Not sure if it's a grid problem or not. But 2 passes overlaid. One fast pass one slow pass. It shifted the same rpm but not at the same time. When you look at it there was .03 difference in time of shift. That's almost the difference in et.

It made 4 passes in a row with the same et. Then it went almost .03 quicker for 2 passes. Then went back to the slower passes for the next 2 passes. The weather never really change much during these runs. So don't think it's weather related.

I'm looking at the fuel and grid side but really don't see anything yet. Just curious what other peoples ideals would be and maybe something else too look at. Thanks

Are you using the Shift Light or Output Switch in Grid to shift your transmission with?

Looks like the engine is accelerating more at the top of first gear on the red graph. To me that's why it is shifting sooner--I don't think it's a grid issue--possibly different air, trans or converter acting different?

Also is all the .03 ET change all before the 330'? On my cars that slight change with the shift wouldn't affect the ET that much.

Shift on time if you want it to shift at the same spot on the track. The rpm will be higher on the faster of the two runs at the shift though, shifting on time.

Shift on rpm, if you want what you have now.

You're shifting on rpm in this example, correct?

[QUOTE]Originally posted by markemark:
Are you using the Shift Light or Output Switch in Grid to shift your transmission with?

Shifting off the output switch.

[QUOTE]Originally posted by N2Ofrog:
Looks like the engine is accelerating more at the top of first gear on the red graph. To me that's why it is shifting sooner--I don't think it's a grid issue--possibly different air, trans or converter acting different?

Also is all the .03 ET change all before the 330'? On my cars that slight change with the shift wouldn't affect the ET that much.

Yea I seen how it was accelerating at the top. That's why I was thinking fuel. But the 60 - 330 split times is where it changes at.

[QUOTE]Originally posted by Mike Rietow:
Shift on time if you want it to shift at the same spot on the track. The rpm will be higher on the faster of the two runs at the shift though, shifting on time.

Shift on rpm, if you want what you have now.

You're shifting on rpm in this example, correct?

Shifting on rpm. I tried to set it up on time but haven't been able to get it to work right with the grid. But I have been shifting on rpm for a long time and it's been deadly until the last few weeks.

quote:

Originally posted by ts393c:

quote:

Originally posted by Mike Rietow:
Shift on time if you want it to shift at the same spot on the track. The rpm will be higher on the faster of the two runs at the shift though, shifting on time.

Shift on rpm, if you want what you have now.

You're shifting on rpm in this example, correct?

Shifting on rpm. I tried to set it up on time but haven't been able to get it to work right with the grid. But I have been shifting on rpm for a long time and it's been deadly until the last few weeks.

Your inconsistency problem you're now experiencing, isn't involving the shift. The example you've provided shifting on rpm, is normal for one fast and one slow run.

Mike the inconsistency problem is what I'm trying to figure out. That is one reason I was looking at a fuel issue. Something is dragging it down right before the shift. I do have a spare convertor that should be a touch looser. I might try putting that in.

If it has been deadly, I'd ohm the wires, cap.

If it's a spragless converter, stick with it (spragless is indestructible). Might be the plug wires, cap or needs a rotor.

Put a new set of plugs in it too and go through the fuel system as well.

If it's methanol put a couple new floats in the carb.

Do a tuneup.

Let us know how progress goes.

Good luck!

quote:

Originally posted by ts393c:
[QUOTE]Originally posted by markemark:
Are you using the Shift Light or Output Switch in Grid to shift your transmission with?

Shifting off the output switch.

You are using the Wrong Grid output to shift your transmission.

The Shift Light output will be the Most accurate rpm output from Grid. It is designed to shift the transmission with the aid of the Gear Shift tab programming.

Output Switch is a “Timer” that has a RPM function. It is not as accurate as Shift Light when using the RPM function.

You are also measuring the shift output from Grid in the wrong location. What you show in the picture you posted is when the transmission completed the shifted. You would measure the Grid RPM output at the time the Output Switch turned ON.

quote:

Originally posted by markemark:
[QUOTE]Originally posted by ts393c:
[QUOTE]Originally posted by markemark:
Are you using the Shift Light or Output Switch in Grid to shift your transmission with?

Shifting off the output switch.

You are using the Wrong Grid output to shift your transmission.

The Shift Light output will be the Most accurate rpm output from Grid. It is designed to shift the transmission with the aid of the Gear Shift tab programming.

Output Switch is a “Timer” that has a RPM function. It is not as accurate as Shift Light when using the RPM function.

You are also measuring the shift output from Grid in the wrong location. What you show in the picture you posted is when the transmission completed the shifted. You would measure the Grid RPM output at the time the Output Switch turned ON.

So Mark should I just hook up the yellow wire to the shift?

I'm not sure how to look at it the other way. When I get home I'll open it up and look at it.

Yea, use the shift light wire to shift on rpm. It's shifting consistent now but Mark knows the Grid, I wouldn't hesitate to take his suggestion at all. It'll undoubtedly be slightly more consistent using the shift light output.

