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Legally pass emissions with SAI faults. Here's how….….
I began a quest this summer to find a solution to my SAI problem after failing my first emissions test last June. Service records showed the car had a history of SAI problems with various "solutions" some legal, some not. My shop guy felt it was the air pump ($1500 part + install). I felt it was clogged ports. Could have been both. Regardless, I was looking at a major expenditure without any guarantee of success.
To make a long story short…I ended up passing emissions a few days later on a technicality that I stumbled upon quite by accident. A light bulb went off: “Maybe this is repeatable”. So I bought an OBD2 reader and began studying how OBD2 worked, doing a number of drives of different lengths at different speeds, overnight cooldowns, start/stops, etc, with the goal being to find a way to reliably put the car into a state that legally masked my SAI problem long enough to get tested anytime I wanted. The car is now off the road for the winter but I was able to come up with a simple procedure that does just that, at least on a 97 C2S 6 speed. Unless Porsche significantly changed the OBD2 system there’s a good chance it’ll work on all 96-98 993’s.
A little background..…
OBD2 cars will fail to pass emissions for 2 reasons. The first is if the required “readiness monitors” are NOT READY. If you go to emissions in this condition they'll send you off to do more driving and invite you back for another try. Note: All 5 readiness monitors reset (go NOT READY) when you disconnect the battery or clear the Check Engine Light (CEL) – that’s why you can’t just clear the CEL and pass. The second way is the way most people fail: OBD2 does its job and detects an emissions fault, lights the CEL and stores the associated codes. You are sent away to fix the problem.
This SAI workaround hinges on two things. First, you don’t need all 5 OBD monitors READY to get your car tested. For 1996 thu 1999 cars, DEP guidelines only require any 3 of the 5 non-continuous monitors to be READY and most states follow DEP guidelines (check your state DMV website). CA requires 4. Second, the OBD system can't throw an SAI code (and trip the CEL) until the secondary air monitor runs to completion (READY). To exploit this all you need to do after resetting your SAI fault and CEL is get 3 of the 5 monitors READY, making sure one of them isn’t the secondary air monitor. If you do that, your SAI problem will go undetected. Simple and legal.
So how do you do that? ….
Get yourself an ODB2 reader, preferably one that can display all 5 readiness monitors on a single screen. It’ll help you track progress as you drive. There may be other variations that work but start with steps below, following them EXACTLY. They have been tested dozens of times on a 97 C2S and work.
In the year since I started this thread, I refined the original drive cycle to where it takes less time and works EVERY time. The drive sets up the car to legally pass emissions even with an SAI-related CEL. The principle is simple: clear the fault codes and CEL, drive til you get 3 monitors READY but don't let the Secondary Air monitor run to completion.
Here's the drive that works on my 97 that I’ve tested dozens of times and used to pass emissions three times:
1) RESET your OBD the night before doing this drive (do this even if you have no CEL) 2) Cold start the car and drive 25 highway miles doing 60-70mph in 6th gear (SUV style). Leave the scanner connected to monitor progress. 3) Pull over, turn off car, remove key, restart. 4) Continue driving 60-70mph in 6th gear until the CAT and HTR monitors set. This should happen in ~20 minutes. 5) Idle a minute or so. EVAP will set. 6) Get tested.
With 3 monitors set emissions will test you everywhere except CA. (CA needs a 4th). You can drive around all you like between steps 5 and 6, just don't let the car cool down - that’ll run the SAI test to completion in 97’s and light the CEL if an SAI fault was detected.
For this to work your 993 will need to be able to display monitors going ready one at a time, as they complete. A number of 97's have reported being able to do this as well as at least one 96. Give it a try to see if yours does.
I did this drive a few days ago and passed emissions for the final time! CT, like many states exempts cars beyond a certain age (25 in CT), so i'm done. I learned something new this time: on the second leg of the drive (step 4) I ran into bumper-to-bumper traffic before completing the leg, actually coming to a complete stop at one point. I thought for sure I’d have to do step 4 over again, but, no, a short time later, CAT and HTR went ready. What's interesting is it happened only 15 miles into the run, around 20 minutes after starting, which means the legs are probably time-related, not distance-related. It’s also interesting that the stop and go didn't prevent those 2 monitors completing, so either it’s cumulative time that counts or I had gone at least 20 minutes before hitting the traffic. I suspect steps 2 and 4 may be 20 minute legs not 20 mile legs but need to confirm that. Either way the whole thing can be completed in about 45 minutes.
The last report is shown below. Like the previous two it shows only 3 (non-continuous) monitors ready, Secondary AIR not ready, and PASS. (The CEL turned on the next day, after the Secondary Air monitor completed).
Last edited by Jay777; 07-03-2021 at 12:47 PM.
Reason: new details on drive
Glad this worked for you Jay. In Massachusetts 15+ year old vehicles are exempt, so a piece of electrical tape sufficed to get the car registered here.
