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Discussion Starter #1
Hi All,

I'm building a car for the GRM 2k challenge. This is my first time tuning any sort of vehicle. The program is Tuner Express.

The car-
D16A6,
z6 intake,
LS TB
OBD0 in a 91 CRX

I got the ostrich and wideband setup last week, downloaded a stock-ish .bin from PGMFI and modified the fuel tables so the car can drive around and mostly stay between 11 and 15 AFR. I haven't touched any of the ignition maps.

Right now all I'm doing is modifying the fuel trims by load column, and haven't used the smooth function, or spent time modifying individual cells.

Can you guys critique my fuel and AFR maps and tell me what I should be focusing on next?

Any advice on street tuning would be welcome-I'm unable to pay for dyno time because of the budget constraints of the challenge.

AFR Table-


Fuel Map-


Spark Map-
 

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Meat Popsicle
91 CRX Si
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2,936 Posts
It’s hard to judge based upon the table values. It looks like you’re pretty rich at WOT at 4690 RPM. I’d take some fuel out of the cells that are 12.x.

Since you’re NA, there’s not a reason to go too much richer than 14.7:1. Personally, i would shoot for around 13.5:1 in your peak RPM WOT cells. I generally adjust fuel in 2-4% increments. As you become more comfortable and familiar with things, you’ll have a better feel for what 2% vs say 6% fuel trim will accomplish.

I find it’s easier to get a feel for things by viewing the 2D graphs. I also prefer to make fuel adjustments based on the AFR from the CSV datalogs as opposed to the recorded AFR table. The table is cumulative and tries to average the value of that cell based upon how many times it’s been hit and what the values were. The table will help you see what’s going on during part throttle and high load/low RPM situations but isn’t as accurate as the actual datalog.

Your idle cells should be at 18 degrees BTDC to match the base ignition timing.

Do you have a det can so you can start making ignition adjustments?
 

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Discussion Starter #3
Thanks Patricio!

It’s hard to judge based upon the table values. It looks like you’re pretty rich at WOT at 4690 RPM. I’d take some fuel out of the cells that are 12.x.
Got it. It looks like I'm rich all the way across the 4690 RPM load range...I'll adjust these values on the next version. This build will have a turbo in the next few months, I'm just getting used to tuning before I boost it.

I find it’s easier to get a feel for things by viewing the 2D graphs.
Interesting-I know Tuner Express has the ability to show 2D graphs, but I can't figure out how. I'll email the developer and see what he says. Will re-post when he tells me what I'm doing wrong.


Your idle cells should be at 18 degrees BTDC to match the base ignition timing.

Do you have a det can so you can start making ignition adjustments?
I haven't even started to look how to modify the timing. Do you just add or subtract a percentage, one column at a time, similar to adjusting the fuel table?

No det cans yet-what kind do you recommend?
 

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Meat Popsicle
91 CRX Si
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2,936 Posts
There’s a write up from FarmerD regarding the det can.

Learn what detonation sounds like. Here’s a great video. Use headphones.


For ignition tuning, I do a WOT pull with the stethoscope earpieces in and listen for detonation. I use my phone’s voice memo function to record notes about where I heard it. I always pull 2 degrees when I hear detonation.

A dyno is really the only accurate way to effectively tune the ignition map.

You should do some reading regarding ignition timing and MBT to better understand how ignition timing affects the torque curve.

Also, you should always aim to prevent detonation by reducing timing, not by adding fuel.
 

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Meat Popsicle
91 CRX Si
Joined
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2,936 Posts
Ugh tuner express makes it tougher to visualize the graph with those giants dots at the data points.

I would take those boost cells that overlap and add fuel to move them out of the way.



It’ll make it easier to see the cells you’re worried about right now (being NA) and will also help you be ready for when you go turbo and use the boost columns.
 
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