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View Poll Results: About this thread:
This thread was helpful to my DISA diagnosis 1 33.33%
This thread is useless and the OP is a Lewzer 1 33.33%
I contributed to this thread by way of constructive feedback 0 0%
I replied with a stupid condescending comment 1 33.33%
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Old 03-24-2013, 06:45 PM   #1
Yewzer B Lewzer
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Join Date: Jan 2013
Location: St. Petersburg FL
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My Ride: 2003 325i
DISA Troubleshoot (Lean Codes PO171 and PO174)

So I had an issue with lean codes and it took me a week or so to diagnose. I combed through this forum for clues and the one I found the most helpful was jfoj's lean code thread that he has on his signature line (there may be other helpful ones, but I didn't stumble on them). I did however find that thread to be slightly overwhelming with regard to the amount of information on all things associated with lean codes. I wanted to start a new thread with just my DISA troubleshoot effort that is a little more concise. I think it may be helpful because I retrieved freeze frame data at the beginning, when it first threw the code, and a couple of times after leading up to the full DISA failure of the butterfly. The first freeze frame data captures were before the DISA butterfly failed totally, and it didn't make any noise. That said, I probably missed a few things that if pointed out to me I will go back and edit my OP and correct or expand on.

Condition of car before codes:
2003 325i, Automatic, 132k miles. I have had the car for 12k miles. Ran very good, idle speed drops a bit from 700 to 600 when put in drive, may be a dirty throttle body and/or ICV (next weekend's project). No codes pending or recorded. Unknown history regarding intake boots or DISA replacement.

The first SES was immediately after I had been cruising at 40 MPH in Drive, then selected Steptronic Manual Mode dropped down two gears and dumped the throttle. RPM's went from... somewhere around 1,500... to somewhere around 5,000 quickly as I passed a slower car. In hindsight, now that I understand the DISA system, it is obvious what happened: DISA went from Closed to Open quickly with a high differential pressure. This most likely partially broke the old fragile plastic DISA butterfly shaft, which a couple of days later fully broke. Also in hindsight, the DISA is very easy to remove and examine, so this should be done at the same time as checking the intake boots for tears. After the SES light came on the idle became slightly rough.


Original Freeze Frame - This was the same day as the code threw and the DISA had not yet started rattling. No clue yet why I have lean codes. Note that the long term fuel % trims for both banks are over 10% indicating a problem (thanks to jfoj's thread I recognized this as a problem).



Second Freeze Frame - I had cleared the codes and they came back within a few miles of driving. Still no DISA rattle. Long Term Fuel % Trim still over 10%. Inspected intake boots for tears and found them to be in very good condition.



Third Freeze Frame - Diagnosed problem as DISA after the butterfly completely failed (duh). I removed the butterfly valve and pin from DISA while new DISA was on order to keep them from getting sucked into the intake. This was the FF data that was stored from before I removed the butterfly. Idle with the DISA Butterfly removed was rough, low RPM torque was bad, and my fuel economy dropped from 25 combined to 21 combined.



I replaced the DISA and cleared the Trouble Codes. This is the initial PID from when I initially started the car. Note the Long Term Fuel % Trims are way off the charts trying to richen the system (held over from having no DISA butterfly) and the Short Term Fuel % Trim is now trying to correct the system the other way.



After 20 minutes of idling and a few revs with the new DISA, Long Term Fuel % Trim is now becoming more normal and codes don't return.




After driving for a week with the new DISA, Long Term Fuel % Trims near zero (this was probably the case an hour after I replaced the DISA, but I didn't read the data again until a week after)
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'03 325i. '74 Jeep CJ-5. '93 Sailfish 170XL. '12 Westside SS Longboard. One of these four are sure to be running at any given point in time.

Last edited by Yewzer B Lewzer; 03-24-2013 at 08:02 PM.
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Old 03-24-2013, 07:02 PM   #2
wildirish317
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Quote:
Originally Posted by Yewzer B Lewzer View Post
Also in hindsight, the DISA is very easy to remove and examine,
You should've highlighted this. The DISA is very easy to check and eliminate as a problem. It either works or is broken. Why spend weeks looking at computer data?
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Old 03-24-2013, 08:05 PM   #3
Yewzer B Lewzer
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Quote:
Originally Posted by wildirish317 View Post
You should've highlighted this. The DISA is very easy to check and eliminate as a problem.
Done, now you can change your vote to "contributor."

Quote:
Originally Posted by wildirish317 View Post
It either works or is broken.
Not exactly... I had a 2 day period where it was somewhere in between.

