Thread: Best way to increase fuel at idle?????

Whats the best way to increase fuel at idle , if it runs a bit lean?

- VQ table?
- Fuel Map?
- Injector Latency?

I know the first 2 things I have listed will work but what about the third? Wouldn't changing latency effect things globally like "K constant"?? I often hear this as a recommendation

Now back to the first 2 things listed. Lets say you change the VQ table around your idle/maf value. Now upon a cold start, as it starts to warm up and the idle comes down and air fuel gets leaner. Now wouldn't all of a sudden the idle get rich as it falls into that adjusted value.

Now lets say instead you add some fuel around your idle cells. Now if you rev it up some its going to go LEAN for a bit/ like tip in.

I find all these ways of adding fuel for a richer idle cause small but noticeable issues, So whats the best method here?

Injector Latency will affect the idle the most, but will also affect the whole fuel map.

Best way is to increase the 4 cells around idle area.

You mean increase 4 cells around idle area, right?

Yup my mistake, for some reason I thought he wanted to decrease fuel

haha i read vadims decrease as adjust :P

Also consider if your O2 sensor is getting a decent reading at low gas flows. I often set K value or Fuel Factor (MAF or MAP) while cruising, rather than idle. The car should naturally idle at a reasonable afr if the fuel factor is correct, and cruise will be about right too.

I also use latency to adjust at idle if need be, if everything else is looking within spec and it just needs a bit more at idle. Latency affects fueling more at idle than at higher rpm, but i only use it for a bit of fine tuning.

This is just about exactly what I was going to say.

You can definitely use the injector latency to help fine tune your idle fueling, especially if it fluctuates with electrical load.

On the subject of electrical load, I also had a failing alternator a while ago. Would idle lean when stopped at lights. Did give me a good opportunity to adjust the voltage vs latency table tho.

I logged battery voltage and afr went leaner as the alternator dropped off and batt voltage dropped.

With RT, latency was calculated based on a linear latency vs. battery voltage algorithm, whereas the SA version has a latency vs. battery voltage table, so it can be tuned in a non-linear fashion.

Dave