Need some help from people with knowledge
 

Ok long story short my tuner thinks im getting valve float because as you can see in my dyno sheet im losing power at top end . Its od to say i have valve float as i never pushed the car passed 7200 on a zzp reflash. So im confused becasuse my best budy says its not valve float he is very familiar with engines but dosent mess with gms. The car pulls hard as hell even got my buddys srt4 caliber by 4 cars and he has 275 to the wheels . Im really stressed out big time !!!!!!!!!!!!

I also have a po0496 code wich i already know is giving my a randam misfire.
Last night i pushed the car to about 120 without redlining any gears shifting from about 6000 and it wnet into power reduced mode i picked up a po0068 code with my scan gauge wich i googled and came up as a vaccum problem some guy with the 2010 camaro had the same problem . Im wondering if this mite be casuing the lost of power at top end but again my buddy said we dont make vaccum at full throttle . So im stuck anybody with experince please help !!
2 different dyno sheets the first is were she drops for a bit the 2nd looks a little more normal ThANKS IN ADVANCE !
https://www.cobaltss.net/gallery/fil.../4/0/gfgfg.jpg
https://www.cobaltss.net/gallery/fil.../4/0/gfhhh.jpg

What mods are done to your balt? I assume you have an aftermarket intake manifold. Now as far as the P0068 code thats the absolute manifold pressure code and if you have an aftermarket intake manifold then you can clear that code altogether as its normal. Your buddy is right that we dont make vacuum at full throttle. As far as the graphs go they look fairly normal. The first graph looks a little bit odd but I would assume its nothing out of the ordinary. And the random cylinder misfire is common with the balts. Everyone I have worked with has had this even stock. You really notice the misfire moreso when moded to the nines hence the reason that with hptuners you want to add short pulse adders to your fuel injectors and tune properly to smooth out the idle and the misfires. Im still tripping that code with tuning but my misfires are not nearly as severe as they were after my turbo conversion.

Op - You can send me over your tune file and I will take a look / fix it for you if you would like.

!!
 

2.8 60,s zzp 3'' intake, jbp header catless down pipe 3'' ,2.5 catback, ls4 tb, dual pass option b ,front mount h/e, meth kit but didnt tune with becasue tuner told me to get the progressive controller so i havent used it.
solid mounts ,engine damper .

I dont have an after market intake manifold i wish i did !!
aas for the random misfire i see it is normal as i have been doing alot of reading but also has to do with this stupid po0496 evap code wich im planning to get fixed this week.

Like you said the first looks odd and the tuner said the same the car dosent wana pull at a certain rpm he said he has never seen this before and he has tuned over 100 cobalts he eve showed me a few other dyno sheets of guys with similar mods pulling over 250 to 260 that leaves me with about 10 to 15 hp less than the other guys and he says its coming from the drop in the graph if it wouldnt drop it would contineru making the power wich left him thinking VALVE FLOAT as the only reason why this mite be happening .

anymore ideas keep em coming

How would i do this i didn t tune the car myself and i dont have hp tuners on my laptop.
I dont want this guy to know im going around looking for the solution if its bullshit i wana know and then let him know whats up .

It's not valve float, I can tell you that much. The stock valves on the LSJ are good to 7250, some people even run them up to 7500rpms with no trouble. As far as sending me the tune to look at it, you would have to have your actual tuner send me the .hpt file. I would put money on it that its the tune causing the issue. If he doesn't want to send the tune file, have him send over the log of the car. It could be knock causing you to lose power. It really just depends on whether or not the tuner knows what he is doing.

could be running out of fuel.

No, its not running out of fuel.

Are you using the meth kit untuned? If so what mixture are you using, and what kit is it? If you are not tuned for methanol injection I recommend running just straight distilled water, once tuned for it run whatever mixture you would like.

You would be able to hear it if you were floating the v-train

Im not running the meth kit at the moment and i wasnt at the time of the tunning . As for the tuner having experience he does he has tuned hundreds of cobalts in the newjersey area people with my set up have made more power from him he has shown me numerous dyno sheets . He currently is working on a 500 hp turbo cobalt so yes he knows his stuff .

We sat there talking and dicussing what it could be and it was the only thing he could think of .

Has anybody else experienced this ? Its weird because you can see the power drop loop then it goes back up again.
i remember him saying something about the car going rich at top end its were the loop happens so thats how im losing the power he thought it was being caused by my cat being clogged but then reminded him im catless

I like your style. Seems as if you are very helpful.

Generally, and i say generally most stock cammed lsj's make peak power at 64~6600 rpms, however there are exceptions to the rule. The dynojet graph looks normal to me with no signs of knock.

The mustnag dyno looks like you knock just over 6k rpms.

What do your iat2's look like up top?

i will answer this later on tonight im gona check it out i really havent looked at the iat 2 when at open throttle im trying to see were im going so i dont run into anything LOL

I was talking about the dyno, the road and the dyno are two different animals. Your iat2's will almost always be higher on the dyno.

/\true/\ it definatly sounds like ur getng timing pulled... but i have no clue as to why it would kick right back in after it drops... hope u get this figured out.

Bump

Just got home from work and i was remembering everything that went down that day and i think he said the car was going rich or lean im not sure at the time when it loses power in that little dip you see . Still trying to gather info on whats going on just want the beast ridding correct !!

Does anyone think this can be due to an exhaust problem i do have a custom exhaust that consists of 2 mufflers no resonator and no cat .1st muffler is in the resonators position maganaflow round straight through muffler its 36'' long and 6'' round and at the end i have a dyno max also staright through with an offset oval about 14'' long 4'' thick. Anybody think this could be the problem .
Also someone here said it looks like im getting knock when it drops but if it was knocking he would tell ofcoarse and fix it ! HE is a good tuner i believe anybody in nj ny area may know his shop down by toms river this guy does all gm and also subarus he knows his shit wich is why i dont get whats going on and he said valve float may be the only thing he could think of

It's not an exhaust issue and it's not valve float. Push the car to 7500 and see what happens on the graph that will prove its not valve float. Try and get a log via hptuners of the car and I/we will more then likely be able to solve this issue.

When you say log you mean its like i can get it printed out or something sorry but i have no idea what you mean

Its a scan in hptuners. It lets us know everything that the car is doing.

ok after i get this scan how will i let you know hwat it tells me is it printable ?
Another question if my tuner emails me the tune file can i forward it to you ?

Yes thats what I need done is I need either the tune file or the scan file emailed to me. It will be from hptuners which is the program he is using. Once you email me that I will more then likely be able to solve your issues and possibly gain you a few more pony's =P.

Hey man thanks alot very much appreciated !!
Not many people like you trying to help someone out they dont even know !!

No problem man that's just how I was raised. I do it all the time =D. I also tune cars for a living so it's just work haha.

tell matt. it is not valve float. if he questions me on this. he has my number.

You do realize i answered the question right?

Area your a trip man ever since i been on this forum you make me laugh with your comments and arguements wich are good ones by the way.
But how in the world did you know it was matt ? Did toms river give it away ?lol:lol:

Yes but now its time to sit down with the tuner and discuss he a cool cat as area knows him i guess but its almost like insulting someones knowledge when you go behind someones back to get second opinions on there tune and shit . But will def get him to check for knock and it seems like area knows the solution but like always he is like zorro about his stuff . LOL

oh by the way just pmd you about the tvs LOL