I am trying to get my 1995 4runner to run better. It runs very rough and stalls at idle. Poor power. New o2, and temp sensor installed. Plugs still read very very lean. I tested the fuel pressure and it is good. If I plug the return line it will run a little better. Please help.
Thank you.

Darrin

 

Might want to test out the Throttle Position Sensor and Air Flow Meter:
http://www.4crawler.com/4x4/CheapTricks/TPS/index.shtml
http://www.4crawler.com/4x4/CheapTricks/AFM/index.shtml

And see if there are any store trouble codes in the engine computer:
http://www.4crawler.com/4x4/CheapTri...CheckConnector

And what brand O2 sensor and plugs did you use? Denso works the best in the Toyota engines. Bosch parts tend to not work well in the same application.

 

I pulled codes. No codes present. I tested tps and air sensor. No problems found. I did even swap with a knowen good air sensor. No change. I found that my egr valve was leaking so for testing purposes I took it off and pluged the hoses. I have to wait for a new one to come in. It ran great for a few min, then it reverted to its old bad running self. As far as plugs and wires and o2 sensor brands. All toyota.
Darrin

 

post up some pics of the plugs.

 

you might have a vaccum leak somewhere. bad gasket or hose...

 

Make 100000000% sure your intake is not leaking.

 

I'd still like to see pics of the plugs.
Incorrect ignition advance could make the plugs look as if it were a lean mix, cause rough idling, etc.

 

Here is a few pics of the plugs.



You guys are probably right. I just can't seem to find another vac leak, if it has one.
Darrin

 

hard to say, can't see the electrodes very well, but they don't look like they've run lean since there is some carbon on the center electrode and no evidence of blistering that can be seen.

 

The carbon is probably due to me squeezing off the return line to try and keep it running at an idle to try and trouble shoot the issue. It smooths right out and runs nice at twice the fuel pressure.

 

your injectors might be plugging up. does the vehicle spark knock?

 

Update,
Well we found it to be the upper intake gasket. The thing that made it odd is that the leak came and went depending on load. After getting it apart, I found that the gasket was actually moving back and forth. So at times it would reseal itself. Thank you all for your help.