sigh.. CEL
 

car running fine with no problems.. got home from work last night, washed it and stored it for the weekend... (change in weather overnight.. lots of rain and overcast now). go to run some errands today and about a mile from home, the CEL comes on, but car is running fine. It is a solid CEL and not flashing...

I am trying to get a hold of a OBD scanner at the moment but I am nervous driving with a CEL on.. is it safe/stupid/bad for engine if i drive with a CEL?

i have noticed lately that sometimes, about 10 seconds after starting the car, the idle would "hunt" for a second or two around 500rpms and then slowly "normalize" itself and run fine...

please don't say MAF :)

Man that sucks. Go to an advance auto parts and ask for a scanner. They can scan it for free and give you the code. The hunting thing with the RPMs, I've noticed that on mine to when there isn't a CEL so I'm guessing that's normal.

Don't panic. A solid CEL is something that needs attention but no immediate danger to car or driver. Get your codes read ASAP and report back here along with year, model, mileage, and any recent work or mods done.

I've driven for 3 months with a CEL.. but then I know why its on.
If it starts flashing... shut it down!!

ok, ended up buying a reader (only $59 at AutoZone) and got the codes:

Car Specs:
2000 non-S
no mods
54k miles
oil change 3k miles ago
no other issues with car

Codes are:
0410 and 1411

which appear to be (respectively):
P0410 Secondary Air Injection System - Signal Implausible (Cylinders 1 - 3)
P1411 Secondary Air Injection System - Signal Implausible (Cylinders 4 - 6)

is this an MAF issue or something simpler? I bought maf cleaner while i was there, but would like to not have to dig into the engine compartment if unnecessary.

thoughts?

Same codes I have!!
Look at the post called Help!
You probably need a new air pump valve and new switch.


http://986forum.com/forums/showthread.php?t=21780

I erased the codes using the reader and then restarted & let the car run for about 15 minutes (minor revs throughout) and the light did not return.

now, I'm smart enough to know that this didn't "fix" the problem, but has put me at ease for the time being... good to know I can drive with it if I need to as well.

I am taking it in tomorrow for non-related routine maintenance anyway so I will have my guy check it out as well.

*stupid question warning*

would washing the car and getting water in a "no water zone" cause this? I did manage to wash EVERYTHING and probably aimed the hose in some wrong places... just a thought, but curious.

thanks guys

Washing the car won't cause this. Just a stuck valve or a vacuum leak not allowing the valve to fire.

If you happen to change these before me... please take some pics of the job.
Good luck

Flow chart for diagnosis
 

Link

Could be any of a half dozen things, probably an air leak.

Good flow chart with diagram Mike.

Probably not MAF related. If the problem occurred soon after a little invasive washing you may have gotten the pump or a relay wet and toasted a fuse. Real easy fix. Also check for loose or damaged wiring to the air injection pump. The "signal implausible" term is a weak German/English translation for "open circuit" or "no signal" from the sensor.

Good luck with your fix. Definitely not the end of the world.

was kinda hopin' it was an MAF problem now lol.. seems like an easier fix.. the word "pump" makes me think $$$...

anything I can fairly easily self-diagnose (the fuse you mention) before taking it in tomorrow?

so yesterday i made a quick run to the ice house after clearing the CEL to see if it would come back. when I started it, it BARELY started!!! what the... like OVERNIGHT my car went from fun as hell to omg i hope i don't break down...

so.. i drive it to work today and when i started it this morning, i see this big puff of white smoke! i know i know, but this isn't the normal white smoke, larger puff than normal, and it did the "sputter" thing like it was hunting for the right idle, then it normalized... still no CEL, idled ok i guess.

i've been reading a lot about the different possible causes and what all is involved with replacing certain items. im pretty sure i hear the "small hoover" sound at startup that is supposed to be the air pump, but one man's hoover is another man's "whirring" or "whining" so im not sure if it's the right noise..

