993 and OBD II Issues
01-02-2015, 08:55 PM
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993 and OBD II Issues
I am starting to look for a 993, and have been talking with several PCA members whose opinion I value about what are the things to look for when considering a 993. I have owned 8 Porsches over the past 10 years, including a 1988 3.2 Carrera, and several modern water-cooled cars including two 997 GT3's, but have never owned, or seriously looked at, any 993's. After a bit of research, it seems that except for the 1995 model cars with the OBD I systems, the 1996 and 1997 cars with OBD II can be ticking time bombs, and when the "Check Engine Light" comes on, it can be a signal to open your checkbook and write out a hefty one for between $7-15K for a top end re-build. This seems to be due to the potential for carbon buildup in the exhaust ports from the "added on" secondary air injection system mandated by US emissions standards. Living in metro Atlanta I must live with annual emissions testing, so this is a serious concern. In summary, my questions are the following:
1) If a 993 has had a top end rebuild (to rectify this problem), is it likely to recur even if I take precautionary measures during my ownership (these seem to include frequent addition of Techron to the fuel, refraining from short, infrequent drives, and the frequent use of the "Italian Tune Up" method of spirited driving?
2) If a 993 does not appear to have had work addressing this issue, and the PPI seems to indicate the car is running well, is there a relatively simple/inexpensive way to check to see if it is about to happen?
3) What procedures should I ensure my mechanic follows during a PPI to check on how healthy this particular engine is?
4) If you personally have owned a 993 with OBD II for any length of time, have you been able to avoid this significant repair, or should I assume that "they all do it", and it is something I have to plan on?
5) And lastly, should I let the possibility of this problem occurring dissuade me from purchasing a 993, or do you feel the rewards of ownership are more than worth the trouble? (I should add that I have driven a very nice 993 recently, and simply loved everything about the driving experience. Plenty of power, excellent ride and handling, great brakes, and that hard to define thing called "character" that the air-cooled cars seem to have. It is like they took my old 3.2 Carrera and fixed everything that would make it better without diluting the "pure Porsche experience"!)
Thanks for any advice and suggestions!! Much appreciated!
Ben Przekop, Roswell, GA
1) If a 993 has had a top end rebuild (to rectify this problem), is it likely to recur even if I take precautionary measures during my ownership (these seem to include frequent addition of Techron to the fuel, refraining from short, infrequent drives, and the frequent use of the "Italian Tune Up" method of spirited driving?
2) If a 993 does not appear to have had work addressing this issue, and the PPI seems to indicate the car is running well, is there a relatively simple/inexpensive way to check to see if it is about to happen?
3) What procedures should I ensure my mechanic follows during a PPI to check on how healthy this particular engine is?
4) If you personally have owned a 993 with OBD II for any length of time, have you been able to avoid this significant repair, or should I assume that "they all do it", and it is something I have to plan on?
5) And lastly, should I let the possibility of this problem occurring dissuade me from purchasing a 993, or do you feel the rewards of ownership are more than worth the trouble? (I should add that I have driven a very nice 993 recently, and simply loved everything about the driving experience. Plenty of power, excellent ride and handling, great brakes, and that hard to define thing called "character" that the air-cooled cars seem to have. It is like they took my old 3.2 Carrera and fixed everything that would make it better without diluting the "pure Porsche experience"!)
Thanks for any advice and suggestions!! Much appreciated!
Ben Przekop, Roswell, GA
01-02-2015, 09:18 PM
#2
Rennlist Member
Regards,
.
01-02-2015, 09:30 PM
#3
Three Wheelin'
I'm sure you'll get lots of opinions on these questions. Here are my comments as a 130k mile 97 owner in a state where the check engine light matters. Hope this helps!
1) If it has had a good rebuild (there are reports of very bad rebuilds), I would expect it to easily go over 100k miles.
2) Supposedly with a PST2 or later Porsche tester, you can run the SAI pump while also monitoring the O2 sensors. A good shop should be able to run this test to prove that the SAI passages are open and working well. There may be other ways to verify proper SAI operation without taking anything apart, but I haven't heard of one. Perhaps some of the experts can comment.
