P0410. 1998. 170. SLK 230. - PeachParts Mercedes-Benz Forum

dkveuro · #1 10-19-2013, 12:35 PM

Good day folks. Have searched the archives for this P0410 with no definitive cure.

Question ?
What is the logic chain to operate the AIR relay to allow air flow to exhaust when cold?

I have performed the following...

Launch X413 Master Scanner in Mercedes: 'Actuations': 'Perform check'. 'Aborted'.

This function 'Aborted' on every actuation request. .

Replace all soggy vac' hoses. Check operation of AIR diverter valve: Okay and clear.
Vac' tested AIR control valve : Opens and closes and flows okay. Air pressure from compressor okay at control valve.

Air flows into exhaust if vac' applied to valve....then O2 drops to single mV numbers.

Check AIR flow to system. Okay. ( Can blow into AIR check valve to flow air to engine with little restriction...through metal pipe to engine block.)

Check operation three-way relay and vac' to it from intake: Okay, 17 inches at relay....Blue check valve working.

Check electrical operation of 3 way relay whilst engine on cold start : No vac' passes from relay to control valve, only boost pressure when opening throttle. Test light shows power to relay and most of the time to ground side but no vac' passes to control valve.

Watched O2 warmed up on throttle closed from brief WOT ....-3mV for 3 seconds.

Code P0410 is not setting after three cold starts. This is only code to set after customer drives a week or so.

Maybe head AIR passages restricted but not measuring any air flow control as control valve never gets a vac' signal.

I'm going to Startek soon, although folk tell me that's not a great help either.

Thanks in advance for any pointers you know.

regards

dk

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97 SL320 · #2 10-19-2013, 01:34 PM

" Check electrical operation of 3 way relay whilst engine on cold start : No vac' passes from relay to control valve, only boost pressure when opening throttle. Test light shows power to relay and most of the time to ground side but no vac' passes to control valve. "

What is the history of the car? Is the problem new, after recent repairs, hanging on for years or is this car new to the owner?

My somewhat similar 97 SL320 ( M 104 6 cyl ) runs the air pump for a few minutes at cold start and sometimes again when stopped after driving ~ 3 miles.

If I'm reading this right, the vac solenoid isn't letting vac to the air pump valve so no air is being pumped in to the exhaust.

If the front O2 sensor is lazy it might cause this code, do you have a spare to swap in?

As a test, I'd be real tempted to bypass the vac sol and allow operation when the air pump is running. ( be sure that constant operation won't allow exhaust to enter the air pump, if it does, jumper the vac sol to the air pump electrics. )

Also have a look at CrossfireForum.org as they might be of some help.

Make sure to post the results here for others.

dkveuro · #3 10-20-2013, 01:16 AM

Thank you for your post 97. Please bear with me here.........

The 2.3 ltr 111 engine has a 'a/c style clutch', Detroit Blower type compressor that boosts intake pressure as well as acting as an AIR pump. It only comes on a 2500 rpm if driving gently and is activated by the ECU. At idle and warm up only when ECT is under 60C......or so says the MB site.

At warm idle, it is activated every second or so for a brief moment and cycles like this all the while engine idles.

I checked swing of O2 by running engine at 2500 rpm steady until I got a normal cross count of 2 a second from 110mV to 800mV. Then going to WOT very briefly and letting off the throttle. MB says then the O2 should drop very quickly to under 100mV within 20 seconds. This test was passed okay.

I cannot find a vac' schematic for the 3-way change over valve on the front of the valve cover and can only assume it is connected correctly to the three vac' hoses.

Hoses on the 2 pin electric change-over relay are... from blue one-way check valve carrying intake vac' signal to the 3 o'clock position nipple. Boost hose goes to the 12 o'clock nipple and hose to the AIR flow check valve ( Japan made...DENSO (??) ) comes of of the 9 o'clock nipple. This check valve is open (flowing air ) when vac' is applied to it.

I have activated the relay by letting power go to nearest pin to valve cover (Brown/Red.) and grounding the (GREY.) pin. Applying vac' to the 12 o'clock nipple allows flow but vac' to the 3 o'clock nipple allows no flow activated or not. So in any case...the is no vac' signal getting to the check valve to allow AIR flow.

Attaching a pressure/Vacuum gauge with a tee tap at the 3 o'clock nipple shows only positive boost pressure when engine revved but never vac' suction at any time, cold through warm, at any throttle position or idle.

If the hoses are on correctly, this seems to point to a ECU problem or a bad change over valve relay. There is 12 volts to the relay KOER and KOEO.

History is: Mercedes installed an exhaust gas back flow check valve and hard line to block 2 years ago for same code. It is still working and not blocked or corroded.

This code came back 2 weeks ago.

The Grey wire to the relay lights a test lamp too, but not as bright as the Brown/Red pin when connector is correctly connected ....which is consistent with a component Ground....but I cannot confirm wiring anywhere.

Relay 'clicks' if grounding it, when 12vdc applied to other pin.

regards

dk

PS.....I noticed #3 cylinder is always 3% to 5% and ranging, unlike other three cylinders on engine smoothness check. You can feel the slight miss at idle but no P0300 codes. O2 does not seem to react to miss.(?)

