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View Full Version : Guess this DIP...


GoldLS1
03-26-2007, 10:52 PM
I was looking at my graph from the dyno day, and realized that it dipped pretty big... so name the cause of the dip. Is it belt slip??
03LightningRocks
03-26-2007, 11:07 PM
The last time I saw that, the guy pulling the dyno caused it by putting the truck in drive when making the pull. The tranny may have shifted right at that point.
GoldLS1
03-26-2007, 11:28 PM
The last time I saw that, the guy pulling the dyno caused it by putting the truck in drive when making the pull. The tranny may have shifted right at that point.

Nope, truck stayed in 3rd.
GoldLS1
03-27-2007, 09:14 AM
ttt... I know everyone has an opinion.
slick-svt
03-27-2007, 09:19 AM
You broke the tires loose on that bad boy :burnout:
BC Lightning
03-27-2007, 10:36 AM
The last time I saw that, the guy pulling the dyno caused it by putting the truck in drive when making the pull. The tranny may have shifted right at that point.

I don't remember which truck it was, but one did shift into drive
Mark #2
03-27-2007, 05:50 PM
Rich, ran out of MAF or injectors, goes lean so the curve goes up. Get the A/F.
GoldLS1
03-27-2007, 08:46 PM
I don't remember which truck it was, but one did shift into drive

My was the 4x4 DSG with KB, JLP sheetmetal intake.
03LightningRocks
03-27-2007, 10:13 PM
Rich, ran out of MAF or injectors, goes lean so the curve goes up. Get the A/F.


I would be surprised as hell if he ran out of MAF at the HP levels he is at.
GoldLS1
03-28-2007, 08:52 AM
I would be surprised as hell if he ran out of MAF at the HP levels he is at.

Actually Terry told me my MAF was done when we were tuning it. I forget what numbers he rattled off, but he said that was damn close to being peg. He said the maf should be my next mod. Also when we were tuning it he said the truck didnt want a lot of fuel uptop compaired to most others hes done w/ close to my combo?
03LightningRocks
03-28-2007, 10:10 AM
Actually Terry told me my MAF was done when we were tuning it. I forget what numbers he rattled off, but he said that was damn close to being peg. He said the maf should be my next mod. Also when we were tuning it he said the truck didnt want a lot of fuel uptop compaired to most others hes done w/ close to my combo?


How much HP is your truck making? The graph above peeked at 380.

Your truck doesn't want alot of fuel up top???????? What???? I am not sure what you mean by that. Is your MAF out of calibration?
L8 APEX
03-28-2007, 11:40 AM
I can't see the data log but I think the maf was reading about 1000 counts, they max out at 1023 counts. It only needed 2% or so more fuel up top to reach the desired A/F. Most KB's like 3% or more fuel but his is only at 12psi if that. It would need a MAF pretty quickly.
03LightningRocks
03-28-2007, 05:29 PM
I can't see the data log but I think the maf was reading about 1000 counts, they max out at 1023 counts. It only needed 2% or so more fuel up top to reach the desired A/F. Most KB's like 3% or more fuel but his is only at 12psi if that. It would need a MAF pretty quickly.


Makes sense now. I didn't realize he was modded that much when I saw the low HP on his dyno. Yep.....new MAF and fuel injectors are in his future:).
L8 APEX
03-28-2007, 05:31 PM
It may have something to do with the filter layout. I have not seen stock MAF's peg that quickly before... The truck is not fast it will barely spin a tire from a roll. I was suprised the MAF was reading that high. It has enough fuel for now.
bluesvt
03-28-2007, 05:33 PM
If the MAF pegs out will the truck stumble in WOT? I used to get a little stumble shifting from 1st to 2nd without hitting the rev.
L8 APEX
03-28-2007, 05:49 PM
If the MAF pegs out will the truck stumble in WOT? I used to get a little stumble shifting from 1st to 2nd without hitting the rev.
There is a lot of speculation to what happens when the MAF pegs, none if it is good. Most say it defaults to a stock table which is too lean for most of us.
Mark #2
03-28-2007, 08:46 PM
Makes sense now. I didn't realize he was modded that much when I saw the low HP on his dyno. Yep.....new MAF and fuel injectors are in his future:).

So I got right? Yes?
I might be smarter than a 5th grader;)
03LightningRocks
03-29-2007, 12:00 PM
So I got right? Yes?
I might be smarter than a 5th grader;)


Maybe/maybe not. But your SWAG is a possibility;) . If his other three pulls look the same, I would say it's a possibility. Otherwise, I would still say....look at some other cause. I had the issue you speak of at one point when building up my truck. I was thinking the graph looked different. I will see if I have them in my gallery.
Sixpipes
03-29-2007, 12:07 PM
Maybe/maybe not. But your SWAG is a possibility;) . If his other three pulls look the same, I would say it's a possibility. Otherwise, I would still say....look at some other cause. I had the issue you speak of at one point when building up my truck. I was thinking the graph looked different. I will see if I have them in my gallery.

I say the operator adjusted his foot on the pedal for a split second. Since there is no time quadrant on the graf, that would be my best guess. But what do I know, I'm only smarter than a second grader. :D
03LightningRocks
03-29-2007, 12:29 PM
I say the operator adjusted his foot on the pedal for a split second. Since there is no time quadrant on the graf, that would be my best guess. But what do I know, I'm only smarter than a second grader. :D

Foot slip(adjustment) would fit it better than running out of injector/fuel. It seems to me that if it ran out of fuel, it would not suddenly decide to go back up. If the injectors/fuel pump isn't enough, it seems the graph would hit a wall and just stay there or even drop off. I also wonder why it would not have started detonating right there on the dyno if it started running lean. As we all know, our trucks don't have a knock sensor to retard timing, so when they go lean...they just keep on going until boom.