How much would a new air changeover valve (exact name?), AOS, and electric changeover valve cost to replace? parts only.

also, i have read that the alternator needs to be removed for the air and electric c/o valve (ugh.. bad memories there) so how many hours of labor would replacing these 3 items take?

anything else I should have my mechanic check while he's in there?

996-605-123-01-M244 Change-Over Valve for Air Injection, 993 Carrera 2/4 (1996-98), $23.50 Pelican parts

993-113-245-01-M100 Cut-Off Valve for Air Injection, 993 Carrera 2/4 (1996-98), Each, $104.75 Pelican parts


But your description sounds a lot worse.

I have a 2000
anyone know the EXACT part I need (a link would be awesome, not particular about vendor, just price)

I think I'm going to tackle the AOS myself and see if that fixes some of it...

I would like the AOS itself (the revised version if it will work for my car)
and possibly the tubes or other parts I might find myself needing during the install.

2000 non-S, 52k miles, Tiptronic

Thanks!

Gentle suggestion,
Use the TS flow chart and pinpoint the failure first, then fix the problem. Changing the AOS or the MAF might be fun but it will not fix air injection pump issues. Did you check for a blown fuse? Your manual will show location and fused circuits ID. It really could be that simple.

opened it up tonight to see if there was oil everywhere and it isn't too bad.. i have oil here:

i'm having it looked at tomorrow and was wondering if it's safe to drive to the mechanic

ok, so had some diagnostics ran, found out the oil separator was bad and had a vacuum leak... replaced the oil separator and now no more smoke and no more CEL's, BUT I still have a scary hunt for idle on startup...

tonight was the worst... started it (starts fine every time) and it started hunting right away, usually it will "catch" itself after like 5 seconds, this time it went on for a good thirty seconds and I heard some (hate to use the word "knocking"), but it sounded like the cars in the movies that run out of gas... heard it about 3 times (sounded like a "burp" or loud "gurgle" if that makes sense)

it only started doing that if i lightly rev'ed it to get the rpm's up.

mechanic said it might need some time after the AOS replacement to get back to normal.. but I had never heard my car make those noises before and the idle hunt was exactly the same as before the AOS replacement, just no smoke..

ONLY 53k miles!! WTF! i lose faith in Porsche's dependability a little bit more every day... when they're working, they're a blast, when they're not, it's the biggest pain in the ass.. and it seems like way more frequent than on other cars.. what gives??

EDIT: could this also be caused by the MAF? I was going to attempt a "clean" before I had my mechanic do the AOS.. should I still do it? What is causing this wicked idle hunt?

Its time for you to step away from the car and take a couple nice, deep relaxing breaths. You are getting wound up too much about the car.

Yes, it is possible that it is the MAF sensor causing the issue, BUT you would be better off if you first started by cleaning the throttle body, since you had an AOS failure, there is bound to be lots of carbon build up on it.

I am sure that once you clean the throttle body, your hunting will be reduced, if not eliminated. If you want, you can even buy some MAF cleaner, and spray it down, too.

I have a '98 with nearly 89k miles on it, which I bought back in February, and I've put on 10k of those miles myself. I just had to replace the MAF yesterday on my car, because it went bad, and set off the P0102 code, and I checked its functionality with my Durametrics program, and saw that it was out of spec. That cost me $180 to replace, but its the first actual problem the car has had in the 10k miles I've put on the car.

I'm just glad I bought the Durametrics tool back in the summer so that when I needed it, there it was. If you don't have that, you might want to invest in it, if you are mechanically inclined, that is.

BC.

maybe I will try tackling the TB and MAF cleaning tomorrow. I actually bought a can of MAF cleaner when I bought the scanning tool in preparation for the MAF clean so all set in that regard.

just.. the sound it makes at startup is SCARY lol... you know when you have a water bottle and you blow back into the straw to make bubbles, that's kinda what it sounds like, but ONE big bubble.

it did it again this morning, started it, let it run for about 5 seconds until i heard it happen, turned it off immediately, then restarted it immediately and it was smooth??? confused

really hope it isn't internal engine problems or something and something eas(read cheap) to fix

the fact that it runs great (even feels better now that the AOS was replaced) when it is warm means the internals should be fine right?

the startup thing is my only issue and after that "burp" i smell a STRONG gas smell from the tailpipe.. I had read that maybe its the air change over valve? I don't want to ruin the cats...

checked and "cleaned" the MAF yesterday and it looked brand new. car is running top notch. go to start it this morning and minor hunt at idle again. last 3 cold starts were perfect, no hesitation or hunt at all.

half way to work, CEL comes back on (after 3 days of solid driving). Car is running great though.

so I guess my next step is to have the Air Change-over valve and the Electronic Change-over valve replaced.

