E40 50% scaled transmission line pressure

Hey guys, I have an E40 running the 2.5bar OS that's scaled 50%. This was required to be able to use the spark table for controlling timing in higher boost levels. Originally was set up by halving IFR and doubling stoich but was exceeded cylinder airmass, by a lot. Obviously scaling essentially cuts the torque calculation in half, what are folks doing to get the transmission line pressure corrected? I've corrected the shift tables but we have no tables for line pressure so the transmission slips from not enough line pressure to hold the clutches. I know later ECMs have tables we can change to correct the torque calculation, not so in the E40. I don't want to alter the force motor tables but it seems it may be my only option to get base line pressure up.
Thanks in advance!
msnookums

How much are you gaining by not carrying the same spark timing out from the 1.36g/s rows? Is it enough to justify the transmission problems you're now dealing with? Is it enough to even be measurable with a dyno or timeslip? Why does 2g/s need spark timing any different than 1.36g/s?

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Originally Posted by blindsquirrel

How much are you gaining by not carrying the same spark timing out from the 1.36g/s rows? Is it enough to justify the transmission problems you're now dealing with? Is it enough to even be measurable with a dyno or timeslip? Why does 2g/s need spark timing any different than 1.36g/s?

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I can see your point. It was all an attempt gain a little better spark control under boost. I'm off the timing table by 10psi or so. Running 18 psi, I was hoping to gain a little by not having to drop the 1.36 cells down to final timing so early. Will it make much difference? I won't know until I go run it. Shifting pressures are easy to scale, seems like we ought to have the ability to modify delivered torque or line rise. I will mess with the force motor tables a little bit and see if I can find a sweet spot, otherwise I may just have to flash the old file, run a stand alone TCM or ditch the E40.

By scaling it like that you're losing resolution everywhere and that includes the parts where it really is beneficial, that being the vacuum/non-boost areas. You could pretty much hold one single value for everything above say 0.70 or 0.80g/s and carry that all the way out and see zero negative effects. I just feel like the people who worry about that 1.36g 'limit' are giving up something really useful in exchange for something that doesn't help anything, and creates not-insignificant... if not problems, at least annoyances.

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Originally Posted by blindsquirrel

By scaling it like that you're losing resolution everywhere and that includes the parts where it really is beneficial, that being the vacuum/non-boost areas. You could pretty much hold one single value for everything above say 0.70 or 0.80g/s and carry that all the way out and see zero negative effects. I just feel like the people who worry about that 1.36g 'limit' are giving up something really useful in exchange for something that doesn't help anything, and creates not-insignificant... if not problems, at least annoyances.

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I think I'm going to end up going back to the old tune at this point. I was ok with giving up some resolution to get a little more timing control in boost but it's doesn't work out great. We still have better resolution scaled than some aftermarket ECMs. I spent hours yesterday logging and tweaking the force motor tables and could get it better but still not right, how they calculate torque at least scaled with the 2.5 bar OS is certainly not linear. I could get part throttle working good in vacuum but when it transitions to boost sometimes it's fine, other times it would seem to stick in the 600-700ma range for force motor current. There are definitely tables that are either in the E40 or T42 that we don't have access to, it is capable of TPS based line rise but there's no way to force it to run that way.

I also think you'd be better off with the double stoich method.

No reason to really optimize timing at say 7/8 throttle vs 100%. Just worry about whats happening at full throttle full boost.

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Originally Posted by Alvin

I also think you'd be better off with the double stoich method.

No reason to really optimize timing at say 7/8 throttle vs 100%. Just worry about whats happening at full throttle full boost.

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Thanks Alvin. I'm going to head back that direction. I'd rather sacrifice a little timing control up there than have to worry about what my transmission pressures are doing.

Do you have data on trans pressure measured with an actual gauge before and after the tune scaling? I am interested in the differences at cruising/steady state pressures.

If you don't get that gauge pressure info back form the OP, these equations are in the ball park.
Do some WOT shifts and look up the calculated results against the shift pressure table for that pattern and gear. Bet you'll find they're bloody close.
Calculated Line Pressure Lower Range ≅ PCS_1_kPa x 2.045 + 300
Calculated Line Pressure Higher Range ≅ PCS_1_kPa x 2.335 + 300

Is PCS_1_kPa from a gauge or from a logged channel in the scanner?

Scanner

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Originally Posted by eXo3901

Do you have data on trans pressure measured with an actual gauge before and after the tune scaling? I am interested in the differences at cruising/steady state pressures.

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Without doing extensive testing, where I used to see a little above 150 steady state, is now 90ish or so. I didn't want to keep testing because of the slip but gathered enough to know what was going on.