92 LC running rich (High CO and HC) failed emissions... (1 Viewer)

Joined
Nov 17, 2012
Messages
37
Location
Denver
First off, I would like to thank the community that is IH8MUD. I have spent countless hours reading on these forums the past two months and have gained a vast wealth of knowledge.

This happens to be my first post so I will try my best to be as thorough as possible.

To give some background...
92 Land Cruiser 3FE
192k
Failed Colorado emissions
runs rich
around 8mpg
new thermostat
new tps
new plugs/rotor/wires/dizzy
ect, maf, tps, o2, cats all check out...

The strange thing about this new addition to my toyota armada is that i cant figure out why the hell its running rich! So I come to you my trusted forum users.

This happens to be my first post so I will try my best to be as thorough as possible.

Here are the results for the emissions test:
HC 9.6 Limit 2.5
CO 242 Limit 25
CO2 617 Limit ----
NOx 2.0 Limit 4.5
Units are grams per mile (GPM)

Ok so here's the strange bit, I drove around monitoring my 02 sensors output voltage with a volt meter, it runs rich most of the time, but, when I am accelerating and then immediately let off the gas, the reading drops to about .1V???? Strange to me. Most of the time I get a reading of .9 to 1V. My FSM says that .9 should be the highest that it reads but it reads a tad higher. I don't believe that its a big deal but I could be wrong. The interesting thing here to me is that i get an immediate drop when i let off the gas... It only lasts one second but i know my O2 sensor works because of this drop. Also when the car is cold and its warming up, it takes the engine about 30 seconds to climb to achieve max O2 voltage. Again, strange... I think that maybe its a fuel pressure issue??? I don't know. I have also taken out the ECU and taken a look at the thing but couldn't see anything or smell anything in there that shouldn't be. I've heard these things are like tanks but i suppose it could be it.

Im about to run bk44 (i think that's what its called) through it in hopes that it will clean the injectors (a possible problem as well). Also gonna check the fuel pressure. BTW does anyone know where i can check the pressure with my "modified" 12mm by 1.25 banjo bolt? My Haynes manual sucks and I'm too poor to buy the real FSM

Any suggestions and help would be greatly appreciated!

salute! :flipoff2:
 
Joined
May 31, 2005
Messages
7,014
Change the O2 sensors. You're way past due.

Check the timing as well.

Welcome,

Curtis
 
Joined
Nov 17, 2012
Messages
37
Location
Denver
Awesome, super fast response thanks.

1) I did the timing but was unsure of if i needed to leave the paper clip in (terminals E1 to TE1) while i did the timing or leave it out.

2) I realize the O2 sensors are past due, but should that be the only reason to replace them? They seem to be working OK and I don't really have any money to throw at the problem.

The O2 operates as follows:

It outputs a few mV when below operating temp.

It starts to rise once they warm up and hit operating temp. Usually takes about 30 to 45 seconds to reach .9V

They output .9V to 1V the entire time I drive except when I abruptly let off the gas pedal. When I do this, it drops to a few mV again for about 1 sec, then rises immediately back up to .9V~1V.

From my understanding, the O2 sensors outputs have an inverse relationship with the oxygen content in the exhaust.
Therefore at .9V, they are saying to the ECU "hey we're running rich" and at .1V it says "hey were pretty lean".
Or am I backwards?

thanks
 
Joined
Nov 17, 2012
Messages
37
Location
Denver
I'm informed that high CO means its running rich. I can also smell it in the exhaust, which drips a lot of water... I live in Denver where we are required to do an emissions test every other year. I just bought the truck a couple months ago and I'm trying to get it plated. Who ever had the truck before me didn't take care of it.

By the way, do i leave the paper clip in Terminals E1 and TE1 for the timing?
 
Joined
Nov 17, 2012
Messages
37
Location
Denver
Any thoughts on the O2 sensor? Its old but is that the only reason needed to replace it? I want to be sure i need to replace it. From what I could tell it was in spec.

Thanks
 
Joined
Nov 17, 2012
Messages
37
Location
Denver
O2 Senors become less effective with age and mileage. Just because you don't have a code doesn't mean they aren't beginning to fail.

Did you test them according to the method in the FSM?

Pretty sure I figured it out, I only have the Haynes manual but from what it said it pretty much checks out. It says it should operate at .1 to .2 volts when cold (open loop) then it will operate in the range of .1 to .9 volts when hot (closed loop).

Mine does this, but stays 99% of the time at .9 to 1 volt when hot... (so maybe a smidge outta spec? is that a big deal? idk..)

also, when i turn off the engine the O2 still outputs a voltage that takes about 5 min to slowly drop back down to 0 volts. the manual doesnt mention anything about this but i just thought you guys might know something more about it???

thanks for your insight
 
Joined
Nov 27, 2009
Messages
33
Location
Vancouver, BC, Canada
i got a set a brand new denso o2's sitting on the shelf for over a year now.....
bought to use on my 92 but ended up diesel swapping it...
i wouldn't mind at all to throw em your way if it helps out...

:cheers:
 
Joined
Nov 17, 2012
Messages
37
Location
Denver
i got a set a brand new denso o2's sitting on the shelf for over a year now.....
bought to use on my 92 but ended up diesel swapping it...
i wouldn't mind at all to throw em your way if it helps out...

:cheers:

This is the best web site! You guys rock!:clap:
 
Joined
Dec 8, 2006
Messages
9,903
Location
New Jersey
O2 sensors and catalytic converters don't last forever. If every other system is in good shape and you have used OEM parts, then it's time to change things. By the time the O2 sensors throw a code and illuminate the CEL, they are far past their usable life.
You will notice increased fuel economy and better power with new OEM O2 sensors.

Catalytic converters also have a lifespan. They can become clogged and less effective over the years. OEM replacements will cost you way more than aftermarket. I've purchased mine from discountconverters.com. OEM fit, bolt on installation. You will need new OEM hardware and gaskets.

I also sell the 91/92 FSM in PDF format, but mine includes a ton of other goodies not found easily. Link in my signature.
 
Joined
Nov 17, 2012
Messages
37
Location
Denver
Gonna check my fuel pressure today. I heard that the fuel pressure regulators in these things can cause it to run rich...
Right now I'm waiting on the jb weld to dry on my "modified" banjo bolt. I'm going to use this to plug directly into the fuel rail (hopefully). It has a hose attachment so it can read out to the gauge. If you cant buy it, make it....
 

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