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View Full Version : In SD Now, should we re-implement the maf?



SUPRSLO
February 9th, 2006, 06:16 AM
Question guys. I've tuned the z06 i've been talking about in SD mode (01 z06, stock heads, lg long tubes, borla stingers with no cats, ati 10% underdriven ballencer, 30lb SVO injectors 37ish with ls1 fuel pressure, lg motorsports 90mm throttle body with fast 90 intake, vara ram, spec 3 clutch, 239/242 .651/.612 110lsa 110icl cam and all apropriate valve train stuff, comp adjustable timing set, ported ls6 oil pump). The car still has the maf plugged in but is disabled via fail frequencies set to 0 and 1 for low and high frequency fail respectively. Have to leave plugged in because this car has it's IAT sensor in the maf. Now that being said i've set this car up according to the directions of the EFI Live SD tuning tutorial, that is above 70kpa and above 4000 (or close to) rpm the car will be at 13 to 1 a/f and below those figures at 14.7 to 1. I've left the pe table values at 1 so all my wot tuning occurs in the appropriate cell values of the ve table as well. The car hold an idle just fine and the commanded a/f values seem to be in line with what i'm seeing on the wide band.

This car has always been run in open loop as the car has always been stronger this way every since he put on the headers and forgot to bolt up his oxygen sensors. When logging it looked great so I just told him to not put them back on.

That being said this guy is complaining of the car smelling like gas and pipes turning black now that we've done the cam and i've done the speed density tuning. The car runs real strong and drives just fine and he's perfectly happy with that. Now, for the questions.

The reason this car is in speed density mode is that during driving with the maf the low activity code will set and usually sets when the car starts loading up (his cruz a/f would go from 14.7 ish to 12-11 to 1 while the bucking occured). This being said it would seem that the maf is getting reversion caused by the big cam with lots of overlap. I don't think there is anyway to tune this out, except for physically modifying the intake tract. Am I wrong on this? I'm trying to decide that since i've got the ve table taken care of should I go ahead and try to re-implement the maf?

Second, do you think more timing will clear up some of this smell?

I'm getting the car this weekend or soon after if the weather doesn't cooperate so i'm going to try some of these things with it then. In the mean time feel free to make any suggestions. Thanks.

zrx1200
February 9th, 2006, 10:00 PM
get a air intake sensor from a earlier model, throw maf in bin, update to twin table custom o/s ..and you wont go back...

Black02SS
February 9th, 2006, 11:52 PM
When does it stink? I have found that no matter how hard you try, any car without cats is going to have a certain smell to it. I have found that if you try and reduce the startup AFR to be a little leaner, it will help some. I don't see hooking the MAF up fixing the problem.

SUPRSLO
February 10th, 2006, 12:59 AM
Thanks guys, I was kind of thinking along the same lines but am always open for suggestions. To be honest this is something i'd never complain about, but just trying to get this car as right as possible for the owner.

joecar
February 10th, 2006, 05:56 AM
"The smell of gasoline in the morning smells like... Victory!"
:D

bink
February 10th, 2006, 10:04 AM
I have an 01 Z06 with LGs (well Kooks going in now) and a 239/251, 106 lsa cam. It runs well through the MAF. I'm not sure what you mean by an "Activity code". If my MAF isn't within range of predicted air (dynair) then it falls off the MAF (sd) and pulls timing (falls to the lowest available value which is usually the base tables). The cure was/is rescaling the VE and/or MAF. Bumping the Idle timing into the 26 - 28 range really helped with the fuel odor (catless) - thank you Dirk ! Hope this helps some.
:cheers:
joel

bink
February 10th, 2006, 10:08 AM
"The smell of gasoline in the morning smells like... Victory!"
:D


.................................or a fuel pump going out.
:mrgreen:


:cheers:
joel

Redline Motorsports
February 10th, 2006, 10:43 AM
When does it stink? I have found that no matter how hard you try, any car without cats is going to have a certain smell to it. I have found that if you try and reduce the startup AFR to be a little leaner, it will help some. I don't see hooking the MAF up fixing the problem.

I agree 100 %. Putting the cats back on will solve the problem. Personally a set of high flow cats will only grab 5 hp which may be worth it in the long run. My stroker car has no cats and you smell like a smoke bomb after some street beating. This is way my New ZO6 is keeping the cats!

SUPRSLO
February 11th, 2006, 10:29 AM
Bink, you just gave me an idea on the maf thing!!!!!!!!!

I too have my timing set that high at the suggestion of Dirk.

Something else I just thought about, I think I set the DFCO to a lower rpm, I wonder if that is causing some smell? Thanks guys, doesn't look like this weekend is going to work for the tuning though, less anyone's got a recommendation for a nice 18" snow tire, lol.