$8f tuning. boost values

[jman093]

Looking for any tuning help I can get. First test and tune at the drag strip is this weekend. Going with a buddy running an RX7. Trying to work on the tune at the last minute here after having all winter to do so. Car has some sort of aftermarket turbo on it and was hitting the 8.32 psi overboost fuel cutoff (code 31) on the track when I went last year when we went. Could only go 15.4 with the car cutting off fuel like that throughout the run.

 

When editing the boost tables and the overboost cutoff, it won't let me enter a value higher than 10.61 psi (208.80 kpa). If I enter a higher value and save the scalor (is this the right term?) tunerpro automatically backs it down to 10.61 psi. Please tell me this isn't some maximum allowable value. The boost tables allow for more desired boost than that! And this turbo will make it too. I currently have drafted it to maxing out at 12.20 psi on the top end. If 10.61psi is some max overboost value, is there some way around it to allow higher boost? I know there are lots of TGPs running aftermarket turbos, so there has to be some way.

[RobertISaar]

the 10.6PSI value is actually a bit incorrect.... when someone made the definition, they used the wrong conversion to arrive at the factory value. maxing it out to "10.6" is actually 208.8kPa(assuming a standard barometric pressure, around 14.5PSI of "boost", since the TGP code considers anything above the sampled barometric pressure boost).

 

I never corrected the PSI conversion, but the value in kPa is one I added and is the correct scaling. If you want to correct the PSI value, change the conversion to -13.2+(X*.1137) for both the cutoff and restore.

[RobertISaar]

other boost conversions may be slightly off or appear incorrect as well, such as the desired boost table... I corrected that one to appear as absolute pressure rather than gauge pressure(since that changes with different barometric pressures). just something to keep in mind since the table appears to allow 30PSI, just subtract 14.5 for a rough idea of sea-level gauge boost, could either do that with the conversion math, mentally or with a spreadsheet.

[jman093]

Great news. Thanks for being a rock star. I noticed the psi and kpa didn't seem to match, but assumed it was only due to atmospheric and vacuum pressure differences and thought little of it.

 

This all seems screwy. Logically, it seems every boost related scalar in kpa would use one equation, and every boost related scalar in psi one would use another, because they all should using the same integer X, with X being some MAP-based input. But there are now 4 different equations for the 4 different parameters. The numbers do make sense now assuming too-low boost kpa numbers are this way as a means to convert psi readings from absolute pressure to atmospheric pressure. It still seems like it would be better to edit this to have all four readings accurate in kpa and atmospheric psi.

[RobertISaar]

it would be better, and it can be done, I just didn't do it to get the XDF with other major corrections out the door.

[jman093]

it would be better, and it can be done, I just didn't do it to get the XDF with other major corrections out the door.

 

Alright, thanks. OBD 1 tuning seems to be a complicated affair to say the least.

 

BTW, here are changes I've made so far. All I'm trying to do for right now is:

 

1:raise the boost pressures

2:raise the overboost cutoff point

3:allow for boost to be built on the starting line so it can be launched under at least a little boost (and also spool more quickly as this turbo does have a bit of lag compared to the dinky stock T25 which is almost completely lag-less).

4:eliminate torque management if there is any (or at least scale back. I would prefer not to blow anything up).

 

 

Changes:

 

1:Desired boost pressures have been raised in the higher RPM and TPS ranges maxing out at 12.20 psi. Up from technically 9 psi, but really about 7.32 psi.

 

2. Overboost cutoff raised from about 9.5 to 13.52, and the overboost restore raised from 5.32 to 9.5

 

3. "Brake Torque MPH Threshold" was lowered from 6 mph to 0 mph, and the "brake torque time limit" was upped to 20 seconds. I'm not sure if these operate as a both/and or an either/or, so I raised both. The "TPS threshold to step-up boost" was lowered from 12% to 5%. I'm hoping this is all I need to do to allow for building some boost by two-footing it some on the line

 

4. The torque management confuses me. There's a couple places it lists "launch mode" scalars and tables. I understand very little of what they indicate. Am I right in even assuming this is torque manamgement? If so, would just changing something like "Launch mode vehicle speed threshold" to 0 mph" essentially disable it?

 

 

 

How's this all looking Saar or anyone else who understands it?

[RobertISaar]

launch mode can be used to either add or subtract advance when in a torque stall situation(either on the brake and throttle at the same time or just heavy into the throttle at low speed), it's detected via measuring the ratio of RPM for the input(crank sensor) and the output(VSS and knowing roughly what gear the transmission is operating in), low ratios indicate lots of stall.

 

the way torque management works with all of the MPFI 60V6 code(and others) is that there are tables used to setup a maximum amount of spark advance allowed for a given situation, if advance is tried to be run above it, it gets clipped to that value. should have 2 tables visible for that, they get added together for the final amount of allowed advance, raise either and you'll have more advance allowed.

 

the shift spark retard stuff is also available, but I believe none of the stock calibrations had the flag enabled.