Bad30th

iTrader: (13)

Alright... I'm taking another stab at VE tuning. I had it "good enough to drive" for a while and finally have some time to take another crack at it.

So, here's where I'm stuck... I log AFR error% with my LC1 and paste special/percent half to the primary VE, copy changes to sec VE (99 OS). Flash. Logging with the new tune the values are all still waaay rich even in the cells I've changed. Paste special/percent half, reflash. Log again, same rich values. I can keep this up indefinately until the car runs and shifts like **** from the super-low VE values.

I followed these steps (from the HPT SD how-to and reading/advice here) :

save stock tune

log and correct RAF values (LTIT, STIT), from cold startup, in park and in gear
reset fuel trims with scanner

set OLFA above 140 degrees to 1.0
disable long term fuel trimming
Under Fuel Cutoff/DFCO set DFCO enable normal to 284°F
disable COT (Cat over temp)
disable PE by setting high threshold MAP/TPS values (why tune VE in PE ?)
set All Closed Loop Enable Temp vs. IAT cells to 284
Set MAF fail frequency to 0.
set P0101, P0102 and P0103 to set MIL at first error
copy high octane spark to low octane spark table
set cylinder charge temp bias to 0.0 across all values (bases calcs on IAT not ECT)
save tune as SD1.hpt, flash PCM
unplug MAF

Drive at low loads and log AFR Error% in VE table via AFR Error% histogram

apply logged AFR error% to primary VE table with paste special/percent half

apply changes to primary to secondary VE table (1999 OS)

save as SD2.hpt, flash PCM

repeat logging/VE correction until AFR error% is -2 to 0 across all cells - but it never gets that close.

What am I doing wrong ? I'm attaching a couple of logs to show what I'm talking about.

Thanks for any advise fellas.

Cheers,
Rob (Bad30th)

foff667

iTrader: (2)

I'd like to see a copy of the hpt file if you dont mind.

foff667

iTrader: (2)

also try logging 24 or less bytes with a 48 max...you get much better resolution. Also why in the first one you go into pe even at like 18% tps towards the end of the scan?

foff667

iTrader: (2)

personally I always set it up to be 1.0 in the open loop table & setup my pe table as I'd like it to be when im done. My thinking was since pe is open loop anywayz and all your trying to do is get your a/f to match it really shouldnt matter how you do it. In the end either way will get you to the final goal. In his case with a blower I wouldnt even attempt a 1 bar speed density tune but thats up to him in the end.

Bad30th

iTrader: (13)

foff667 shoot me a PM with your email and I'll send you the tune files.
I do have the 2-bar HPT upgrade but still have the stock MAP sensor in the car. I think with only 8-9psi I can tune it OK using PE for when the MAP hits the 105kpa ceiling.

I'm having bad surging issues at part throttle cruise, which is what's motivating me to get this straightened out. Feels like the MAF is way off and the car is stumbling.

Thanks for helping me get this straightned out, I've been struggling with it for a while now.

Here's my (small ) list of mods to consider when looking at the tune :

ATI P1SC Procharger, 3.60" blower pulley
MMS crank blower pulley, currently running 8-9 psi boost
42# greentop SVO injectors
ATI crank pin kit
dual ATI air-to-air intercoolers
SPAL 16" Extreme fan
West Coast Cylinder Heads (WCCH) 71cc CNC Stage 2 5.7L LS1 cylnder heads
222/224 .571"/.571" 114 LSA Cam Motion Cam
Crane dual valve springs and titanium retainers
hardened 7.40" pushrods
Rebuilt LS1 block 12550592 and rotating assembly
ARP rod bolts
ARP head studs
JWIS heavy duty timing chain
SLP LS6 intake manifold
LS1 speed blue anodized fuel rails and braided line/fittings
Don Lee Auto Ported LS6 oil pump

Jantzer Ported/Polished/Powdercoated Throttle Body and (screened stock)MAF ends
Hypertech 160 degree thermostat
JBA CARB-legal coated shorty headers
Magnaflow stainless dual 2.5"->3" custom catted Y-pipe
Magnaflow custom 3" stainless catback/muffler
Magnaflow dual stainless rounded exhaust tips on each side
Walbro 340 in-tank fuel pump
NX wet Nitrous MAF kit, 50 shot jets, 10 lb. bottle

Continental 3400 stall torque converter (custom built)
B&M 16,000 GVW Tranny Cooler
3:73:1 GM Gears


Thanks !
Rob (Bad30th)

Bad30th

iTrader: (13)

I think I forgot to reset the fuel trims before logging that... LTFT's are disabled but probably forgot to reset them.

Rob (Bad30th)

Bad30th

iTrader: (13)

Also forgot to mention that most of the surging at part throttle cruise goes away with the MAF turned off, but the fueling is still all whacked...