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TimFreeh · #4 10-22-2013, 09:35 AM

I fought a highly intermittent P0410 in my C230 Kompressor a couple of years ago over a period of six months.

It ended up being a clogged EGR feed line, I think there was a thread on it... have you seen it?

I found it....

http://www.peachparts.com/shopforum/tech-help/193953-99-slk230-code-po410.html

Don't know if its your problem but it would appear that the car you are working on is prone to clog the EGR line since MB apparently replaced the line at least once. BTW no need to replace the hard line, its easily cleanable.

dkveuro · #5 10-22-2013, 09:55 AM

Thank you for the link. This is where I got the info' about reading the O2 voltage test, which is seems to pass okay.

I checked for vacuum at the three-way change-over relay on the front of the head. Vacuum to it is 17 inches, I found the valve never opened vacuum to the cut off vacuum valve , the valve just before the one way air valve....we call this a 'gulp' valve on LBC.

I feel the electro-vacuum change-over valve is the problem here, so I am ordering up a new one. After all, if the system is never opened with a vacuum signal to the flow valve, it's not going to admit AIR flow to the cat' during warm up.

BTW.........I applied vac' to the top port too but no vac came out of 9 o'clock port either....I activated the change-over valve by grounding it externally with a jump wire while inboard pin had 12 vdc on it.

regards

dk

dkveuro · #6 10-29-2013, 07:44 PM

UPDATE ; Bit long....

Installed a new 3 port Change-Over electronic valve. #A 000 540 98 97. During this test, ambient temperature was 73 F.
With engine start up cold, have a little fluttering of vac' signal to the AIR flow valve. Maybe 1/4 to 1/2 inch of vacuum.The Change Over valve is PWM by the ECU.

After engine warmed up, I ran a scanner check on the AIR 'on' and 'off' to see the results on the O2. With AIR 'off', O2 reads 180 mV to 790mV and ranging. With AIR 'on,' O2 drops to -4mV in around 15 seconds. On subsequent tests it drops rapidly to below 20mV in around 10 to 12 seconds. So this is a PASS for this test.

Monitoring the vac' to the AIR flow valve shows no readable vac' signal when AIR is scanner activated, although with extension vac' hose to my mouth, I feel a little fluttering pressure....this pressure/vac' is not enough to pull the flow valve diaphragm open to start AIR flow to the check valve ( Gulp Valve ).

If you apply 12 vdc to one pin on the change-over valve and rapidly touch the other pin to ground, vac' will slowly start jumping up to around 15 to 16 in and you can here the AIR/Kompressor pumping air into the exhaust and also watch the O2 drop to zero.

The Change-Over valve only passes vac' signal to the flow valve briefly when grounding the valve on and off quickly. To get vac' to 15 inches or better, on/off with jumper to ground and it builds up in 1/2 inch increments.......if you apply 12 vdc to inboard pin and ground the other pin, no va'c' will pass. Vac' only passes during the very brief period the ground pulls the Change Over valve 'on'. If it is 'off', no vac' passes and if it's held 'on,' no vac passes.......?

So, valve is only open during it's brief actuation period. Knowing this ...the ECU is pulsing this valve and should apply differing amounts of AIR flow...but watching for vac' signal during warm up, I didn't see any vac' signal going to the flow valve...

Code is not setting...so far, but I don't understand why I see no vac' signal to the flow valve during warm up. The scanner AIR Kompressor test shows the O2 dropping below 40mV so this test passes too.

Do I call this a fix or what ?

regards

dk

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97 SL320 · #7 10-29-2013, 10:14 PM

" The Change-Over valve only passes vac' signal to the flow valve briefly when grounding the valve on and off quickly. To get vac' to 15 inches or better, on/off with jumper to ground and it builds up in 1/2 inch increments.......if you apply 12 vdc to inboard pin and ground the other pin, no va'c' will pass. Vac' only passes during the very brief period the ground pulls the Change Over valve 'on'. If it is 'off', no vac' passes and if it's held 'on,' no vac passes.......? "

This does not sound right. The vac sol should apply vac to the control valve at some point and block it at the opposite not ratchet things up. There has to be a vac hose routing problem.

Have a look at club202.com someone there might have a routing diagram.

dkveuro · #8 10-29-2013, 11:11 PM

Thanks for the insight 97.

I think what Mercedes is trying to do is allow blower pressure to overcome any vacuum to the flow valve. It is also a PWM signal to the Change-Over valve that is designed to fail shut with or without power.

It is operated by the ECU pulsing the Change-Over valve so the vacuum signal can be adjusted to regulate the AIR flow into the exhaust ports and then down stream.

The faster the C/O valve is pulsed the stronger the vacuum signal is and the more the flow valve opens....just like some of those domestic EGR valves on Chebbies and such.

The only time this valve passes a vacuum signal is as it opens ...allowing just a small volume of vacuum to pass.....it appears the flow valve will never see a full intake manifold vacuum of 17 inches.

Maybe the O2 signal is referenced in the ECU, and as O2 signal drops the PWM signal also drops, reducing AIR flow. i am now wondering if there is a chain of reference to the CTS.

I have not found any explanation of the 'Logic Chain' for this system. I wonder if Beckmann technologies has any insight to offer.

regards

dk

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