Fritz1

'can't get to (California) smog my CLK 55 because secondary air monitor is not resetting.
had put in a new intake manifold and replaced the 2 front cats to clear the MIL

Read all I could find on this forum about repeated cold starts and letting engine warm up, driving cycle, etc - to no avail.
Any other ideas out there ?

no MIL light or trouble codes but still wonder if there is anything wrong with the system that keeps it from resetting even without triggering an MIL?

air pump comes on upon start up for 40 or so secs but not sure what else to check

thoughts ? - thanks for your help

ricecooker713

The secondary air pump actually does a second check before the monitor is set. Give this a try.

1. Cold start - secondary air pump should come on, wait for it to turn off
2. Go for a short drive and get the car to operating temp.
3. Park the car and let it idle for 10-20 minutes - within this time frame you should hear the secondary air pump come on again for it's second check

Fritz1

thank you much ricecooker - I tried your suggestion this morning - took a 10-15 or so minute drive and then let idle and the pump did not come on again -'wonder if my drive was too long. Will repeat tomorrow morning with a shorter drive.

MarcusF

I just went through this and the problem could be a number of different parts. If the secondary air injection pump is turning on, the relay could be slow to react (going out), the changeover valve could be bad, one of the vacuum lines could be bad, one of the air valves could be bad, the oxygen sensors could be bad, or, in a worst case scenario, a secondary air injection port could be clogged. Having identified and replaced tow bad vacuum lines (dry rotted), disassembled and cleaned my air valves, installed new primary O2 sensors (mine were due), installed a new relay and fuse, and installed a new changeover valve, I was able to confirm the port was clogged. If you pull the air valves (do not drop a bolt under the intake or you'll have to pull the intake) and start the car, exhaust should come from both ports. If it comes from one port, or neither port, one or both ports are clogged. This can be confirmed again by pouring a couple of ounces of Sea Foam (or some other carb cleaner) down whichever port does not allowed exhaust to escape. If the cleaner fills the port, it's definitely clogged (2 ounces should tell you). If it fills, you can let it sit overnight and hope it breaks the carbon up. Mine didn't, so I vacuumed the Sea Foam out, used a rubber nozzle on the end on an air gun to seal the clogged port, and pressurized the port with about 110 psi from my compressor. That cleared the port. Then reinstall the air valves in you're set. If you take it to a dealer, they'll recommend pulling the head and drilling out the carbon. That works but it's a bit of overkill.

The one thing that surprises me is you're not getting a P0410 error code when you fail the secondary air injection retest while driving. If you have a ME 2.0 car that may explain the missing code.

If if you want to know how the system works, just post a note and I'll explain it. This is a common failure for both Mercedes and Porsche. The fix is the same for both Mercedes and Porsche as well. I hope that helps.

Fritz1

Great reply Marcus ! - this gives me things to check out this weekend. I had just replaced the intake and had the air valves off but did not check them (Instead broke its metal sleeve that slides into the intake on one of them that was fused solid. Since it's still held by a bolt as well I just used some RTV sealant when I moved it over to the new intake. I did replace all the vacuum hoses.

Yes, I'd be interested in your explanation on how the system works

thanks much !

MarcusF

This is how the system works. The system pumps air into the exhaust right after a cold start. This is to cause the catalytic converters to warm up faster.

Some time during a normal drive cycle, a system check is performed. The check works similarly to the cold start – except the ECU checks the O2 sensors. This is the check – the ECU (the main engine control unit) turns on the secondary air pump, which is cycled for a short period of time (30 to 120 seconds). The ECU also sends a signal to the changeover valve, which opens the air valves. When closed, the air valves keep the secondary air pump separate from exhaust pulses. With the pump running and the valves open, additional air is added to the exhaust through an air port in the head. During the test, the ECU uses the oxygen sensors to determine if the oxygen levels in the exhaust have changed. This test happens regularly, and it is undetectable when the system works. If the ECU does not detect the change, it will flag a secondary air injection error.

The EXACT same test is performed on a Porsche 911. The 993 series 911 is notorious for failing this test due to clogged ports. The fix on a 993 is the same as it was on my CLK. (1) Determine whether the port is clogged. (2) use carb cleaner to try and break up the carbon. (3) As a last resort, use air pressure to break up the carbon. 100+ PSI of air has worked in every instance I've heard of except 1. That was on a 911 and I don't know the details of why it didn't work. I will tell you, had it been me, I would have taken the pressure up to 150 PSI. My thoughts are - packed exhaust carbon is not stronger than an aluminum head.

BMW 6 cylinders also regularly fail the SAI (secondary air injection) test. So much so, that there's an aftermarket tool to break up the carbon for a BMW.

v8sonly

From my notes on my W210, which should be similar/same to yours:

Cold start, engine temp below 45* C
Run in Park with AC off, hold above 1400 RPM until engine temp is above 83*C
Drive for 5-10 min

I just had to do the same thing, the procedure to reset ALL the monitors needed for CA smog is pretty annoying, especially if you've recently disconnected the battery.
Do you have a code scanner that can check monitor readiness?

Fritz1

thank you very much Marcus and V8sonly - followed the cold start process twice in the last couple days - still shows not ready. Have a cheap OBD scanner that checks readiness for the various systems - 2ndary air is the last one/only one that does not seem to clear. No codes, no CEL.
Have read all about BMW and Porsche owner's issues with carbon deposits etc - thanks for the tip Marcus.
Will dive into relay, changeover valve etc as suggested tomorrow and report back

Fritz1

So I tested the relay, cleaned the contacts etc, relay checked out, then removed and cleaned one of the air valves and it looked pretty decent - not much carbon in there so I did not bother with the other. Fiddled around some more and then did v8sonly's cold start process again with my little cheap scanner plugged in and once I started the actual drive after the 1400 rpm warm up, the monitor switched to "ready" ! Yeahh ! - drove straight to the smog place and it passed.

Thanks much Marcus and V8sonly - Great help !!

v8sonly

Glad it worked!

My conclusion after reading the step by step process that I could find, is that the readiness monitors were programmed to cycle exactly to the commute of the engineer who programmed the ECU. It's a rather absurd, complicated and specific process.

dashii111

This worked for my w211 E55!