Have you pulled the disa to find out what is loose? A friend pulled his after it started to rattle and found the pin partially backed out. He's chasing high speed lean codes too but that didn't fix it. A smoke test will help find leaks. His showed a leak where the boots meet but that was after he replaced both of them. His cold start mis-fire went away after fixing that, the codes didn't reset on their own yet.

Actually he reset them but they haven't come back 'yet' but it's only been 3 days.

 

Please give this your attention:
https://forum.e46fanatics.com/showthread.php?t=897616

I suggest you remove the flapper & pin from the DISA unit, then reinstall. Expect a small dip in torque at low RPM. The rattle should be gone for the time being. The G.A.S. rebuild kit is the way to go imo.

If you can fit the DISA unit to the IM without resistance, the o-ring is shot.

 

No to the DISA and no to a vacuum leak. Small Vacuum leaks are only prevalent under idle conditions, when the throttle is closed and the vacuum created by the engine can find a less restrictive path (i.e. leak). Under throttle, of any kind, vacuum drops significantly to the point the ECU wont notice it. Lean under load could be any sensor (or wiring) involved in fuel/air metering, a poor spray pattern on an injector, an exhaust leak. Usually I would look to the air mass meter(MAF) first. If it isnt reporting correct values, the ECU wont know to account for engine load by adding fuel. In my experience (years and years professionally) cleaning an air mass meter is only ever a temp fix, if it works at all.

 

Bad disa makes car unfun to drive. Did not cause codes

fix it,or replace it and make sure to replace the intake boot underneath it while you can access it easier. the boot could easily be your problem.

( i just did this with my e46 a few days ago )

I got a rein one (CRP automotive) for a really good price.

 

Mine drove perfectly fine with a broken DISA flap and no check engine codes. I took it out one day and found that the pin backed out and the base of the flap was broken. I replaced it but did not notice any improvement in performance. It is a 325i SULEV though. When the DISA causes a lean code, it is usually the DISA gasket that fails. I have come across three E46s with lean codes that went away by putting some RTV on the old DISA gasket. Another way the DISA can cause a vacuum leak is when the diaphragm inside fails. You can test that by taking the DISA out, closing it, and putting your finger over the hole on the bottom of the DISA. The DISA flap will open about 25%, but it should stay at the position until you remove your finger. If the diaphragm has failed, the flap will slowly open up to 100%.

 

If it's rattling then you are right to investigate paying particular attention to the pin that holds the flap in place. If it's missing then you need to find it and retrieve it before it ends up in a cylinder where it can do a lot of damage. I would suggest you do that without haste. Lean codes? If the gasket is leaking sure. But otherwise probably not.

 

A friend of mine had a vacuum leak around the Disa gasket, a good point was made about this above. RTV or a new gasket is a good idea.

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The DISA was one of the culprits causing a couple lean codes on our car. For us, it was the last nail in the coffin on DTC's popping up. Pull the valve, and test it. If it's like ours, the pin had fallen out, but we caught it before the engine got it(thankfully). The flap valve was completely shot. I ordered a new unit from BMW. Our car took a bit of "righting". I did:
1)fuel pump, filter/regulator, o2 sensors, injector seals
2) CCV and all associated hoses, intake gaskets, air bar o-ring seals, all vacuum hoses
3) plugs, new bosch coils, motor mounts, napa 800 cca agm battery
Good luck with it.
Regards

 

Actually - my last set of lean codes where caused by my broken DISA valve.

 

I'm not stating that a leak around a DISA cant cause a lean code, any vacuum leak can and will cause a lean condition. However, if you guys read the OPs scenario, he states the code is triggered during highway speeds, aka under load. There is near zero possibility that a vacuum leak triggers a code under load, without also causing noticeable issues at idle. This isnt something I heard from a friend or a creepy uncle, I'm an experienced diagnostic specialist and electrical engineer with experience in control systems in European vehicles and heavy equipment.

Fact: a manifold leak, on a normally open circuit, will impact running condition greatest at idle, but will DECREASE its impact when throttle is applied. This is due to increased air mass entering the engine through the metered inlet. The difference in ratio between an intake leak vs a closed throttle, and an intake leak vs an open throttle is massive, and under open throttle that tiny bit of air entering the system that the ECU is unaware of isnt enough to significantly impact stoich or fuel trims.

Layman's terms: if I hold a 5 gallon bucket of rams piss over your head and poke a little hole in it, it'll leak and you'll know there's a hole because you're slowly getting rams piss dripped on your head. Now if I poke a hole 100x bigger than that one (i.e. open the throttle) how likely are you to still notice that little hole while you're gettin soaked in rams piss from head to toe, via the big ol fat hole I just made.

 

Thanks for all the advice. Does the rattling mean that the pin is going to fall out once I remove the DISA or is it possible the pin is still intact? My worry is that when I pull the DISA off, the pin will fall out immediately. I suspect the seal is worn and this could be wear my lean code is coming from.

 

You can pull it out super carefully and it shouldn't fall out

 

If the DISA is rattling, you're 50/50 on whether the pin will end up in your intake. If its your daily, or only source of transportation, I would recommend picking up some intake manifold gaskets in case you need to pull the manifold and go on the hunt. Whatever you do, don't fire that engine up until you physically have the pin in your hand.

If its not your daily, why not pull the manifold, clean it up and replace gaskets, spray test the injectors and replace the likely bad o-rings? Plenty of videos on DIY injector testers out there, and should give you some peace of mind they aren't causing your lean condition.

 

The DISA pin will only fall out of the rear if the DISA and if you are careful it should not fall out and if it does, you may be able to get it with a flexible magnet.

The pin missing will be obvious once the DISA is removed and if it is missing, you just need to find it.

 

Just my 2 cents on the topic because I've personally dealt with a pin and chunks of Disa flap going through the valve train, and I've also had a diaphragm go bad in a disa unit that caused a lean code. (Would go lean and misfire on disa activation, that was a fun one to make the correlation on and then diagnose)

If in doubt, change the DISA. If it even looks at you funny, change the DISA. Been there, done that. (Total was 4 intake, 3 exhaust valves got pretzeled)

 

Ouch. At how many miles did the original DISA unit lose function? Could you share a photo of those valves?

 

Car had 214K miles, and i'll bet it'd had never been touched. I have pics somewhere of the process...I'll see if I can upload some.
Just chased the ripped diaphragm in the disa last week. 02, 525. It would activate the disa at 4K rpm, and go lean...waaaaay lean. lol

 

Just chased the ripped diaphragm in the disa last week. 02, 525. It would activate the disa at 4K rpm, and go lean...waaaaay lean. lol

A ripped DISA diaphragm would not cause the engine to go waaaay Lean, not gonig to happen something else is up with that car.

 

What went through...

 

Well a quick question guys today i was checking the disa on my 02 325 it was fine it wasnt broken but when i close the flap and put my hand on the hole the flap open slowly and dont hold on 25% open ,after cleaning it with crc cleaner it started to stay open on 25%, and when i installed it on the car and went for test drive i felt more power on 4k rpm in every gear[emoji848]so should i replace the disa with new one or what?

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Praise Pete, please punctuate your posts!