3) The above test plus the usual compression/leakdown tests seem pretty common.
4) There's a thread with recent posts on this exact topic. Many cars are well over 100k miles without needing a rebuild. Also, you can always clean out the passages in order to pass smog. Most view this as a temporary fix. I would expect a shop familiar with 993s in your area can perform this service.
5) There are others much more opinionated than me on the forum that can address this question ;-)
1) If it has had a good rebuild (there are reports of very bad rebuilds), I would expect it to easily go over 100k miles.
2) Supposedly with a PST2 or later Porsche tester, you can run the SAI pump while also monitoring the O2 sensors. A good shop should be able to run this test to prove that the SAI passages are open and working well. There may be other ways to verify proper SAI operation without taking anything apart, but I haven't heard of one. Perhaps some of the experts can comment.
3) The above test plus the usual compression/leakdown tests seem pretty common.
4) There's a thread with recent posts on this exact topic. Many cars are well over 100k miles without needing a rebuild. Also, you can always clean out the passages in order to pass smog. Most view this as a temporary fix. I would expect a shop familiar with 993s in your area can perform this service.
5) There are others much more opinionated than me on the forum that can address this question ;-)
01-02-2015, 11:48 PM
#5
Banned
95 HAS THE SYSTEM BUT DOES NOT HAVE THE CEL - LIGHT - Being an OBD1 Car
Conclusions - 95 Has the issue whether Monitored OR Not !
My car has 143 xxx and 102 After Top End Rebuild
My 97 is Subjected To Tail Pipe Emissions ONLY in Ontario, Canada.
She Has Never Failed Emissions Although I had a CEL - Light lit when I took her in for the Test.
CEL is Insignificant as my car is Odd Year - a 97. (This could be a Factor dependant on where u live?)
More significant, some 993 have / or had Bad Valve Guides.
Valve Guide Wear is what Needs to be Tested to know whether u r buying a Good Car with a Good Solid Motor.
One Indicator / Factor is Oil Consumption.
Records help But may or may not be available.
Leekdown Results are a Good Indicator of Motor's Condition.
As recomended to me by a well known and Trusted Adviser here, Valve Guide Wear should be Tested by a Proven Professional - when doing a PPI.
There are Many more knowledgeable RL People on here than I.
Hope this is Helpful and sends you in the right direction.
Regards TJ
PS a Higher Mileage Car is Priced Properly - Well below a Low Mileage Car
If all the Correct maintenance is done, then you are Buying In Low <> As as compared to the Cost of a Garage Queen
so How much is an Engine Refresh cost ? Comparson?
Food For Thought.
Conclusions - 95 Has the issue whether Monitored OR Not !
My car has 143 xxx and 102 After Top End Rebuild
My 97 is Subjected To Tail Pipe Emissions ONLY in Ontario, Canada.
She Has Never Failed Emissions Although I had a CEL - Light lit when I took her in for the Test.
CEL is Insignificant as my car is Odd Year - a 97. (This could be a Factor dependant on where u live?)
More significant, some 993 have / or had Bad Valve Guides.
Valve Guide Wear is what Needs to be Tested to know whether u r buying a Good Car with a Good Solid Motor.
One Indicator / Factor is Oil Consumption.
Records help But may or may not be available.
Leekdown Results are a Good Indicator of Motor's Condition.
As recomended to me by a well known and Trusted Adviser here, Valve Guide Wear should be Tested by a Proven Professional - when doing a PPI.
There are Many more knowledgeable RL People on here than I.
Hope this is Helpful and sends you in the right direction.
Regards TJ
PS a Higher Mileage Car is Priced Properly - Well below a Low Mileage Car
If all the Correct maintenance is done, then you are Buying In Low <> As as compared to the Cost of a Garage Queen
so How much is an Engine Refresh cost ? Comparson?
Food For Thought.