It's odd to me that the AFR error % is so rich in SD but the LTRIMS are so high with the MAF on.

Rob (Bad30th)

gameover

the default MAP scaler values for the 2bar prog are setup for the 2bar sensor, if you are using the 1bar sensor still then that is a big part of your problem.

foff667

iTrader: (2)

hes still running the stock OS which I think might be part of the problem...here are the tunes he sent me.

http://mysite.verizon.net/whenn1/SD3.zip
http://mysite.verizon.net/whenn1/driving%20tune.zip

Bad30th

iTrader: (13)

I am not using the 2-bar tune yet because I still have the stock MAP sensor in.

I want to run the MAF if I can, only because my SD fueling is all over the place. Maybe if I got it straightened out I wouldn't care either way...

Thanks for the help/advice fellas.

Rob (Bad30th)

Bad30th

iTrader: (13)

TTT tuning gurus, hoping for a light-bulb moment here...

Can someone double-check the IFR table, I never did confirm that it was correct for the 42# greentop SVO injectors and have seen a couple of different table values.

Cheers,
Rob (Bad30th)

muncie21

iTrader: (14)

Looking at your scans, you are running rich (WB vs. commanded AFR) even at steady state idle. This makes me think you've got a fuel related issue (vs. airflow miscalculation). Have you measured your fuel pressure at the injectors?

Here's what I came up with for SVO 42# at 58PSI
48.505784
48.820075
49.134368
49.448659
49.762953
49.972481
50.286773
50.601066
50.915357
51.124886
51.439177
51.753471
52.067762
52.277291
52.591584
52.905875
53.115404

The numbers being higher than what's in your tune will result in leaner operation.

Bad30th

iTrader: (13)

Here's what's in my tunes... This is the right table, right (IFR vs. KPA VAC)? Sure doesn't look right to me...



I wonder if this is the cause of my problems.

Rob (Bad30th)

muncie21

iTrader: (14)

To get your flow rate, plug your injector specs into an injector size calculator (Here's one... ) and it will spit out the flow rating.

BTW, the SVOs are 42#s at 3 bar or 43.5 PSI. All you need to tell the calculator is the new fuel pressure rating; 58 for LS1s.

Injector flows in the IFR table that are smaller (lower) than spec will produce (generally) richer results. Flow numbers larger (higher) than spec will result in leaner numbers.

As yours appear to be lower than spec, it could explain some of the rich AFR values you are seeing.

If this pans out (don't get too excited, I'm sure there are other issues) you can buy me a beer

Bad30th

iTrader: (13)

Using the calculator in that link I got these numbers (rated pressure=43.5, rail pressure=58, injector rated flow rate=42)

48.49827788
48.80053386
49.10092925
49.39949798
49.69627298
49.9912862
50.28456864
50.57615042
50.86606077
51.15432813
51.4409801
51.72604355
52.00954459
52.29150865
52.57196044
52.85092404
53.12842289

Pretty close to what you posted... I'll try yours.

...and if this pans out I'll send you a case of your favorite beer, haha. This has been a thorn in my side for a very long time, haha. Thanks for all the info.

Rob (Bad30th)

Bad30th

iTrader: (13)

Well, threw in the new IFR values and reset the fuel trims - the car is running like **** and the fuel trims are doing real wacky stuff - all over the place... I will post the log here in a few minutes.

I'm sure the new IFR values are probably correct but something else is up ?

Edit : Attached log of "driving tune" with new IFR values - new-ifr.hpl

Later this morning I will try the new IFR values with the stock pri/sec VE table. The current VE values are from a local shop's tune.

Rob (Bad30th)

RedHardSupra

iTrader: (1)

well yes, if you had it 'tuned' on screwed IFR and then fix it, all your VE is gonna be off. use the log to get your VE back in line and you should be all better.

muncie21

iTrader: (14)

OK, I looked over the scan you did this morning. Here's my humble take on what's going on.
At the beginning of the scan you have hi LTFT/STFT, showing a lean condition that the PCM is trying to compensate for. This is expected if your previous VE was tuned using smaller injector values. The larger IFR numbers will squirt less fuel (leaner) into the engine at given VE values.

Good news is that the when you went into PE (towards the end of the run) you didn't see KR. So your AFRs are not lean there. At least not lean enough to cause KR with 18* of timing.

Phil99vette

iTrader: (11)

Rated pressure for the SVO 42# is 40 not 43.5.

Bad30th

iTrader: (13)

Hmm, thanks. I will re-calculate the IFR table with the 40# rated pressure and pop the stock VE tables back in when I get out of work for lunch (next hour or so).

Thanks for all the help guys, you rock.

Rob (Bad30th)