Advance calculation

[rsicard]

The timing displayed in TP should match what's measured. You should have nearly 100% correlation. If there is an error it should be restricted to a fixed amount consistent at any commanded timing. You should not have to alter the calibration to make the displayed timing match measured timing. What you are describing is atypical.

It is possible that TP is not displaying the right value. The datastream definition must match the mask ID of your calibration. You should be able to command a fixed spark advance by using the max advance and max retard values. Set them for a specific value, such as 12 degrees. The timing light and the value displayed by TP should match your limits. Disconnect KS as some calibrations apply Knock reductions after max retard limit is checked. Watch TP to see what is displayed. Setting limits should eliminate all ECM based variables. Seeing 10 degree changes after changing limits implies problem is faulty ECM or in TP definition file.

Thanks much for the response. Quite likely TP may be displaying the wrong value. Where are the max advance and max retard values located in TP5? Are these in the scalars or elsewhere? The KS has been replaced by resistors of the appropriate value to satisfy ECU test, open wire, short or defective KS sensor. Knock reduction parameter(s) should not be affected. Need recommendation of appropriate TP definition file for 1995 Chev C-1500 TBI 350 V8 16197427 ECM being converted to 350 Vortec with 454 Throttle body. Hope the one being used is what it should be. Need to try another ECM to see if there is more appropriate timing correlation. Two good possibilities for current situation.

[1project2many]

I generally don't use TP so someone else might be able to give better help. I've been trying to use TP with an $0D ALDL definition file in my '57 but the only variables it seems to read from the datastream are TPS and MAP. I've got so little time that I haven't been able to troubleshoot it.

In general the definition files you use need to match the Mask ID of the calibration you're using. There are several different Mask ID's that will work in the 7427 so you need to determine what yours is. Maybe this has been done already. If you're using a well known calibration then someone else can chime in. If your calibration is less common the best verification might be for someone to view it in a hex editor.

Max advance and max retard should be in the scalars if the definition is set up properly. There is a parameter search function that is very helpful.

Although you may have no problems leaving the knock sensor disabled, I would not try to enable the knock test. I also would not install resistors to simulate the sensor. Some calibrations have an additional max retard value which is used when knock is detected. Although no knock should be detected with the resistors, I would either confirm there is no alternate limit by looking at a partial disassembly, or I would attempt to disable knock sensing altogether.

[rsicard]

I generally don't use TP so someone else might be able to give better help. I've been trying to use TP with an $0D ALDL definition file in my '57 but the only variables it seems to read from the datastream are TPS and MAP. I've got so little time that I haven't been able to troubleshoot it.

In general the definition files you use need to match the Mask ID of the calibration you're using. There are several different Mask ID's that will work in the 7427 so you need to determine what yours is. Maybe this has been done already. If you're using a well known calibration then someone else can chime in. If your calibration is less common the best verification might be for someone to view it in a hex editor.

Max advance and max retard should be in the scalars if the definition is set up properly. There is a parameter search function that is very helpful.

Although you may have no problems leaving the knock sensor disabled, I would not try to enable the knock test. I also would not install resistors to simulate the sensor. Some calibrations have an additional max retard value which is used when knock is detected. Although no knock should be detected with the resistors, I would either confirm there is no alternate limit by looking at a partial disassembly, or I would attempt to disable knock sensing altogether.

Which EFI tuning software do you use? What EFI systems have or are you tuning? Please advise. Thanks.

[1project2many]

I started doing efi tuning in '96. There were only a few different vendors of software back then and most it was not cheap. Many of us were busy hacking the GM computers just to locate basic tables back then. We didn't have complex tools and I'll still use a hex editor to make changes. Somewhere around here is a thread where I've posted screenshots from some of the old software I own.

I don't have anywhere near the time these days to do this fun stuff anymore. The '57 was set up with Crossfire injection in '91 (or was it 92?) and as of 2009 is running on a 7427 pcm.

[sturgillbd]

A quick search turned this up... http://www.gearhead-efi.com/Fuel-Inj...ghlight=tuning

[corvairnut]

Rather than speeding tons of time... I took a timing light and measured my true timing and then go to conversion tab in the spark advance part of TP and change until the math works. I would think its all relative at that point.

Ted

[rsicard]

Rather than speeding tons of time... I took a timing light and measured my true timing and then go to conversion tab in the spark advance part of TP and change until the math works. I would think its all relative at that point.

Ted

Ted: Trying to locate the "conversion tab" in spark advance part of TP. Have 16197427 BJYL PCM. Where does one find the conversion tab? Please advise. Thanks.

[rsicard]

A quick search turned this up... http://www.gearhead-efi.com/Fuel-Inj...ghlight=tuning

Brian: How does one go about canceling EGR in TunerPro 16197427 BJYL PCM? Please advise. Thanks.

[1project2many]

Ted: Trying to locate the "conversion tab" in spark advance part of TP. Have 16197427 BJYL PCM. Where does one find the conversion tab? Please advise. Thanks.

I believe he's talking about editing the ADX file... the definition used to interpret data from the pcm. I'm sure you can understand the potential danger in doing this. Ted has the advantage of years of working with the engines that he's converted to EFI so he can tell what he needs to see at the balancer to ensure timing is correct. I'm not sure he's followed the problem that your experiencing, either... that the range of data does not appear to be correct.

[corvairnut]

I believe he's talking about editing the ADX file... the definition used to interpret data from the pcm. I'm sure you can understand the potential danger in doing this. Ted has the advantage of years of working with the engines that he's converted to EFI so he can tell what he needs to see at the balancer to ensure timing is correct. I'm not sure he's followed the problem that your experiencing, either... that the range of data does not appear to be correct.

I was..... and thanks for clarifying that 1project2many. I hope I didn't send you down the wrong path.

Ted

[rsicard]

I was..... and thanks for clarifying that 1project2many. I hope I didn't send you down the wrong path.

Ted

Thanks to both 1project2many and Ted.