Ran my truck on the dyno today, three pulls. my a/f ratio was sitting at 13.9 pretty much across the board, the dyno guy allowed me time to make changes to my programming, got 5.5-6.5k rpm fuel curve down, need to mess w/ the rest, my power suffered pretty bad from the lack of fuel, wish I had more time, money, and dyno time. best numbers were 274.5 hp and 337.6 ft/lb of torque AT THE REAR WHEELS. If you look at the graph, you can see where my hp curve looks like it could have been a lot damn better if I could have gotten my wot fuel table right.

http://www.hpphoto.com/servlet/LinkP...67a534ee&size=

mods: 94 LT1 (~70k mi) LT4 conversion, BBK 52mm tb, tb mod, 1.6rr, lt4 hot cam, svo 30# inj, crane hi-6 ignition, taylor 8mm wires, 1 5/8 headers to 2.5" custom y, 3" off road pipe, flowmaster, 3.73s, zexel torsen diff, tci 3500 stall, trans go shift kit, stock fpr

 

Get the tune right and try again man, should make in the 340+ range.

 

if it was me I would put on afpr and raise the pressure a bit.

 

thanks all.

looking over the datalog, run 2 and 3 were in open loop, I didn't give it time to hit closed loop, so basically my programming was not there. going to see if he still has the first run available, that was the only run I got w/ the truck in closed loop. I guess he didn't print that one out becuase it was inconsistant w/ the other numbers?

 

Seems a lot of people are having problems with pcmforless.

Try Fastchip.com He's been around longer.

 

my advice would be try tuning by yourself, it is fun and great learning experience. You start to understand what goes behind controlling the ignition/combustion... For me as a graduate engineering student majoring in controls this was a great opportunity to apply what I learned in school. The people who do mail in orders program your PCM just by having a dozen examples of professional tunes done by somebody else, and then they just interpolate...., which might work out sometimes, but most of the times they are off. Quite a few people on this board know more about tuning and can help you for free. When I asked for help, I got free tuning software, free examples of people's tune.

BTW, my old tune was done by a well know mail in dyno tuner on the board, and with his tune and my mods I made just 338rwhp and 369 tq, which were very low numbers for my mods. After doing some research, getting help from board members, and fiddling for a three weeks with my tune, now I got 386 rwhp and 391 tq, which is damm good numbers for me, and great improvement from what I used to have

 

Near peak HP the AFR looks pretty good to me, 13.0:1

Obviously you need more fuel below that but its not going to help your peak power any. Something's up becasuse you are about 70hp short of where you should be....fine tuning the AFR isn't going to net you that much.

Either the tune is way off in other areas or there is a mechanical issue.

 

PCM4LESS = 355rwhp
Self Tuning = 380rwhp
Dyno-Tuning = in two weeks

 

I've had problems w/ pcm4less for a while, been tuning on my own for about 5-6 months now, still learning. found out our pcms kick out of closed loop in wot, closed loop is mainly for emissions.. soo, i am going to check everything out, adjust my rockers, etc etc. been searching for wide band o2 sensors, found a auzzie based company that sells diy kits for about $140.

Sometimes the truck feels like it could pull a freightliner down the road, and other times it feels like it's holding back. I'm getting a lt4 knock module since I have the roller rockers and headers, hopefully that will help.

I talked w/ the owner of the dyno for a while today, he gave me some information/advice, put me in the right direction.

thanks for the help offers people, I will take you up on it.

I'm running datamaster to datalog and lt1edit to tune.

 

Im gonna guess that the cam is a tooth off. 275 is WAY too low to just be tuning. If I remember right, atljar's car had a problem after his cam install. It was only running low 14s around 100 mph. When he got the cam installed right the car eventually went 11.98. Thats a BIG gain from the cam 1 tooth off. I'd bet that the cam is installed retarded, and thats what is killing your power. It might be a pain to check, but its a lot cheaper than replacing everything else, or tuning it till your blue in the face.

 

lol, yeah, I installed the cam, a verified retard...

I reckon i can check the setup of the cam when I pull the valve covers to re-adjust the rockers.. preciate the advice. it won't be too bad changing the cam, I might could do it with out a lot of trouble.. need to fix a oil leak anyway..

 

think i might have figured out what went wrong, was looking at my datalog this morning, my torque converter doesn't lock up till 95 mph, 5250 rpm, definitely explains the downward curve and bump at that rpm. sucks. will have to remember that for next time.

 

You need to pull the timing cover off to see if the timing gears are lined up correctly.

 

The air fuel looks good up top, but is a little lean in the middle. Look though at 5200 RPM how your HP reaches it's peak and flattens out. Looks to me like a possible valvetrain issue.

 

There is definitely something wrong with the engne mechanically. I have done a ton of hotcam tunes and they are always very repeatable. Both the low power and the tune not working right for you really point to a mechanical problem. Load a stock tune in it and try that, and you will see it is still way down on power. There is only so much potential out of a tune, if the motor has mech issues you can't fix them with the computer. Too many guys have botched installs, O2 sensor issues, wiring issues, ported MAF's, etc... and the first thing they assume it is the tune that is wrong and there is no way it is the work they did.
But, I have had tons of guys that assumed this and then later realized the chain was a tooth off, the o2 wires melted on their headers, etc....

As a matter of fact, Kreinmc, wasn't yours one of the cars that the timing chain was a tooth off and then after double checking you repaired it and the car ran great. At least you realized this and didn' t jump on the "it must be the tune" bandwagon, and are now enjoying the power your car is making.