I am currently tuning a 98 camaro with a 76mm turbo. Car is making 13lbs of boost. But while making a run on the dyno it seems to hit a wall. I don't know what it could be. The car does not have a MAF on it and I have been told that on 98 cars a MAF is required to get them to function correctly because of the way the computer reads. Is there any truth to this.
Here is a copy of the graph so you can see what it is doing. Any ideas are appreciated.
A log/tune would be more useful. AFR looks really lean at the start.
Sulski Performance Tuning
2000 WS6 M6 - LS6 (long block, refreshed top end), 10.8:1 CR, 90 mm ported FAST, Exo-Skel, 227/232 cam, QTP HVMC, EWP, GMMG, 9" w/4.11s
2018 Sierra SLT 5.3L A8 - Airaid intake tube, GM Borla catback, L86 Intake/Ported TB
as a guess from that picture....lean and possibly out of injector
please post a log from the scanner
and MAF is not required.....and the car doesnt care if it has a MAF or not...
I've done countless #'s of 98's without MAF
in SD...
1 bar
2 bar
open loop/closed loop
the whole kitchen sink fill of possibilities...
Last edited by S2H; 03-04-2009 at 07:38 PM.
-Scott -
I will get a log tomorrow when I get the dyno up and running. I doubt it is out of injector as they are 65s. and as for how lean it that is at 14.7:1 never had a problem with any car doing that before this. the reason it is showing lean at the end is I was pulling fuel thinking it was too rich. doing so caused the graph to improve falling off harder with the same pattern at 3K. Thank you for confirming my beliefs about the MAF, but I heard from several people that it would correct the problem.
I also noticed that during a run, the check gauges light will flash dimmly. do you think it could possibly be a ground issue with the car?
Last edited by 30thta436; 03-04-2009 at 08:23 PM.
Post the tune as well when you post the scan
-Scott -
here is the tune
well...looking at that Tune...you got some pretty hacked up stuff going on there....
I am going to take a wild stab and say the problem is in your tune...
your VE is a very bad looking table...it shouldnt shelf off like it does...and it shouldnt be so rough down low either
so thats probably main problem #1
you need to do some IFR scaling cause of the size of your injectors...
are they really 65's?
and what are they rated at? 40psi? 58psi?
I'll help you with what to do to scale things around...takes some trickery...but its a better approach than your flatline approach in the IFR right now
also your PE is set flat.....you need to command most of your boost AFR in the Boost Enrich EQ vs MAP table...you will get much more consistent results that way
it should be gradual as well... 2psi doesnt require the same fueling as 13psi.....
does this car have a cam / heads / Long tubes / what other mods?
-Scott -
I've never had a problem with SC cars using a constant injector flow rate. They are on a boost referance regulator. they are 65lb/hr injectors at 43.5psi. I've never messed with the boost enrich table it's obviously a multiplier, but how does it affect the VE or the PE?Originally Posted by soundengineer
BE is PE for boost (or that is what it is used for). I think it will take the richer between it, PE, and OLFA. I could be wrong on that though.
Sulski Performance Tuning
2000 WS6 M6 - LS6 (long block, refreshed top end), 10.8:1 CR, 90 mm ported FAST, Exo-Skel, 227/232 cam, QTP HVMC, EWP, GMMG, 9" w/4.11s
2018 Sierra SLT 5.3L A8 - Airaid intake tube, GM Borla catback, L86 Intake/Ported TB
quick question....
does your boost referenced regulator also keep it 65 when there is vacuum..or just when there is boost?
the boost multplier kicks in when you go above 100kpa...
you can command NA fueling for the PE as all of your non boost (PE 100and below)stuff will seem like it has a lot more "get up and go" to it
then you can slowly increase the A/F to match boost....
as I said...4lbs boost doesnt need the same fueling as 13 lbs boost
you can literally just go to your blow off valve and crank it off and work it up slowly and see where the car makes the best power per each lb of boost
what you will find is as your boost goes up you will get there faster...
meaning you climb in power quicker which means you win more races
building and maintaining boost is hard...if you can maximize the power at all boost levels you can build and maintain it much easier
what you are going to most likely find is that at close to 13lbs of boost its going to want 11.5~12.0 ish AFR
and it will scale backwards towards 12.5~12.8 ish at 100kpa
and man will the car be more responsive after that
-Scott -
The 1:1 regulators normally pull down pressure when under vacuum so you run a constant flow rate, at least all the ones I have seen.
Sulski Performance Tuning
2000 WS6 M6 - LS6 (long block, refreshed top end), 10.8:1 CR, 90 mm ported FAST, Exo-Skel, 227/232 cam, QTP HVMC, EWP, GMMG, 9" w/4.11s
2018 Sierra SLT 5.3L A8 - Airaid intake tube, GM Borla catback, L86 Intake/Ported TB
Fuel pressure is set at 43.5 psi and it is remaining constant when there is vacuum.
Here is an updated tune file....I spent last night smoothing the VE......and here is a log file. the trend is the same on the dyno.
What octane fuel and what spark plugs/gap?
Hopefully no worse than 93 octane and a TR6 at 0.035"
What is the CR?
Sulski Performance Tuning
2000 WS6 M6 - LS6 (long block, refreshed top end), 10.8:1 CR, 90 mm ported FAST, Exo-Skel, 227/232 cam, QTP HVMC, EWP, GMMG, 9" w/4.11s
2018 Sierra SLT 5.3L A8 - Airaid intake tube, GM Borla catback, L86 Intake/Ported TB
I'm wondering if you are blowing out the spark too....
-Scott -
I thought spark as well, infact that was my first thought, however leaning it up some progressivly moved when this happened from 3k to 3600.......Fuel is 91 octane. TR6 @ .035
Also on a side note, when I was playing with the boost controller, it did this same trend but then shot off like a rocket to 450hp and 550tq. it was 15+lbs of boost though. Probably in the neighborhood of 18psi, but the scanner only reads 15psi.......which made me question spark
try taking a few degrees out of it
then try the opposite...see if it just needs a little different timing(you can just use the VCM controls add/subtract function)
also try increasing the spark dwell time some....
not anything drastic...but it may help keep the spark lit.....
I'll try to dig up a 2bar 98 camaro that I did and do a compare to yours...it seems like a problem I remember having...but I dont remeber wht the solution was at that time
-Scott -
No idea on the compression ratio? I would try to back the boost down to 8 PSI or so and see how it does. If the SCR is high, you might be limited by the fuel.
Sulski Performance Tuning
2000 WS6 M6 - LS6 (long block, refreshed top end), 10.8:1 CR, 90 mm ported FAST, Exo-Skel, 227/232 cam, QTP HVMC, EWP, GMMG, 9" w/4.11s
2018 Sierra SLT 5.3L A8 - Airaid intake tube, GM Borla catback, L86 Intake/Ported TB
SCR is 9.3:1 like I said this think spiked power and boost when I was messing with the boost controller
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