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Running rich

bix

bix

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Hey everyone, ive ran into an odd situation. I currently got my k5 back on the road and in the process noticed that my FPR was leaky and all brown, so i decided to clean my TBI. I cleaned and re did all the gaskets, and reinstalled the TBI. its running rich , like it stinks of gas as it idles. I Replaced the ECT sensor, MAP sensor and o2 sensor. I also checked all of the TBI for fuel leaks and its not dripping or spraying when the ignition is on and the engine is off. Im pulling code 44 which is saying Lean exhaust indicated.. I tried to clear the code to see if it would run better after the code is cleared but it wont let me clear them( it says to consult my gm manual for the fuse or procedure needed). Ive disconnected the battery a bunch so im assuming its throwing this code continiously ( the CES light is NOT on) i dont understand why its throwing that code when the exhaust is so rich?

Any ideas would be great
 
Im assuming its running rich because the computer thinks its running lean, but what could make it think its running lean?
 
Common causes are, exhaust leak before the O2 or a missfire on one or more cylinder.
 
There is only one o2 sensor on the driver side header right after the first junction. A foot or two from the engine block and only the one code came up when i pulled out the obd. Its running so rich i am getting 200km to a tank.. I will double check for exhaust leaks but it is very close to the engine so id be suprised.
 
The engine is idling fine, no hiccups or anything. Idling at about 800rpm during warm up and then settling downto 550 or so. No backfires, no misses. Just very very rich. When driving i do notice a lack of power until the rpm gets up there. If that helps any. Does anyone know what ground affects the o2 sensors and others? I was told if the o2 sensor is faulty it will read lean and the wiring could be my issue?
 
Does this truck have catalytic converters still installed? Mine started smelling a bit on the rich side after I had to eliminate them for a long term, semi-permanent temporary refab of the exhaust so I could continue to drive it.

I would think the O2 sensors would pick up on the rich exhaust and either throw a code or something.
 
Hey it doesnt have the cats installed anymore since we have no emission testing around here, im burning a tank of fuel in 200k when it should be 250-300,so shes burning rich lol. Im just worried about carboning everything up and also gas isnt cheap but winters coming and this ol girl isnt going through our ****ty winters so ill prob park her soon. Maybe ill figure it out over winter.

Yea thats what has me puzzled. No codes coming up at all. I highly suspenct my o2 wire to be messed up somehow and somewhere, ive seen them on rockauto ( the female connector and wire) so il going to test the wire itself today and if its got voltage through it i will put a new end on it and buy yet another o2 sensor.
 
OK, this is going to sound weird, but how did you hook up the new O2 sensor?. If you used the connector and wire that came with it, no problem.
But, if you spliced in the wire, that may be your problem.

O2 sensors have to have an atmosphere reference, access to outside air. The amount needed is tiny, but they have to have it or they cannot work.

Most of them actually get that through the connector wire. It seeps in between the wire and the insulation.
If you cut off the connector and splice it, you usually seal up the connection too good, and the sensor cannot work.

Sounds like the sensor is showing a continuous lean condition. But I'm surprised its not showing a code.
 
Hey i appreciate the reply, i used the existing connector and wire ( female side ) and the new male end attached to the sensor. I did a little test today by running it with the o2 sensor in and then out. If the o2 sensor was unplugged, should the ecm have thrown a code, because it didnt and didnt run any different plugged in, or not. I triedto get a voltage reading from the sensor end (female) but had troubles, through what ive read on here it only shows 1v when its rich and the voltage goes down as its leaned out? Me and electrical dont mix at all but im very tempted to pay someone to figure this out, and thats the last thing i wanna do ive just ran out of ideas besides changing the wire itself but it dissapears into the big loom and id prob get lost trying to chase it down
 
I had this happen on a TBI that I transplanted into a Jeep but it would run so rich at idle that it would flood out and quit. Turns out the return line to the tank was plugged and the excess pressure had nowhere to go except to the injectors. I could unplug one side and it would run.

Also had a neighbor with a similar problem, his was throwing an coolant sensor code so he replaced the sensor. Turns out his problem was a bad connector to the sensor. You could wiggle the wires at the connector and it would straighten up and run properly.

Maybe something you missed when you cleaned the TBI? Did you disassemble the entire unit?

I hate problems like this........good luck with it.
 
Yea i have tried moving the wire around but being alone id almost need someone at the exhaust smelling as im in the hood , its rich but its not burning smmoke or anything just alottt of fuel, how would i check a fuel line for being clogged. When i disconnected the return line from the tbi no fuel came out so im assuming it might not be plugged. I dont know what i coulda missed on the tbi, its so simple but maybe ill have to do it again just to check. Ive watched my tbi while its running and i dont see anything going into the fins but fuel from the injectors, should the ecm throw a code if a sensor is not plugged in?
 
Hard to tell by just pulling the return line at the TBI unit. You really would need to check it back at the tank to see if there's excess fuel going back into the tank. I know that's a PITA but there should be some fuel coming out the return especially when it's idling. The TBI system pressure is regulated at the unit so the pressure from the pump is constant. Excess pressure/fuel gets sent back to the tank.
I'm not saying that's your problem and I don't want to send you on a wild goose chase, but it's one that I've had with a rich running TBI motor.
 
