william_b_noble

well, I've got the "non continuous monitor" issue again
Car = 97 993 Cab
- I have been testing various OBD scan tools to read engine parameters
trying to find something that would be suitable for this car. One
vendor I went to visit saw the Check engine light on and cleard it
before I could stop him. So, now it's a matter of hitting the exact
drive cycles to set these monitors. These are catalytic converter,
evaporative system, secondary air system, O2 system and O2 system
heater.

I have a copy of pages B3 and B4 from the porsche service manual
(Porsche faxed me these pages, they aren't in my set of factory
manuals) that describe "driving conditions for reaching readiness
code". It says that two trips must be run (that's pretty clear). It
then lists 6 cycle flags and the conditions for each.

The first is "Catalytic Converter Efficiency" (cycle flag 1). It says
"the diagnostic procedure takes a total of 300 sec. The engine must
run through 4 speed and load ranges. The procedure isinterrupted when
the engine leaves the relevant ranges and continued again when the
relevant speed and load ranges are reached again. This means that it
is not necessary to run the engine in these ranges for a continuous
period of 300 sec."
"Manual Transmission"
Engine speed: 1120 -2,800 RPM
Engine load 1.0-3.0 ms
Calculated catalytic converter temperatu4re >300C"

ok, now how the heck can I make sure I hit these conditions? I have
two OBD code readers - the one I would prefer to use is the AutoXray
6000. That tool has a readout of "load value" which may be the same
thing as "engine load", but the units of "load value" are percentage,
and the Porsche manual talks about "ms" (milliseconds?). I can
certainly monitor RPM, but what are the 4 speed ranges?

Does anyone have more information that might let me set these flags?
The last time I had this problem, the final solution was to pay a
Porsche dealer $350 to drive the car around with their tester hooked
up until all the flags set - there just has to be a better way. Does
anyone have more information, or additional relevant manual pages, or
???

thanks
Bill

www.wbnoble.com

Don Plumley

I have found it essentially impossible to reset the readiness indicators. I took the car to a smog referee and passed w/o the indicators being set. (Ahem, theoretically, it also opens an interesting SAI opportunity should you ever need it...)

william_b_noble

I had and solved the SAI problem, my current problem was due to an "overly helpful" rep clearing the fault - I was waiting for it to disappear on its own after replacing the SAI check valve and clearing the passages - by the way, a hint on that - just change the valve at about 100K miles whether it needs it or not - I think my problems were caused by a damaged (worn out) valve rather than blocked passages - only one passage seemed to be mostly blocked when I cleaned everything.

now, back to my problem - there must be more data out there as to exactly what these two manual pages mean - how the heck can "load" be measured in units of milliseconds? - I think if I had that critical piece of information I might be able to get the proper conditions - though it would sure be great to see a flag that shows when one of the procedures thinks it's active and the timer is running....

g_murray

Long story short ...

The PO let the battery die over the winter. Then he merely recharged the battery (every 2+weeks) so that the car would be 'ready' in case any prospective buyer wanted a test drive.

After I bought it -- and before my New York state DMV-issued '10 day inspection' sticker expired -- I dutifully brought the car to my local garage for its 'real' inspection.

It failed inspection. (BTW, they STILL charged me $35 to 'test (yet fail)' the car)

Reason? Yep, you guessed it, none of the readiness monitors were set.
The garage owner said "go drive the car" and then come back.

It took 700 miles of 'various types of driving' before all 8 readiness monitors would 'set' to "OK".

Then the same garage charged me $25 for a 're-test' ...and, of course, 5 minutes later, it had 'passed'.

OBD-ii ...can either be a pain or a blessing.

(And yes, earlier on -- after it had failed -- I DID go thru' the 'drive cycles' -- and drove myself nutty trying to 'duplicate' the conditions. But to no avail. You see -- not even my $$$ codereader would say whether a 'drive cycle' had been 'successful' or not. So I was operating in the dark all the time. And THAT's what it took ...TIME.)

