Help with CEL - 986 Forum - The Community for Porsche Boxster & Cayman Owners

Jeffkay1967 · 11-18-2017, 11:19 AM

Hi, My problem started with my 1997 986 with code p1126 and CEL. I determined the AOS was bad (oil in j pipe to intake, oil filler cap vaccum extreme). I replaced the AOS and the auto-topsy showed the diapharam was ripped in two places. So i assimed this would be the last of the problems but the CEL returned this time with secondary air pump code p0410. I thought maybe the problem was from a vacuum leak i caused when breaking the brittle oil dipstick tube. I sealed that and can find no evidence of any vacuum leaks. After this the CEL came back. This time at around 70mi. I actually heard the secondary air pump start (i was driving, not starting cold) amd suddenly the light went on. This time i got p1126, p0410 and p1411. The pump starts in the mornings and runs the minut or so. I cant find any leaks. I thought maybe i knocked something when putting in the AOS which now i dont even know if it caised the original problem. I am thinking to rig some kind of smoke test but thought i would post this and see what you all think...

JFP in PA · 11-18-2017, 12:18 PM

P1126 indicates a possible vacuum leak on bank 2 (overly lean condition)
P1411 indicates a secondary air injection fault on the same bank (signal implausible)
P0410 is the same secondary air fault on the other bank.

Possible fault areas are a wiring harness problem, air supply lines are restricted or blocked, a fault with the electric change over valve, or a vacuum leak.

You need to do some digging................

Gelbster · 11-19-2017, 08:03 AM

Those of us who have been digging in the SAI rabbit hole would tell you the problem is access. Renntech has some excellent threads with diagnostics. A lot of dismantling and part removal is required to do a really thorough job. Anything less may result in a re-do. Consider replacing all the vacuum lines with good quality silicone hose and brass fittings. There are 2 valves to check - buried behind the alternator and the vac accumulator(leaks in the base?)
One awful issue often overlooked is that the SAI ports in the cylinder heads can become plugged with carbon.
Good luck !

boxfix · 11-21-2017, 06:52 PM

I had the same SAI code problems.

I found that the check valve on my 2003 had fallen out of the rubber manifold. I fixed this with a brass barged fitting that I plugged into the rubber manifold and they used a piece of high temp silicon tubing to connect it to check valve.

I also found that the vacuum reservoir was leaking. This is a common problem. I tested the installed reservoir with a vacuum pump and gauge. It would not hold vacuum. A new reservoir is a little more than $20. I installed a new one and hooked up a vacuum gauge to the system and pulled 16 Hg to 19 Hg. Which is good and where it should be.

With these fixes my vacuum problems were cured.

Jeffkay1967 · 12-07-2017, 11:19 AM

UPDATE: Took out passenger side intake manifold. Found vacuum check valve was disconnected from hose for secondary air. The valve was also passing a bit of air both ways so I replaced it for 17 bux. Seems to have solved it so far at 104 miles (past drive cycle). To get to intake manifold head bolt by firewall, reach around with your hand. You do not need to take off cabin firewall access panel.

Jeff

chemistone82 · 04-09-2018, 11:46 AM

Quote:

Originally Posted by Jeffkay1967

UPDATE: Took out passenger side intake manifold. Found vacuum check valve was disconnected from hose for secondary air. The valve was also passing a bit of air both ways so I replaced it for 17 bux. Seems to have solved it so far at 104 miles (past drive cycle). To get to intake manifold head bolt by firewall, reach around with your hand. You do not need to take off cabin firewall access panel.

Jeff

What was your method of fuel rail removal? I'm wondering why everyone goes behind the alternator to fix this? Seems like there is much better access to check/fix by intake removal

Boxstard · 04-10-2018, 05:56 PM

I hated SAI fix... took TB and intake manifolds out for full access to replace two bad metal valves, whatever they call them, rubber diaphragms were deteriorated into goo. At least I did vacuum lines rigged up to control PSE exhaust valves while driving was there and also cleaned up all intake path and reattached that helmholz chamber thing that was kinda hanging loose...

But now feeling good every time that SAI cycling completes without annoyed by CEL and keeping emission low! Well it did come on once about a year after the fix but luckily it was just a blown pump fuse in trunk.