ok i am using tuner pro rt with 4 apu1 and gp1 adapter for 95 burb 7427 ecm. i was trying to make sure the cid is correct in the bin i used and i wondered how this is calculated. when i open the constant for cid it shows 6.7 as the value. this is suposed to be one cylinder value but this does not work out to 355 when you multiply by 8 cyl. secondly i have raised the fuel presure from 13 to 18 psi, stock injectors are 61pph at 13 psi if i cross multiply and divide this means they are now flowing 84.46 pph is my assumption of flow correct? here is the lowdown on engine build. 5.7 vortec, lt1 cam,30 over with open carb manifold adapter for tbi, stainless shorty headers with large bore single exhaust no cats, new billet distributor,replaced all sensors new, i know the truck runs ok but i just need to do a little tweaking for things like disable egr since intake has no provisions, timing tweaks fueling tweaks anyone want to steer me on some of these items?

 

making progress but i have drivability issues i cannot figure out. truck wont go over 20 mph. using stock bin no mods to bin. what is there to check its barely running. ive swapped all sensors to new units fuel psi is 18 steady all fuel and ignition system is brand new stuff tank to tbi plugs wires distributor. verified timing ect.... im stumped

 

Something seems wrong with the XDF if you are getting that number for a cylinder displacement. Might try another XDF. You have to use the square root of the pressure change. I am getting 74.71 lb/hr from my math.

 

Barely runs as in it falls on its face? Loses power? Backfires? Surges?

I had a friend build a similar engine in his Yukon and it drove decently on the stock tune for months. Vortec cam, TBI heads, Headers and an Edelbrock Torker2 intake. My old G-van build ran on the stock tune as well and actually ran pretty decent.

Perhaps you have a corrupted bin file or the wrong XDF for the bin. Being a 95 it should be a $OD file since 95 4L60E has a PWM Torque Converter clutch.

I would see if it runs decent on the stock chip if you advance the timing to about 6-8° with the EST connector unplugged. It should run ok atleast driveable this way. You can rule out mechanical or electronic issues this way.

 

The truck is 95 3/4 ton with 4l80e trans. I loaded a chip with a stock bin that did match turned out i needed tonuse $31 not $oe. Without changing any parameters on the tune its ******* real bad

 

Sorry was thinking 1/2 ton. Not many 3/4 ton 350s out there. $31 does sound correct for a 95 HD. Being that it is a HD application those run even lower timing values in the factory timing map. I have seen them run 18-20° advance. The TBI heads like 28-30° advance at WOT and higher rpm. Disconnect the EST wire and set the timing to 10°. Then plug the EST back in and clear the PCM codes by disconnecting the negative cable and touching it to the positive. A hard reset. Generally even a mild cam will want alot more timing than the tiny stock cam and even the stock cam engine runs better with higher timing.

 

Years ago I put a production LT4 cam and 1.6 rockers into a 8.75:1 1ton 350 TBI. Had an edelbrock intake bored to 2", a 1" open center 454 TBI spacer, and a 2" Marine TBI unit with 74 lb/hr injector flow. 46# injectors at 28 psi. Doug Thorley Tri-Y headers. I did some tuning on the dyno and also ran the thing on the stock chip. With proper tuning it gained about 10% torque through the midrange compared to un-tuned. With the timing at 10* BTDC on the stock chip it still made 300 ft/lbs at the wheels and had perfect driveability. Peak HP was almost unchanged before and after tuning though. If your intake is a low rise single plane it should still have decent throttle response on the stock tune. How did you adjust your rocker arms? If its stock GM lifters (Except LS7) I run zero lash plus 1/4 turn. I find zero lash with a running adjustment. Back off until it clicks, tighten it until it just stops, then slowly 1/4 turn more. If you have a valve or two hanging open the engine will run terribly and no amount of computer tuning will fix it.

 

If you would like send me a copy of your stock bin file and I will send you back a best educated guess for a startup tune. Will be alot closer than what the factory chip would be. I have done enough of these now I can rough in an approximate fuel and timing map for that setup.

 

this is what im starting with, i had set the timing at 0 with est wire disconnected under dash of truck. this engine i had in another truck a 97 vortec, i junked the truck and kept engine because it only had 20k on it since i had i rebuilt. long story short i swapped an intake on it and adapter plate so i could drop it in my 95.

 

Just noticed you said it was Vortec heads. Definately advance the timing to 10°. Also re-read and you said open adapter. I was thinking open plenum single plane intake. Does it have something like a carb dual plane performer intake on it?

 

jegs open plenum intake

 

i just went out and bumped the timing to your recomended 10 deg, its better but still real doggy. if i put the truck in gear and hold brake and gas it, it almost dies. at idle it might be a touch rich but not real bad. off idle it has no ***** in gear. at idle it will rev up but its slow to do it

 

Do you have a link to the manifold?

 

jegs 555-513004 its dual plane, i kept thinking it was an open plenum but it isnt