TURBHOE

iTrader: (4)

ok my truck i think has a problem and i don't know where to start. here is the deal. i have mods all listed below. snake eater has a yukon xl with a magnaflow muffler and k&n intake and tune all on 5.3. and from a dig in 4 hi (both of us) i launch like crazy and jump out in front of him but at the top of second gear and through the rest of the run i do not pull on him anymore. tune seems spot on i'm running 30* of timming till about 4,000 the it goes to 28* shift at about 6200-6300 rpm. what can cause such a loss in top end would it be cats clogged. i ask this because when i first put the motor in i wen tthrough about 3-4 quarts of oil in about 1500-1700 mile. now it doesn't use so much. but it just seems my truck is getting slower and slower will spark plugs do this?? i data logged and i'm getting no KR for the most part i think i got like 1-2* once. so where should i look??????????

here is the funny part i grab a second gear 4hi bark two or three times today with stock 245/75r16's on. but at the same time thats low rpm there not high.

Snake Eater

I think I would get rid of the slow 5.7 and get a powerhouse 5.3L. LOL

That stall really gets it off the line, but once I hit 3K rpms I stay right there through the rest of 1st gear, all of second gear, and into 3rd gear. From a roll punch its dead even pretty much.

With my Yukon weighing 800lbs more I should get my *** handed to me. We will be doing a compression test tonight to make sure it hasnt lost compression. From there all I can think of is the tranny slipping, which its not, or the tune being off.

The tune APEARS to be good while data logging, no real KR, good LT fuel trims, timing is 28-30* WOT. One thing that gets me thinking the tune is missing something is over a certian RPM the MAF bounces back and forth between 45-50lb of air. I know its not making the power to pull 50lbs of air but thats what its reading. I MUST be making quite a bit more power to move 800lbs the same speed and I am pulling a fairly consistant 35-36lb of air.

Could we have the fuel and timing perfect but the air WAY off?

Zick

iTrader: (18)

I feel your pain. My LS1 sounds just like yours. I was burning a lot of oil at first and now its not anymore. Feels a lot slower than it used to be.

I plan on fixing that real soon by swapping it out for a LQ9...


Curious, what year is your LS1? I figure I can blame my problems on mine being a 98' w/ high miles.

Snake Eater

its out of an 02' vette. Not sure about the miles but the waterpump pully doesnt even have any wear from the belt. My Yukon with 10K miles looks like it has more wear than the LS1 did.

Then again it could have a new waterpump and 200K miles. LOL

I guess the compression test will tell.

TURBHOE

iTrader: (4)

i looked at you last run we did today and it fluxes just the same. i changed few things but i don't know how to go back to useing the maf after loading the sd tune