I have read many past post about this issue, but still have questions. I am re-thinking my strategy on prom tuning. Before I have been running orginal arap code, then backing down the spark timing till the knock ret. stops. Bad plan when you think about it, I don't need anything melted! My question is, should I replace the spark tables in ARAP with 89 vette timing tables and then work up? Or should I back the arap table down maybe 5* then work up? Which do you think would be an easier way to tune? I am running at the strip on Sunday so I plan on running weaker spark table till I have time to tune. Just wondering which approach you guys use with messing with the spark tables.

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1988 IROC 350
Vette heads, SLP headers/Y-pipe,No EGR.

 

I haven't messed with the spark table yet, I run the stock ARAP one, and it works okay with my iron headed L98..... But I am thinking just the same thing that you do, but I am trying to gather the facts and get this timing thing straight before I do something that might be stupid.... Make sure you have some kind of scantool or laptop with scanner software before attemting to experiment with spark tables!!!


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ZaphodB a.k.a Carl Andersson - zaphodb@faxancruisers.org
'89 Camaro IROC-Z 5.7L TPI - Mods under construction :-)
Custom ARAP Chip Under Development/180 t-stat, Edelbrock TES Headers,
SLP Airfoil, K&N Filters, Accel 8mm wires, Relocated MAT, AFPR @ 45 PSI

 

I'd start with the stock AUJN main spark and PE mode spark advance tables.

 

Z28, I notice you are not running with an EGR. If so, you will not be able to run very high spark advances as you can with a functioning EGR.

The dilution effects of the EGR not only allows you to run higher spark advances, it kind of forces you to, or your throttle response gets "spongy". You may find that you may have to back off your spark advance 4-6* without a functioning EGR. This is from the stock spark advances. The ARAP is even more advanced than that (about an extra 5-7* depending on the load in the mid range area).

 

Glenn,

The EGR is disabled in the software. I did have to reduce the timing off idle to get rid of a stumble. So is it far better to have an EGR then not to? I didn't because of the vette heads, I didn't want to rig a pipe off my headers to the EGR valve. So you think I should start with stock code or the code Brent recomended? I also have Stage 1 89 Jett code pull the tables off of. This is my last trip to the strip this year, I want to make it a good one!

Ohhh on more thing...I finished re-doing the home built ram air, man did the temp decrease! I runs around 109 or less, I am starting to think that may cause issues. I haven't looked into it yet, at ideas if this will mess with the calcs? Thanks guys!

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1988 IROC 350
Vette heads, SLP headers/Y-pipe,No EGR.

 

Can someone email me the AUJN bin, I look at the various sites but didn't find it. Thanks!

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1988 IROC 350
Vette heads, SLP headers/Y-pipe,No EGR.

 

If you have the idle and cruise stuff right, then I'd start with taking 5d off of a AUJN or some similiar bin, and work up from there.

There is an article called tuning.doc at DIY_EFI, where I tried explaining where to start and where to go.

Remember, as little as timing as consistant with best performance, not the max possible. Get to best performance and drop 2d for street use. If you wind up with over 32d timing you've probably missed something (assuming 64cc heads, mild cam), AL heads over 30 and you've missed something.