Gear detection struggles

[tepid1]

Quick intro:
Honda 4 speed transmission
Uses OEM vehicle speed sensor (5 pulses per rev)
Gear ratios are as follows:
1st 3.000
2nd 1.917
3rd 1.333
4th 1.045
Final drive output is 4.20
Front wheel drive

Speed detection is good. Don't get any speed errors on the drive.

I can get gears 1-3 to detect just fine with a 'gear estimate tolerance' setting of 0.320.
Since the ratio between 3-4th is only .288 if I put a tolerance setting of .140 then gears 1-3 don't detect and display default, and 4th sometimes displays the correct gear.

It seems like I need multiple tolerance settings to detect my gears properly.

Can anyone advise?

Thanks,
Chris

[tepid1]

This is with .150 in tolerance

[David Ferguson]

I find it helpful to log Gear Estimate Ratio and Gear Ratio -- if these two aren't the same, then something is wrong (like final drive isn't correct, or some piece of wheel speed information is wrong). I see from your Tune screen shot that that may be the case here. Your one time it was detected, you can see the estimate is higher than the actual ratio -- why? Is the tire circumference incorrect? Drive Ratio really different (have you counted the teeth on the ring & pinion?)

I suggest you start by finding the average value of the Gear Estimate Ratio (use the "measures (M key)" on the time distance graph then zoom into to just one gear and see what the "average" value for Gear Estimate Ratio -- then enter that value into your Gear Ratio table.

For example, looking at your sample, why don't you have 2.092 in your Gear Ratio table for 2nd gear? And it looks like first would be detected if your Gear Ratio was 3.15 instead of 3.0.

You should be able to have a Gear Ratio Tolerance of 0.1 or less.

Good Luck!

[tepid1]

Thanks for the reply!

So, I thought about that as well. I could essentially just say forget what the gear MFG says the ratio is and just enter what the M1 is calculating it to be and all will be well. I may just go that route.

What I'm finding is that if gear estimate ratio and gear ratio aren't kopasetic with the number that works in the tolerance value then those numbers for gear ratio and thus gear detection doesn't work at all. My thought was that tolerance being set to .100 was too small and just didn't jive. Sounds like I have something else to figure out.

[David Ferguson]

Looking at the error amount (about 5% high). Any chance your drive ratio is really 4.02 and not 4.2?

So is this an automatic transmission? It seems all the Honda manual transmissions are all 5-speeds and according to this webpage http://hondaswap.com/threads/honda-tran ... ecs.29132/ manuy of them have a 3.2 1st, and some have a 2.09 second, hmmm that lines up with what you are calculating in the Gear Estimate Ratio.

I would probably enter the Gear Estimate Ratios in the the Gear Ratio table and everything (including rev matched gear shifts) should work as expected.

[tepid1]

This is a unique gearbox. It's in a Honda case and 5th gear is removed. It's a dedicated drag car and uses a PPG straight cut gear box with dog engagement gears.

If anything, the final may be 4.21or 4.22 instead of 4.20. I'm getting conflicting info from dealers.