| :THANKS A TON! I have posted this info several times with no luck! Do you have a program that changes these into graphs? If not, you have an incredilbe ability to read these in table form! I use excel for graphing like in this case. I also use LabVIEW but more for software applications. When I get a little time, I'm going to write a TP trace program which reads conZult logs and a 32K bin file and performs session based TP traces over the fuel and timing maps. :I have tested for leaks a lot, fixed several --- I have one on the lower part of the EGR, but EGR operation is normal The EGR leak might be normal as long as it isn't preventing you from holding pressure for a while. If you pressurize to 5 psi and is still holding *some* pressure after 1 minute, then you're good. If you lose all pressure in less time, especially much less, like 10 seconds, then it will be an issue. The valve cover leak isn't an issue unless your PCV valves are bad. One thing I like to do is pressurize the manifold to much higher pressure like 15 psi(which you can't do at the intake) to test for smaller boost leaks or if there are a lot, to help isolate them. If you do this, you need to plug the secondary air return used for idle that goes the intake pipe on the driver side. Also, the other source of a boost leak that won't show up when you pressure the intake is a leaking recirculation valve. I've had several bad recircs. One had a leak in the diaphram and wouldn't open up all the way or close all the way in some cases. Another valve was just stuck open causing one turbo to work much harder than the other. This didn't show up until higher airflow and boost levels because at lower levels, the balance tube evened things out. You'll also want to make sure your injector connectors aren't intermittent. Mine were. I finally replaced the entire EFI harness and upgraded to the newer style injectors.
:Anyway, again, I really thank you for your response...no one has been able to say what you have said. When I try to get my alphas (air/fuel, right?) the program locks up ---
The alphas are a correction factor that the ECU uses to get to stoichiometric (14.7:1) AFR. The short term alphas are instantly calculated any time during closed loop. If they are higher than 100% during closed loop, then there is some lean condition which the ECU is compensating for by adding fuel. i.e. 105% means the ECU is adding 5% to get you to stoich. If you're O2s are good, then in closed loop, the ECU will will do whatever is needed to keep the proper AFR. This is why the Z32 can still get great fuel economy with massive boost leaks as long as you're not boosting. The short term alphas are averaged over some window of time to create long term alphas sometimes referred to as slow alphas. These are used in closed loop, but also at idle which is not really closed loop. Since the O2s don't work so well at idle, they ECU will use what it knew needed to be the correction factor in closed loop to get idle to stoich. As it turns out, the O2s can and often do flip even idle and the fast alphas will often adjust slightly after coming to idle. None of the alphas are used in WOT states. The reason is that if you're O2s are off and measuring too rich, then you would be too lean under WOT if the alphas were used.
it also eliminates them as an option when I CHECK FOR REGISTERS. Perhaps the program/consult tool I use is not effective enough for this kind of trouble-shooting. I have no idea what a 3rd Order Polynomial trend is, but I'm guessing you mean that a third measurment with the RPM and AIRFLOW might provide many answers???
This is just an equation that takes a weighted average over a moving window to created a trend line. It's just at stastical function. You see it used all the time in stock charts to calculate moving trends. When you do this to short term alphas, you can tell if the car is running lean or rich and get a pretty good idea just how lean or rich without the use of a wideband. I prefer a wideband myself. I finally bought an LM-1 because I decided I was going to tune my own ECU.
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