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If you have TunerPro set to "View by: Parameter Category," open the section for Idle Air Control (IAC), and you'll see address 275B, Idle Speed Target RPM. This is a table that shows you the target RPM versus engine coolant temperature. If you are using an automatic BIN, it also lets you set different idle targets for neutral gears versus drive gears.
If you have TunerPro set to "View by: Parameter Category," open the section for Idle Air Control (IAC), and you'll see address 275B, Idle Speed Target RPM. This is a table that shows you the target RPM versus engine coolant temperature. If you are using an automatic BIN, it also lets you set different idle targets for neutral gears versus drive gears.
One question, on the Videos showing the data while the car is idling and at 1000 rpm both show the same Knock Count of 4578 and that does not change while the engine is running?
The Oxygen sensors in the your Corvette John look to me like they are staying on the high side in the averaging.
Thanks for your input Chris. I’m sorry I can’t answer your question about the knock count. I’m still new to this. I also saw that valve but have not determined yet anything about it.
My o2 sensors are new and they are GM Genuine. As far as I can tell they are working well.
Cylinder efficiency comparison looks better, what say you? Still a little something going on towards the front. If the upcoming intake gasket change doesn’t improve it, I suppose it’s just engine wear. Valves leaking a tad or maybe a bit of blow by. Although the cranking compression was really even across all cylinders. We’ll see...
Looks roughly like my engine. If the intake thing doesn't fix it it makes me wonder if there's something fundamentally wrong with EEHack's test. Or maybe just all stock LT1 manifolds have garbage balance.
So what exactly do those reported numbers in the test represent? And is the difference reported in this example really all that much?
It's exactly what the description says. The numbers are useless; it's only a test to show you the relative difference between each cylinder. As to whether the difference matters, well...good question. I don't have enough data to say, and I didn't write the program.
If the intake thing doesn't fix it it makes me wonder if there's something fundamentally wrong with EEHack's test.
You might be on to something here. I noticed something when doing the test. Immediately after beginning the test, the PCM starts acting to correct for conditions that the o2 recognizes. When the test starts dropping cylinders one at a time, the overall equation begins changing as the PCM starts attempting to correct. You can see it in the fuel trims if you watch during and at the end of the test.
So I figured through a curve ball at it and I did the test in open loop. I used the control panel to force open loop and tested at 100 degree and 195 degree coolant temps. Here’s the results with the cooler one first.
You might be on to something here. I noticed something when doing the test. Immediately after beginning the test, the PCM starts acting to correct for conditions that the o2 recognizes. When the test starts dropping cylinders one at a time, the overall equation begins changing as the PCM starts attempting to correct. You can see it in the fuel trims if you watch during and at the end of the test.
So I figured through a curve ball at it and I did the test in open loop. I used the control panel to force open loop and tested at 100 degree and 195 degree coolant temps.
Oh wow, this looks WAY better. Okay, I wonder if forcing the car into open loop should be a requirement for the test. I didn't know it was trying to do corrections on the fly despite a clearly incorrect operating condition.
I mean, based on your 195-degree open loop test, I'd say your engine is fine.
I’d like to to note that once I allowed closed loop during testing, pcm made adjustments and I could not duplicate that clean test, even after forcing it back to open loop. I think once the closed loop data stream was in the memory it would take a while to settle it down or maybe even a cool down period to duplicate the clean open loop results.
I hate to keep having to say this, but I don't know. BLMs shouldn't matter in open loop, but I haven't looked into the intracacies to see if there's an exception or something like that.
Though to be honest, I just plain wouldn't worry about it. If all the rest of the parameters look good and it's performing as expected, then I wouldn't be worrying.
Another part of my problems might be my temporary fuel delivery system. Although the pressure at the rail is correct, I noticed the gallon container warming up quite a bit. I’m thinking if I run it long enough and the gas gets too hot is can oxygenate or approach the vapor lock stage.
Obviously the hot gas returns from the rail and into only the gallon jug. If it were traveling back to a 20 gallon tank with much more gas in it, the heat would not build. But let me tell you, it’s building in the gallon jug.
I finally got the intake gasket swapped out. When I removed the intake I could see that the drivers side gasket had slid down slightly leaving cyl 1 and 3 with really small gasket coverage at the bottom of the runners. Very likely to have had a leak here. This time I did not use the Felpro, which did not have the locating pins. Instead I went with OEM GM, with locating pins. The engine now idles smoother and the fuel trims look much better.