Last edited by TJ993; 01-03-2015 at 12:08 AM. Reason: typo
01-05-2015, 12:35 AM
#7
Burning Brakes
Most folks who experience the issue with plugged air injection ports, don't see the issue until they have 60 to 70k miles on the car. So, if you were to start out with a "fresh" upper end, you should be able to make that 60-70k miles before encountering the SAI issue. How many years of driving would that take?
When Steve Weiner rebuilt my heads on a recent engine overhaul, I sent him the cam towers with the heads, and he drilled out the air injection ports to an oversized diameter in both the heads and the cam towers, which should extend the run period before passage plugging occurs......say to over 100k miles.
I guess you have to assess how fast you will put mileage on a 993. If you drive the car daily, it would still take you 5 to 10 years to encounter SAI plumage issues, if you start with an engine that has been freshened.
And, I am not certain about how many miles you can drive after you have had the plugged passages rodded out by a mechanic (I'm told this is about a $500 bill). But, there seems to be some relief offered by having the ports drilled out and Techtron flushed through the system. Again, there are lots of postings on this issue that can be read.
When Steve Weiner rebuilt my heads on a recent engine overhaul, I sent him the cam towers with the heads, and he drilled out the air injection ports to an oversized diameter in both the heads and the cam towers, which should extend the run period before passage plugging occurs......say to over 100k miles.
I guess you have to assess how fast you will put mileage on a 993. If you drive the car daily, it would still take you 5 to 10 years to encounter SAI plumage issues, if you start with an engine that has been freshened.
And, I am not certain about how many miles you can drive after you have had the plugged passages rodded out by a mechanic (I'm told this is about a $500 bill). But, there seems to be some relief offered by having the ports drilled out and Techtron flushed through the system. Again, there are lots of postings on this issue that can be read.
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01-05-2015, 08:57 AM
#8
RL Community Team
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If you ar looking at a car with over 80K miles on it the ports probably have already been addressed. If the secondary air injector ports become clogged. I have no experience with this however the previous owner of my car did. I have read anecdotal notes such as it shows up more in cars that have spent most of their life in hot climates and that it is related to valve guide wear as the original guides are made of a slightly too soft metal. I have also read that once the valve guides are replaced the problem seems to not return. There is more than one approaches to fix this issue or simply getting the light to stay off:
o Remove the exhaust manifold & air supply and clean the passages/ports with a wire snake attached to a hand drill & flushing with cleaning solvent. With this process you will replace the check valve, some do this as a DIY project;
o Add electronics so engine management thinks the clog does not exist, something that may not be legal as well as a disclosure issue when you sell your car, also a DIY item or;
o Disassemble the engine to clean the ports/passages and replace the valve guides. The official Porsche solution, the one your friendly neighborhood automotive shop will $love$ to recommend.
My gut tells me that by now many 993s have had their valve guides replaced, on my car it was done in-warranty years ago. If you do experience this problem you may be able to forestall a full-on disassembly & valve guide replacement for tens of thousands of miles if not indefinitely by engaging in one of the less invasive fixes.
Also a bad air check valve, leaking air hose, faulty air pump, or deteriorated wires (known issue) on the back side of the engine leading to and clamped above the air pump can also cause the same light to come on.
o Remove the exhaust manifold & air supply and clean the passages/ports with a wire snake attached to a hand drill & flushing with cleaning solvent. With this process you will replace the check valve, some do this as a DIY project;
o Add electronics so engine management thinks the clog does not exist, something that may not be legal as well as a disclosure issue when you sell your car, also a DIY item or;
o Disassemble the engine to clean the ports/passages and replace the valve guides. The official Porsche solution, the one your friendly neighborhood automotive shop will $love$ to recommend.
My gut tells me that by now many 993s have had their valve guides replaced, on my car it was done in-warranty years ago. If you do experience this problem you may be able to forestall a full-on disassembly & valve guide replacement for tens of thousands of miles if not indefinitely by engaging in one of the less invasive fixes.
Also a bad air check valve, leaking air hose, faulty air pump, or deteriorated wires (known issue) on the back side of the engine leading to and clamped above the air pump can also cause the same light to come on.
