'97 993 Secondary Air Injection (SAI) Problem...

[911 tweaks]

I have read in the past about this common problem on the 993 cars...
If memory serves me Bruce Anderson wrote in an article a little while ago = 1-4 yrs ago about a trick he had to be the best approach to clean out the system = shy of dis-assembling the engine...

Q1: does any one remember his suggestion as i believe it was in an Excellence magazine tech article & I cannot find the article...?

Q2: does any one have any "successful" approachs to most accurately trouble shoot what may be the cause of the CEL which is on...:

The codes I found using my durametric scan came up with the following codes:
1. #80 = SAI cylinders 1-3...
2. #43 = rear blower motor stage 1...
3. #14 = o2 heating 1 behind catalytic converter...
4. #15 = aging o2 sensor cylinder 1-3...
5. #23 = aging o2 sensor cylinder 4-6...
6. #24 = ignition angle invervention - discontinuity/short circuit to ground or plus...

Thx for any & all tips, suggestions procedures that have been successful in determining what is the cause a/o needs cleaning ~ replacing, ect...

[rattlsnak]

Strictly going off of memory, the SAI issue requires you to remove the exhaust headers and the SAI pipes on top of the heads and clean out the passageways.. PITA but doable..

[911 tweaks]

thx rattlsnak for your info...so after removing said parts, is one able to then use compressed air and/or something else possibly ??... to possibly clean out the air inlets and/or air outlets ??...or other area(s) in hope of cleaning SAI up well enough to resume use of the car ? Subject car is not consuming oil to the best of my knowledge and has about 50k miles on her...

[911 tweaks]

any other info...? thx, bob

Lots of B12, beer, coathanger wire, wire brushes, patience, beer, shop towels, rubber gloves, beer, and beer. Lot's of talk on RL 993 forum about the procedure.

[Deschodt]

The article mentioned some cleaning solution that needed to be penetrating for a few days...
It also mentioned that the carbon did not build up by magic and you likely needed valve guides... Still the soak beats the $6000 rebuild the PO did to my car, if you are just trying to resell it without a CEL...

[911 tweaks]

thx guys...can you post the link to the RL article here as I could not find it... thx, bob

[R K T]

Here's the most recent....there are a few threads on this subject.
DIY - Changing the SAI Check Valve - Rennlist Discussion Forums

[911 tweaks]

thx R K T for this rl thread... can you post here a thread on how best to clean out the passage ways or to check if they are blocked...thx for your help...bob

[911 tweaks]

any one have any cleaning threads to read or have info...? thx, bob

[jackb911]

I had a 1996 993 that developed the SAI check engine light syndrome.

The SAI ports clog easily as the car gets older, it seems to be more of an issue on vehicles that are not daily driven.

I did a ton of research and came to the conclusion that the necessity of replacing the valve guides was way overblown. If your exhaust doesn't smoke continuously after startup and if your oil consumption is normal, your guides are probably OK. Clogged SAI passages do not affect the performance of the car. Flushing the ports works sometimes to clear a check engine light, sometimes it doesn't.

I invested in an Actron code scanner that allowed me to check the trouble codes and clear the CEL. We have emissions testing here and the car always passed emissions after clearing the CEL and going through a "drive cycle" to clear the readiness codes. The drive cycle is a minor PITA that takes about 45 minutes and you have to find the right roads to accomplish it.

After I passed my emissions test, I removed the CEL bulb from the gauge, reinstalled it before next years' test.

There is a ton of info on '96-98 993 SAI issues on that "other" Porsche forum that starts with a "R". The 993 forum there is very active. Do a Google search for "993 SAI problems" and you will find a lot of helpful information.

[jackb911]

Here's the drive cycle to clear the readiness codes after the CEL has been cleared with the code scanner:

Start engine, let idle for approx. 2 min, 10 secs.

Accelerate to 20-30 MPH, Maintain steady speed for approx 3 min, 15 secs.

Accelerate to 40-60 MPH, Maintain steady speed for approx 15 mins.

Decelerate and come to a stop. Then:

Idle in Neutral for 5 mins. (manual trans.)

Idle in Drive for 5 mins. (Tiptronic trans.)

During the drive cycle, do not exceed 3,000 rpm or 60 mph.

[911 tweaks]

ok thx jack...I'll see how this all works & I will google the subject...

[mysocal911]

Originally Posted by jackb911

Here's the drive cycle to clear the readiness codes after the CEL has been cleared with the code scanner:

Start engine, let idle for approx. 2 min, 10 secs.

Accelerate to 20-30 MPH, Maintain steady speed for approx 3 min, 15 secs.

Accelerate to 40-60 MPH, Maintain steady speed for approx 15 mins.

Decelerate and come to a stop. Then:

Idle in Neutral for 5 mins. (manual trans.)

Idle in Drive for 5 mins. (Tiptronic trans.)

During the drive cycle, do not exceed 3,000 rpm or 60 mph.

A minimum of two of the above, i.e. two trips with a cold start between each
and in some cases three, are required.

[911 tweaks]

thx guys...not to sound like a wise a$$, but, how accurate do i need to be for the amt of time for each of the elements of the drive cycle...? = should I use/get a stop watch...?

[sand_man]

Maybe more than you ever wanted to know:
Recap of the SAI circuit - Rennlist Discussion Forums
993 - SAI System - pcarworkshop

[john walker's workshop]

the computer just needs to be tricked into disregarding the input signal that triggers the fault. i know it's been done. electronics gurus please stand up.

[jackb911]

Originally Posted by mysocal911

A minimum of two of the above, i.e. two trips with a cold start between each
and in some cases three, are required.

Evidently that depends on the car and/or how closely the drive cycle parameters are followed. I had to go through this inconvenience three consecutive years before I sold the car but only one drive cycle trip was required each time to clear the readiness codes and, no, I didn't use a stopwatch. The myriad of SAI threads I researched did indicate that some owners had to do the cycle two or three times, though.

The SAI problem could be why clean, well-maintained 1995 (pre-OBD2) 993's are so highly sought. If I ever own another 993, it will definitely be a '95. In my old age I just don't have the patience to deal with the drive cycle foolishness.

Isn't it ironic that EVERY generation of 911 has some sort of inherent "issue"?

[mysocal911]

Originally Posted by jackb911

Evidently that depends on the car and/or how closely the drive cycle parameters are followed. I had to go through this inconvenience three consecutive years before I sold the car but only one drive cycle trip was required each time to clear the readiness codes and, no, I didn't use a stopwatch. The myriad of SAI threads I researched did indicate that some owners had to do the cycle two or three times, though.

The SAI problem could be why clean, well-maintained 1995 (pre-OBD2) 993's are so highly sought. If I ever own another 993, it will definitely be a '95. In my old age I just don't have the patience to deal with the drive cycle foolishness.

Isn't it ironic that EVERY generation of 911 has some sort of inherent "issue"?

"I had to go through this inconvenience three consecutive years before I sold the car but only one drive cycle trip was required each time to clear the readiness codes and, no, I didn't use a stopwatch."

Then the other trips were completed prior to the final one that SET the monitors.
Remember, the monitors are RESET when either a CEL is RESET or the battery
is disconnected. Furthermore, all monitor tests must be completed before any
of the monitors are indicated via an OBDII reader.

[sand_man]

Originally Posted by jackb911

The SAI problem could be why clean, well-maintained 1995 (pre-OBD2) 993's are so highly sought. If I ever own another 993, it will definitely be a '95. In my old age I just don't have the patience to deal with the drive cycle foolishness.

Yep. One of the first things I did when I got my '95 was to ditch the SAI and plug the ports.