175 DISA error

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mrscalex
Joined: Fri 13 Mar, 2015 09:14
Posts: 910

  Z3 roadster 1.9

175 DISA error

Post by mrscalex »

I'm getting a 175 DISA error on a 1998 1.9.

I'm ready to put a new part on if needs be but as it's an expensive part (up to £250) I want to make sure I actually need to do it. There is no noise coming from the part and no loss of power.

I'm looking at changing it a) in case the error is a warning the part could break-up as per the horror stories and b) there is a high idle problem which I'm guessing might be related (I know there are plenty of other causes too).

So does anyone know if there could be another cause of the error that I should check first?

Also does anyone know where to get one of these for a decent price? The only ones I can find are on Ebay from the States for £250 ish. BM Mini Parts have non in stock.

The part number is 11611438404.
ImageImage
2001 Z3 2.2 Topaz Blue (Trudy) - Keeper rebuilt from a write-off
2002 Z3 2.2 Titan Silver (Cookies) - Keeper rebuilt having been bought with a seized engine
2002 Z3 3.0 Sapphire Black (Peanut) - Keeper awaiting rebuilding having been bought as an abandoned project
Plus Willy, Kodak & Maycee - All 2.2 Sport projects. Yes, 6 is a lot of Z3s :)
Always happy to try and help with spares :)
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colb
Joined: Sat 05 May, 2012 22:46
Posts: 690

  Z3 roadster 1.8 TU
Location: Newport South Wales UK

Re: 175 DISA error

Post by colb »

I changed my Disa valve unit out for a oem replacement when I had running problems, mine started making a clacking noise so deduced it was on the way out. Costly replacement but only viable way to go using oem part. Also replaced the Maf sensor for oem part, don't waste money on cheap pattern parts I did at first and wasted money.

I had all sorts of running problems at the time and worked my way through all the sensors, lambda sensors in the exhaust were finally replaced using Bosh sensors, again costly but solved all my problems in the end.

Colb
Colb
1999 BMW 1.8 Z3
2003 BMW 2.5 Z4
1998 Honda Deauville NT650V
Del
Joined: Sat 19 Nov, 2011 18:35
Posts: 2136

  Z3 roadster 1.9

Re: 175 DISA error

Post by Del »

Some technical notes I've collected from various sources over the years:-

DISA valve

"The DISA valve has an outer seal (inside the manifold) and a diaphragm inside the valve itself. The valve is constantly fed 12 volts during normal throttle operation and then open circuits on higher RPM and throttle opening. This de-energises the coil which stops the manifold vacuum from reaching the diaphragm. The butterfly then springs open."

DIfferenzierte SAuganlage ("Differential Air Intake") valve

Rough Idle and codes P0171 and P0174 and misfire codes

Optimizes the engine’s running under partial and full load as it adjusts the intake manifold runner length to improve engine performance. The DISA valve is located in the inlet plenum chamber and controls the variable length intake manifold giving better torque at low revs by closing, keeping the intake runner long. After higher engine speeds, it opens up and makes the intake runners shorter for more horsepower. When it fails it can lead to a rough idle, reduced performance and at times a rattling noise or Check Engine light. Suspect the DISA when the engine has over 60-80K miles, shows signs of rough running, or reduced performance.
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BladeRunner919
Joined: Fri 17 Feb, 2012 20:18
Posts: 2225

  Z3 roadster 1.9

Re: 175 DISA error

Post by BladeRunner919 »

If you have INPA, you can actually activate the DISA valve through that to see if it is working. If not, you may be able to work out from the wiring diagrams how to activate it with a voltage across the pins. Have you taken it out and had a look at it - it's very easy?
mrscalex
Joined: Fri 13 Mar, 2015 09:14
Posts: 910

  Z3 roadster 1.9

Re: 175 DISA error

Post by mrscalex »

I have INPA which is where I got the code from. But I'm new to it. Where do I look to activate the valve? And what am I looking for it to do?

The actual description for code 175 is DISA Control Circuit Electrical. So that sounds like a failure in the electronics to me rather than a mechanical failure.

I called a couple of BMW dealers today and they both wanted £234 for this part. So I'm even more motivated to see if this error could be caused by something that might result in a less expensive fix than a replacement unit.

