ok guys i need a little help with the 2 bar setup. exactly what all tables do i scale in half for the initial base tune in tunercat?I understand about only using a few columns and scooting them under 50kpa but which ones? Do i need to do the same with the tranny tables?

 

I dont know about trans tables but I would think anything with MAP tables get cut in half just like the timing table.

There's too much for me to remember, easier if you download the File I posted and compare any MAP based tables you can find.

Every single MAP based table should need scaling in some way, usually by 1/2 to start.

I might update the file with my #156 since I fixed a delayed warm start problem I was having then you can compare easier.

 

ok is that a tunercat file or a edit file?

 

I tried to save the file but it said that it wasnt there anymore?!?

 

It's and LT1 file and if you cant download it then maybe your internet blocking programs are blocking it.

No offense, but if you cant tell if it's an LT1 or Tunercat file then you should not be using it.

 

jeez man gimme lil bit of credit..lol. i figured it out and will be playing with it this weekend..I will post up results..thanks again for all your hard work figuring this stuff out and sharing your file for the rest of us to reference off of.

 

Well Im serious, alot of work goes into a standard tune let alone a modified boost-a-tune.

Just dont want to hear a bunch of "well I loaded your file and blew up my motor"... and when you cant tell a differerence between a LT1 file and a Tunercat file that's the second thing I expect a person to post.

So just take it easy, make sure boost starts low and stays low, make all timing low and increase slowly, and nice rich fueling to make sure things are reading correctly, then start tweaking.

 

1992 supercharged corvette here, running 12lbs boost with 60# Siemens injectors and alky. Currently a 1Bar tune, very rich in boost because it isnt dialed in right. I'm planning on trying a 2Bar tune to make dialing in the boost easier.. I'm assuming all the principles in this thread are the same for a 92 SD Y-body?

The only thing I am concerned about is the min PW which in my current tune is set to 0. I guess I'll go with it for now, and look out for issues described earlier with PW less than 1.0.

As an aside, this morning I emailed TC for a Baro-reset version of $DA2; and within 5 hours I have it!

I'll probably post back here with progress. Thanks for an inspiring thread!

Andy

 

A possible contribution to the body of knowledge in this thread. The latest version of DataMaster has a set of comparisons of voltage vs MAP for GM Map sensors (1, 2 and 3Bar) in the help files. I loaded these into a spreadsheet.

VERY INTERESTING: when comparing the 1Bar and 2Bar sensors, for a given voltage the scaling isnt exactly 2x. For example, at 1.998volts, the 1Bar sensor will be detecting 48.1 kpa; the 2Bar sensor will be sensing 60.63 kpa, which is only a scaling of 1.3x, not 2x.

In fact (and I would like someone to check my work - see below for a link to the spreadsheet), the 2Bar sensor delivers the same voltage as the 1Bar sensor at 30kpa !!

1Bar 2Bar Comparison


I hope this is useful - if correct it may help speed up the tuning process

 

See above; this also has interesting implications when scanning the car (I think). Using a 2x assumption, if the scan shows data at 50kpa (i.e. the sensor is sending 2.1v), we were assuming that the car was actually at 100kpa. IN fact - the car is "only" at 70kpa. I dont think it hurts tuning, because the ECU will be looking up the 50kpa column and that's where we would ajdust VE. But I wonder if it impacts decisions regarding onset of PE / etc.

All this is making my head hurt. Comments anyone?

 

There are no interesting implications Im aware of, proof of this is at key on and not running vs known boost where my:
1 bar sensor showed 103kpa and now my 2bar sensor shows 53kpa (1/2).
2 bar sensor at ~7-8psi shows ~75-78kpa (also = 1/2 boost on this 2 bar setup).

So, ignoring a bunch of basically useless internal sensor cal values I skip forward to the real world test above and know it's reading properly based on datamaster's displayed MAP sensor results.

The only time it wasnt reading right was when the BARO-Reset's were happening.

 

Interesting - there's no disputing your experience. Given the sensors have very different voltage scales, I'm curious as to how the ECM is calibrated, probably some other factor I'm unaware of. I'll maybe do some further research and post separately.

 

Are you guys doing anything specific with AE, or relying on lowering the injector constant to improve pump shots?

 

Im not sure what your referring to as "AE", and yes the reason the injector constant is less that 1/2 is to compensate (and to increase) the pump shot because with 1/2 injector size the same lean tip in stumble was occuring as with my 1bar with 83lb injectors.

There is no adjustments for pump shot, so if you have a problem with lean tip in that's not due to a VE or MAF problem then lower the injector constant and lean out other settings to compensate.

 

On my 1992 LT1 Y-Body (mask $DA2) there are a bunch of Accel enrich tables specifically to control pump shot (vs TPS for initial tip-in, and vs MAP to bridge the gap to PE, and a few other controls).