1227165 Tuning Advice

[Bruce & Lisa Wilcox]

Thanks Bruce,

How is LV8 calculated??

Best Regards,

Bruce Wilcox

-----Original Message-----
From: Bruce Plecan <nacelp at bright.net>
To: gmecm at efi332.eng.ohio-state.edu <gmecm at efi332.eng.ohio-state.edu>
Date: Thursday, April 22, 1999 8:26 PM
Subject: Re: 1227165 Tuning Advice



> When looking at the timing table, I need to look at the points in the
table
> where the RPM and LV8 locations match the conditions of the Diacom data
> acquisition. Right??

Yes..

> The "Main Spark ADV vs LV8 vs RPM"  table is listed below.
>From looking at the Diacom data and the above table, the advance in
degrees
> looks like total advance. I am running a base timing of 10° BTDC rather
than
> the factory 6° BTDC setting. The closed loop performance is great with
this
> 10° adjustment. So the actual total advance is 4° greater than the table
> data would suggest.

Set the timing back to 6, and redo the table, or redo the spark offset.
BUT, sometime when you least expect it don't be surprised when the car is
really hard to start.  It will be on a hot day when you want  the A/C.
After a not to long sit out in the hot sun.  Even with a GRD Vette stater
and good battery and cables.
6d is a very good number and I've tried them all many times.  But, if ya
gotta do it just remember my advise.

> Overall, the high load/ high RPM advance does not look radical.

It shouldn't..

> Are there any WOT spark advance parameters??? The car runs great during
part
> throttle closed loop operation. Maybe I can adjust the spark table for WOT
> and minimally effect the part throttle response.

Yes, there probably is a Spark Adder for PE.

> I looked at the BLM during WOT and it was set to 128. I guess this means
> that there is no WOT A/F ratio compensation via the BLM.

OK, now what was you max grams/sec, and LV8?.  Not that I want to know, but,
that you should know..

> The BLM is 128 only at idle and at WOT. Typical part throttle data is
listed
> below.
>
> The data is very interesting. At low rpm / low load, the A/F ratio looks
> good. At low RPM/ high load, the ECM corrected a long term rich A/F
> condition. Mid RPM / low load, the system looks ok. At mid RPM / high
load,
> the system looks lean. Maybe the engine is running lean! However, I am not
> sure if a fuel pressure adjustment will work. What is your opinion??

It all works in concert.  You have to measure the car's performance, to see
what it wants at WOT then work back and forth for optimizing the
AFR..............
>
> The knock count rate is fairly consistent w.r.t. the diacom frame rate.
> Roughly 11 knock counts are detected in 88 diacom frames. The frame rate
is
> roughly 0.150 mS, so the total test run is 13 seconds (gears 1, 2, & 3).
The
> parameters when the knock count starts to increment are listed below.
>
> Gear = 1st
> RPM = 3025
> LV8 = 247
> TPS = 4.55 Vdc
> O2 = 0.836 V
> MAT = 82° F
> Coolant Temp = 176° F
> MAF = 167 g/s
> Injector PW = 10.4 mS
> BM Cell = 15
> BLM = 128
> INT = 128
>
> >From the above spark advance table and 10° base timing, it looks like the
> total advance is 18 +4 = 22°. Is the timing really the problem or is the
> engine slightly lean???

You have to find that out by tuning, and measuring performance changes.
>
> It is getting late so I need to sign off.
>
> Best Regards,
>
> Bruce
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