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YOUR RESEARCHHelp - 02 sensor and fuel trim datastream
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Check ignition coils
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I changed the sparkplugs and checked the coils, but still problems.
Leading evidence: 'Check ignition coils' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Check between pin 1 and pin 2' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
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I cleaned the MAF and the intake, still had codes.
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I replaced on O2 sensor that was loose, still threw codes.
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I changed the sparkplugs and checked the coils, but still problems.
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I ran checks with my Durametric and got several error codes.
Replace converters teh factory reference manual says
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Suggestion
However, before replacing the converters teh factory reference manual says to if the P0420/P0430 error codes are accompanied by any aging O2 sensor codes to replace the indicted sensors then clear the codes and road test the car.
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I am new to this forum and have a lovely 996.1 year 06.2001 (black/black). It has around 75 k miles on it. I have an Dansk sports exhaust system on including manifolds, mufflers and 200 cell cats. The engine pulls strongly and idle is fine.
I have been having an issue with the CEL light coming on ever since I got the car 1,5 years ago. I have had it looked at by Porsche mechanics and thay did run a diagnosis on it but could not really see any faults.
As I don't want to start changing every single part of the entire exhaust and emissions system ((which might be fault less) I decided to buy my own diagnostic scan tool and to start identifying the root cause my self. And now I am here
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Status:
The fault codes are p420 and p430.
I have been doing some datastream on 02 sensors, MAF and fueltrims. To me these data does not show any trouble - but can someone here confirm or not if these measures seems ok?
what do i need to look for in order to solve this issue?
See YouTube link below.
youtu.be/ZGCx-n8ltTA
You're looking at the wrong O2 data. You need to read the post-cat O2 sensor voltage in addition to the pre-cat O2 voltage, which was captured in the vid. The post-cat O2 sensor voltage should stay steady at 0.7v most of the time (other than off throttl). If that voltage mimics the pre-cat reading, your cats are toast.
Without seeing any data, your DME is most likely correct that the 200-cell cats are not efficient enough per Porsche criteria.
thanks. doesn't the first part of the movie (0-035) show all four 02 sensors in operating mode? Pre being fluctuating and post being more stable ? Or am I mistaking ?
I will try doing some new datastreams, looking for what you suggested.
I have cleaned the MAF, new air filter, and the Porsche mechanic tried installing a new 02 sensor and changing the from left to right, but no real idea yet. Problem continues.
Then i mounted the 02 simulators on post 02 sensors but it still throws a CEL p420 and p430. Which to me it shouldn't?
The mechanic dont belive the cats are seized since it did throw both p420 and p430 at the same time and as the emissions test does not show wrong numbers.. mhhh
No, the 4 in your vids are pre-cat sensor voltage and O2 sensing.
O2 sensing is very similar to pre-cat sensor voltage but you still didn't show post-cat sensor voltage. Try to look for "behind cat" PIDs.
Again, you need to read the post-cat voltage to make a conclusion. Barring any exhaust leak, the DME is very accurate in terms of poiting out "bad" cats because it takes many different tests at different load levels and conditions and multiple drive cycles to flag those two codes.
If you clear the codes, do they pop back on fairly quickly like in a couple of days worth of driving?
The tests on those cats are somewhat indepent and can conclude oat different times hence the codes could log at different times.
Not sure what you meant by "emission test does not show wrong numbers". A tailpipe test? What numbers are you talking about?
This behavior is a little bit strange. Usually it takes longer.
The DME doesn't care about the actual emission numbers as it has no way to analyze the exhuast gas for its C)2, NOx contents, etc. It only monitors the O2 level (and how the level changes) using the post-cat O2 sensors.
ok hereby new readings with voltage. 2-3500 rpm fairly hot, done in garage. Remember. I have mounted 02 simulators on after cat sensors - maybe why they read 0.440 volt. But they are fairly steady as I see it. But what do you think?
You Tube
I'm pretty sure the DME doesn't like seeing 0.44v on any O2 sensors. That also explains why your CEL comes up so quickly after reset. I suggest you remove the simulator and install the correct post-cat sensors but with O2 sensor extenders. That should solve your problem.
The DME likes to see 0.6-0.7v steady for the post-cat sensors when engine is idling.
sorry, maybe I wasn't too clear caused by my lack of knowledge - but it is 02 extenders (metal extenders) which is mounted- not a software simulator. And one of the post cat sensors are actually brand new. Don't know which of them however.
I was wondering : If the engine is not at fully operational temperature including 02 sensors when testing - what does that matter to post cat voltage figures? Are they lover then ?
It was poring down heavy today so didn't want to take her out drive but it went idle in the garage for 5-8 minutes before doing the readings...
I will try doing new readings after a 'race around town' when it stops raining to see if that changes anything... mhhh
Thanks allot for all the input so far! Really appreciated
That completely changes the diagnosis. When you run a cold engine for say a few minutes, your post-cat sensors should start to work so the reading should change and not stay at 0.44v. Granted it will take longer that you have an extender but 5-8 minute should be more than enough to make the sensor hot enough to start working.
