Another Twist on the SAI Issue
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From: Ocean View Delaware
Another Twist on the SAI Issue
My 97 Cab is at the shop for a 90K maintenance, a LWF and clutch, a SSK and a few other minor items. I have been having a CEL due to SAI every 500 miles or so for the last couple of thousand miles so I ask them to change out the check valve and have a look-see at the SAI ports when they have the engine/trans out. Sure enough the old SAI check valve is rusted and such, but the SAI ports look clear as best as the mechanic could see, but here is where things get a little interesting. The "distribution body" that the SAI check valve mounts on has several tubes running to the manifold etc and has two steel caps that apparently cover machining holes from the production process. Well the bottom line is that these steel caps (the distribution body is aluminum I think) have small holes due to rust in them and APPEAR to be the cause of the CEL. Has anybody ever seen/heard of this??? My mechanic had never seen it before. Perhaps Steve W. could offer his take on this situation. No I don't have pictures because this happened while I was out of town and the mechanic did not have a camera.
Racer
Joined: May 2003
Posts: 364
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From: New Hampshire
Yup, see my posting from this past April - I put pictures of the rusted out plugs:
https://rennlist.com/forums/993-forum/346656-sai-housing-questions.html
Obviously any moisture in the air from the pump settles into the manifold (since the tubes exit upward), the manifold acts like a water trap, and rusts the plugs. I replaced the plugs.
https://rennlist.com/forums/993-forum/346656-sai-housing-questions.html
Obviously any moisture in the air from the pump settles into the manifold (since the tubes exit upward), the manifold acts like a water trap, and rusts the plugs. I replaced the plugs.
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From: Ocean View Delaware
Big-BRO - thanks for the info - I missed that thread in my search. I still wonder what happens to the system when those plugs develop holes due to rust. Is it a vacuum leak? Does it cause CEL? The mystery continues!
Race Car
Joined: Feb 2005
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From: Johns Creek, GA
Great post Ralph. That makes sense. When the pump runs, air never gets downstream due to the air leak.
The SAI passages could be perfectly clean, but since air never reaches its destination, the system assumes that the passages are clogged and thus the CEL.
Another thing to check before forking out $5K in repairs.
The SAI passages could be perfectly clean, but since air never reaches its destination, the system assumes that the passages are clogged and thus the CEL.
Another thing to check before forking out $5K in repairs.
Racer
Joined: Sep 2004
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Just a thought, but couldn't these plugs be duplicated in stainless steel or something to prevent the problem from happening again? I don't think there would be any issues with a SS plug threaded into an AL hole (I could be wrong). And given today's CNC use and availability, I am sure someone could commission a run on them and sell them....
Just a thought.
Just a thought.
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From: Ocean View Delaware
KKim - the error codes were the dreaded P0410 every time. I did ask my mechanic about the use of SS for the plugs and he said maybe, but the best thing is to change the SAI check valve every few years.
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