Black smoke when shifting

[mrxchan]

Car: 95 Eclipse GS-T

Usually when im drivin on the highway at high rpms.. when i shift..my friends in another car behind me tells me that black smoek comes out my exhaust.. shifting at typically around 4-5000.. even when i did oil change.. any ideas what cudd be causing that black smoke?

 

[ken06]

Venting your BOV will cause the car to run rich between shifts meaning black smoke.

 

[andymoraitis]

It's hard to tell because you haven't filled out your mod list and we can't tell what's on the car. While BOV venting can be one cause, if the motor's stock, your ECU is running at a 9.5:1 air/fuel ratio. This is factory programmed for safety margin and not performance and will commonly idle rich and especially blow rich at higher RPM's. As you upgrade and lean the car out to around 11:1on pump gas, there's a greater performance increase from the lack of excess fuel being dumped into the combustion chamber.

The only way to change a rich factory A/F is to use a chipped EPROM ECU, DSM Link, AFC or a standalone like an AEM EMS with larger injectors.

Make sense?

Andy