well i went down to m&o and we ran a koeo test and it only spit out two numbers. 173 which says lack of heated oxygen sensor switches indicates rich bank 1. and then 176 which is lack of heated oxygen sensor switches indicates lean bank 2. i am noticing that the paper that has the codes printed out on them shows that the guy helping me put in y for the 8th digit of the vin while mine is an x. would this make any difference on these codes? i was going to go back tomorrow and try the koer test to see what that tells me.

 

Well - it's a different motor for sure. Mine is X also. I'll try to find a listing and see if it would make a difference or not.

If it's true, kind of strange to get lean one side and rich other. I'd say one or the sensors is probably bad - probably the one you did not change yet.

O2 sensors can mess your performance but I don't think 5-6 MPG worth - maybe?

Try 1) Get the codes again with an X in the reader. 2) Do KOER test and see if any real time failures can be picked up. 3) Disconnect battery and clear everything. 4) Run KOER again. 5) Drive it and see if it runs a little better.

I want to make sure you get all the stored codes so you have the history. And then clear it all out and go back to non-modifed or non-learned correction factors, running the stock "every thing OK" A/F and spark advance tables.

If a O2 sensor is bad, not switching, it won't use the O2 reading to change the A/F mixture but it will still use the previously learned correction factors. Clearing the correction factors and running in open loop (bad O2 sensor) the car should run OK, for a little bit anyway, if the problem is a O2 sensor. See, you take it out of the equation this way. If it does still run bad, the problem is something else - and you might have a O2 problem and another problem simultaneously.

 

Since he ran the KOEO self test, these 2 codes would be stored codes.

Code 173 if valid could also show up on the engine running test but the code 173 should show up as a code 136 in the engine running test.
Should be interesting to see the codes from the running test.

Dialtone

 

Dial - I think you mean the 176 will show up as a 136 - same left side lean problem for each but 136 is the real time code where 176 is the code stored in memory from a past occurance.

All right. Here's my prediction:

173, right side rich happened previously so the right O2 sensor was changed.

Now 173 still occurs plus 176, left side lean.

You have a mulitport FI car co all 3 injectors on a side fire at the same time. So the PCM can make either side rich or lean independently and via the O2 sensors mainly.

Since the right said it was rich, new O2 and it stills says rich, it probably is rich.

176 says lean on left which is probably a false reading. If it says it's lean the PCM will compensate and give more fuel actually causing a rich condition. I want to now what the plugs look like.

Gee the MPG is down to 10 - it is using way too much gas.

I think the fuel regulator might be bad, forcing too much fuel into all injectors and right side with new O2 confirms. This is problem 1.

Problem 2 is a bad left O2 sensor which is causing left bank to run even richer.

If all this is true, there must be a lot of black smoke out the tail pipe.

FOOF - let us know.

 

i will pull the plugs and take a look at them to see what they look like. the O2 sensor on the drivers side was coated in carbon when i replaced it. how do they determine right and left sides on the engine. is it as you look at it from the front or as you look at it from the seats? about erasing the codes to see if it runs better. the guy at m&o did that for me today and it ran better for like 2 minutes then back to normal sluggish acceleration.is there a way to remove the o2 sensors and directly test them to see if they are ok. i just replaced them and though i know it can happen it doesnt seem too likely that both would be malfunctioning right out of the box.

 

Now I'm getting confused. Drivers side is left, passenger is right. Been like that since the model A. Sorry I didn't realize you have changed both O2 sensors already.

You replaced the driver's side O2 before because it was carbon coated. This happened to me on same side too. It broke internally and was reading lean so the PCM richened it up and actually made it rich, not lean, but it's a dumb computer so it didn't know. You should have gotten a 176 code and not 173 for this side. I wonder if you misread the blinking light code reader.

OK. You first had a 173 which is for the passenger side - reading rich. This code is still there so the problem is still there. This does not mean the O2 sensor is not the problem, even if it's new.