I had read elsewhere that the Tiptronic models have an extra vacuum valve or something that can also go bad... since it requires taking the alternator out to replace these, I want to replace as much as possible all at once.

what can i expect to pay in labor? and should i replace the seconday air system hoses as well?

I have had all the same fun and games you are describing with my 2000S. It turned out to be an MAF on the way out and a pair of oxygen sensors in a really bad way, one so bad that that bank was bringing up misfire codes. When I replaced both the MAF and O2 sensors it was back to normal.

On a side note, if your car has been doing this for some time you may want to check the catalysts for damage. I switched to bypass pipes when I replaced the sensors as it was a less expensive option than new cats. I am now catless, as in Australia we only have to run one set of cats so the Boxsters only have the main cats and one set of O2 sensors.

Good luck.

this all started within about a month.
tonight on the way home from work, i threw another code (only 1 this time)
p1128 which looks like a rich threshold on banks 1-3

i'm suspecting some kind of vacuum leak at this point but will have to dive in tomorrow morning. how does a "driveway mechanic" spot a vacuum leak? any tricks?

i was all ready to just have my air changeover valve and ECO valve replaced, but this code might indicate something different. I scoured the net, but haven't found too many people with just the ONE code, many had the accompanying 1130 code. What does having one code indicate?

*thanks for all the help and suggestions, hopefully i'll get her running top notch again soon*

I believe if you look for a vacuum leak, you will be looking in the wrong direction.
I believe that this code is going to point more in the direction of the two O2 sensors on that bank of the exhaust going bad.

When the exhaust passes through the headers and past the O2 sensors, the computer receives a signal that tells it if there is or isn't alot of Oxygen in the exhaust. If there's too much Oxygen, then the computer richens up the mixture. If there's too little, then the computer leans out the mixture.

Right now, the O2 sensors are saying that the one bank is running too lean, and the computer can't richen up the mixture for that bank any more than it already has, hence the CEL being lit.

If you replace those two O2 sensors, that will most likely resolve the issue.

Some recommend just replacing all 4 at the same time for the best results.

BC.

consensus seems to be that it is the O2 sensors that are REPORTING the problem, but are NOT the problem. They don't really affect the mixture, they just report it.

You're most likely going to find out that your impression is incorrect.

If the sensors are faulty, then they will send the wrong signal to the computer, which causes the computer to richen the mixture.

Here, try this:

Switch the O2 sensors from the left exhaust to the right exhaust, and vice-versa.
If the problem follows the O2 sensors, then my suggestion is correct.

If the problem stays with the bank, then you are on the correct path.

It won't cost you anything more than about an hour's time to swap the sensors, and a day to drive the car around.

BC.

sounds logical. i'll give that a try! googling some more and I keep coming across people stating the MAF.. yada yada... When I looked at mine, it looked BRAND NEW! Does a failed/failing MAF have any visible signs of failure or do they just "not work" after some point? also, during reinstall of it, could that have introduced a vacuum leak where it connects? I've read that if you get BOTH codes, it is most likely the MAF, one code and it means something is wrong on that side... (might go along with the 02 sensor theory, but i haven't had ANY indicators up to this point that an O2 was on the way out)

Also, and this may be far-fetched, but I have been using 92 octane (Valero) gas for the past few weeks only because my Shell (only 93 octane in town) is not on my daily route. Could this cause some kind of lean issue as well?

Would filling up with 93 and maybe some additive do anything for me?

