Hey guys I got a 94 4Runner with the 3.0 and Auto trans. and well its running so rich at idle it almost made a buddy pass out who was standing next to the car while it was idling. I cant for the life of me why it would run this rich when it doesnt have ANY codes what so ever.

it starts up fine when cold idles around 1500 then after a bit it goes down to 1000 then finally 800 but a lot of the time it will idle at 500 or so and i dont know why. the idle adjustment screw doesnt affect the idle when it does this.. if i turn the screw to idle higher the truck will idle higher but still go down to 500 a lot and it starts to shake the truck.

the truck runs ok i cant smell gas while im driving around but when im sitting there idling it gets really bad. smells worse then my dads old 69 350 C-10 and thats saying something. Without a code I just dont know where to start on how to make it run leaner. It has spark plugs wires cap rotar all with less then 5K miles and a fuel filter with about 10K on it. had the HG replaced after it blew by the dealership about 10K ago as well. timing is advanced to about 15 BTDC if that makes a difference. my entire exhaust tip is solid black on theinside and if i run my finger in it it comes out with a lot of black crap on it and i only have had the tip on for maybe 3K miles. i dont ever see black smoke come out the pipe either.

the smell has gradually gotten stronger ever since i bought the truck a year ago. and its gotten so bad now its really hurting me at the pump, im lucky if i get 13 MPG with this thing and its killing me.

anyone with advice on what to do to make it stop running so rich cause i know its going to get carbon build up on the engine cat and everything else and ima be in trouble.

 

AFM could be a start. There may not be a cel becuase it is still functioning but it is not functioning right.

https://www.yotatech.com/forums/f2/how-test-afm-68048/

These ecu's where pretty primative. My buddy had an o2 cel for the longest time and the truck ran perfectly normal. Then after he adjusted the time which I believe reset certain areas of the ecu the truck ran like crap. Replace the o2 and truck was back to normal.

 

i want to test the AFM and the TPS but my ? is for the TPS does the Throttle body need to come off? and if so do i need to buy certian gaskets or anything else that will need to be used when putting the TB back on:?

 

start with the afm. chance are you will need a new one

 

I tested the AFM and this is what i got.

e2 to vs - 220 ohms
e2 to vc - 0 ohms
e2 to vb - 279 ohms
e2 to tha - 1300 ohms
e1 to fc - infinate

from what i read e2 to vc should be between 100-300 ohms and it was reading 0 ohms... so this has me worried. what does this mean and can it be fixed? or do i need a new AFM?

 

no one knows what those readings mean?I dont gave any money to replace the AFM so if its possible to fix i will do that.

 

new afm

 

im not sure if this is related but i threw a code 71 today for EGR gas temp or something. besides how to fix this can this be related to the rich exhaust smell coming from my tailpipe? i hope it does and it finally just got bad enough to throw a code.

 

Well if your exhaust is pouring out rich black smoke then the EGR is going to put a bunch of that right back into your intake so it definately cant be helping the situation.