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1999 SLK230 Sport
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Discussion Starter #1
Hello. I've been lurking here for a few weeks, and am hoping you can help me ID the faults indicated by the following codes:

1420
1525
1235
1236

The car is a 1999 SLK230 with about 81k miles on it. I am currently experiencing some misfire problems at higher rpms. Until I reset the codes, the supercharger clutch was not engaging. Now it is.

I plan to check the MAF sensor and the check-valve on the S/C plumbing this weekend. Thanks in advance for your help.

Geoff
 

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2000 SLK230, Subaru BRZ
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363 Posts
I doubt it is the MAF Sensor, I replaced that already and had no change, also replaced check-valve...
 

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1999 SLK230 Sport
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Discussion Starter #4
Hi aceangel. I just went out to the car and played with it a bit. Specifically, I removed the bypass air hose (short one that goes from the airbox to downstream of the s/c) and revved the engine to see if the valve closed when the s/c engaged.

What I found was that the valve was not closing. If this is true under normal driving conditions, I beleive this could be causing the malfunction described above. The s/c would be pumping air back into the airbox/atmosphere, disrupting the air/fuel delivery to the engine.

Does anyone else have any info on this valve and failure rates? Is my theory sound, or am I missing something?

Geoff
 

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2000 SLK230, Subaru BRZ
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Good job, that may be the problem. However it doesn't seem to be in our codes. We should have an air-flap actuator code P0803 or P0243.
 

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1999 SLK230 Sport
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Discussion Starter #6
aceangel - 10/5/2005 6:10 PM

Good job, that may be the problem. However it doesn't seem to be in our codes. We should have an air-flap actuator code P0803 or P0243.
I believe the 1420 code refers to this valve. P0803 & P0243 are emmissions-related, right?

Geoff
 

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1999 SLK230 Sport
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Discussion Starter #8
aceangel,

I see what you mean. Here is an image of the valve that I am referring to, along with some documentation on how it is supposed to work:
 

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2000 SLK230, Subaru BRZ
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Yeah. That might be the problem. Maybe OBDII can only store 4 codes at a time?
 

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1999 SLK230 Sport
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Discussion Starter #10
Sometimes codes are funny. If I have some time tomorrow, I'll pull out the multimeter and see if the air flap actuator is getting any current under load. It would also be nice if someone with a proper-functioning car could pull off the rubber tube at the valve and do the same test I did above. If the valve closes at all when the s/c clutch engages, I think we have our culprit.

Any volunteers? [8D]

Geoff
 

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2000 SLK230, Subaru BRZ
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Yes. Any help with this will be greatly appreciated! (Saves 2,000 from the dealer!)
 

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1999 SLK230 Sport
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Discussion Starter #12
Just a quick update...

Called my local MB dealer and ordered the valve referenced in my above post. (p/n 111-098-00-09, ~$300) They should have it in stock tomorrow. When I get it, they are going to let me plug it in and check the operation. If it works, then I believe we are in business. If it doesn't do anything differently, they will allow me to return it. Nice guys, eh?

While I feel I am closing in on this, it would still be a big help if someone who has observed the valve operating properly could chime it. [:)]

I'll let you know what I find out tomorrow.

Geoff
 

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Hi Geoff, I just tested mine, the air flap actuator also doesn't work! I revved the engine until the clutch engaged, and it didn't even make a click or a move rather.
 

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Discussion Starter #14
Got codes, now need expert insight

I also tried to get in touch with a guy at my office who has a 98 SLK to see if he would let me poke around under his hood for a few minutes to make sure that the valve closes when revving in neutral.
My concern is that it might remain open due to the light load when revving while parked, but close when the MAF detects an appropriate amount of load on the engine.

Anyway, I left a voicemail for this guy, and hopefully he will let me take a look at it tomorrow. I am surprised though that no one on this board has chimed in on this, given the number of posters who have tinkered with aftermarket intake setups. Surely someone has witnessed this valve in action? [not flaming, just puzzled]

Geoff
 

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I don't know if it will help much but I posted a thread in the C230 Kompressor forums to see if they have had the same experiences or would like to help troubleshoot.

http://www.benzworld.org/forums/forums/thread-view.asp?tid=1229090&posts=1&fid=15

Since the 4 cyl kompressor engine is pretty much the same...
 

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RE: Got codes, now need expert insight

wgharper - 10/8/2005 10:20 AM

I also tried to get in touch with a guy at my office who has a 98 SLK to see if he would let me poke around under his hood for a few minutes to make sure that the valve closes when revving in neutral.
My concern is that it might remain open due to the light load when revving while parked, but close when the MAF detects an appropriate amount of load on the engine.

Anyway, I left a voicemail for this guy, and hopefully he will let me take a look at it tomorrow. I am surprised though that no one on this board has chimed in on this, given the number of posters who have tinkered with aftermarket intake setups. Surely someone has witnessed this valve in action? [not flaming, just puzzled]

Geoff
IO will try and have a look but havnt gor car for the next 2 days..
Your diagnosis sound good though, a freind had same part go.

bazzle
 

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Discussion Starter #17
RE: Got codes, now need expert insight

aceangel,

Good thinking. I'll monitor that post as well.

Bazzle,

Thanks for your help. With any luck, we will have this thing licked by the time you get your car back. If not, any input would be much appreciated.

Geoff
 

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Discussion Starter #18
Well, bad news and really good news

First the bad news:

I went and purchased the valve mentioned above, and tested it without "installing it". When I revved the engine, it did in fact move, though it didn't completely close. Just to be sure, I plugged it back in on the old one and tested one more time, and this time it did move! So, leaving the old one in, I hooked everything back up, cleared the codes, and tested the performance. The car was still showing the same symptoms listed above. Bummer, but the new part was not what I needed.

Now, the good news:

While at the dealer, I picked up some additional parts to do maintenance: oil filter, air filter, and bypass valve (small one behind the airbox, screws in). I had read in other posts that this should be replaced every 50k miles or so. Well, I pulled out the old valve, and it had disintigraged internally, allowing free airflow in both directions! I put in the new valve, reattached the hoses, cleared the codes, and all is right again!

Here is a link to a good post with pics:

http://www.benzworld.org/forums/forums/thread-view.asp?tid=1209880&posts=5

Angel, I hope this helps for you too. The part wasn't any more than $40-50, and I have my car back again. Please let me know if you need any additional info or need me to check anything else.

Geoff
 

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RE: Well, bad news and really good news

I'm glad you fixed it Geoff!
I also have good news and bad news...


First the bad news:
I replaced the check valve a while ago so that couldn't have been a problem. So that meant something else was wrong, meant something else, something electrical.

Now the good news:
I found a post with similar codes saying stuff to check the K40 relay. Lo and behold, there was a very badly burnt solder joint! I just resoldered that burnt contact in the K40 circuit board, and tested it out. I revved the engine (on neutral) and now it doesn't seem to limit me at 4000 RPM anymore! Best of all, it sounds like all the power is back and no check engine light!

Take that mercedes dealer![:D]

So everything is up and running. Thanks for the help!
 

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I have the exact same 4 codes as you aceangel.
1420
1235
1525
1236

I'll start by checking the relay and fuses. In regards to the bypass valve, I'm a little confused as to which one to check. As for the actuator flap, is it supposed to move while revving in neutral?

Thanks,
Zo
 
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