S14 KA24DE fuel enrichment under throttle stab/crank enrich

[klattr1]

Car is a 1995 240sx KA24DE.

For the most part, I would say that my car/setup is tuned pretty good (idles good, partial throttle is smooth, WOT is dead nuts on)...there's just a few small things or annoyances I'm trying to fine tune. The list is below.

1) fuel enrichment under acceleration - let's say I'm at idle or cruising around at a steady 14-15:1 range and then I just go almost 100% with the throttle, for a brief moment/split second the throttle goes from 14:1 to 10.8:1 range and then immediately to the appropriate open loop value under WOT (11.8:1 till redline)...it happens so quick that it's almost hard to notice on the wideband but it seems like it kills engine response somewhat and bogs down for a split second...what table do I need to modify that's causing the issue I'm describing?

2) crank enrich/warmup - the engine fires up just fine but for the first 15 seconds or so as the motor warms up, I have to keep the throttle near 50% to prevent it from idling too low and dying...now, I don't have an idle air valve on the car so I was thinking it was either because of that (where the ECU would normally raise idle dynamically on startup and warmup) or because it's possibly too rich in that scenario...I can't measure how rich it's running under cranking or idling obviously until the wideband 02 sensor warms up...now once the wideband sensor warms up, it shows up first around 12:1 afrs and linearly rises until coolant temps reach ~170 deg....questions are:

• a) what AFR do you guys typically try to run under warmup conditions in this scenario (it's around 70 deg. F ambient in the morning right now)
  
  b) if I have it set too rich, then which table do I need to be modifying to get it to not stall under startup/warmup without having an IACV? (is it crank enrich or crank offset?)
  
  c) how does neutral idle target rpm/stabilization table fit into all of this? or is that dependent on using an IACV?
  
  d) or do I need to leave things where they are at and just install an idle air valve and be done since that will dynamically raise idle under startup/warmup and then level out when coolant temps are stabilized?

much thanks,
ryan

I can post screenshots of any tables if requested.

[Matt]

1. Modify the 'increase fuel table'

This looks at the TPS voltage and compares it against the table values. If it is higher then it will access the last column on the fuel map (map trace cannot show this since it happens in the background and causes your rich condition)

Higher TPS voltage in this table will result in it not jumping to the end and adding more fuel

2. Crank enrich

Crank enrich offset is the table which seems to have effect during starting. Reduce the table by the % increase of your injectors. So if injectors are double the original size, then halve the values in this table to avoid flooding on start

AAC valve is used for stablisation, Idle air valve is used for air conditioner compensation

(a) I would still try to run 14.7:1 or a bit richer during startup - so what makes the enrich run smoothly during cold starts

(b) Crank offset is the one to modify for cranking only

(c) Neutral target RPM will adjust timing only to maintain that RPM. No effect on enrichment. Stablisation tables I believe are the same in that they only affect timing (never needed to change these)

(d) Once you have your cranking not flooding the engine then focus on the warm start enrich table. There is also a corresponding 'cold start enrich' table but seems to be used under different conditions that I cannot replicate

SR20DE models have 2 of these tables

SR20DET (JDM) models have 4 of these tables. For JDM SR20DET models:
Warm Throttle Enrich - TPS = not idle
Warm Start Enrich - TPS = idle

Attached is a pic with the Warm Throttle Enrich table for the SR20DET I was using last night

Adjusted from 0% upto 120% and you can see the effect on injector pulsewidth on the graph when adjusting these. I suggest taking a log and watching injector pulsewidth whilst adjusting the table. See pic below of how it affects the pulsewidth (hence afrs)

[modulation]

I have a 1995 ka24de in my s13.
I also have no EGR, IACV or any emissions. I started out with stock 280cc injectors, and then moved to 380cc injectors.
The 380cc injectors were definitely more tricky to get cold start to work perfectly.

Tuning to start with no IACV and hold idle wasn't very hard except for the first cold start of the day, when the outside temp is below 55 degrees or so. I had to try 10 times or so to get it perfect so that it'll start first time without having to touch the gas.

I've attached my BIN, it's a obdi, but I think you could look at it compared to a stock one to see what I've modified.

[klattr1]

Matt, thanks...I adjusted the "crank enrich offset" table just like you mentioned and that seemed to make the biggest difference...car starts up and stabilizes idle without having to keep my foot on the pedal...not sure if I fully understand the "increase fuel" table fully yet but i'll look into it some more.

The weirdest part I noticed during some logging today was that certain parameters were flatlining (RPM's at 2900 rpms, MAFS at 2.835 volts, etc) after reviewing the log. Log is attached.

[Matt]

Never seen that before, its like all your consult data just froze up for a number of seconds, but the AFRs were still recording okay

What I think that is - you are probably getting consult errors and its recoverying and retrying in the background

Time to check your engine grounds etc and make sure no issues with noise getting in the consult lines (see diagnostics manual on the website for more info)

[msaunders]

OP:
I've also been working on fixing the rich tip-in on an S13 KA24DE with 370cc injectors.
FWIW, "Increase Fuel" didn't change AFRs at all.

What did make a difference was an address that isn't included in the standard file @ 0230. It has something to do with actual TPS voltage enrichment on fast movement. It "adds" TP, you can see in consult when modifying the table. After taking a chunk out of these values I noticed that once cruising and stabbing the throttle AFRs no longer went down so low. Try this.

I haven't played around too much with the new table but still have an issue at idle. When punching the throttle, it bogs down to ~9 for a second and catches up.

[Matt]

What is the name of that particular table (did it come from a tunerpro XDF?)

[msaunders]

Matt, I first found out about it here:

http://www.ka-t.org/forums/viewtopic.ph ... fbcb111e7f

And yes it is in the Tunerpro XDF.. it's called "0230 - TP Accel Enrichment."

From my testing it seems to affect TP, and thus AFR, everywhere but off idle. Any ideas for the off idle rich bog?