01-05-2015, 03:11 PM
#9
I am starting to look for a 993, and have been talking with several PCA members whose opinion I value about what are the things to look for when considering a 993. I have owned 8 Porsches over the past 10 years, including a 1988 3.2 Carrera, and several modern water-cooled cars including two 997 GT3's, but have never owned, or seriously looked at, any 993's. After a bit of research, it seems that except for the 1995 model cars with the OBD I systems, the 1996 and 1997 cars with OBD II can be ticking time bombs, and when the "Check Engine Light" comes on, it can be a signal to open your checkbook and write out a hefty one for between $7-15K for a top end re-build. This seems to be due to the potential for carbon buildup in the exhaust ports from the "added on" secondary air injection system mandated by US emissions standards. Living in metro Atlanta I must live with annual emissions testing, so this is a serious concern. In summary, my questions are the following:
1) If a 993 has had a top end rebuild (to rectify this problem), is it likely to recur even if I take precautionary measures during my ownership (these seem to include frequent addition of Techron to the fuel, refraining from short, infrequent drives, and the frequent use of the "Italian Tune Up" method of spirited driving?
2) If a 993 does not appear to have had work addressing this issue, and the PPI seems to indicate the car is running well, is there a relatively simple/inexpensive way to check to see if it is about to happen?
3) What procedures should I ensure my mechanic follows during a PPI to check on how healthy this particular engine is?
4) If you personally have owned a 993 with OBD II for any length of time, have you been able to avoid this significant repair, or should I assume that "they all do it", and it is something I have to plan on?
5) And lastly, should I let the possibility of this problem occurring dissuade me from purchasing a 993, or do you feel the rewards of ownership are more than worth the trouble? (I should add that I have driven a very nice 993 recently, and simply loved everything about the driving experience. Plenty of power, excellent ride and handling, great brakes, and that hard to define thing called "character" that the air-cooled cars seem to have. It is like they took my old 3.2 Carrera and fixed everything that would make it better without diluting the "pure Porsche experience"!)
Thanks for any advice and suggestions!! Much appreciated!
Ben Przekop, Roswell, GA
1) If a 993 has had a top end rebuild (to rectify this problem), is it likely to recur even if I take precautionary measures during my ownership (these seem to include frequent addition of Techron to the fuel, refraining from short, infrequent drives, and the frequent use of the "Italian Tune Up" method of spirited driving?
2) If a 993 does not appear to have had work addressing this issue, and the PPI seems to indicate the car is running well, is there a relatively simple/inexpensive way to check to see if it is about to happen?
3) What procedures should I ensure my mechanic follows during a PPI to check on how healthy this particular engine is?
4) If you personally have owned a 993 with OBD II for any length of time, have you been able to avoid this significant repair, or should I assume that "they all do it", and it is something I have to plan on?
5) And lastly, should I let the possibility of this problem occurring dissuade me from purchasing a 993, or do you feel the rewards of ownership are more than worth the trouble? (I should add that I have driven a very nice 993 recently, and simply loved everything about the driving experience. Plenty of power, excellent ride and handling, great brakes, and that hard to define thing called "character" that the air-cooled cars seem to have. It is like they took my old 3.2 Carrera and fixed everything that would make it better without diluting the "pure Porsche experience"!)
Thanks for any advice and suggestions!! Much appreciated!
Ben Przekop, Roswell, GA
If I were you, I would do more reading on the subject of 993's...If these cars are the ticking time bombs as your pals have stated, why in God's name would they be such a desireable, appreciating item?
Most like the simplicity of the OBDI 95 model for their lack of a feedback loop on the SAI system. (No CEL for SAI system clogging)
...but the 95 does not have the Varioram and the 10 claimed additional hp it provides.
Maintenence, condition, and a comprehensive PPI, will be your best friends in the acquisition/chase phase.
Personally, I think a compression and leakdown test can tell you if have a healthy engine, with well seated rings and non-scored cylinders that hold compression; the leakdown can tell you about how well the valves are sealing. I think both tests are above and beyond the price of a PPI...But that depends on who is doing said inspections. Insist on a well respected, air cooled 993 specialist shop in your area.
