Problems with SAI, CEL codes P0410 + P1411

[MagnusO]

My 1999 C4 Cab threw a CEL a couple of weeks ago. Codes were P0410 and P1411, indicating a problem with the SAI or secondary air injection system. I read up on the forum and found many helpful topics related to these codes, and who the likely culprits were: SAI pump or either of the two valves that regulate the flow to/from the engine. I could check the SAI pump myself and it was working fine, so I assumed the problem lied with the valves.

 

I decided it looked too complicated for an aspiring hobby mechanic to tackle (lots of vacuum hoses and stuff to remove) so I took the car to my trusted independent Porsche specialist for them to fix.

They have now spent a fair amount of hours diagnosing and trying to pinpoint the problem. Apparently the valves were working fine as were the oxygen sensors, but the airflow to one side of the engine was restricted when compared to the other side. This imbalance was likely enough to trigger the CEL in their opinion.

 

The solution they’re offering consists in removing the heads on both sides and do a deep clean & decarbonization of all the cylinder heads, ports, and air passages. This should bring the airflow back to normal and cure the CEL. No parts are involved, but it is a fairly labor intensive job and will run me upwards of $2,500 + tax.

 

I plan to sell the vehicle and want it to be in perfect shape so my question is if it is worth the money to fix this? Are there alternative methods that could be used and that my shop could consider? Anyone has prior experience with something like this?
 

If I were a braver man I would probably attempt this job myself but I’m not so looking for your advice... :-)

 

 

[judgejon]

I feel your pain. 
but just curious, would a Durametric check have cleared the codes?  Is this just a freak occurrence?

I’ve never read about this one.  New Porsche mystery to me.  Others will likely have some substantial answers.
Good luck. 

[MagnusO]

The shop has the Durametric and a Porsche Gold Meister technician on staff, so I’m confident they’ve tried to simply reset it. The most likely culprit is gunked up inlets on the cylinder heads causing a restricted airflow, or that’s what they tell me. The car has just reached 100k miles and it is not uncommon for them to get this way apparently. It’s 15-16 hours of labor to disassemble & clean everything, hence the cost.

 

Since I plan to sell it soon I’m leaning towards biting the bullet and making sure the next owner gets a clean engine. We’ll probably do gaskets and other stuff while we’re in there too.

 

I’m hoping someone on this forum has managed to clean these inlet ports without having to disassemble everything and is willing to share the method, but I know it’s a long shot...

[DBJoe996]

In my opinion, the secondary air injection system is a bandaid to USA emissions control and should be entirely eliminated.  You should consider the cheaper alternative of having the ECU/DME programmed for ROW (rest of world) coding to eliminate/ignore the SAI system.  Try the ECU Doctors...they can do it.

Specialized ECU Repair, Replacement Testing of Electronic Control Unit

WWW.ECUDOCTORS.COM

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Porsche, BMW, Ferrari - We'll make any used ECU work - Send us your damaged ECU and we'll TEST and REPAIR your unit and send it back to you with our 5 YEAR WARRANTY.

 

Edited July 16, 2020 by DBJoe996

[mdreef]

I have a 2001 996 Cabriolet with 140,000 miles and I continue to love my weekend driver.  However, I've been fighting CEL P0410 and P1411 for months!  In fact, my state inspection is due soon and I'd like to get this resolved once and for all. 

 

With the exception of the SAI pump, which is still operational, I have gradually replaced every component associated with the Secondary Air Injection System.   I thought I was in the clear after driving over 800 miles without the CEL, which I achieved by finally replacing the vacuum reservoir, which was leaking.  I replaced all vacuum lines, rubber elbows, Y connectors, electronic change over valves, check valves, shutoff valve, EVERYTHING!  As part of other CEL crisis situations I also replaced the AOS, the camshaft position sensors, timing chain guide rails, catalytic converters, o2 sensors, and a number of other sensors while I was in there.

 

The past couple of days I noticed that during a cold start the engine would start normally, except it would immediately rev down once to almost stall and then stabilize to normal warm-up RPMs.  I didn't think anything of it until my friends CEL P0410 and P1411 came back!  I cleared them and then the next cold start the CEL came back immediately.  Usually the CEL registers after driving over 60 miles, which causes me to wonder why it was immediate this time.

 

I sure hope that I don't need to pull the engine again to perform the recommended "cleaning" by MagnusO's mechanical team.  Does anyone agree with their recommended solution?  I'm a bit suspicious of it because the openings through which air is supposed to flow are pretty big, and it would take a great deal of carbon build-up to clog them up - am I wrong?  That's just my thought, but if it is indeed the cause, then I supposed that's the only thing left for me to do.  I will pray for someone to reply with a better solution (PLEASE!)

 

I've thought about the SAI delete option recommended by DBjoe996 but I'd like to keep my car as stock as possible.

 

Thank you for your guidance everyone!

 

 

 

[MagnusO]

For clarification, they're not entirely clogged up, just enough to have the airflow differ from one side to the other. It is that difference that triggers the CEL. I have given the indy permission to proceed with a cleaning and will report back on whether it worked or not. 

[judgejon]

Good luck. 

[mdreef]

3 hours ago, MagnusO said:

For clarification, they're not entirely clogged up, just enough to have the airflow differ from one side to the other. It is that difference that triggers the CEL. I have given the indy permission to proceed with a cleaning and will report back on whether it worked or not. 

Thanks for the clarification - I hope your investment pays off for you - which for me sounds like I might be in for another big project if it fixes your problem.  Thanks again!

 

[mdreef]

One additional thought for my CEL is that I noticed the clip that connects the upper AOS tube (#5 in the diagram) to the AOS is broken. This means that the o-ring is likely not making a positive seal.  Could this be the cause of a vacuum leak that would affect the SAI system?

 

 

[MagnusO]

I'm sorry but I have no idea, I'm not a mechanic... My indy mechanic says they tested all the vacuum lines & reservoir before resorting to the cleanup method. We will know soon enough if it worked I guess.

[DBJoe996]

15 hours ago, mdreef said:

One additional thought for my CEL is that I noticed the clip that connects the upper AOS tube (#5 in the diagram) to the AOS is broken. This means that the o-ring is likely not making a positive seal.  Could this be the cause of a vacuum leak that would affect the SAI system?

 

 

Yes, that could cause a vacuum leak.  Probably not an issue/problem for secondary air injection.  SAI pump runs and pumps air (positive pressure) into the exhaust system to light off the cats.

 

[mdreef]

14 hours ago, DBJoe996 said:

 

I have a feeling the vacuum leak would keep the system from creating a vacuum in the reservoir, which is required for the change over valve and shutoff valve to work.  I went ahead and ordered a new upper tube and will post an update if this takes care of it.

[judgejon]

Good sound move. 
When in doubt do the suggested fix. 
Cheaper in the long run, and nice peace of mind. 

[MagnusO]

So, picked up the vehicle today. No CEL and it runs beautifully. Have driven it through 3 cold starts and 80 miles so far, so I figured if the light was going to come on it would have done so by now. Total cost for the cleaning was $2,300 and it was pretty much all of it labor cost + a couple of gaskets & cleaning liquid. The work involved taking off intake manifolds and heads, and clean up all the ports, valve seats, and other areas through which air passes. Once the job was done the shop took it to get an emissions test done just to be 100% certain that the problem was solved, and the vehicle passed with flying colors. The fix was a bit on the expensive side perhaps, but I'm happy that my mechanic took his time to diagnose it correctly and not just throw parts at it. 

[judgejon]

Sounds like money well spent. 
Enjoy the ride !!!