The car is idling at 1400 rpm. So there is possibly a vacuum leak. Could that cause a false DISA error?

Also, any ideas if I could fit the electronics from a mechanically dead valve to mine? Or is the whole thing a sealed unit?
ImageImage
2001 Z3 2.2 Topaz Blue (Trudy) - Keeper rebuilt from a write-off
2002 Z3 2.2 Titan Silver (Cookies) - Keeper rebuilt having been bought with a seized engine
2002 Z3 3.0 Sapphire Black (Peanut) - Keeper awaiting rebuilding having been bought as an abandoned project
Plus Willy, Kodak & Maycee - All 2.2 Sport projects. Yes, 6 is a lot of Z3s :)
Always happy to try and help with spares :)
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colb
Joined: Sat 05 May, 2012 22:46
Posts: 690

  Z3 roadster 1.8 TU
Location: Newport South Wales UK

Re: 175 DISA error

Post by colb »

Have you considered getting a used part to put in to see if it cures your troubles?
Got to be a cheaper option before lashing out on an new one.
As has been said earlier you can test its operation by putting 12v to the contacts to see if it is working.
Colb
Colb
1999 BMW 1.8 Z3
2003 BMW 2.5 Z4
1998 Honda Deauville NT650V
Del
Joined: Sat 19 Nov, 2011 18:35
Posts: 2136

  Z3 roadster 1.9

Re: 175 DISA error

Post by Del »

mrscalex wrote:The car is idling at 1400 rpm
That's very high, a smallish vacuum leak can push up the idle but nowhere near that. A large vacuum leak would cause non-start problems and lean error codes. I wonder if something is stuck e.g. the throttle cable or the butterfly valve in the throttle body? :shrug MAF sensors can be a bit troublesome sometimes by not providing issues that enable them to be immediately pinpointed as the problem - what is the idle speed like with the MAF disconnected?

Most M44s idle somewhere between 750-900 rpm. Because many reported a slightly rough idle when new (which appears to be a normal characteristic of many M44s) BMW technicians had a standard practice of making a small adjustment to the ignition timing - my research has suggested that many were altered automatically under BMW service regimes - this increased the idle slightly to around 900 rpm. However, as said above your 1400 rpm is not in a normal range.
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BladeRunner919
Joined: Fri 17 Feb, 2012 20:18
Posts: 2225

  Z3 roadster 1.9

Re: 175 DISA error

Post by BladeRunner919 »

mrscalex wrote:I have INPA which is where I got the code from. But I'm new to it. Where do I look to activate the valve? And what am I looking for it to do?
I can't remember offhand - I think it's in a special tests menu or something similar. You can actually hear the disa flip open and closed if you do the test.
mrscalex
Joined: Fri 13 Mar, 2015 09:14
Posts: 910

  Z3 roadster 1.9

Re: 175 DISA error

Post by mrscalex »

Del wrote:That's very high, a smallish vacuum leak can push up the idle but nowhere near that. A large vacuum leak would cause non-start problems and lean error codes. I wonder if something is stuck e.g. the throttle cable or the butterfly valve in the throttle body?
Yes, the throttle cable was stuck solid when I started it up again after the lay-up. I had to give the throttle pedal a good kick. So it may well be that. As the car isn't insured/MOT'd I can't give it a blast to find out if it will free itself up until it's taken for the MOT. I guess I could try and back the throttle linkage off by hand if the cable has some give in it?

If I unplug the MAF do I do that with the engine running? Do I need to do it with the engine running or is that just to listen for more subtle changes?
ImageImage
2001 Z3 2.2 Topaz Blue (Trudy) - Keeper rebuilt from a write-off
2002 Z3 2.2 Titan Silver (Cookies) - Keeper rebuilt having been bought with a seized engine
2002 Z3 3.0 Sapphire Black (Peanut) - Keeper awaiting rebuilding having been bought as an abandoned project
Plus Willy, Kodak & Maycee - All 2.2 Sport projects. Yes, 6 is a lot of Z3s :)
Always happy to try and help with spares :)
Del
Joined: Sat 19 Nov, 2011 18:35
Posts: 2136