I have tried almost everything at this point. i Have ordered a new female connector for the o2 sensor and wiring with it. If i unplug it and do not get a code 13, Is that a fault in the ECM or the wiring ? If so is it easy to change the wire all the way back to the ECM? If it is the ECM, how can u go about fixing them?
 
Im assuming that it must be the ECM because a bad wire or connector should still set off a open circuit code ( 13 ) for the o2 sensor. Is there anyway of checking this? Can you flash these, or do you generally need to replace the whole ECM and PROM?
 
would i get a code 51 is the ECM is bad?
 
OK, I run Fords, so I don't know the answers from experience. But, since no one else has figured it out, I decided to jump in.
You would expect a code 13 if you unplugged the O2 sensor, but you might not get it.
Certain other conditions have to be met before the ECM will think there is a problem.
That sensor does nothing until it reaches 600 degrees, so the ECM does not expect anything at first.
It puts about 450mv on that line, and then measures it. Since the sensor is supposed to be open until it starts working, the ECM should see 450mv whether its hooked up or not.
So, no code.
If the line were shorted, then it would see 0 volts, and might set a code.

Then, it waits. If other conditions are met, and there is still no action, it then will set the code.
I did not know all the necessary conditions, but I have looked them up. Here is a listing......

Trouble Code 13 indicates that the exhaust stream oxygen-content sensor (O2 sensor) is not responding as expected. When cold, the sensor is 'biased' by the ECM to about 450 millivolts. Before it warms to at least 600 deg F (315 deg C) it acts as an open circuit and when the ECM reads it, it reads the 450 mV bias. The ECM expects the sensor to warm in a short period of time and begin sending its own voltages. The general conditions for this code getting set are:

- engine running at least 2 minutes

- coolant temperature at least 50 deg C (122 deg F)

- O2 voltage not fluctuating (i.e steady between 350 and 550 mV)

- TPS signal above idle

- all above conditions met for 60 seconds

Typical causes may include:

1) Defective or degraded O2 sensor

2) Deposit-contaminated O2 sensor (running leaded fuel, RTV silicone deposits etc)

3) Corroded/defective O2 sensor connection

4) Defective sensor ground circuit

5) Defective connection at ECM

6) Defective ECM

NOTE: If codes 21 and/or 22 are also present cause '4' above should be checked first.
Click to expand...

So, in theory, if you leave it unplugged, let the engine run until its warmed up, then run it above fast idle for at least a minute, it should throw a code 13.

As for the code 51, that is only if it fails a certain internal check. If that part checks good, you should not see that.

Be sure to check all grounds you can find. Take them loose, clean things up and replace them.
Don't forget any around the battery or the ECM.
 
Thanks alot man. I doubt my ECM is bad since i am getting fuel, injector pulse and the thing runs fine besides terrible gas mileage and the brutal stink of fuel from the exhaust. most connectors have awesome voltage readings. I am just at a loss and appreciate all your info. I unplugged the o2 sensor but never revved it up above normal RPM and let it really heat up. I will do that next time and see if i get any results. Its getting cold here and soon it will be minus 40 deg c and not having a garage is a huge PITA haha

BTW i changed out my thermostat and fuel filter today as i noticed the thermo was failing to close sometimes and the fuel filter just looked awful. The return line appears to be okay as much as i could check. Thinking of having a garage completely replace them since i do not have the space to do so right now. Could maybe be the issue, plus doesnt hurt to have new fuel lines front to back.

I am also going to see if it goes into closed loop also with the paperclip test i saw. I bought a nice OBD code reader. but it sucks i cannot see live data or sensor readings
 
Yeah, if it never gets to normal op temp, the ECM might be ignoring that sensor until it does.
Since its a high temperature chemical reaction that produces the voltage from the O2 sensor, its a common problem to have issues when someone puts on headers or does major exhaust work.
That sensor MUST be very hot to function. So, in real cold weather they sometimes never start working.
Other times, they will work until you stop at a light and idle for a while, then they will stop.
That is why many car makers have gone to heated O2 sensors. They have a couple more wires that power an internal heater to keep it hot. There have been several threads where people have converted over to them to make their truck stay in closed loop.

To really tell what is going on, you need the computer hookup that lets you read the data stream in real time.
There are many threads here about doing that. Its fairly simple and cheap if you have a laptop.

That way, you can see what the ECM is seeing and doing at all times.

And I know what you mean about cold weather. Its almost 19 degrees C down here in Fl right now.............

I may have to sleep under a sheet tonight.........
 
hahaha i wish it was 19 deg C, I do have a laptop but its a mac.. i dont think the WINADLD will work since its a windows program.. i hope i can figure it out before it leads to needing that. I could always try and borrow a laptop to do so. Or do the dreaded thing of paying a shop to do it... Will the ECM and PROM in these trucks work using a heated o2 sensor? i have a rebuilt exhaust but it is still a manifold type setup
 
They should work just fine with heated. The sensor part is pretty much the same. It just has a couple of extra wires for the heater.
The trick is to hook the heater up so that it only comes on when the engine is running.
You don't want it drawing current when its off. Battery life would be short. Most folks wire it to a relay that comes on when the key is in ign position. But I have heard of some that wired it so that it only came on when the alt was making power, or when the fuel pump was running.

There are threads here about the conversion too. Plus, I think I have heard of someone getting a version of WINALDL to work with MAC, but not sure right now.

I have this link bookmarked, not sure why or when......

http://www.obd2allinone.com/diagnosticsoftware.asp
 
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