You're looking at the right screen, the only thing you're interested in is when the shift occurs. It's shifting consistently so there's no reason to trouble shoot Grid shift output.

You're on the right screen.

If desired, you can place the Yellow wire right on top of the Brown/ White. Just disable the Output Switch functions. This way if you wanted to switch to Time shifting you’d be able to easily do so in the programming.

Here’s my car shifting with both the Shift Light ( set to 6925 RPM) and Output Switch (set to 5.21 in Time).

Like you, I record the maximum RPM and time when the transmission Shift actually occurred to help determine inconsistencies. For this run it was 7023 rpm @ 5.239 seconds.

If you measure the actual rpm the Shift Light (6929 in my photo) or Output Switch set to RPM turns on and compare it to what you programmed (6925 mine) in rpm to turn on, you’ll find the Shift Light to be more accurate, and vary less than Output Switch.

When making measurements with cursors in Data Acquisition, it’s wise to expand the Data Acquisition view to the maximum resolution to achieve the most accuracy in your findings.

Grid outputs are not as accurate as one would believe. But I believe using the most accurate output for shifting to aid in consistency.

Mark I will hook the yellow wire up tonight and try it. I did try to hook it up a while back and shift off time. I was trying to make it see rpm and time so it wouldn't fire the solenoid every time I hit the trans brake button. But I had something wrong in the program some where, cause it would just sit there and fire the solenoid multiple times. I never got a chance to look everything over and see where I went wrong.

I did go over a lot of the car last night. I found the intake is leaking oil on the back rail. I don't think it had a vacuum leak but I am going to replace the intake gaskets just incase. I also found that my pinion angle was jacked up. Some how I got it 1.5 degree plus.

Sorry about digging up this 2 yr old thread, but I was trying to find this exact subject ! My car has been having some consistancy issues that I have traced down to my shift varying 200 rpms. I am shifting off of the yellow wire on the grid. Rpm is set for 7300, i have found shifts as early as 7310 and as late as 7520 ! Thru the racepak voltage graph I can see that the shift is happening when commanded. It varies 200 also. Anyone have any ideas to fix this? In past seasons this has been very consistant.

quote:

Originally posted by 27Keith:
Sorry about digging up this 2 yr old thread, but I was trying to find this exact subject ! My car has been having some consistancy issues that I have traced down to my shift varying 200 rpms. I am shifting off of the yellow wire on the grid. Rpm is set for 7300, i have found shifts as early as 7310 and as late as 7520 ! Thru the racepak voltage graph I can see that the shift is happening when commanded. It varies 200 also. Anyone have any ideas to fix this? In past seasons this has been very consistant.

In Grid Review of the DA, if the Shift Light is activating at the correct rpm (7300) +/- 5 rpm, but the shift is not being completed within 100 rpm of the activation it could possibly be several things.

I assume you are using a large electric coil for shifting. If yes, select the Voltage channel in Grid Review DA and see if the voltage drop from shifter energizing lines up with the Shift Light output turning ON. In these two channels, if Shift Light goes ON (7300 all the time) and Voltage drops 1 volt or more at exact same time, then I would say shift from Grid Shift Light is being activated properly.

Anything shared from Grid to Racepak is time delayed. Use Grid to troubleshoot this problem. It’s controlling the shift rpm activation.

What does Grid Review show?? I can explain next step to look at but need to know this.

Here’s something I record religiously from my Grid DA ….. the Maximum rpm the engine obtained prior to engaging High gear. Because I do this, I know the trend of what rpm my transmission is completing the shift.

Last weekend my CO2 bottle that uses a fixed 100 psi output regulator indicated 300 psi at the bottle when I turned it on. I’m looking at my shift completion rpm from the first two runs and both are higher by over 25 rpm than normal. My first thought is “am I low on CO2 and is the shift cylinder moving slowly”. Attached to Grid and set the Shift Light “Power-ON Test” to ON, put the trans in second gear and turned on the ignition. Sure enough, the shifter was moving slower than normal. Removed the 10 oz CO2 cylinder and the gauge dropped to 200 psi. The gauge is faulty. Replace the CO2 cylinder with a new one and shift completion back to normal.

quote:

Originally posted by 27Keith:
Sorry about digging up this 2 yr old thread, but I was trying to find this exact subject ! My car has been having some consistancy issues that I have traced down to my shift varying 200 rpms. I am shifting off of the yellow wire on the grid. Rpm is set for 7300, i have found shifts as early as 7310 and as late as 7520 ! Thru the racepak voltage graph I can see that the shift is happening when commanded. It varies 200 also. Anyone have any ideas to fix this? In past seasons this has been very consistant.

I think my problem might of been a little different but I changed to shifting on time and I also changed my carb jetting. It went back to being consistent after that.

I think yours sounds like a shifter issue to me. Linkage binding or shifter solenoid.

Without seeing the drive shaft this is all speculation, but the tire might not be hooked.