Engine Running Parameters

[minny]

I previously posted about my Tiptronic gearchange being slightly jerky and sometimes its as if the ignition is not momentarily retarded during the change. Although no CEL present, on the durametric it picked up one of my O2 sensors was impaired so I changed both and the gearchange is much smoother. Obviously the affected fuel trims were affecting power and the retarding of the ignition during a gearchange. I would like to know if anyone has any information on the short term and long term fuel trims at idle so that I can see if my MAF is working at optimum state. Also what should the load be at idle which should indicate the state of the MAF. If not I might clean it or replace it. I've read the threads on cleaning it but some have advised against it in case it gets damaged. At least with the parameters I can see what the engine is doing before I do anything. My car now has no recorded codes but I've had others where the O2 sensor and MAF have been dodgy but still working enough for a CEL not to light. I live in UK where the ECU is less sensitive to emission issues than USA i.e less likely to light the CEL initially.

[vizcarra44]

I previously posted about my Tiptronic gearchange being slightly jerky and sometimes its as if the ignition is not momentarily retarded during the change. Although no CEL present, on the durametric it picked up one of my O2 sensors was impaired so I changed both and the gearchange is much smoother. Obviously the affected fuel trims were affecting power and the retarding of the ignition during a gearchange. I would like to know if anyone has any information on the short term and long term fuel trims at idle so that I can see if my MAF is working at optimum state. Also what should the load be at idle which should indicate the state of the MAF. If not I might clean it or replace it. I've read the threads on cleaning it but some have advised against it in case it gets damaged. At least with the parameters I can see what the engine is doing before I do anything. My car now has no recorded codes but I've had others where the O2 sensor and MAF have been dodgy but still working enough for a CEL not to light. I live in UK where the ECU is less sensitive to emission issues than USA i.e less likely to light the CEL initially.

In the U.S. the mass sensor value should be around 17 to 19 max on the Kg/hr at idle, your Oxygen sensing Lambda value should be around .98 to 1.05 and your Rkats should be no more than 2% positive or negative, if your reading short and long term values on your tester, then short should not pass 10% positve or neg and likewise for long term.

Vizcarra44

[Loren]

I previously posted about my Tiptronic gearchange being slightly jerky and sometimes its as if the ignition is not momentarily retarded during the change. Although no CEL present, on the durametric it picked up one of my O2 sensors was impaired so I changed both and the gearchange is much smoother. Obviously the affected fuel trims were affecting power and the retarding of the ignition during a gearchange. I would like to know if anyone has any information on the short term and long term fuel trims at idle so that I can see if my MAF is working at optimum state. Also what should the load be at idle which should indicate the state of the MAF. If not I might clean it or replace it. I've read the threads on cleaning it but some have advised against it in case it gets damaged. At least with the parameters I can see what the engine is doing before I do anything. My car now has no recorded codes but I've had others where the O2 sensor and MAF have been dodgy but still working enough for a CEL not to light. I live in UK where the ECU is less sensitive to emission issues than USA i.e less likely to light the CEL initially.

In the U.S. the mass sensor value should be around 17 to 19 max on the Kg/hr at idle, your Oxygen sensing Lambda value should be around .98 to 1.05 and your Rkats should be no more than 2% positive or negative, if your reading short and long term values on your tester, then short should not pass 10% positve or neg and likewise for long term.

Vizcarra44

According to Porsche the acceptable range at idle (engine warm, no AC, etc.) is 12 - 24 ML in kg/h.

[minny]

Thanks guys, always amazes me the amount of information available on Renntech