2002 C5 3.0L Catalytic Converter CEL Question
#11
AudiWorld Super User
"Your best way to diagnose is to use vagcom to see real time values and pending codes that are not latching but resident."
Those codes can also be from leaking flex pipes and the list goes on so do your detective work and then come back and report the findings.
4Driver4 is spot on with the CTS if it has not been changed, I'd take his advice too.
#12
Cat codes are they because the car "needs" cats...according to the crappy programming in the ecu anyway.
Poor fuel economy and cat codes are unrelated.
#13
Are there any symptoms of a 'bad' CTS? Can a partially plugged heater core impact the CTS readings? Some loss in heat, performance, and fuel economy this winter.
Last edited by ajg617; 03-31-2014 at 06:19 PM.
#14
Yes sorry to blend the issues but if the cats are ok and won't cause any further damage I am alright with the CEL on. I wasn't sure if poor econ/ foamy oil was a cause/symptom.
I just got in touch with a guy who is going to vagcom my car Thursday.
Is there specific tests that should be done? Sorry I'm not familiar with the software or procedure.
I just got in touch with a guy who is going to vagcom my car Thursday.
Is there specific tests that should be done? Sorry I'm not familiar with the software or procedure.
#15
AudiWorld Super User
in simple terms - the CTS is one of the highest failing parts of our cars , and yet one of the cheapest to replace . i would consider it a maintanance item for every 5 years just to keep it from annoying me.
The CTS will monitor the coolant temp .. it richens the mixture when the car is cold and leans it out as the senses the coolant warm up . depending how it goes bad it can dump fuel in constantly thinking the car is cold. therefore bad fuel consumption and cooked cats.
The CTS will monitor the coolant temp .. it richens the mixture when the car is cold and leans it out as the senses the coolant warm up . depending how it goes bad it can dump fuel in constantly thinking the car is cold. therefore bad fuel consumption and cooked cats.
Last edited by Airbag; 04-01-2014 at 11:55 AM.
#17
AudiWorld Super User
Quote>
So, now that we know that the ECU wants to be able to control the A/F ratio. It has a prescribed set of values (maps) for a given RPM, Load, etc. So, the ECU tells the injectors to pulse for exactly XX.X milliseconds and that SHOULD get us the proper A/F ratio that we want. Well, if you tell an employee to go do something, you want to make sure they actually did it, right? The ECU has some snitches (the front O2 sensor and the MAF, for the most part) that will report back whether or not the desired mixture has been attained. The rear O2 sensor is used mostly to monitor the condition of the catalytic convertor, although in some applications it also contributes to trim information.
#18
AudiWorld Super User
We of course dont know if the OPs are that way but removal and inspection would make it clear. It may be like the 2.8's in A6's and the logic to set the code is too sensitive. Set of oxygen sensor spacers seem to trick them pretty good.
#19
It appears as though you are disagreeing with me? I am stating, for a fact, that there is post catalyst lambda control on his 3.0.
I can happily show you in the factory calibration if you'd like.
I can happily show you in the factory calibration if you'd like.
#20
AudiWorld Super User
If you are referring to the Bosch LSU 4.7 Broadband Planar technology I don't believe it was used on any C5, we do in fact use the (new design at that time) LSU pre-cat sensor and the LSF post-cat sensor system that go back to the Motronic M5.4.2 that Yes suggest the post sensing does play a role in the "Long Term" fuel trim information not "Short Term Directive" considering that no related DTC's exist.
So here is my question:
Why would any engine management system allow more fuel enrichment
under a known cat performance DTC issue leading to more damage?
I'll sign that class action lawsuit all day long!
Last edited by jcman; 04-02-2014 at 05:22 PM.