i've got a problem with the truck, but i'm not sure what it is..

when i go to WOT the truck makes a heck of a racket (sounds like a helicopter coming out of the exhaust) and it doesn't really fall on it's face, but acceleration is suffering.. kinda like dragging a parachute.. on second thought it's kinda like hitting the rev limiter. kinda. the problem starts around 3000 rpm's though..

all is just fine if i am driving normal.. no sounds, nothing amiss..
even if i slowly mash the gas & gain boost & speed it is fine till it goes WOT.

i thought it might be misfiring, but the motor doesn't miss on a heavy (not WOT) acceleration.

when the truck does the weird thing, i don't lose any boost, nor do i hear it ping (kinda hard with the loud *** exhaust sound)

i put a 90mm MAF, 90mm airkit, 4lb lower, oil cap breather, gatorback belts and a newly reburned 4 way chip in a week ago.. the truck ran just fine till a couple of days ago.

my truck has denso IT20's in it.

things that it may be:
hose came loose in gastank?
blew exhaust off? (wouldn't i hear that all the time?)
sparkplug or coilpack failure?
new mod messed up? (oil from new K&N on maf?)

i have a autotap, and as soon as i can find a laptop i'll check the misfires.. anything else i should look for?

thanks in advance!

 

sounds like a launched plug if you ask me, except you'd hear that under the hood from the front of the car, not from the tailpipes.

 

maybe it launched it outta the tailpipes? lol

 

aargh.. what is it?

 

update:

used the autotap, and found no codes.. had a friend ride with me & watch for misfires, ect & got nothing whatsoever..

i also put the truck in neutral & held the RPMs from 2k-4k without the problem happening,,,

checked chip, maf, exhaust, and wires/vac hoses for anything out of the ordinary,, found nothing amiss.

it only happens while the vehicle is under a load.


i took my videocamera with me & will post some .mpg's in a bit..

crap.

 

My truck was acting like that awhile back. I could not tell if it was misfiring or not, no codes were found. But I did find a broken plug due to detonation. If I ever have problems now I check my plugs first. Good luck on finding your problem! Oh the way I found it was to pull coil packs off with it running , untill I found one that didn't change much.

 

I would also think plugs first.
Let us know what it turns out to be, Brooks

 

the truck idles fine & doesn't miss when in neutral & holding it from 2-4k rpm's. that is when the sound kicks in at wot.
plus the autotap showed no misfires.

here are a couple of crappy vids:

http://svt.kicks-***.net/videos/oddsound/odd1.mpg

http://svt.kicks-***.net/videos/oddsound/odd2.mpg

http://svt.kicks-***.net/videos/oddsound/odd3.mpg

you can really hear the noise in the second video.

help!!!

 

definite miss. i'd say either a plug or coil pack, that has no problem keeping up,,, until "wot"

 

i wonder why the autotap didn't pick up any misfires. aargh.

i hope its just a coilpack.. i actually have an extra one of those. lol

 

Maybe, one of your cats came apart, the substrate broke and maybe you are hearing it at wot. Just an idea! Good luck on finding your problem. Jim

 

the autotap is just a scanner no?

the EEC V processor didn't pick up the missfire, not the autotap. sometimes it just doesn't, or else it takes a while. oftentimes a coil missfire will be VERY noticeable, but will not set a code or the "Check Engine" SES light.

now to find out which one is the culprit. I'd still pull those plugs and check them though.

good luck

later,
chris

 

Brooks sounds like what mine did when it ate 2 plugs at Hallsville..

 

YEP, I'd say plugs too,

I actually made a 1/4 pass with these at the track

Didn't do so good, but it actually ran ok on the street, or so I thought. Mine sounded the same way yours does, but I had a little more roughness on idle.

Dude you got major boost at low RPM's, hope your tuned for that

 

Plugs(as everyone says) and/or clogged exhaust???

Dan