Quote:
Originally Posted by wildirish317 View Post
Why spend weeks looking at computer data?
I spent an hour over a one week period.
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Old 03-24-2013, 08:30 PM   #4
wildirish317
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Quote:
Originally Posted by Yewzer B Lewzer View Post
Done, now you can change your vote to "contributor."



Not exactly... I had a 2 day period where it was somewhere in between.



I spent an hour over a one week period.
Not sure I can change my vote, but if I can, I will. How can the DISA be somewhere in between broken and not broken? If it's loose on the shaft, it's broken. If it's in pieces in the manifold, it's broken (and you're fuqed).

My experience with the DISA (short version, long version is in a thread titled "Critique of the Dorman DISA") is that I removed it, found the butterfly loose on the actuator shaft, cleaned everything, reassembled the butterfly and shaft with plastic epoxy, and everythings fine. We'll see how long it lasts.

[edit] I can't change my vote once it's cast. Gotta love the American voting system.
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“The test of the machine is the satisfaction it gives you. There isn't any other test. If the machine produces tranquility it's right. If it disturbs you it's wrong until either the machine or your mind is changed.”

Last edited by wildirish317; 03-24-2013 at 08:32 PM.
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Old 03-24-2013, 08:45 PM   #5
Yewzer B Lewzer
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Quote:
Originally Posted by wildirish317 View Post
How can the DISA be somewhere in between broken and not broken? ... My experience with the DISA ... is that I removed it, found the butterfly loose on the actuator shaft, cleaned everything, reassembled the butterfly and shaft with plastic epoxy, and everythings fine.
[edit] I can't change my vote once it's cast. Gotta love the American voting system.
I agree that IF I had removed the DISA at the beginning I would have quickly found the issue. What I was looking at was lean codes and what I found mostly on this forum was information about intake boot problems. I am a fairly new e46 owner so it was not as obvious to me as it would be to someone with more experience. MANY people that post lean code questions on this site have little experience.

Quote:
Originally Posted by wildirish317 View Post
I can't change my vote once it's cast. Gotta love the American voting system.
No problem, I was joking about that anyway.
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Old 03-24-2013, 09:07 PM   #6
wildirish317
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When I was a noob (newcomer), I was intrigued by the DISA, thinking it was some complicated, magical device that has a huge affect on engine performance. I've since researched and disassembled the thing, and found that it's a simple two position valve which changes positions between about 3750 and 4100 rpm (depending on the rpm going up or down). I unplugged the thing (before doing the epoxy fix) and found no difference in performance. Keep in mind that my 4100+ rpm driving is probably much less than 5% of my driving time. That being said, I had another problem that was affecting performance (http://forum.e46fanatics.com/showthread.php?t=966614) that led me to the DISA. The DISA, while broken, was not the cause of my particular problem.

It's fixed now, and I don't have to worry about it. I just don't think it should be on the top of anyone's list of things to check when their engine isn't running right. On the other hand, it's so easy to check, why not check it? I'm waffling, I know. You tend to do that when you get old.
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Old 03-24-2013, 09:22 PM   #7
Yewzer B Lewzer
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I agree that it isn't rocket science, but it is something that I have never seen before until I bought a BMW. If stuck closed it may be almost undetectable unless you push the car hard. If stuck open (or broken off the shaft as in my case) it is very noticeable. Rough idle, bad low RPM performance, and poor fuel efficiency.

I will read the critique thread when I get a chance, thanks.
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Old 03-24-2013, 10:15 PM   #8
jfoj
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My info has a pretty clear section devoted just to the DISA.

DISA will likely not stick closed.

DISA O-ring leaks very common problem area for idle.

DISA valve loose, 2 bolts, 1 wire connector is all you need to inspect it.

Unfortunately I can no longer edit the thread, but I think it should be pretty obvious based upon my info you should pull the DISA, inspect is mechanically and replace the O-ring.

If you have not read all the links in my signature, suggest you check them all out! Thermostat is likely soft, fuel filter needs replacement and if you fuel pump is over 7 years old, you are on borrowed time!

Welcome to the E46.
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Solve your misfires, lean codes, rough idle - http://forum.e46fanatics.com/showthread.php?t=897616

Fuel pump failures - http://forum.e46fanatics.com/showthread.php?t=929501

Temp Info - http://forum.e46fanatics.com/showthread.php?t=964491

Hidden OBC Menu - Check Voltage, Temps, Fuel Level - http://forum.e46fanatics.com/showthread.php?t=239619

E46/E39 GM5 Door Lock Info - www.bmwgm5.com

Lower hose fan switch O-ring - BMW #13621743299
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