Forum » General Tuning Discussion » rough idle help please

rough idle help please

General Tuning Discussion

Discuss all things tuning in this section. News, products, problems and results. 

Page 1

hi guys i have a log attached of my car idleing. want some advice please. the car idles rough and jumps all over the place. mechanicalt it is fine i just cant seem to figure out why it wont idle smooth! the engine is a built cosworth yb engine. siemens dekka 875cc injectors. coil on plug conversion. bd14 inlet and exhaust cams 8.1 compression ratio. link monsoon ecu. just want it to idle smooth but its all over the place! help please!

Attached Files

If someone is familiar with that configuration they can probably make suggestions.

For an angry port/cam often a wideband reading around 0.85 lambda is most stable. You probably want to make an "ignition well" at the rpm/load area where you want it to sit stable. You can usually get a decent idle doing that without a throttle bypass or stepper.

Idle is the hardest think to do remotely as it is simplest to do by ear.

Can you post a screen shot of the area in the log you are concerned about?

Hi mate. There is no particular point in the map. The whole map is of the engine running. And it’s really lumpy!

Just took a quick look at the log you've posted and the first thing I noticed was that the battery voltage is all under 13 volts and your ignition angle is at 0 degrees.

Could you post the map up to let us compare it or mail it over and I'll take a look?