Shift MPH/RPM Problem

[coachcrow56]

I have a strange problem----my car will not shift at the speeds or RPM settings in my tune.

I have 1-2 shift set at 47---it shifts at 58.
I have 1-2 shift rpm set at 5800----it shifts at 6300 to 6400.

What is going on? Attached is a quick scan in first gear and my tune.

[BlackZJ]

Hi

I asume we're talking about WOT Shifts, right?
Do you have a Performance- or SGS Button?
You only set these values in the performance tables so you need to be in "performance mode" to use these tables.

What works best for me is. I set the shift rpm just a little lower than the desired value. Then I take a log of a WOT shift to see at which speed we are around that RPM. Then I set the speed a bit lower than that measured value. On some VCMs you can just set the speed to 0 MPH and the VCM will shift only based on RPM. But that dosn't seem to work with all VCMs. On my Camaro for example, it doesn't work right.

Hope this helps!

- Mat

[coachcrow56]

These are WOT shifts---in Performance Mode----outside air temps were 35. The car used to shift really close to settings, but now it is way off. Did the cold air raise the boost?

[murphinator]

both conditions need to be met for it to shift both speed & rpm , I always creep them up a bit at a time until I like the results

[coachcrow56]

What is strange is that I had lowered the shift rpm down from 6000 to 5800, and the shift mph from 50 down to 47, and now its shifting at a higher rpm and speed.

I took the car back out this afternoon----if I go WOT from a rolling start in 1st gear, it shifts way beyond the settings. But if I punch it in 3rd and downshift it into 1st, it shifts much closer to my settings in the tune. Could this be a transmission issue?

[Perforator]

I always set my MPH low so it's controlled by RPM. I think you have to hit the MPH first before it looks at the RPM.

[coachcrow56]

I have the mph set at 47, and it is shifting at 57 to 58 mph. So that doesn't seem to be working.

[Perforator]

Were talking WOT shifts here right? Do you have a scan?

[BlackZJ]

The problem is that we can't really see the important part in the log. The framrate is to slow. But I would set mph to ~40 mph. 47 mph seems to be to close to 5800rpm.

[Perforator]

ok, sorry didn't see the scan. the way it works is it checks the mph first. once you hit that it checks the rpm. now once you hit the rpm it doesnt shift to the next gear immediately. it's a transmission and it takes a little while to actually do the shift so this scan looks perfectly normal. it looks like the shift actually takes place at 6178 rpm. I believe as you go up in gears the actual shift occurs closer to the desired but it may just be an individual transmission thing. try lowering your rpm value if you want it to shift sooner.

[coachcrow56]

Finally got it to work. I lowered the shift speed for 1st down to 40, and now it shifts at the rpm I want it to. I had originally made a couple changes to my tune, and I didn't realize that my tires were trying to spin all the way thru 1st gear (Kuhmo's don't make any noise), and reaching the shift point faster and higher than my settings, which made me think something was wrong with my car. DUH!!!

[Perforator]

Yea it doesn't pay to floor it in first with these cars unless you like buying tires lol.

[coachcrow56]

LOL Yes---thats true about these cars, but I don't give it full throttle till about 25 mph---its running great right now. I usually drive like an old man so that teenagers think its a slow 4 door grocery getter--until they pull up at a red light in their Mustangs, Camaros, Chargers, and Rice Burners----and I embarrass them.