2xLS1

iTrader: (25)

Take a look at these two pictures. I ATapped this car on the dyno today. Look at the A/F graph vs what ATap logged B1S1 and B2S1. Does this look right? The wideband looks pretty good, but the ATap log looks really lean. Any comments?

MM98

iTrader: (13)

Hey guys this is the owner of the car that was dynoed as mentioned by 2xLS1 in the above post... My mods are in my sig & the car is running on a stock tune... Any help or ideas on what might be going on with the car would be greatly appreciated.

Thanks,
Mike.

Cal

iTrader: (1)

This is a perfect example of why you can't tune WOT AFM from stock O2 readings. Looks like the car is tuned about right.

jrp

iTrader: (16)

wideband > ATAP. alot of guys freak out when they see a really lean or rich read out from atap, then once they get on the dyno w/ wideband they find out its not so bad.

getting a bit of KR there, is that false knock or indeed true knock

MM98

iTrader: (13)

I'm not sure... How would one go about finding out if it's true or false??? Could it possibly be a bad knock sensor or banging of a header on the k-member at wot??? I'm inexperienced when it comes down to tunning.

Thanks,
Mike

Nickn20

race gas

2002WS6_MN6

So now he knows what his O2 voltages look like at a given AF ratio at WOT.
Is this a usable number for tuning (.7 - .8 mV range?) for his car?

2xLS1

iTrader: (25)

What about the calibration on the wideband. The last time this car was on this same dyno, it showed an A/F of around 16:1. I did not ATap it that time. I think the only change to the car between the 2 dynos was MACs/ORY was removed and Pacesetters/ORY installed. Mike, try and find that chart and post it. Also, if the ATap O2s are so wrong, why are the LTrims so high.

CamaroCain

iTrader: (1)

I'm with 2x on this, the longtrims show the computer constantly adding fuel throughout the run, why would that be happening???

tony99vette

It looks like its lean on both the autotap and dyno.....Am I seeing something wrong here????

MM98

iTrader: (13)

Here is my previous dyno graph with the Macs & ory... This was done in early Nov 03'.. The A/F is almost of the charts, but I'm not sure if that was an accurate readindg at the time...Thanks again for the help.

Mike

Tom99SS

iTrader: (2)

This is happened to me almost 2 years ago. Had the car dyno tuned after the cam install (no headers yet, I know I did it backwards). Had no KR, 29-30* timing and 02's around .840. Went to the track to run it and there I get KR just like you. High 3's in KR. Went back to the tuner and this time we did the fine tuningon the street. He was in the car and recorded with A-Tap. We would stop, he would do a few changes with Edit and then A-Tap it again. He did his little tweeks until he was happy.

After reading posts on here it seems that some tuners are now doing a dyno tune to get the baseline. Then they go out on the street to fine tune it. When on the dyno, the load is not as great as when on the street. This is why you got no KR on the dyno but had some on the street.

I am no tuner but this actually make sense to me but then again I could be all wrong.

MM98

iTrader: (13)

The car was ATAPPED while on the dyno not while driving on the street... That is the ATAP file from the dyno run that 2xLS1 posted...

JxxxOxxxE

iTrader: (1)

Hey glenn, shoot me an email, I lost your email address. I wanted to talk to you about the tuning we did a month or so ago with EDIT....

To the subject, If I remember right, Briand and I were getting O2 mV readings that were a ways off of the wideband we were using. We didnt do any other testing though to see why the difference was there...

2xLS1

iTrader: (25)

I'm beginning to suspect the accuracy of the wideband on this dyno. Joe, were you using the wideband at Alternative?

JxxxOxxxE

iTrader: (1)

yes, the one at alternative...

strokedls1

iTrader: (1)

I think you are still running way lean. With my wideband reading 12.9-13.1 on the street the o2's on atap were .905-.915 mV. No way is a .7 something reading equivalent to 12.8 af. I have tuned seven cars and this was always the case. Richen that thing up before you detonate the motor apart like I did. Stock pistons hate knock, and a lean condition will cause knock. Just take this as my .02

MIGHTYMOUSE

iTrader: (59)

i would be suspect of the dyno's wideband.. especially after the second graph you posted where the dyno's wideband is completely wacko.

you are not running enough timing to have detonation if the dyno is right.. therefore i would agree with the a/f the factory is outputting..

i 100% disagree. i would put money on the factory sensors being closer to correct based on the knock.. unless its false knock.. looks too much to be false to me. add some fuel anyway, watch the knock go away and hp go up..

2xLS1

iTrader: (25)

We changed the MAF on the car and we are going to ATap it again.

mcflyz28

It's a 98, need to change out those knock sensors.