Top causes for KAE running rich?

[benemorius]

I would never deny anybody from posting in my thread, but what I'm really looking for here is a response or two from folks who have been working on KA's for years and seen dozens and dozens of them...

I recently talked a friend into buying an s13 which turns out to be running pretty rich from what he's telling me. So what I'm asking is - from your experience, what seem to be the top reasons for a KAE to run rich? I don't have access to this car, fyi...

[180fan]

Leaky injector or effed MAFS.

[navysnail]

mine runs way rich at high rpm's and WOT, other then that it is fine, just the way these engines work

also, dont forget about the coolant temp sensor on top of what 180fan said.

[NISTECH]

He needs to check his ground connections in general as well as the ground on the MAF. Also due to the age a full work up on the O2 should be performed. The O2 should be able to go over .8v in an enrichment condition[adding a little propane to the intake can acheive this] It should be able to drop below.175v in a lean condition, poulling a vaccum line other then the fuel pressure regulator. it should sweep more then 5 times in 10 seconds [you can do this with the procedure listed on 240sx.org's FAQ section. and the O2 should rise from lean to rich in less the 100ms [from below .175volts to .8v] These are the three common failures for a rich condition on the KA. MAF or poor signal from itCoolant temp or poor connection at itO2 sluggish[lazy]

[benemorius]

Thanks, Scott. Exactly what I was looking for. He was unsatisfied with my opinion and threatening to take it to a mechanic, so I promised him I'd get the opinion of a Nissan tech.