A constant 0.44v means you either have a wiring problem or the post-cat O2 sensors are toast. You need to remove the post-cat O2 sensor connectors in the engine bay and with ignition ON, check if you get 12v on pin 1 (black wire) on the car side of connectors.
Just a suggestion, check the cap on the oil filler tube to make sure it is tight and there are no leaks on in the tube. Last spring my car started to through CEL's and would run rough ir with a varying/high idle. I ran checks with my Durametric and got several error codes. I would clear them, the car would run rough for a few miles, then even out, then the codes would come back. Every time I cleared the codes it would run poorly for a few miles then even out, then the codes would come back. I checked for vacuum leaks and could not find any. I cleaned the MAF and the intake, still had codes. I replaced on O2 sensor that was loose, still threw codes. I changed the sparkplugs and checked the coils, but still problems. Then I went to add some oil and found the the filler tube cap was not tight. Tightened it and within a few miles the CEL went off and it has run as smooth as butter for several weeks and almost 2,000 miles on two road trips.
Sometimes it is the simple things that we miss. Worth a try.
BTW, also check between pin 1 and pin 2
of the post-cat O2 sensor
with it unplugged from the car. You should see 1.8 - 2.5 Ohm at 20C. That verifies the heating element.
I agree- my experience so far, sending the Porsche to an Porsche mechanic is a high bill but without actually finding the root cause. So I decided to buy my own code reader and try figuring out the root cause. I hope I succeed with it. So far I will start measuring voltage on the wording as suggested I will look into your advice too, thanks
I was in doubt if the previous test of 02 sensors (volt) was completely correct as the car only sat in garage 5-8 minutes to achieve full operational temperature on the engine, 02 sensors and cats. (And i can read that if engine is pr 02 sensors are not fully in operational temperature the 02 volt will be sat to around 0.44 volt by the CPU until proper temperature is reached - is this correct?)
However today I had a window to do a proper long drive and Theo do a test today - and now the data are a different story. The post 02 sensors dies no longer stat at around 0.44 volt. I have added links to both 02 sensor data in volt and Fueltrim values.
I am however not so happy with the test result of the 02 sensors I think. Remember I have 02 extenders mounted for the post cat sensors. The post 02 sensors seems to fluctuate- as I understand this is or could be a sign that the cats are toasted.
But what do you read in the New datastream and Can we conclude anything on these measures yet? Maybe some more tests?
You Tube
You Tube
i only owned the car for like 1.5 year (don't drive winter) and it had the cel light coming on ever since and I have had it investigated by a Porsche mechanic who couldn't find the foult which puzzles me looking at the data I am now pulling out of my own OBD2 tester.
I don't know if previous owners did some of the things you mention but I wouldn't think so . I am not sure when the sport system was installed. Guess for around 80.000 kilometers ago looking at info I have on the car.
I have seen others complaining that the Dansk sport cats don't last so long so maybe they just got tired over time - if they are toasted that is
Here another test I did today now with graphs + data - graphs are however quite tiny. Engine fully up in operational temperature and at 2500-3500 rpm. 3 minutes test. Cell 420+430 by the way came up again today since my last test, where I erased it.
You Tube
P0420 and P0430 arise because the converter associated with the error code is not operating up to full efficiency. The converter is not able to store oxygen.
However, before replacing the converters teh factory reference manual says to if the P0420/P0430 error codes are accompanied by any aging O2 sensor codes to replace the indicted sensors then clear the codes and road test the car. Then if the converter error or errors return replace the indiciated converters.
Normally provided there were no O2 sensor error codes I'd offer the converter or in this case converters are toast (been through this with my 2002 Boxster) but the presence of post converter O2 extenders makes for a more complicated diagnosis.
The #2 O2 sensors want to be and should be in the factory exhaust system right at the optimum location to sample the exhaust gas from the converter. The sensors need to be hot and proper positioning is critical.
With extenders all bets are off. Usually extenders are used with aftermarket converters. Have you tried removing the extenders?
Be sure the exhaust system is leak free.
Last but not least with some OBD2 code readers/data loggers/data viewers you can run some DME resident O2 sensor tests and from the results of these tests often identify O2 sensor problems.
ok thanks for the input. Just to be clear: It is an aftermarket exhaust sports system from Dansk. I however guess this doesn't change the fact that the extenders might jeopardize readings in some way - how I don't know. I had the same cel 420 and 430 coming on before I mounted them, so guess chances are low, that I would not have fluctuating 2nd 02 sensor readings without them.
I however also wondered if the extenders would jeopardize the data so might be worth a try to unplug these and do a new reading. I think the probability that the cats are toast is very high - based on all the input from you guys and my growing knowledge of functioning of 02 sensors. Will test for exhaust leaks and maybe dismount extenders - last try before new cats. Thanks allot for all inputs.