Well, I just changed my MAF on Friday.
The old one was just as clean as the new one I put on.

In fact, when using the Durametrics program, I was getting the same Air Flow readings and Air temp readings with the new sensor as the old sensor. The only difference was in the Voltage reading, which was 1 volt constantly across the rpm range, while the new sensor increases as the rpms rise.

As for the gas, it would affect both banks, not just one.

If you wanted to get technical, we could break down the different fuel systems piece by piece:

MAF sensor - tells computer amount of air being ingested by the entire engine (doesn't differentiate between cylinder banks)

Air temp sensor (in MAF) - Tells computer temp of air being ingested by the entire engine (doesn't differentiate between cylinder banks)

Throttle body - Controls amount of air ingested by entire engine (doesn't differentiate between cylinder banks)

Vario-cam valve timing - Adjusts opening and closing of valves in relation to crankshaft position and engine speed. Both banks are activated at the same time at certain rpm points, but controls just an individual cylinder head. Should not affect fuel mixture in any way.

Fuel injectors - Each one is assigned to a cylinder. If one was sticking open, could cause a bank of O2 sensors to report an error, but would also be associated with a cylinder misfire, and bad engine performance. (opposite of what you are experiencing)

Spark plugs and Ignition coil sticks - One per cylinder. If one is failed, cylinder misfire, bad engine performance, and too rich of a mixture would be reported on that bank of cylinders. (opposite of what you are experiencing)

Cat converters - Two per bank - the second set of O2 sensors will be able to point out if the primary cat converter is not scrubbing the exhaust optimally.

O2 sensors - Two per bank. First set of O2 sensors controls the mixture as the computer uses its signal to determine the Oxygen content of the exhaust stream. Second set is primarily used to check the efficiency of the cat convertor, and determine if it has fully warmed up, based on the differences between the two sensors in that bank.

The O2 sensor swap is probably your best bet for quick and easy, with no cost involved.

BC.

wow great info!

ill try to swap them when i get home tonight.

any thoughts on what the "thunking" sound is on cold starts? like hitting the side of an empty 50 gallon drum with a hammer.. or a low steel drum.. i hear it randomly about 3 times on cold (not driven in 10+ hrs) starts, if i turn car off and then restart, it's fine, but idles at 1k steady. When i put it in R, it goes down to 500 like normal.

That I don't know.
I would have to hear the noise from the cabin to hazard a decent guess.

Personally, I would check the condition of the engine mount first, because if it is really bad, the engine could be flopping around when the engine cranks to life. That's easy to do just by removing the engine cover, and driving up and down the street in first gear, flooring the car to see how much the engine moves.

Do you park on a slight incline of decline when it makes the noise?

BC.

flat surface when parked and Tiptronic trans. I might try cold-starting it with the engine cover off and viewing it topside to see if I can better place the source of the noise. Wouldn't I hear the noise on warm starts too though if it was the engine mounts?

seen a lot of posts recently about engine mounts so I was getting curious about mine.. I might try to get a "look" at them if it is even possible without dismantling stuff.

Again, I had more or less the same problems. The new O2 sensors fixed everything. I actually could not believe how much the computer relies on their readings for the air fuel mixture. If they are bad they also throw other electronics out and cause multiple error codes.

Try changing them and see what happens.

it's back!

car running fine for quite some time (since last post) with no CEL (only thing is it seems like the idle might be high at startup, 1k)

driving to school like normal today and raced a yellow light :)
when i stepped on it (read, accelerated real fast) about a minute later, the solid CEL came on... I haven't had a chance to read the codes yet, but I will when I get out of class

again, I started scouring the net for symptoms.. I have a pre-existing exhaust leak that is "minor" but should be noted. Is there any way to "bench test" an MAF? mine looked brand new when taken out to inspect, so I'd hate to replace a good one..

also, my mechanic has offered to smoke the exhaust system and attempt to fix the leak.. what does it cost to have this 'smoking' done?

thanks!

EDIT: I should note that the AOS was replaced since last post as well. Wasn't sure if I mentioned it. No smoke is present now.