VINCE

iTrader: (1)

What would cause my air/fuel to go from low 10's to 12.5 right at 5500rpm? Fuel pressure shows steady while looking at the gauge, but air/fuel changes quickly. I have a 408ci Twin Turbo Vette.

MECHAM

iTrader: (4)

out of injector - what were the inj duty cycles?

tune!

Slowhawk

iTrader: (12)

If your running a MAF it can easilly happen.If not it's the VE table.

onfire

iTrader: (17)

If you're running a maf, you're PE table may need some adjustment.

ls1290

iTrader: (20)

Those would be my guesses in that order

Keith

VINCE

iTrader: (1)

Off the wastegate spring during the day it hits 60% and close to 70% at night during colder air.

VINCE

iTrader: (1)

I did not log it last night to see if anything has changed. I will do a run today to see if I see anything using the scanner. I have been running the MAF the entire time.

ABeasst

iTrader: (5)

so has this just started happening all of a sudden or did you just get the setup put together and are tuning it?

VINCE

iTrader: (1)

One of my friends thinks I was spinning the tires and probably did not know. I have spinned them on channel 2 in 4th around 5500rpm, but not off the wastegate spring. My car sits at 12.5 to 13lbs off the wastegate spring, but I was spiking the boost controller up to 16 and 17 last night. I had the meth all the way up and one point to see if anything would change and it made the car super rich and then leaned to 12.5 up top. I looked at the PE table and it does add fuel in that range. I can add more to be on the safe side. I really just need to get the 3 bar SD tune done.

VINCE

iTrader: (1)

I dont go WOT very often. I just put in a Tex Twin Disc clutch, but I also noticed the air/fuel going up like that on my old clutch and just thought the clutch was slipping because I could smell clutch. This time I dont smell clutch. I had a mishap early last year and it was discovered I had a bad lifter. We repaired the bent valves, replaced the lifters and removed my old suspect cam just in case it was damaged. I am still running that exact same MAF tune as b4. I have no doubt it needs some tweaking. I just want to make sure everything else is ok b4 taking the road trip to get the 3 bar SD done.

ABeasst

iTrader: (5)

I'd say its in the tune. Did you put in an aftermarket cam or another stock one?

2001-WS6

Vince, are you talking about being on 16 or 17lbs of boost or you just turned the gain up on your boost controller to 16 or 17? Figure a 16-17 gain on a cold night put you at about 15lbs of boost?

Did you pull beyond 5500 rpms or let off each time it got there and the A/F went to 12.5 each time no matter what the meth was set too?

Make another pass with no gain and base meth settings. Does the car pull past 5,500 rpms? Need to validate that there is no valve float.

Rick

VINCE

iTrader: (1)

Rick I never touched the boost controller. All settings are set to the same as they were when I picked the car up in November of 2006. The car pulls all the way to 5500rpm and above. The a/f jumped up to 12.5 with the meth set to the original and with the meth set to 100%. I am running the Patriot Extreme Gold springs. I had the car on the dyno a lil over a month ago to see if I was getting valve float and the graph was smooth all the way to 6500rpm. Not saying somehow the springs could not have weakened, but who knows.

onfire

iTrader: (17)

Trying to run 12 psi to 17psi on a single maf/PE tune is crazy. If you tune it for 17psi it will be crazy rich at 12psi. If you tune it for 12psi it will probably go crazy lean at 17psi and B L O W.

Tiago

iTrader: (27)

Yes, MAF tune cannot correct AFR for boost changes!

VINCE

iTrader: (1)

It spiked to 17psi, but did not hold 17psi. I know that it's rich at the lower boost setting. The car has been running this same tune since day one and it has seen over 900rwhp on a loaded dyno w/out any issues and the a/f was fine. I recently repaired a boost leak, but I could not get on the car because I was breaking in the clutch. Well doing short spurts I noticed the car was feeling a little sluggish. I did get on it some post repairing the boost leak and it responded well. Over time that new hose I replaced blew off. This was discovered like 20 minutes ago. That hose comes right off the turbo and goes toward the intercooler. I think that is my air/fuel issue.

stevieturbo

missfires will show as lean.....

VINCE

iTrader: (1)

I would think it would misfire all the time and run lean all the time.

2001-WS6

The boost controller is a Blitz SBC i-D III (maybe a color one) multi channel controller guys. Flipping through the **** adjusted menu has been known to cause opps when distracted on the road or the pits. I've been there. So Given no changes to the tune and no intentional changes to the settings on the boost controller, there may be an accidental change to the boost controller that is getting to you. So it would help to review the controller settings when you get a chance and post them here.

The boost controller has an Auto and a Manual mode. The Auto mode has a learning feature that allows the controller to learn the car and provide an easy "tuned" approach to reaching the boost target. The auto mode does not work well with dual turbo setup or higher boost settings. There is too much room for error in most cases. The Manual mode does what you tell it to do and is used by most of us with these controllers. So that's a potential opps if you go from Manual to Auto mode and the controller is learning which could cause the spike. This setting is under the Main Menu... Boost... Auto/Manual menu item.

The Manual mode can be set to different gain levels on each of its 2-4 channels (depending on the model). This allows you to quickly move between preset boost levels and use the scramble modes with timers to switch on the fly. The trick is that you have to be careful when selecting the channel or changing the gain for a selected channel at the main display rather than using the Menu items to make these changes. It's just easier to make a mistake at the Main Display and not realize it.

The tune would have been set for the highest gain settings probably set on Channel 2 originally. Let's say 0 gain on channel 1 gives him his normal "on waste gate spring" setting of 12.5-13lbs of boost. Then channel 2 might have the gain set to 20 to allow a 15lbs boost target. We just need to confirm what these current gain settings are to do the math for the target boost.

The controller also has another gain setting under the Main Menu... Boost... Gain menu item. This gain controls how quickly the controller allows boost to rise to meet the target Channel Boost Gain settings. So if it is set to 100 it will shoot there faster and may spike on the way to the target. Out of the box setting might be 15 while external waste gate applications may need higher settings. I run 100 because... instant boost at the track is additive.

Colder air will result in a higher amount of boost being allowed by the controller at a given gain level. Every lb of boost is probably worth a bit more than .5 a point of A/F on your 60deg nights right now. So if you find yourself 4lbs of boost over your intended 13lbs target for example, there went your A/F ratio. That's where the guys are explaining that a standard MAF tune will not adjust to that missed target level of boost.

So it's important to figure out what is causing the boost spikes and reviewing the controller setting would be a good place to start first.

Rick

VINCE

iTrader: (1)

My car was tuned in the winter time in Michigan. It was colder then than it was last night in Tampa, Florida. I guess some missed the part where I said I found a major boost leak right off the turbo? My Boost Controller settings are the same as when the car was delivered.

Channel CH1
Auto/Manu MANU
Set 0
Gain 0
Graph Scale 20

Channel CH2
Auto/Manu MANU
Set 31
Gain 0
Graph Scale 20