Dr. No

Does anyone know (or think) that emissions test results are a good proxy for how clear the SAI ports are? Is a clogged car a "dirty" car from an emissions standpoint? Or is is just a function of generating a bad OBD II fault code?

I've searched and haven't seen anything much more descriptive than "I failed my smog test - #@$&$ SAI" and was wondering whether increased emissisons could be the "canary in the coal mine" for impending SAI trouble.

(Just curious, BTW, as my car passed smog pretty easily (whew!) and the PPI indicated the ports had been cleaned)

ecobb993

There have been a number of very extensive threads on this malady. But in a nutshell, the SAI system only operates for the first minute or so after cold startup. Since you're fully warmed up when you go for the emissions test, the SAI system has already run it's course. The only impact of a non functioning SAI system would be a CE light which, in most states would flunk your test.

Edward

JC's got it right: once car is warmed up (which if one is smogging, one wants the car hot hot hot), the air pump goes off. If the SAIs are "getting" mucky, you won't know until the CEL trips. AFAIK, there is no way to tell w/o actually looking inside.

Edward

coltj

Speaking of looking 'inside':
I saw the SAI ports on my '96 C4 when the engine was apart earlier this year. They were about 8-10 mm in diameter. Can anyone describe the "plumbing" from the air pump to the SAI ports? I'm wondering if one could use a small diameter videoscope(I have access to a 6mm industrial videoscope) to inspect the SAI ports without tearing down the engine(obviously engine off, and cool)?

humans get colonoscope at 50yrs, 993s get scoped at 50K??

Dr. No

Again I credit Rennlist with (possibly) saving myself a headache, as I've read a lot of the "Failed Smog Test" threads and had the car good and hot when I took it in and made sure they would do it right away. I just didn't recall anyone ever asking whether there was any correlation between the state of the SAI ports and other emissions results. The scope idea is kind of interesting . . .

trojanman

I passed my smog with flying colors (extremely low emissions readings) and CEL'd with SAI code 85 miles later... hope that doesn't burst your bubble.

ecobb993

trojanman,

Just shows how little the SAI system does to reduce emissions.

Dr. No

Me too and based on my PPI I don't think it will - but that is exactly the kind of thing I was wondering.

trojanman

Just spoke to the shop and he said he's pretty confident it's O2 sensors and not carbon... hope he's right.

SCMomentum

Trojanman,

What was the verdict?

Dave

trojanman

Hey SCMomentum... see thread below. No verdict yet but it's gotten very interesting.

https://rennlist.com/forums/993-forum/205453-cel-saga-continues.html

Rick Lee

Has anyone in VA had an inspection station plug anything into the OBDII port? For my last emissions inspection they only did the tailpipe sniff test. Coming up again next month.

Lorenfb

Check here ( www.systemsc.com/pictures.htm ) for pictures of the SAI ports
in a disassembled 993 engine.

duc916

Loren,
Do you know how the SAI system faults work. If one bank flows freely but the other bank is plugged will the CEL light come on?

Dan

Lorenfb

"Do you know how the SAI system faults work. If one bank flows freely but the other bank is plugged will the CEL light come on?"

I've never tested for this condition, but I assume that OBDII requires that if either
side fails, a CEL must result. OBDII wouldn't logically allow for a partially functional
emission system.

Side note: I ride a 996 & GSRX1000. 916/996 are both great.
Ducati wins AMA SBK @ Pikes Peak over Suzuki.