Trucks always felt weak but I just thought I was crazy I took it to the track and ran a best of 16.8 at 82mph tonight mods are what are in my sig. What are Yalls thoughts?


NO CEL LIGHT EVER.

EDIT
Little background
Motor was installed in 2009 ran great for 700miles then fell on it's face and always ran weak after that.
Compression 190+ and close in all cylinders
New parts maf, knock sensor/harness, o2s, water temp, plug wires, plugs .38 gap, new walbro 225 fuel pump, fuel filter, few other parts to just can't remember. Didnt mess with the truck much cause i played with my ss and a few bikes. now im back at trying to figure this out. Had it retuned 5 times with not much better results. All plugs are firing.

truck has a miss threw all rpms its worse between 2000-2500 but you can feel it everywhere its hit and miss. during light accel the rpm gauge will be going smooth then just start to bounce about 100 rpms(the miss) then if you give it alittle more gas it will work its way threw it. its like the timing is retarded a crazy amount all the time.


my fix is i bought a bigger cam and some dual valve springs just trying to rule out everything.

could it be the crank positioning sensor, or tps?

60ft 2.53
1/8 et 10.9
1/8th mph 65.22
1/4et 16.80
1/4mph 82.75
Tires didn't spin at all

 

Are all cylinders firing?

 

Little background
Motor was installed in 2009 ran great for 700miles then fell on it's face and always ran weak after that.
Compression 190+ and close in all cylinders
New parts maf, knock sensor/harness, o2s, water temp, plug wires, plugs .38 gap, new walboro 225 fuel pump, few other parts to just can't remember.

Had it retuned 5 times with not much better results. All plugs are firing.

 

Sounds like weak valve springs or a few broken ones. A dynograph would show where the power is falling off at. Mine ran 16.8 @ 89, but that's because it was pissing coolant out a headgasket and had an exhaust manifold leak.

 

Slight miss at 2000-2500 valve springs all look
Good. I'll be more detailed when I get home on my computer

 

Either you have knock sensors that haven't been tuned for the cam, or you have an ignition problem.

How do the plugs look and what brand/style are they? If the valves are good then I'd go with bad plugs... I've seen perfectly good "looking" plugs fail on a dyno- swap them on the spot and the engine runs beautifully. I don't know what the proper spark gap for your application is, but isn't .38 a bit small?

When you say the timing is retarded, can you hook a scan tool up and get a spark advance reading for us? That would help tremendously. Autozone should let you borrow one or do it for you. You need an Actron CP9180 or higher scan tool. If you see it subtracting advance, it will almost certainly be an untuned knock sensor or bad IAT sensor.

 

brand new tr6 plugs (gonna spray it if it ever runs right) i had 4 or 5 sets of plugs in it i know thats not the prob. and my tuner said i wasnt getting any kr last time i was there cause that was a prob at first. but i will borrow a scanner from a friend latter and see if its still pulling timing.


and a dyno will show where the powers falling off, hahah no need for that the truck wont even do burnout it NEVER makes any power.

 

Just an "ugh" question based on personal experience, how is your timing chain doing? Have you checked it for excess slack? I put on a JP Performance kit and the chain was shot inside of 400 miles. The cam was being pulled at -4 degrees advance and the truck was on its face the whole time. I put a GM Performance kit in and the problem has not been seen 3000 miles later.

 

idk im swapping in the texas speed tq v.2 cam today so im going to check all that. its a new timing chain but i guess it could have got excess slack within those 700 miles before the truck took a crap on its self. im going to go get a scanner right now to see if its pulling timing then when i get home ill report back, and start the cam swap.

 

You should find the problem during your cam swap. The 5 retunes tells me something is mechanically wrong and tune cannot fix that.