Road tuning ?

[dooda]

Hi all,
I have been on here for while now and here is a quick overview of what i have achieved =

I have a vn commodore with a 355 stroker , running delco ecu with 12P code. I am not using live tuning capabilities at the moment , I am purely logging wideband AFR and modifying my tables and then programming the memcal.


Now my question is i am having a hard time getting a good tune, I have a tune that is running well but does have some issues with surging at light throttle and flat spots under heavy load. I dont have access to a dyno so I am trying to tune on the road. I am mostly doing this by disabling closed loop and doing a data log on road from take off to high speed/rpm as smoothly as possible. I have mostly been doing this on the flat but have done some hills as well.

Now what i am having a hard time with is, Am i purely trying to fill as many data cells on the ve tables etc as possible or should i purely be doing smooth full power runs etc etc? and am i correct in only having to disable closed loop for logging?

Thanks for any help at all anyone can provide

[krusty]

You have a 355. Have you adjusted to the correct cylinder size?

[VL400]

Now what i am having a hard time with is, Am i purely trying to fill as many data cells on the ve tables etc as possible or should i purely be doing smooth full power runs etc etc? and am i correct in only having to disable closed loop for logging?

Depends on what your trying to tune. For the majority of fuel tuning your wanting to keep it smooth and hold it on the load points of the table. When tuning fuel you dont want the AE from masking VE problems ie a lean VE point but rich AE can make the point look ok as you press the throttle, but holding it on that point it will become lean after AE finishes. Using hills can help you hit heaps of load points. You want closed disabled so the int and blms are kept at 128.

WOT tuning can be more difficult as 1st gear can be too short to stay on load points long enough, steep hills can help.

[Holden202T]

what cam is in this motor ?

i have found a few v8's i've tuned with big cams need more than 14.7 at light load to stop surging, try changing the AFR's below 2000rpm to about 14.2 and see if that improves it at all ?

[dooda]

Thanks heaps for the replys guys,
the cam is nothing to crazy (unsure of the number will find out shortly ). that is the exact answer i am after so i am basically trying to acheive hitting all the load point possible on the road.

when the surging occurs i am seeing a definately lean out in mixture and have since done a couple of logs on the road where i have kept the surging point in focus and tuned from there which has dramatically fixed these surged

One more quick question on overrun down hills i am getting a fairly big leanout on the wideband - i presume this is purely because i am off throttle so no injection is occuring is this correct? i am only concerened in case this can cause engine damage?

[VX L67 Getrag]

To make it easier is there a AE & DE enable that you can disable while BLM's are disabled to so you know there is no fuel trimming from outer sources at all, might feel like crap to drive but at least you know everything in the VE history table isn't fudge n any way?

[antus]

Yeah it'll go lean in two stages when you are decellerating. Firstly it'll just lean off a point or two, then if your foot is off the throttle and you are decelerating quickly enough it will do a complete fuel cut. You'll see it on the wideband, but its fine.