Red_Z

I'm the latest victim of the CEL and P1411 & P0410 error codes. I've read a number of postings including this one that seems pretty informative. http://www.renntech.org/forums/index...howtopic=10184

I do have a couple of questions though.

1) Are the diagnostics around these error codes the same for the non-turbo and the turbo? The link above appears to be for non-turbo, so I'm wondering if there are other things I need to be checking (i.e. diverter valves) in addition to this.

2) Does anyone have any advice on potential culprits based on the symptoms that I am seeing. Reading through these errors, it seems that most say this is just an emissions issue, but I do seem to be having some performance issues.

Symptoms:
- CEL light is on steady (not blinking)
- After clearing the codes the first time, it came back on after driving a couple of more short distances
- The car is very grumpy with cold starts now. Starts right up and idles fine, but when trying to get going it wants to buck and stumble pretty violently. This seems to clear up after 20 seconds or so of driving, but is pretty consistent everytime I do a cold start.
- After warm-up, the car runs normally and strong with the exception that it still seems to stumble very slightly on throttle roll-on between 2-4K rpm. If I go to wide open throttle, it is responsive and runs strong. It idles perfectly. Its just on gentle throttle (like pulling away from a light, etc.) it just seems to hesitate a bit.

I have listened to the air injection pump and can hear it working so I don't think that is the problem.

Advice is very much appreciated!

Dave
'01 996TT
56K miles

Macster

Since you can hear the pump running and based on the symptoms I'd say there's a vacuum leak.

The basic check out of the system at the link appears to match up well with the Turbo. The secondary air injection system is basically the same from engine to engine.

Certainly the visual inspection pointers given could be followed.

Here's what I have but as you can read the instructions primarily assume one has a PST2 handy. However, I think there are a few tests that can be done without the tester.

P1411
208 Secondary Air Injection System, Bank 2 – Below
Limit
Diagnosis conditions
• Intake air temperature 4.5 - 60 °C
• Engine temperature 4.5 - 102 °C
• Mass air flow 36 - 150 kg/h
• Engine starting temperature less than 42 °C
• Altitude correction factor greater than 0.75
• Oxygen sensors 1 and 2 ahead of TWC are ready for operation
• The secondary air injection pump is switched on
• Diagnosis has not yet taken place during this cycle
Possible fault cause
♦ Secondary air injection pump is not triggered
♦ Secondary air injection pump does not work
♦ Air supply lines restricted
♦ Electric change-over valve does not function
♦ Air change-over valve does not function
♦ Vacuum system leaks
Affected terminals
III/11 and III/14


Note! Secondary air diagnosis can be activated with the Porsche System Tester 2 in the "Short test" menu.

Work instruction Display OK If not OK
1 Activate secondary air
pump
♦ Remove relay of secondary air injection pump.
♦ Jumper terminals 30 and 87.
♦ The secondary air pump must be running (audible function).
– or
♦ Connect and switch on Porsche System Tester 2.
♦ Select DME.
♦ Call up "Drive links" menu.
♦ Select "Secondary air pump".
♦ Activate secondary air pump
(audible function).
⇒ Step 3 ⇒ Step 2
2 Check triggering of secondary air pump
♦ Check fuse (Maxi Fuse) of AIR pump (on relay carrier 2).
♦ Remove relay of AIR pump (on relay carrier 2).
♦ Measure voltage between pin 3 and ground
♦ Push relay back on.
Battery positive voltage
Check wire from pin 2 to DME control
module pin III/11 for continuity.
♦ Remove connector of AIR pump.
♦ Measure voltage at pin 1 and pin 2
Battery positive voltage
3 Check vacuum system for leaks
Seal vacuum system
4 Check electric changeover valve
♦ Remove two-pole connector of electric change-over valve.
♦ Trigger AIR pump with Porsche
System Tester 2.
♦ Measure voltage at pin 1 and pin 2
Battery positive voltage
♦ Remove vacuum hose of electric change-over valve with the engine running.
Vacuum must be present

