Need a little help.

[1985BuickGN]

Just took the car out for a spin, first after getting it together. It's an 87 Buick drivetrain, Fast system, 80lb injec., 208 cam, 72mm turbo, front mount IC, BG intake and upper plenum, forged JE pistons, stock crank, stock rods, GN1 heads untouched and a Bruce built trans. Had this set-up running in a hybrid car and had a bigger cam in it (218), now it's where it should be (in a Buick) and I'm trying to tune it (guy that I had helping before is'nt around now and I'm on my own). Got it to idle well and tip-in response was pretty good, so I went for a drive and under light acceleration it surges, not bad but enough to notice it also does it at cruising speed, the rpm's jump up and down a few hundred. Not sure what I need to adjust for this. Did a WOT blast for a few seconds to get some numbers logged and the O2 correction is at 24.2% as soon as I let off it goes down to -25%. Should I adjust the VE numbers up for +O2 correction and down for -O2 correction? Boost is at 12psi (playing it safe for now) and A/F ratio at idle is at 13.0. If anyone knows of other things I should check/set I would really appreciate the help. Thank you. Paul.

 

[bobc455]

I wonder if your timing is causing the misfire/surging. Have you tried to change your timing to correct this?

If you are seeing O2 correction (especially that much) then your VE table probably needs to be tuned. Increasing the VE values in the appropriate cells will reduce the amount of O2 correction. And BTW You are smart to keep the boost down until you get the tuning close- you don't want to run 23# of boost with a 15:1 a/f ratio!!! Start safe and work toward the ideal values.

-Bob Cunningham

 

[1985BuickGN]

That's kind of what I thought about the VE tables. The program I'm using is from the set up in the other car. The only 2 differences are the fuel pump (aeromotive external to in-tank Walbro 340 now) and the cam (218 to 208). I was also going to try loading in the demo program and resetting the configuration for my set-up and slowly adjust it from there. If anyone knows of anything that I should'nt mess with, please tell me. Thanks.