Quote:
Originally Posted by porschefan76
Yes, I agree. As you pointed out though, the downstream O2 sensors do look like something is up, so I won't ignore them.
The MAF appears to be operating properly, 15 kg/hr at idle and the Voltages looked about right last time I pulled data. I pulled some data on my test drive after changing the fuel injectors but I was in a rush and I'll need to pull more. Will pull MAF, O2, Fuel Trim and Engine Load data next test drive after I test cats, smoke the intake and replace the spark plug tubes.
Thanks again!
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A test I do is compare MAF signal to Throttle position sensor signal.
There is a direct correlation between the two.
I hook up my Durametric and put the MAF signal and the Throttle position sensor signal on the same Graph. Then I take the car for a good long drive.
I set the laptop on the passenger seat so I can watch the two signals.
What you should see is the two signals paralleling each other. The TPS signal is slightly smoother then the MAF but by very little. That just the difference between air movement generating one signal and mechanical movement generating the other signal.
So you should see Both signals following your foot so to speak. If your very smooth on the throttle both signals should increase with the same smoothness. If you floor it both signals should react the same way. If your smooth on the throttle or holding a steady RPM both signals should follow each other. If you see something erratic in the MAF signal when your throttling smooth or holding a steady RPM then there is an issue with the MAF.
I do this with my car over a 52 mile loop. Gives me every driving condition one would ever encounter. City stop and go, to country flat out, hills, curves the works.
Actually a fun test to do.