal operation is valve closed or open but the likely outcome of removing the DISA internals is you would lose one of the intake manifold options (longer or shorter, don't know which) resulting in sub-optimal engine performance under some operating conditions. This might trigger a CEL but then again, it might not. Does this qualify for the $1M? :rofl: How about $.50 and a bimmmerfest sticker?

edjack · Sep 26, 2011

I believe it has something to do with flattening the torque curve, so you may lose whatever low-end torque you have now.

agent15 · Sep 26, 2011

For the part call Chris at BMW of Schererville; tell him Chris from TN referred you.

I just did this myself: http://www.bimmerfest.com/forums/showthread.php?p=6333559

540indiana · Sep 26, 2011

That looks like an identical part in what they use for the blend door on explorers. They are garbage.

I googled the hell out of this. Im guessing the 2000 540's dont have a disa?

teklord69 · Sep 26, 2011

Bluebee, thanks for doing the thumbnails. I agree, aside from the cooling system, the DISA valve is the next crucial thing to check starting from 80K miles! Its amazing here how many people keep pushing the VANOS seal advice over and over, but checking your DISA should be more important.

Fudman · Sep 26, 2011

teklord69 said:
Its amazing here how many people keep pushing the VANOS seal advice over and over, but checking your DISA should be more important.

I think that is because the Vanos seals is a known inevitable failure due to material degradation that happens in EVERY e39 (symptoms appear worse for the double Vanos). The consequences of Vanos seal failure are more annoying than catostrophic. The failure of the DISA valve has not been well documented, as yet, so the likelihood of this event appears to be fairly rare. Nor has the consequences of a DISA valve failure been well documented previously (at least I haven't really noticed much talk about the DISA).

But I totally agree that this is something that should be monitored by every owner as it appears a failing DISA valve can cause catostrophic engine damage. You are doing all of us a service by highlighting this failure mode and the possible consequences of it. :thumbup: Thanx! :roundel:

teklord69 · Sep 26, 2011

Well i took out the flap and loose pars and put the DISA shell back in without plugging in the electrica connection. I need to use the car before my part arrives. The car should still run but will have crappy performane and idle.

bluebee · Sep 26, 2011

After all this, I think we should see if we can get a group buy from one of our sponsors for a percentage off the ridiculous price for the DISA if we agree to buy enough from the sponsor.

Any ideas how to organize that?

teklord69 said:
Well i took out the flap and loose pars and put the DISA shell back in without plugging in the electrical connection.

Please 'do' let us know how it works out as that's a great test, for the team!

Fudman said:
In theory, there should be some impact on overall engine performance

We did try to quantify what the DISA does over here:
- How the DISA valve operates (0)

below ~ 3750 RPM closed
above ~ 3750 RPM open
rest position, i.e. when removed - flap open

Personally, I never understood what the DISA actually does, that is of benefit to us.

The resonance system provides increased engine torque at low RPM, as well as additional power at high RPM. Both of these features are obtained by using a resonance flap (in the intake manifold) controlled by the ECM.

During the low to mid range rpm, the resonance flap is closed. This produces a long/single intake tube for velocity, which increases engine torque.

During mid range to high rpm, the resonance flap is open. This allows the intake air to pull through both resonance tubes, providing the air volume necessary for additional power at the upper RPM range.

When the flap is closed , this creates another "dynamic" effect. For example, as the intake air is flowing into cylinder #1, the intake valves will close. This creates a "roadblock" for the in rushing air. The air flow will stop and expand back (resonance wave back pulse) with the in rushing air to cylinder #5. The resonance "wave", along with the intake velocity, enhances cylinder filling.

The ECM controls a solenoid valve for resonance flap activation. At speeds below 3750 RPM, the solenoid valve is energized and vacuum supplied from an accumulator closes the resonance flap. This channels the intake air through one resonance tube, but increases the intake velocity.

