DSMlink Air/Fuel Ratio

[GSTdude06]

How do I get my air/fuel ratio down? Its at 18:1 just at idle..... isnt it sopose to be around 11:1

 

[Staytuned]

You need to input your injector size and deadtime values into the props section.

 

[GSTdude06]

what about the 3rd box below both of those? I did that 650 and the deadtime that the manuel says but it just brought it to around 13-14

 

[GSTdude06]

What do you mean by that? Sorry im a newb when it comes to tuning here I just got my DSMlink in yesterday.

 

[Staytuned]

Your car at idle will be around 14.3 - 15.3 AF ratio, it nevers stops oscilating up and down.

 

[GSTdude06]

ok how would I bring it down?

 

[Staytuned]

what about the 3rd box below both of those? I did that 650 and the deadtime that the manuel says but it just brought it to around 13-14

Just leave that one alone, it is set for pump gas.

 

[GSTdude06]

Its at around 16.3 tho....

 

[super95awd]

The A/F ratio that DSMLink displays is not entirely accurate anyways. Tested against a true wideband, sometimes it's close, sometimes it's not. If the car settings are right, then it should oscillate somewhere around what Staytuned said. If it doesn't and you know your global settings and deadtime are correct, then don't worry about it.

 

[keymaster]

Log your LTFT Lo, LTFT Mid, and STFT at idle and report back on what they say. That will show a more clear picture of where your fuel settings need to be.

 

[GSTdude06]

Idk how to do all that

 

[MrBoxx]

Go to Captured Values (under the "ECU" tab) in the DSMLink program. Move LTFT (lo), LTFT (mid), and STFT over to the right side of the dialog box, to "ECU will log". Then follow these steps:

Use the long-term fuel trim (SelectedLTFT) value calculated by the ECU as your guide. The following outlines a good procedure for getting the dead time right for your setup.

1. Car must be fully warmed up then must be operated at cruise for about 10 minutes followed by idle for 5 minutes to get stable LTFT values.
2. Compare the LTFT at idle and cruise. You want both to be right about zero (+/- 5% or so).
3. If the two are about the same, dead time setting is good.
4. If they are equal but non-zero, adjust the global setting.
5. If idle LTFT is more positive than cruise LTFT, increase the dead time, less, decrease.

Log all of step one, from the moment you start driving to the time you shut off the car. Go for a drive on the highway for 10 minutes, then pull over and idle for at least 5 minutes.

Don't worry about messing around with the dead time and global setting if you're not sure what they do. Just get a good log and attach it to a post.

The Air/Fuel Ratio is an estimate that DSMLink puts together based on the MAS readings or airflow and divides by fuel flow estimated from injector size, deadtime, and specific gravity of your fuel. If you have an airflow metering issue or fuel delivery issue, the estimate will be off as well. In other words, don't use the DSMLink A/F estimate as a true reading. A wideband O2 would probably serve you better for that purpose.

In case you haven't yet, download the user's guide from the downloads section of the DSMLink home site. It's got all the information you need to get started.

 

[TimG]

When I installed an AEM wideband in a 2G race car last winter, I connected the input wire from the wideband into the rear O2 wire at the ECU and prompted DSMLink to use the signal from the rear 02 as the AEM wideband.

I did the same with mmcd newer version on my 1G.

Buy a wideband if you want proper and near perfect fuel maps set up. It's by far the best investment you can ever make for your car.

I suggest a wideband to every new car owner right after an exhaust system installation. It's information is invaluable.