John Crisalli

I'm planning to use the bicycle brake cable method to clean out the SAI ports by the exhaust valve. About how long a cable do I need? How far up the port will the cable go before reaching an obstruction. Has anyone tried to take out the check valve on the top of the motor and run the cable thru that way?

All help much appreciated

JC 98 C2S widebody

tsloeza

I've done this method quite a bit, bicycle cable is to thin and flexible, you want to use motorcycle throttle cable it just think enough and flexible enough to work its way through the passages. I will use some where between 18-24" of cable but have some extra because it can twist up on you. As you get closer to the flywheel side less and less cable will go in. I have never gone in on the check valve side, it can all be done from the bottom. My method I remove the pipe that goes into bank 2 cylinder head(need crows foot wrench) and use air hose with a threaded fitting that I install into the cylinder head and then can hook up the hose to air compressor line and be able to blow shop air pressure through the passages one bank at time. This allows me to first check and see how clogged the passages are, then run the cable through and blow out any debris and see how much air flow you have after. For bank 1, I will attach my air line to the check valve block(where pipe for bank 1 threads into)and put the check valve back in place so I can now blow air through bank 1 and do the same process. If I need to I can add cleaner in to the hose I attach the head and then use air pressure to blow it threw the passages to clean them out.
Remember this is just a temporary fix, may last a few years depending on how bad you guides are.

pp000830

Before you go to all this trouble be aware that the Motronic controller identifies clogged air injector passages indirectly via information from the oxygen sensors.
If one or more of your sensors is out of specification it may be contributing to an erroneous diagnostic code,
Due to the difficulty in cleaning the ports, I would first replace both oxygen sensors on the side of the engine listed by the fault code, bank 1 or bank 2 and replace the air pump check valve and see if the code comes back. Also if you used Durametric to diagnose the system make sure you are using the latest software version. I go to the extra step and validate what Durametric is reporting with a 2nd handheld reader as Durametric has proven to produce erroneous codes in combination with non-existent codes at times due to communication errors with the ECU.
Andy

pp000830

Or is a temporary fix if you are overfilling your oil and continue to do so. Oil should be filled to the lower 1/3 of the range on the dipstick and not above for a fully hot running engine. Any overfill is sucked into the intake where it passes through the engine and can cause deposits much like oil sourced from leaking valve guides.
Andy

Todynot

OP -How many miles on the engine?

pp000830

Interesting question, for an added data point I got the clogged OBD Code for bank 1 at about 95,000 miles and replaced the oxygen sensors, the check valve and updated Durametric to the latest software and the code never returned, go figure?

PRSWILL

I did this 2 years ago and the ports were completely clean- no carbon anywhere in the system or on the valves- but the check valve was really dirty. We replaced it and did the whole flush thing to be certain and all ports ran clean- so you may not have a clogged port- might just be the valve. Just sayin'. My car had 110K on it when we did this.

John Crisalli

The car has 61K miles and is driven regularly. I can test to see if the ports are open by observing the O2 sensors with my OBD software. When I trigger the pump, the O2 sensors react as they should so i know that some or all of the ports are open. I replaced the check valve when I first got the car 12 years ago and it only has about 20K miles on it. The problem has continued all of those years and I'm careful not to overfill when changing/adding oil. I'm guessing that any clogging would be close to the port in the head since that's where the excess oil from overfilling or valve guide that is burned would begin to collect. I want to check the ports because I continue to set SAI CEL's. If I let the engine idle for 2 minutes after start up to the end of the SAI cycle, it will not set a code. If I start up and drive away immediately, a SAI CEL will be set for one or both sides 90% of the time. I want to clean out the ports to eliminate any possiblities. I changed all 4 O2 sensors awhile back and the problem diminished, but didn't disappear. Now it's back with greater frequency.

Talking with another Pcar owner and he suggested an old speedometer cable? It's a little thicker and should be flexible. Yea or nay on this idea? Just wondering.

Thanks for the info to all that replied.

JC
98 C2S widebody

PRSWILL

I had a Bass Guitar string- LOL! Didn't end up using it tho. Also, there's a little vacuum tube by the SAI valve- I knocked mine loose when I did the change-out and it was throwing the code after the blow-out. I replaced it and no more codes- check to see if it's come loose.... may be the only issue.

pp000830

Check valves get old and rusty internally and fail to function properly or cause a restriction even with low miles and even if the outside of the valve looks bright and shiny.
Replace the valve, or continue to look for love in the wrong place, you will find her and she will be an expensive and unsatisfying date, Hey, it's your money time and effort!
Andy

nine9six

JC,
Your description sounds a lot like lazy/aged O2 sensors, but since you changed them recently, did you replace the SAI check valve?

John Crisalli

I changed it when I first bought the car 12yrs ago and it has about 17K miles on it. I will remove it and check to see if it needs cleaning/replacing.

Thanks for your input

JC 98 C2S widebody