When the engine speed is greater than 4100 RPM (which varies slightly - temperature influenced), the solenoid is de-energized. The resonance flap is sprung open, allowing flow through both resonance tubes, increasing volume.

teklord69 · Sep 26, 2011

Agreed, VANOS fails..your car will run fine but crappy. DISA fails, your car will run fine but crappy (plus SES codes). However, its when the DISA fails and left alone for a long time there is a chance that the internals will fall inside your combustion chamber.. There is a documented fact that bluebee linked where the whole flap fell inside the chamber. Even as bad, when the metal pin falls in the cylinders. I was lucky because the metal pin on my DISA was loose..nothing was holding it. I am however bothered by the fact that a piece of plastic from the flap is gone. It may have already burnt out inside the cylinders or it may still be trapped in the intake somewhere. I am tempted to take out the intake just to make sure all is clear.

I visited the E46fantatics.com board where this problem is a lot more documented and talked about than this board. Not sure if the E46 has a higher failure rate than the E39's..But nevertheless, the part is made of plastic and will 100% get brittle no matter what. So just like we all know about the plastic impeller water pumps, the DISA valve should also be a must replace item starting at 60 or 80K miles IMO.

nyclad · Sep 26, 2011

I had the same thing a few years back, but mine DID die a few times while at idling at stoplights. I think it'd die maybe a third of the time while idling.

Before I replaced the DISA, I had tix to an Angels game and had to take my 530i, so I waited until everybody left the parking lot before leaving. That way I wouldn't have to sit in stop and go (i.e. stop and stall...) traffic leaving the parking lot.:tsk:

hkrslot · Sep 26, 2011

Nice report, I had a simualar problem turned out to be a cam possition sencer and plugs. From 540indiana's post I'm not sure if my 540 has this DISA valve or not. I'll check for it!

teklord69 · Sep 26, 2011

Well I need this part today..so I called BMW of Long Beach which is a couple of miles from my work and luckily they had one Adjuster/DISA in stock. The price was $260..I wasnt aware you can negotiate their prices but I tried it and he lowered the price to $218. Which was great because thats about how much I see them online minus shipping charges. Plus I really wanted this today as I need to drive my car.

Shown is the part #

Also, I saw a video somewhere on how to test the vaccum on the valve. Move the flapper to the closed position, then block the vacuum hole with your finger. Release the flapper and it should not open all the way. It will stop in the middle position and wont open fully until you let go of your finger.

Also I noticed the orange gasket..This looks to be a one time deal. And I think that once its taken out, that gasket is no loger a tight seal. As somoeone pointed out here, using orange Permatex is probably a good sealant once you remove the DISA from your car and put it back in.

I will put this in the car when I get back from work and see if all is good..

bluebee · Sep 26, 2011

teklord69 said:
I saw a video somewhere on how to test the vacuum on the valve. Move the flapper to the closed position, then block the vacuum hole with your finger. Release the flapper and it should not open all the way. It will stop in the middle position and wont open fully until you let go of your finger.

Is this test in situ or in vitro?

teklord69 said:
I think that once its taken out, that gasket is no loger a tight seal.

The lack of an o-ring part number (apparently) affects only some E39s (the M54, for sure and I don't know what others).

There are those who have found alternative o-rings:
- Where to get just the M54 DISA valve o-ring (1)

doru said:
The 528 and 540 folks don't have to worry. They don't have that piece of super-engineering attached to the intake manifold.

Ah, so the only E39 affected is the M54 E39, right?

teklord69 said:
I wouldn't recommend rebuilding the DISA or doing a "band-aid" fix.

Nobody would disagree. The stakes are just too high. The engine is toast when the DISA fails. Yes, BMW is at fault; they make a garbage part; but your only choice is to replace old garbage with new garbage. That's why it makes no sense to pay two hundred dollars for BMW garbage - but it does make sense to replace BMW garbage.

I just wonder if we can set up a deal with a sponsor and agree to buy a certain number from them for an agreed-upon price.

doru said:
warned you ... that the goddamn plastic valve starts self destructing at around 90 k miles... the P0304 & P0305 seemed associated with the DISA when stuck.

