StatmanDesigns

A few moths ago somebody on the e-mail list for 911/993/996 on Rennlist seemed to suggest that they had used a simple electronic fix for the CEL SAI proplems ocurring with their 993. Some sort of diode in line with an oxygen sensor. I remember that he claimed it also worked on his BMW or some such.

Since the function of the SAI is for pollution management at start-up only and does not have an effect on performance, why is this not the route taken by all owners of cars with this problem. how hard is it to devise a simple fix that fools the sensor into thining the SAI is no blocked?

I am not exactly sure what the previous poster to the e-mail list did to his sensor, but I can check the archives (or somebody else can to).

Personally, I do not have the CEL SAI problem on my 1996 C2, but if I did, I would look for a simple solution like this long before I spent $1000's to fix a clogged port that doesn't effect performance.

Steve 96C4S

Uh, if someone has this diode and can put it in my car to permanently stop my stupid CEL from lighting up like a Christmas tree in December, I will be HAPPY to pay you for the service. As it stands now, and as most of you know, I guess I have cornered the market on a cheap fix, putting a piece of black gaffers tape cut to trapezoidal size directly over the gauge where this inane light lights up. I do own the Equus device that turns off the CEL but just 24 hours later it'll come back on, so I've given up on turning it off.

So, who can provide this diode in the Rockville MD area?
Let me be the first in line. Also, what happens when you have to go for the emissions inspection with this in place?

Steve

chris walrod

my luck would be that this diode is only available at the dealer and cost $5500..

Seriously now, I doubt a diode on the o2 sensor would do anything, other than limit current flow in one direction. Now if someone was able trick the circuitry that tells the ECU there is a blockage, that would be great news for a lot of people.

Howdy993

Try a search, if I recall correctly a fellow Member had devised a small circuit that sent a signal at start up to the engine management that all was well - thus no CEL.

The problem / issue was finding a suitable multi pin connector and just where to cut into the wire harness to add the small PCB.

Best wishes

StatmanDesigns

I couldn't find the original post using the search feature but another rennlister from the e-mail side of things forwarded me the message. It was an Audi fix not BMW. Here is a copy.


This is a forwarded message

From: John Coffin <911@vintage911.com>
To: "911/993/996" <911@rennlist.org>
Date: Friday, October 22, 2004, 1:33:25 PM
Subject: [911] RE: 993's

===8<==============Original message text===============
I know it works in California since that's where I live. It worked on my Audi S4 too. I'll get a picture this weekend but not much to see now since the diode is shrinkwrap inline. I soldered it in the wire right before the connecters (part of the sensor tail, easy to replace if you want to get back to stock) in the engine bay on the left as you face the engine.

-----Original Message-----
From: TAGadvertising@aol.com [mailto:TAGadvertising@aol.com]
Sent: Thursday, October 21, 2004 6:59 PM
To: 911/993/996
Subject: [911] RE: 993's

John, that diode idea is brilliant. Thanks. You just have to take a photo and post it. Think such a workaround would be passable in all 50 states, even out here in Sschwarzeneggerville?

- Bob Prosser
(about to buy a 993)

In a message dated 10/21/2004 9:23:43 PM Eastern Daylight Time, "John Coffin" <911@vintage911.com> writes:

>I actually found the diode solution on the audi board. *The audi
>bi-turbo
guys (me) remove the pre-cats and need to trick the ECU into thinking the pre-cats are still there. *After thinking about the secondary air injection problem, I thought the same answer should work for the 993 and it did. Another method I think would work is spacing the primary O2 sensor out of the exhaust flow with spacers. *To me, soldering is easier.

Epoxy Rectifier Diode from radio shack, P/N: 276-1141. *You need two, one for each side. Silver bar on the edge of the diode goes towards the ECU.

Randy M '96 Silver 993

As far as I remember, it was just an idea that someone was looking into. They never finished it as I recall. I hope you find it.

Rob Kwate

Do a search under "bypass circuit" You'll find it. The author of one thread is "993,951,944". His name is David. I know he developed a bypass circuit that he installed on his car, which eliminated the CEL. Another guy who has worked on this is Mike J. I don't know how far he has gotten with it though. David or Mike J, are you out there? How's it comming?

kkim

FYI, link to the post...


https://rennlist.com/forums/showthre...bypass+circuit