I dont understand my car is slower than before. Why is this?? I have 2 small leaks in my y-pipe where im goin to have to weld but thats it. OMG i cant believe i spent all this money and got no reward but it does sound good thats about it though. Ran awful at first got a little better but now still not as poweful i was expecting some real gains doesnt shift near as hard as it used to not as fast top end just better sound and it sounds like my tranny mount might be going again b/c when it shifts sometimes sounds like something is hittin underneath the car cant tell if its the y-pipe or tranny mount any ideas on how to get my car to run better im so depressed right now

 

I believe it is pretty common to lose some low rpm toque with LT's on a relatively stock car. Hp should be up though above 3000+ but it's the torque that your butt feels. Maybe time for some programming also. Don't most stock cam/head LT1's run rich with long tubes w/o programming?

Jeff D.

 

Well it feels like i lost top end to why would that be?? also it seems to shake under part throttle i dont understand that but at wot feels strong just by looking at the mph nothing has changed what would cause that shake?? I have ran this car for about 40 miles will it take longer than that for my pcm to adjust?

 

Most likely you have be in open loop the majority of the time. Giving it wide open throttle to see what it's got. Computer doesn't learn in open loop. I would try driving around like a grandma for a couple days and see if the cells readjust while in closed loop. Good time to check the header bolts though.

Jeff D.

 

I would be 90% sure the shake is from running rich. I have also heard of O2's stop working after people swap them to their headers. Finiky I guess. I would log a run if you can.

Jeff D

 

i replaced the 02's when i did my header install any other suggestions?

 

Don't trust the butt dyno. You need before/after track or dyno result, otherwise you're just guessing. I drove a bone stock LT1 a few months ago and it felt faster than my car, but I know mine is faster. You're probably just feeling the loss of low end, especially with exhaust leaks. Stock LT1's feel brutal because all the torque is way down low. You feel a sudden acceleration a lot more in seat of the pants feel than a steady pull.

edit-just read that you feel a shake. Check all your plug wires in a dark garage. Look for sparks jumping to the header primaries from the wires. When I first put mine on I burnt the #6 wire. It would shake really bad under heavy load, like 5th and 6th gear under 2000 RPM's. Also make sure all your wires are securely on the plugs. This is pretty common after header installs, you need to take a lot of time routing the wires so they don't burn.

 

I am not a computer guru or anything but wouldn't it seem that brand new O2 sensor's would read different than old ones with carbon build up in them. I think that the computer just needs a few days to relearn in closed loop. Try not to go pass 75% throttle, if that's possible for the next two days. Not really a good suggestion huh?

Jeff D.

 

Yeah give your PCM time to catch up.
I just got mine running after Torque converter and new tranny install, new front suspension, Eibach drag launch kit, KYB AGX shocks, Hooker LTs, and BMR TA. I am babying it around now cause I did so much on this last round of mods that I have alot of stuff to keep an eye on.
Mine feels a little slower just cruising but I have not hammered on it yet.

 

u got some burn wires dude it happened to me about 3-4 times till it was right im 100% sure u have 1 or more bad wires check em and let us know , did u put better wires on yet or high heat ones cause if you didn't then u will need to do that also

 

same thing happend to me i just put my headers on and i did run fine then after a day it just died not power still would run but like crap turns out only 4 of the 8 wires were ok.... 2 were burnt and 2 got eaten up by the belt...... ymmy

check out all of them and make sure your pugs are gapped right.

brad