G.

william_b_noble

I'm amazed that you got them to set after only 700 miles - the last time this happened to me, I put over 3,000 miles on the car wtihout setting any monitor - I drove on freeways, surface streets, fast, slow, I tried everything. I wonder how your driving is different - I don't think there is a "coastal" function that says "if in california, don't set monitors", so it must be something else.

grrr, as they say in the business......

993inNC

You won't believe this but my readiness codes wouldn't reset with the instructions put out by the emissions machine doing the test. I had every intention of going to the DMV to pay my $250 for the yearly waiver. I took a trip of 300 total miles this past weekend (all highway).....realizing that my CEL did not come on, I ran the car (part of the same trip) to a my buddy with the emissions machine and guess what........all readiness codes were set!!! Wooooo
It didn't blow a single code the entire trip and passed inspection the first time. I have had the dreaded SAI, random missfire and other codes in the past. What was different was that I had been running the A/C the entire time, wasn't going any slower than 80 mph. Not sure what if anything those two items did for the system but whatever....it passed.
Now I have all the parts to do a major tune up (which hopefully I'll get to soon), but for whatever reason, I had no codes......go figure.

amondc

Here is what works for me.
Start the car from cold. Let it idle 3 to 4 minutes. Drive it at below 30
mph and below 3000 rpm for 3 to 4 minutes. Drive at 45 to 55 and below 3000
rpm for 15 minutes. Finish by doing a couple of stop and go situations and
driving below 30 for 3 to 4 minutes.
That routine has worked on several 911s for me and sets all monitor flags.

william_b_noble

good advice Amondc -

well, it was somewhat tedious, but with the help of my wife, I managed to get the monitors to set - I used the AutoXray 6000 OBD monitor to watch the engine load, and drove in the RPM range indicated in the manual for about 20 minutes, keeping the continuous driving segments as long as possible. The indicated load is very low, if you don't have the specs or a reader to show engine load, try about 30 mph in third gear with minimal throttle - you want to be between 1500 and 2000 rpm with just a tiny bit of load on the engine, just a little more than idle. And, when you start the car, let it idle until the SAI cuts off (about 120 sec) - don't know if that helped or not, but now I'm happy.

I think the reason my flags wouldn't set is that I live close to a freeway, so my routine is start the car, and go immediately (no warmup), be on the freeway in about 1.5 minutes, and then drive - at whatever speed traffic permits. The monitors seem to require driving with very minimal throttle. At least if "ms" in the documents really means "percent", then we are talking .9 to 3% engine load, which really isn't much.

thanks for the help

MadMarkie

I just did my second drive cycle this morning using the "BMW" routine which looks almost exactly like what amondc suggests above... and success! What a freaking lug-fest though... I was soo excited to see the monitors had been reset when I stopped, that I immediately went back out for a spirited drive before coming to work!

Cheers, Mark.

Slow Guy

I'm going through this now. Just had a '97 993 delivered Sat. but had to swap batteries w/ my 968. I attempted several (short) drive cycles over the w/e and tried to run the car through TN (Nashville) emissions today but she failed due to (5) conditions/sensors not set. Called Porsche's (PCNA) support for the "drive cycle to set readiness indicators" but all they said was "contact your dealer", still no return call from the dealer's service center. I intend to do "amondc"s procedure in the next few days, I hope that works.

I did notice one thing I was doing wrong, I was trying to keep RPM's in the 3-4k+ range instead of 1.5 - 3k range, oh well.

Is there a way to see if the sensors are set w/ one of the low cost OBDII readers? I have one, don't remember the model right off, but can they tell or do you have to have the Bosch hammer?

Bill W.

william_b_noble

the cheapest code readers wont' help much, but the mid priced ones will - many of them will show you the monitors. I have a spare INOVA reader - if you want it, just contact me and we'll work something out - it shows the monitors, but it doesn't read out power level and stuff. these monitors set during very gentle drive cycles - needs to be level ground, drive gently, very minimal power

993inNC

As a follow up, I again had to clear my CEL (SAI and random misfire prior to tune up). I drove the car long distance (300 miles round trip/150 each way) at pretty constant speed the entire time. Once again the entire trip made without codes being thrown, and for giggle I went to my buddy's inspection machine and once again.......all reset.

Moral........throw away all the instructions, find a nice long road and drive.