I think we need a nice step-by-step DIY for replacing the DISA.

It's problematic without the right o-ring though, so, the steps would need to be (roughly):

a) Obtain the right o-ring
b) Remove the DISA
c) Test the DISA
d) Replace or re-insert as needed

teklord69 · Sep 26, 2011

Agreed. $260 for this pice of plastic garbage is too much. However, I wouldnt recommend rebuilding the DISA or doing a "band-aid" fix. The plastic will be or is already brittle due to the age. There is no getting around that fact. So replacing it is the only choice.

Bluebee, I got this part today so I never got the chance to run the car w/o the DISA.. But I can imagine since my flapper is broken it probably ran always open..Which led to engine running lean and misfires.

The DISA on my E36 is much more reliable (no plastic). The car has 230,000 miles and the DISA works perfectly. It works the same concept..above a certain RPM, the engine gets a little boost in power as the air coming into the engine gets re-routed via the valve.

Mack · Sep 26, 2011

Great thread all! Looks like I need to put this on the "to do" list. Though fortunately I've had no DISA troubles (that I know of) so far. FYI $199 currently at TMS. http://www.turnermotorsport.com/p-2...-x3-z3-z4.aspx?utm_source=goog_product&utm_medium=feed&utm_campaign=11617544806

teklord69 · Sep 26, 2011

Whats your mileage? Take it out and check..dont wait until it stars rattling. Taking it out is a 5 minute task.

agent15 · Sep 26, 2011

$195 at BMW of Schererville (maybe less if you tell Chris I referred you...?).

doru · Sep 26, 2011

He,he, he...warned you gals and guys that the goddamn plastic valve starts self destructing at around 90 k miles...
I had no codes, but I searched many threads and forums, and the P0304 & P0305 seemed associated with the DISA when stuck. I had a faint whirring when I pulled it out, the pin was halfway out....and the flapper had a bit of a "free" movement. It's 200 bux vs rebuilding the engine (sooner or later, depending on your luck).
The 528 and 540 folks don't have to worry. They don't have that piece of super-engineering attached to the intake manifold.

MKJS · Mar 26, 2015

doru said:
The 528 and 540 folks don't have to worry. They don't have that piece of super-engineering attached to the intake manifold.

True, but we have 4 fun cams to time when we have to replace the osv and the chain guides!

doc

poolman · Sep 27, 2011

Guess it was about 4 years ago mine was going south--Rajaie was over at the house and pointed the problem out to me. With the engine at idle you could lean over and place your left ear on the part and could hear it rattle. When you gave it a little gas the part would sound like all he%%ll was breaking loose inside. I removed the part and gutted the flapper and the housing around the flapper and then put it back on the engine. I drove it that way for about a week until the new one arrived. I could tell there was a little less tq on bottom end but it didn't make me feel unsafe and the car performed well out on the highway--no bucking or stumbling and decided that it doesn't or didn't hurt the engine as long as I didn't feel like going wide open--don't do that much anymore as I get closer to 60---dang I'm starting to feel old

agent15 · Sep 27, 2011

I will ask my favorite source for Genuine BMW parts if there is any possibility of them doing a quantity discount.

seemyad · Sep 27, 2011

Great. Please let us know the outcome.

It amazes me to see such a simple $25 gadget cost over $200. I have bought alternators for less than this thing. Oh well. I knew it going into the purchase and still like the car a lot.

adjmcloon · Sep 27, 2011

The M52tu has a DISA valve. My car is a '99 528iT

teklord69 · Sep 27, 2011

New DISA valve installed.

Ok, I installed the new DISA valve and cleared my codes, and I am a happy camper. Right away, the idle was alot smoother and not as high. Throttle response is much better as well as the low end torque. Gone is the sluggishness of the car. Took it to the freeway ramp on manual mode and shifted near redline.. I can feel the "kick" of the DISA opening up around 4500-5000 RPM. And for some reason my shifting is alot smoother. So far no codes have come back.

