Inconsistent idle/bad mpg (1 Viewer)

FishTown

Proverbs 27:17
Joined
Jul 20, 2010
Messages
1,341
Location
San Antonio, TX
 
 
Recently purchased a 1990 4runner with the 3.0 v6. I now understand these vehicles are known to be underpowered. However, I'm concerned about a couple things.

SOMETIMES, my idle jumps up and down. When it does, it jumps from 1100 to 2000 and back. As if I'm tapping my foot on the gas. It doesn't do this all the time.

I picked it up from a shop to get my a/c recharged and get new front brakes. The inconsistent idling was not happening before I took it to the shop. I thought maybe the a/c was causing it, but it still happens when I turn the a/c off.

I've also noticed that I'm not getting as good gas mileage as I thought. I'm getting about 13.5 in town. I haven't figured out the hwy gas mileage yet.

Let me know what y'all think.
 
Joined
Mar 12, 2007
Messages
297
Location
Highwood, MT
 
We had a '94 4Runner that got 10mpg at first. After a good tune up and a K&N intake we got it up to 17 mpg highway, but the 3.0 doesn't really traditionally get good milage anyway...
 
Joined
Apr 13, 2011
Messages
2
Location
Orange, CA
I have a '91 with the same problems. I've been told that the 3.slow should get about 14mpg, and you can tweak it to get 15-16mpg but it's a push. As for the idle problem, mine feels like it could be the throttle getting sticky and sticking open. Although I do have more problems with low idle too. Sometimes mine will idle at a perfect 800rpm, sometimes 1000rpm, and then most of the time 400rpm and sometimes drop to 200rpm and bounce and die every now and then.

I'm going to seafoam it first, then move in from there starting probably with the vacuum system first.
 
Joined
Aug 23, 2004
Messages
3,524
Location
Carolina, RI
 
 
 
idle jumping up and down is consistent with a bad, sticking, or out of adjustment TPS. Check that the TPS is within spec, not sticking, and adjusted properly per the FSM. This will also cause poor mpg.
 

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