That zenith C2S is a peach. The SAI light and clogged SAI ports are merely a matter of emissions, not performance.
Jim, yea, in CT it's 25 years. So until this discovery I was looking at having to pass 3 more tests. Not anymore. I’ve repeated the "drive" enough to satisfy myself I can do it anytime I want, so me and SAI worries have parted ways forever.
Just hoping others will give it a try to see if it’s effective for everyone, everywhere. CA is another story but it IS possible to get ALL monitors except AIR ready, because somehow that’s the state I got in “accidentally” when I first passed emissions. Just ran out of time this season before coming up with a drive that will work in CA. If no one else comes up with one, I'll revisit it in the spring.
This SAI workaround hinges on two things. First, you don’t need all 5 OBD monitors READY to get your car tested. For 1996 thu 1999 cars, DEP guidelines only require 3 of the 5 to be READY. Most states follow DEP guidelines (CA may be the only state that requires 4 monitors). Second, the OBD system can’t flag an SAI problem until the secondary air monitor is READY. To exploit this all you need to do after resetting the OBD system is get 3 of the 5 monitors READY, making sure one of them isn’t the secondary air monitor. If you do that, your SAI problem will go undetected. Simple and legal.
Your understanding of the 993 ODBII monitors system (readiness codes) seems to be lacking, i.e. all the monitors need to be set before ANY will appear
as completed via an OBDII scanner! Having done many 993 monitor setup driving efforts for Porsche shops and owners, that's my experience & reality.
Read here under Porsche 993 Cycle Flag Basics; http://www.systemsc.com/codes.htm
Later Porsche vehicles, e.g. 996, will indicate the completion of each monitor without having completed all monitors.
Therefore, without having completed the SAI monitor test, NO OBDII monitor will appear via a scanner as having been completed.
Jim's comment re: Mass. not requiring DEQ testing for vehicles >15-years young generated the link below.
Staggering to see differences in requirements by state, and within states, Oregon among them.
Although hardly a fan of the Feds, surprised no intervention on this one, given issues of air quality and climate.
....all the monitors need to be set before ANY will appear
as completed via an OBDII scanner!
Au contraire..
MY experience is that monitors come on AS THEY OCCUR, in real time, while driving. If your monitor doesn't do that it's the fault of your reader not the OBD2 data link (at least on this 97 C2S).
MY experience is that monitors come on AS THEY OCCUR, in real time, while driving. If your monitor doesn't do that it's the fault of your reader not the OBD2 data link (at least on this 97 C2S).
Apology accepted
What scanner, please? One of your other vehicles maybe or Photoshop? I use the Porsche factory tester (PST2).
Besides, all 993s require 2 trips (2 cold starts in between), with the '96 993 requiring three trips.
Why do you think so many 993 owners have so much trouble and some just have the DME ECM re-flashed?
After all the years for 993 owners and Porsche dealers having to deal with OBDII monitors, and you discover a workaround, please!
Right there in the original post:
The OBD2 reader I used was an Autel AL519 (Amazon, about $60)
Get one and then we'll make a wager....
Ordered one. We'll see, as I have access to many 993s here in SoCal to test with.
STEP 3: Turn car off, remove key, restart. Don’t let the car cooldown. All 5 monitors should still be off. May not be necessary to remove the key but that’s the way I did it. I let the car sit for at least a minute before restarting.
This voids a partial trip when ALL OBDII tests have not been completed for that trip.
STEP 5: Repeat step 2. Somewhere between 13 and 18 miles into this leg the CAT and O2 Heater monitors will go READY. Sometimes EVAP goes ready at the same time. If not. Do step 6.
STEP 6: Come to a stop without turning the car off and idle in neutral until the EVAP monitor goes ready. This should take less than 5 minutes. You now have the required THREE monitors ready.
There's NO guarantee that the CAT & O2 monitors will be "Ready" after 13-18 miles, i.e. it's all a function of load & RPM, as is the case with all the steps indicated.
Bottom line: Whether the test station's scanner will be able to read any monitors when there're NOT all set.
What scanner, please? One of your other vehicles maybe or Photoshop? I use the Porsche factory tester (PST2).
Besides, all 993s require 2 trips (2 cold starts in between), with the '96 993 requiring three trips.
Why do you think so many 993 owners have so much trouble and some just have the DME ECM re-flashed?
After all the years for 993 owners and Porsche dealers having to deal with OBDII monitors, and you discover a workaround, please!
Loren,
I've met Jay before and no way would I ever believe he would make any of this up, use another vehicle or use photoshop to alter an image to prove his point.
I've met Jay before and no way would I ever believe he would make any of this up, use another vehicle or use photoshop to alter an image to prove his point.
Regards,
.
I was thinking the same thing. I'm pretty sure Jay is just reporting his experience with his car, and the tools available to him. If someone else has had a different outcome, that doesn't mean Jay's is a made up.
11-18-2017, 05:48 PM
Legally pass emissions with SAI faults. Here's how….….