  Z3 roadster 1.9

Re: 175 DISA error

Post by Del »

Engine off, unplug MAF, start engine - the ECU will use factory default assumptions about air volume and temperature which will not be precisely accurate. If the idle speed is still too fast, you have at least eliminated the MAF sensor. As a result of unplugging the MAF, the ECU may have logged a historical error code which you can of course delete with your diagnostic tool.
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BladeRunner919
Joined: Fri 17 Feb, 2012 20:18
Posts: 2225

  Z3 roadster 1.9

Re: 175 DISA error

Post by BladeRunner919 »

Del wrote:Engine off, unplug MAF, start engine - the ECU will use factory default assumptions about air volume and temperature which will not be precisely accurate. If the idle speed is still too fast, you have at least eliminated the MAF sensor.
That's correct, but also potentially misleading.

By unplugging the MAF the engine, as you correctly state, runs on default settings and ignores any airflow information. As you state, if the idle speed is still too high that does eliminate the MAF, HOWEVER, if the fast running disappears with the MAF unplugged that doesn't mean it's a faulty MAF - it just means that it's an air-metering problem of some sort. It could just as well be an intake air leak between the MAF and the engine, allowing unmetered air into the engine.
mrscalex
Joined: Fri 13 Mar, 2015 09:14
Posts: 910

  Z3 roadster 1.9

Re: 175 DISA error

Post by mrscalex »

Well I had what I consider to be a very luck break with the high idle problem.

It took no time at all when I started looking to spot a small line that had perished right through. I'm surprised it was still in one piece, it pretty much fell off when I touched it.

I'd love to tell you what hose it was but all I know is it was right at the front of the engine and one end went into the injector bank.

I cut the end back and refixed it. Job done. 1400 to 900 at idle now.

The hose is a bit stretched now so I will replace it. I'm hoping I can just buy a length of this hose rather than the OEM part? I see it sold like that on Ebay but only from the States.

Any idea where I would get it from in the UK? Part number 11727545323 described as 3,5 X 1,8.

Thanks for the help with this one. I'm very much learning and wouldn't have known to have looked for a vacuum leak as the cause otherwise :oops:
ImageImage
2001 Z3 2.2 Topaz Blue (Trudy) - Keeper rebuilt from a write-off
2002 Z3 2.2 Titan Silver (Cookies) - Keeper rebuilt having been bought with a seized engine
2002 Z3 3.0 Sapphire Black (Peanut) - Keeper awaiting rebuilding having been bought as an abandoned project
Plus Willy, Kodak & Maycee - All 2.2 Sport projects. Yes, 6 is a lot of Z3s :)
Always happy to try and help with spares :)
Del
Joined: Sat 19 Nov, 2011 18:35
Posts: 2136

  Z3 roadster 1.9

Re: 175 DISA error

Post by Del »

If it's the small vacuum pipe ringed in the photo - I replaced mine with some generic (similar diameter) vacuum pipe from my local motor parts shop - around £0.50 and enough to make three :D

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mrscalex
Joined: Fri 13 Mar, 2015 09:14
Posts: 910

  Z3 roadster 1.9

Re: 175 DISA error

Post by mrscalex »

Del wrote:If it's the small vacuum pipe ringed in the photo
Yes, that's the one. Thanks.
ImageImage
2001 Z3 2.2 Topaz Blue (Trudy) - Keeper rebuilt from a write-off
2002 Z3 2.2 Titan Silver (Cookies) - Keeper rebuilt having been bought with a seized engine
2002 Z3 3.0 Sapphire Black (Peanut) - Keeper awaiting rebuilding having been bought as an abandoned project
Plus Willy, Kodak & Maycee - All 2.2 Sport projects. Yes, 6 is a lot of Z3s :)
Always happy to try and help with spares :)
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micklaw
Joined: Sun 13 May, 2012 19:07
Posts: 129

  Z3 roadster 1.8 TU

Re: 175 DISA error

Post by micklaw »

Hi I changed mine last year on an m43 engine had idle problems hunting a little on tickover and also "dont laugh" a noise like someone blowing a raspberry? ?? .
I replaced it with an oem part from bmw £200 but it sorted out the problem. Nows runs ok.
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