kms0521

I have a 1997 993 that I purchased with 35K miles about 12 years ago. The CEL has been on the entire time. Through this forum, I learned about purchasing and OBDII monitor and following the drive cycle needed to reset the codes. I am no longer able to reset the codes and the the CEL comes back on rather quickly now (within a day). I'm considering going ahead to a California STAR smog station, failing the test, and spending the $650 for repairs before a smog referee will give me a 2-year waiver. Short of a top end rebuild (not in the cards right now, hah!), does anyone have recommendations on what a smog certified mechanic should start with? I want to make sure something meaningful is done, even if it doesn't fix the problem. Maybe there is a fix short of a rebuild? I already replaced the EGR valve about 8 years ago, so don't think I need to do that again? Occasionally I also have the P0303 fault (Cylinder 3 misfire), but this has not faulted in the last few weeks. Thanks all

Jon 'Bama

I bit the bullet and did the full rebuild and clean out in the last couple of months. It was not cheap but I love the results and the knowledge that my car is running at peak performance. Feels like a new car again

kms0521

Jon - what did it run you? Was it just top end or full rebuild?

Jon 'Bama

I had a bunch of other issues to fix AC Control Unit, Alternator, new battery, replacing seals throughout the engine while it was out and several other little things that added up. Overall I've put close to 15K into this car in the last couple months.

pp000830

KMS0521
Code descriptions:

• Secondary air System P0410 cylinders (1-3),Signal implausible / Implausible Component Section / Malfunction
• Secondary air System P1411 cylinders (4-6), Interruption / No Signal (P0411 seems to not exist as a valid code in my factory document for a 993)

These codes do not necessarily point directly to a clogged injector system:
Don't be in such a hurry to throw big money at it. First I would replace the air check valve and if you are not in the position to diagnose the oxygen sensors I would replace all 4 at the same time.
$340 dollars in parts if you buy the oxygen sensor brand in the Bosch box and a Saturday morning DIY and your problems may be over.

• For some, the check valve can be stuck and be a little bit trying to remove. I used a hole saw on the end of an impact wrench to rip the housing off its hex mounting base and then used a regular hex socket on the impact wrench to remove the valve base. An electric impact wrench can be had at Harbor Freight for $24. This is the method of last resort if a crowfoot wrench and socket tool doesn't do the job. The impact wrench "shock" cracked the threads loose were applying constant torque with a regular wrench, in my case just seemed to distort and possibly damage the casting it is screwed into.
• The easiest way to replace old oxygen sensors is to use a little penetrating oil on the bung (threaded mount), let them sit overnight, cut the wires to them and slip a closed-end boxed end wrench over each sensor and tap it loose. After the new ones are fully screwed in, using care not to twist its wire pigtail use the old wires to fish the new wire up to their plugs in the engine compartment matching the plug color black or grey to the same color socket on each side of the engine bay. It helps to remove the sheet metal pass-through rubber grommets in the engine tin first. They are easy to put back in position once the wiring is all in place.
• Also, be aware that if you used Durametric to obtain the codes in the first place all but the latest version of Durametric software throws erroneous oxygen sensor codes so be sure to download the latest version and rerun the code before doing anything.

If you would like some more information on the procedures involved it is all here at Rennlist.
Andy

kms0521

Andy, much obliged. I searched as was not able to find what you refer to. Can you point me in the right direction? Really appreciate the advice.

Regards,

Kurt

pp000830

Easy stuff just use the search function menu and select advanced search and enter keywords and select the 993 discussion group on the right.
For example below is a search on the words "air check valve" that produced the multiple discussion threads, several relate to the check valve and crowfoot sizing.:
Search results for "air check valve"

Let me know if I have answered your question.
Andy

kms0521

Andy, can I get deterioration with the SAI issue to the point where I won't be able to reset the codes? That appears to be what is happening. I've been trying multiple drive cycle for weeks and cannot get a reset. going to try the extended drive cycle (20 miles under 60/3000, turn off, restart, do it again, turn off, restart, do it again) but getting to my wits end. Seems like I can only get in one drive cycle now before the CEL comes on again with the dreaded P0410. Not sure I'll be able to do the extended drive cycle.

1997hmc993

I had the same engine light on (97 993) for 3 years! an SAI code on passenger side exhaust port 6.
If you don't mind getting some grease on your face, cleaning out the ports are not as hard as it seems with a right snake made of a short bicycle cable on a drill as suggested by many on this forum. My trick was to make the end tapered so the end is more flexible.
I thougIt removing heat exchangers was hard to do because I read stories of broken studs and stuck nuts, etc.
Start spraying PB Blaster several times 24 hrs before attempting to remove the bolts and nuts made everything easier. I had some valuable tips on the forum.
I have other error codes to deal with, but I don't have the check engine light to stare at 🙂.
if need my tips, let me know.

pp000830

Hi KMS,
Clogged injector ports never need a top-end rebuild to address if your mechanic is suggesting this $8000 to $12,000 procedure, you need a new mechanic. The solution to clearing the clog involves removing the exhaust manifold under the car and the SAI check valve and snaking out the passages with a cable in combination with a carbon solvent.
You mention the ERG valve has bee replaced. If you speak of the SAI check valve located under and behind the air box and you have replaced it in the last two or three years, it is probably good. It can also be tested by detaching the hose leading to it and attaching a short length of garden hose to it. You should be able to blow some air into the hose by mouth but you should be unable to draw air from it if it is working.
Here are some page that discusses the SAI system:
https://993servicerepair.blogspot.co...horror-of.html

https://993servicerepair.blogspot.co...-diagnose.html

Andy

GJSPIN

Maybe there is a fix short of a rebuild?

1. Pull out the ECU and send off to have reprogrammed to remove the SAI portion.

2. Have a local shop clean out the SAI passages. You can find plenty of info on RL on how to accomplish this.

3. As for code cylinder misfire, I would look closely at the condition of your ignition wires and specifically at the bends in the wires. If the wires have any cracks that can be the cause. You can fill any small voids with RTV Silicone until you're able to replace it. Last, have you replaced the Distributor Caps and or checked for carbon tracking??

systemsc

There are numerous Porsche repair shops here in SoCal that can help you resolve setting of the OBDII monitors for an emissions test. Typically when I personally help 993 owners set the monitors while driving, it takes about a hour.
1997 993s typically require two complete drive trips with a cold start between drive trips. Read here for more info under Porsche 993 Cycle Flag Basics; https://www.systemsc.com/codes.htm
Without using a Porsche factory tester, setting of the OBDII monitors is difficult for many.

ahhprods

A few years ago, I had the sai issue. Specialty shop did all sorts of things, but it ended up that it needed to be cleaned out. He did it for free since he had me spend so much replacing other things that he was sure was the prob and it “def wasn’t clogged”.

I thought that was really nice of him, cuz I know he was just trying to save me from the cleaning with each repair, which we didn’t avoid anyway.

never got that cel again.

1997hmc993

I just cleaned my exhaust SAI ports, I hope mine last as long as your cleaning.
Cleaning was not a technically difficult job but it requires patience and ready to clean some oil off your face.
I am still looking for a clamp or a plier that can keep the exhaust clamp spread while trying to put the two parts together!

systemsc

Great! Now you need to use a Porsche tester to determine whether the SAI monitor of the OBDII system test has passed.
If not, then any driving is a waste of time!