Supposedly its worn valve guides that allow escessive oil to be burned and eventually clog the SAI system; but I suspect there may be contributing causes as well, such as stuck SAI check valve, which may help promote clogged ports and deteriorated/leaking vacuum valves within the system.
Last edited by nine9six; 01-05-2015 at 03:32 PM.
01-05-2015, 07:31 PM
#10
Rennlist Member
Let's say you get a CEL and it's clogged SAI ports. It is truly a simple job to rectify and can done in a weekend easily.
The hardest part of the job for me was reconnecting the airbox to the MAF.
The hardest part of the job for me was reconnecting the airbox to the MAF.
01-06-2015, 08:46 AM
#11
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Thanks also to earossi, pp000830, and nine9six for the very helpful advice! Much appreciated, folks, thanks for taking the time to share your experience! - Ben
07-29-2020, 02:37 AM
#12
Rennlist Member
I had a 964 not pass CA smog because CAT cooled after waiting 1/2 hour before test with car not running. I then drove the car a few miles, did some full throttle runs, returned for a re-test done hot without a cooling off beforehand and it passed fine.
OBD 1 993 will show no check engine light with a complete failure of SAI and will pass CA smog.
OBD 1 993 will show no check engine light with a complete failure of SAI and will pass CA smog.
07-29-2020, 10:25 AM
#13
In my opinion, the SAI issue is very overblown. Much like commented above. I'm at 106k with zero indication of any issues. Just got my emissions done last month and passed with flying colors, didn't even warm it up. Sat in line with it idling for over an hour prior to testing. Additionally, the SAI system can be coded out on 96+ vehicles. Another member mentioned that a few months back. I forget the name. Should that happen on my car, I'll go that route and remove the whole system. Everyone loves to jump on the '95 is best because OBDI' stuff but I'd rather have the varioram and deal with a weekend SAI clean job once every decade. Seriously not what I would consider "a ticking time bomb."
07-29-2020, 11:20 AM
#14
Rennlist Member
Two points:
1) The first part of a California emissions check is a "visual" for presence of smog equipment and many test people will look for the SAI system so it is best to leave it intact even if not working.
2) The SAI pump only works a few minutes after start up to pump oxygen into the exhaust to burn off excess hydrocarbon on cold start and warm up the CAT. Air is pumped first too the camshaft housings which have a longitudinal boring about 1/4" in diameter its whole length. From this boring there are diagonally drilled bores around 1/8" in diameter that go through the cylinder head to the exhaust ports where the air emerges into the exhaust gas flow.
My engine had these bores completely plugged solid. As in like stone solid. I had to remove the plugs from the camshaft housing bores and run a long drill through the housing to clear the bore then open the bores in the cylinder heads. A lot of work requiring removal of the induction system, the camshaft housings, the cylinder heads then a reseal of the assembly and setting of the camshaft timing. This is not a trivial service if it comes to this.
1) The first part of a California emissions check is a "visual" for presence of smog equipment and many test people will look for the SAI system so it is best to leave it intact even if not working.
2) The SAI pump only works a few minutes after start up to pump oxygen into the exhaust to burn off excess hydrocarbon on cold start and warm up the CAT. Air is pumped first too the camshaft housings which have a longitudinal boring about 1/4" in diameter its whole length. From this boring there are diagonally drilled bores around 1/8" in diameter that go through the cylinder head to the exhaust ports where the air emerges into the exhaust gas flow.
My engine had these bores completely plugged solid. As in like stone solid. I had to remove the plugs from the camshaft housing bores and run a long drill through the housing to clear the bore then open the bores in the cylinder heads. A lot of work requiring removal of the induction system, the camshaft housings, the cylinder heads then a reseal of the assembly and setting of the camshaft timing. This is not a trivial service if it comes to this.
07-29-2020, 04:05 PM
#15
Rennlist Member
It looks like only certain counties in GA test ( including your county, Foulton) and they also have a 25 yr rule. So if you got say a '96, it would only need to be tested this year after that no worries.
https://www.cleanairforce.com/motori...it%20must%20be
https://www.cleanairforce.com/motori...it%20must%20be