i got a 1990 3.0 runner and when i start it in the morning it really chugs, thats the best way i can think to describe it. when i start my truck the RPMs jump to 1500 or so like they usually do when i first start it, but when i rev the engine it stutters and chugs till it hit 3000RPMs then it revs good till i let off. but from 1500-3000 its really ruff, while its doing this its puffing alot of smoke and right when it chugs black smoke comes out. it only does it on a cold start, like after its been sitting over night.

i've got new cap, rotor, plugs, cleaned the TB, ran sea foam threw the engine and gas tank, and fuel injector cleaner.

it seems to lessen up a bit with higher octain fuel but when i just put in 89 octain from chevron it didnt seem to change it any. im not sure where to start, i was thinking that a sensor such as the o2 sensor might be not working and sending too much gas cuz it seems a lil rich but i checked the codes and got no code so im not sure where to start

would maybe the timing effect something like this, i think that might be my next step to check the timing

any help would be great

thans!

 

Black smoke is oil burning, Is there alot of white smoke? Mine was doing similar symptoms on initial startup and it turned out to be a blown headgasket. I don't know it that's your problem or not tho...

 

Black smoke is flooding.

 

thats what it might seem but what would cause it to flood? im pretty lost at this point. my gas mileage seems to have taken a hit. i never got good milage to begin with but now its worse. i get 12mpg at best! now its 11! might not have to do with this directly cuz its been sputtering in the mornings for a while but i don't know whats going on.

 

First thing I would check is the water temp sensor for the ECU, then the air flow meter.

 

Are you losing oil???? cause that would rule out a lot one way or the other

 

The black smoke should be unburnt fuel. You risk damaging your catalytic converter with the current condition as well as failing smogII, in case you needed any encouragement to get it fixed asap. Probably you know that.

As to what might be wrong, it probable is the ECU getting wrong info from a sensor like the temp sensor or the AFM as 4unnerrx3 suggests.

 

if either sensor was out would i get a code? cuz i checked the codes and didnt get any? how would i check to see if those are working properly.

 

I would do a search on the various sensors, or get an FSM. It is possible to have a sensor not working correctly and not get a code.

I've not personally had to check either of the sensors in question, but I tried a search for the temp sensor.... a ton of good info came up.

 

Could be an injector stuck open. Below 3k rpm's the injector stuck open is giving you too much fuel but when you get above 3k it evens out since it uses up the excess fuel from the open injector. At least that's what the guy at AutoZone explained to me. Makes sense I guess.

Rob