Here's the car:
89 IROC-Z L98, Nothing left unmolested except intake manifold. 52mm TB, ported plenum, ported SLP siamesed runners. 24#/hr SVO injectors set at 25.03 injector constant, and the Wells MAF.

I started tuning using the ARAP as a base image. The car loves the spark advance and I have BLMs 125-128 everywhere (and even at idle for those of you with the dreaded ARAP lean idle )

The problem is this, I was having a bad bog down right off idle if I tip the throttle in quickly. Looking at the 02mV's at that instant on the datalogs it was increasingly evident that I was going very lean. So I undertook the task of raising the values listed in the "Acceleration Enrichment Factor vs. Change in LV8" table. After increasing them significantly on the order of 25% at those particular LV8's that I had observed on the scanner I still was faced with the dreaded low 02mV's of 80-106 for the first 15-20 frames (about 1.7 seconds) until the ECM was able to compensate and cross them over the 450 mV's.

Today I have raised them at the same LV8's to 90.31 and the 02mV's are marginally increased into to low 100's but the time that it stays there has decreased a little to about 1.2 seconds and the bog down just off idle is now non-existent.

As a last ditch effort I have lowered the values in the "Minimum %TPS to Enable Power Enrichment" at 400 and 1200 RPM to 20.31% and that seems to have helped out alot.

Is there something I'm missing here? I can't seem to get the AE vs. change in LV8 to cure the lean throttle tip-in and I feel like lowering the values in the PE table are just a "band-aid" if you will.

Thanks in advance for all your inputs,

Brian P

 

The PE enable vs TPS is by no means a last ditch effort.
It's just one tool to better give the engine what it wants.

Look for a AE vs TPS, or delta TPS.

Might also have to juggle the PE AFR vs temp to get things balanced out.

AE stuff can take lots of work to get right.

A WB with LED display is wonderful for this sort of stuff.

 

Thank you for your reply.

I do not see those specific tables however here are ones that I think close. Maybe you can help me understand them?

"Minimum Delta LV8 For Accel. Enrich" -this value is currently 20 LV8. Do I need to increase or decrease here?

"Minimum Delta %TPS For Accel Enrich"-this value is currently 3.91% TPS. I would figure a decrease here would benefit me most.

I also have a question in this table labeled "LV8 Accel. Enrich Coolant Factor vs. Coolant Temp." -The values at 133, 176, and 219 degrees are .15, .05, and .05. Would raising these values to the same value (.35) as the lower temperatures help me out any here?

I cannot find a table associated with PE vs. AF ratio in WinBin. I am using the 6Ev009.ecu file.

Again thank you for taking the time.

Brian P

 

I agree with Bruce. I recently added 1.6 rockers to my cam and increased the bore size of my TB's to 2.13". I was getting a stuttering effect at 1700rpm until it finally got underway. The solution seems to have come from a combination of changes to the AE vs Diff MAP%, AE vs Diff TPS%, and Fuel #1 and SA Tables.
I adjusted the Fuel Table until it became obvious that the lean condition was transitional and that led me to the AE tables.

 

Answers hidden in quoted material

 

Thank you very much.

I read an article which you wrote awhile ago and that is what got me thinking about what my problem was. I have a 700R4 which I had rebuilt and used the 700R4 non-lockup conversion so that I could use the non-lockup stall converter. In this article you stated that non-lockup cars require a little more AE to get them going. Such was the case with my car. I have nowhere near as much experience and I just wanted to say that I know that your articles/replies/influence have helped me greatly and I know that it has impacted many others. Maybe you don't hear that as often as you should.

Thanks Bruce,

Brian P