When I crank my cherokee, it starts putting out a fair amount of smoke. I let it run today for about 5 minutes and it still smoked. It's not really thick but smoky none the less. What could this be? If anymore information is needed just ask, any help is appreciated.

 

are you lossing any collant, useing oil, or very bad gas mileage

 

Gas mileage is terrible, but then again I only use it on dirt roads, top speeds of 40mph, with 33's and 4:10 gearing. My oil level has been at the same place for the past 6 months, but I only drive it on the weekends so If it does leak, it doesn't leak much. As far as coolant goes, I have no idea. I've never owned an xj before, I don't even know how to check the coolant level. I'm ashamed to admit that. Not engine savvy at all

 

What kinda of oil is in it do you know.

 

I put Castrol High mileage 10w-30 in it.

 

Why hasn't anyone asked what color...?

What color is the smoke? Most of the time, color is indicative of the cause. It could very well just be excess carbon buildup.

 

ha its funny you said that, thats the reason i first asked what kind of oil was put in cause dark grey and even mid grey smoke means improper burning sometimes and could be a build up

 

orignial post state grey/black with the bad mileage i suspect o2 sensor or possible coolant tem sensor iss could be shot since renix has no cel its meter timehttp://www.lunghd.com/Tech_Articles/..._Diagnosis.htm

 

I doubt o2 sensor. I've never seen a 4.0 run so rich it smokes. If anything, these engines run too lean even running rich.

 

http://www.salemboysauto.com/original-faqs/faq-38.htm see this chart

 

Black/dark grey smoke. I was thinking worn rings myself. How would an o2 censor cause smoke?

 

running very rich will cause black smoke

 

So it's running to rich. If it helps, it idles around 500-750 rpm. What do you guys think I should start with to try and fix it?

 

testing sensors to see what the cause is