5 Check air change-over valve
♦ Run engine briefly to produce vacuum.
♦ Activate secondary air pump.
♦ Remove vacuum hose of air change-over valve. Vacuum must be present
♦ After activation, check pneumatic change-over valve for continuity
6 Check air supply lines for blockage
Work instruction Display OK If not OK

Sincerely,

Macster.

puma

are the diverter valves stock? I had one of these code and it was the diverter valve

Robin 993DX

Dave,

Sounds like you may have a defective SAI valve, the 996 NA cars suffers the same SAI failure as the 993s. Here is a DIY replacement I did on my 996, not sure if it will apply to your turbo. But could use it as a reference.

http://p-car.com/996/diy/sai/mainpage.html

TT Surgeon

I had the same thing once, a vacuum leak.

Red_Z

Thanks everyone. I'll check out the various valves. On the diverted valves - they are in fact the original stock ones. Is there an easy way to test if they are failing? Would they cause symptoms like I'm seeing with the stumbling?

Macster

Not 100% sure but suspect bad diverter valve(s) would result in either less than max boost (0.7 bar) boost or perhaps too much boost (>0.8 bar). My info is that the boost gage can register 0.8 bar but it is an artifact the real boost limit if everything working is 0.7 bar and this all all I've seen from my 03 Turbo. And anything over 0.8 bar boost is a sign something's not right.

I think if I were you I'd look over the secondary air injection system and to do whatever is reasonable and prudent to eliminate any suspicions you might have about its proper function before you delve into the diverter valves.

That is unless there is some quick test that you can do that can eliminate the diverter valves or confirm one or both are bad. I'm not aware of any but I have not looked into diverter valve trouble-shooting in depth.

Generally, look at what and where the error codes point you first. This hardware or system or area is suspect #1. Fix or eliminate suspect #1 before going on.

Sincerely,

Macster.

puma

diverter valves do go bad anyway, you will need to change them at some point so you might as well change them now and if that is not your problem, consider it as preventive maintenance since you WILL be changing them later down the road.

Buy some that are aluminum, not the stock one.

PorscheDoc

Pull a line off the top of a diverter valve (the back one is a bit tight to get to), and take a 2 foot piece of rubber vacuum line and install it on the top nipple of the diverter valve (5/32" vacuum line works just fine). Suck into the hose. If you can suck through the valve, then it is bad. If it holds vacuum like trying to suck a thick milkshake through a straw, then it is good. If you have more than about 15k miles on your car, then likely the valves are bad, lol. Do not replace them with OEM valves, get aftermarket units IMHO. If you have a mityvac vacuum tester of course you can just use that instead of the sucking method.

Red_Z

Ok. I finally got a chance to check things out. I was able to put a Mityvac tester on both of the diverter valves. The one that is furthest back in the bay (easiest to get to) could not hold a vacuum at all - zero pressure. The one deeper into the bay actually held a pretty good vacuum. So it looks like I'll be replacing the valves. I'm assuming that I should go ahead and replace both at the same time since it sounds like they are prone to fail anyway.

Will let you guys know if that solves things or not.
Dave

Macster

Well, I would not have started at the diverter valves given the error codes but the test you did is easy and relatively painless.

I'm a bit puzzled by how -- if one is bad -- how a diverter valve can account for the secondary air injection system related error codes but there is much about these engines/cars I don't know.

Won't let this stop me though from saving you post for future reference.

Might add to be sure it is the diverter valve that is responsible for the inability of the diverter valve to hold a proper amount of vacuum and not its hose.

Sincerely,

Macster.

puma

i don't know why but i know i had that code and new diverters stopped it from coming back.

Red_Z

I finally got a chance to install my new EVO diverters this past weekend. This seems to have solved the problem. A week of driving later and the error codes have not returned. Still not sure that I understand the connection, but it does seem to be driving better and no engine light, so I couldn't be happier.

Love this forum. Thanks to everyone for the help!
Dave

DaveK

Interesting. My car regularly throws these codes too - perhaps time to check my diverters.

flyingpenguin

I like the idea of getting a better quality part for hopefully a price that does not include the Porsche tax.

More specifically: Can somebody share what brand of aftermarket air change-over valve (and maybe even a part#) would do the job?

JP