The install took me less then 10 minutes. You just need two tools (flat head screwdriver and T40 torx head):

Unplug MAF connector:

The bottom screw that holds the DISA needs to be removed. No need to remove airbox (I hate removing that thing), just remove the MAF and the hose attached to it. Once you do that it is easy to remove the bottom T40 torx screw. Don't drop it! otherwise this 10 minute job becomes 30 minutes.

Remove the DISA electrical connector. There is a metal pin behind the connector that you need to push in before pulling out the wire.

Now remove the top T40 Torx screw:

Remove the old DISA valve GENTLY! If your pieces are loose, it may drop into the intake..be careful.

Pic of old DISA and new one. Looks the same but the part #s are different.

Before installing the new DISA, clean the opening really well so that the seal will be nice and tight.

Install the new DISA slowly..Be careful not to get the new o-ring dirty or scraped.

That's it. reconnect the DISA electrical connector. Tighten the two T40 torx screws. Replace the MAF and related hoses. Clear your codes and test drive the car.

540indiana · Sep 27, 2011

teklord69 said:
Ok, I installed the new DISA valve and cleared my codes, and I am a happy camper. Right away, the idle was alot smoother and not as high. Throttle response is much better as well as the low end torque. Gone is the sluggishness of the car. Took it to the freeway ramp on manual mode and shifted near redline.. I can feel the "kick" of the DISA opening up around 4500-5000 RPM. And for some reason my shifting is alot smoother. So far no codes have come back.

The install took me less then 10 minutes. You just need two tools (flat head screwdriver and T40 torx head):

Unplug MAF connector:

The bottom screw that holds the DISA needs to be removed. No need to remove airbox (I hate removing that thing), just remove the MAF and the hose attached to it. Once you do that it is easy to remove the bottom T40 torx screw. Don't drop it! otherwise this 10 minute job becomes 30 minutes.

Remove the DISA electrical connector. There is a metal pin behind the connector that you need to push in before pulling out the wire.

Now remove the top T40 Torx screw:

Remove the old DISA valve GENTLY! If your pieces are loose, it may drop into the intake..be careful.

Pic of old DISA and new one. Looks the same but the part #s are different.

Before installing the new DISA, clean the opening really well so that the seal will be nice and tight.

Install the new DISA slowly..Be careful not to get the new o-ring dirty or scraped.

That's it. reconnect the DISA electrical connector. Tighten the two T40 torx screws. Replace the MAF and related hoses. Clear your codes and test drive the car.

You forgot to unhook the battery????

Mack · Sep 27, 2011

Great DIY bro. Nice work!! I wonder if the DISA is more prone to going bad in colder climates?

doru · Sep 27, 2011

Mack, that piece of plastic superengineering, is the same plastic as the colling bits and pieces. Has nothing to do with cold or warm climate, but the hot/cold cycle of the engine. And it's very close to the engine.

Speaking of plastic embrittlement: The air ducts (part #7 in the diagram) will start also going South. Especially the clips that attche to the cowl.
The first one to go was the right (passenger side) one - last year. This weekend, the left one hit the dust (driver side). If not changed, you will fog up the windshield driving through the wash stations (especially when it's colder outside - in winter). But, you will also draw dirty unfiltered air. And they are not cheap. Ordered the 2nd one, and it's on it's way...

Mack · Sep 27, 2011

Yeah mine are in rough shape too. Discolored and hardened. Damn another item for the "to-do" list. Only reason I asked about colder climates for the DISA is that I'm at 167k miles now and to my knowledge it's never been replaced. In reading this and the other threads though I'm fairly confident it's worth replacing at this point. I'll probably order from TMS this week. How much were the intake cowls??

doru · Sep 27, 2011

The first one I had to snag from the stealer here and it was 158 (ouch!!!), but I had no choice, the fogging was getting styupid, and was already a safety issue for me (winter, cold outside, cold windshield - you get the picture).
This one I ordered online and was around 75 bux. I will get it this week.

Bingo!! I may have solved the misfire and lean codes P0171, P0174, P0300

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