Runing rich

raceguy13sc

Registered User
I have a 90 5spd sc. It has a K&N conical fillter and a Hypertech chip. It also has gutted cats. When I give it full throtle in say second or third gear it puffs a big cloud of black smoke. It lookes like a friggen diesel truck. This doesnt seem right to me. Any one have any ideas? Im have also replaced the O2 sensors in the last few months. Thanks for any help.
 
SCs are generally programed to run rich at WOT. One way to lean it out a little is to increase the air flow to provide more air to burn the fuel. Free flowing exhaust, fresh air intake, larger MAF and TB are all good starts.

Or just buy an EEC tuner and lean it out to about 12.75:1 AF ratio at WOT on a dyno with O2 sensors.

Before doing anything you might want to dyno it somewhere that has an O2 sensor to determine what your Air/Fuel ratio is now.

David
 
If you are seeing that much black smoke, a large highly visible cloud from the drivers seat, something else is probably wrong. Are there any other abnormal symptoms? Loss of power, loss of gas economy, missing, fouling plugs, oil loss, ect.. it could be a leaking injector.
 
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