motor issuses

[r3d runner]

Anyone help please motor issuses

i got a 90 4runner 3.0 auto with 31's whats going on with this thing im tired of the gas milage i get like 70-80 miles on a tank of gas thats the top half its crazy man and when i put it in 4 wheel drive the gas goes way down it runs hot but it dont say on the guage whats going on ?? i gave it a tune up and all whats the deal???? when its cold it runs like crap and when i rev it it kinda pops and black smoke comes out whats the deal??

 

[rustyrazor]

more info

The 3L should be getting about 15mpg. I haven't run more than 1 tank of gas in my 3L so I don't know what my mileage is yet. I had the 4cylinder before and it was getting about 20mpg.

So if you're getting 80 miles on a full tank. Mine took 16G from empty, that's 5 miles per gallon which is a big problem. If you were getting 80 miles on half a tank that would be 10MPG which may or may not be a problem depending on how you drive and if you have big tires etc.

I'd check to see if your oxygen sensor is working or if you have a vaccuum leak or something like that. If you see any black smoke than you're running rich and it may be the oxygen sensor. If your idle is high, say 1500rpm, than it may be a vaccuum leak.

Good luck

 

[r3d runner]

only when its cold it runs like crap when i rev it up when its cold it kinda pops then black smoke comes out but when its warm there isnt smoke or black smoke

 

[rustyrazor]

I say oxygen sensor

Here's what may be happening.

The black smoke means it's rich so it sounds like the oxygen sensor could be funked out.

The reason that the smoke clears up once the car warms up is that catalytic converters don't work when they're cold so it lets the smoke through until it heats up then it starts to burn off the extra fuel.

I haven't bought an oxygen sensor for my 4runner yet but with past vehicles they cost less than $50.