Try this - kind of a pain both will be worth it if it works. Move the two O2 sensors to the opposit sides. Swap them pyhsicallay and swap the electrical leads too. Clear the codes out again by disconnecting the battery. Run it and see if the codes switch sides. For left rich you'll get a 177 and for right lean you'll get a 172.

If the codes switch sides, the problem is one or both O2 sensors. Get this part figured out and then we can go upstream to maybe the MAF sensor. I'd say the intake air temp or coolant temp sensors but I don't think those would give you such a gross A/F mix error.

Did you ever clean the MAF sensor? THis is easy and should be done every 30K miles or so to be safe. When it gets dirty it reads lean however and actually reduces fuel. Since you're consumming too much, it's probably not dirty but worth a try. Check here for how to do http://draco.acs.uci.edu/explorer/

 

ok i went back to m&o and redid the koeo test making sure to put the x in for the vin and then also ran the koer test. this is what it gave me 111 at first then 172,173,176,177,189, koer code 536. this just keeps getting funner and funner. it appears to be loosing coolant too. i went and got some coolant dye so i can try and figure that one out.

 

Well, the codes indicate that both O2 sensors are not reading as expected, and the code 189 indicates the computer can not adjust fuel trim enough to get the left side within limits. Code 536 indicates the Brake on/off portion of the test failed by either defective switch or operator error during the test (most likely).

I think I would be looking at the fuel pressure regulator to see if fuel pressure is within specs first. Should have 30-35 psi at idle with vacuum line attached and 35-40 psi (5 psi higher) with vacuum line disconnected. Also check for presence of raw fuel inside the vacuum line in case diaphram is leaking.

After that, start looking at the O2 sensors themselves. If you determine water is leaking into the exhaust (cracked head or blown head gasket) then highly suspect bad O2 sensors as antifreeze tears them up.

Dialtone

 

well it isnt loosing coolant like i thought. went out to fill it up and put in the dye and found that it was still full. the temp guage is going up now higher than normal and so i thought maybe i was loosing coolant. i will try to look at the fuel pressure regulator but i dont have anything to measure psi with so that i might have to try to find someone i know with a fuel pressure guage.

 

Sorry guys - out playing with the kids all day.

I think the fuel pressure regulator might be bad too. There is a vac line that goes to the tree at the back of the intake manifold. Find the right one and pull it. You might need someone to help here - turn the key on and off a few times. Not to start but the on position. This will force on the fuel pump for a couple seconds each time. If any fuel pours out of the line, the reg is bad. make sure the vac line is inside an empty water bottle or equivalent. You don't need a pressure gauge for that.

So I'm thinking a bad regulator is making the entire engine run rich. So one O2 sensor reads that correctly. The other one is bad as it's say you are lean.

Did you try to swap the two O2 sensors as I mentioned? and what are the plugs saying - this is the absolute best diagnostic clue here!

 

ok checked the plugs. passenger side is fine, spot on but the drivers side is really really rich looking. nothing but black on them. i have also noticed that i have a puddle of liquid in the back (closest to the firewall) side of my upper intake manifold. i took a cleenex and poked it back there and it smells like gas. is this normal or could this be part of the regulator being bad. seems like the test you described would mean that fuel is coming through the vacuum hose which is connected to the tree right on the outside of where all this gas is sitting.

 

liquid fuel on the intake is NOT normal and should be investigated and fixed ASAP due to fire hazzard. Most likely, you fuel regulator is leaking into the vacuum hose and also one of the interconnections has decayed. Replace the regulator and repair any vacuum hoses, clear the computer and re-run the KOER test. I think you will find this solves your wierd O2 sensor readings, and makes it run better and greatly improves your gas mileage.

Dialtone

 

Maybe agree. Like I said earlier, I think the fuel regulator might be bad. It is vacuum controled and the tree at the back of the intake is where the vacuum source is. If the diaphram leaks, fuel goes through this port.

Funny thing is though, both right and left plugs should look rich, black. And this is really key since there is only one regulator serving both banks.

One other possibility - the left, or drivers side, O2 sensor is bad and causing the PCM to richen up only this side. And then the fuel you noticed could be from loose intake manifold bolts. This is another known issue on these motors. I also have a 93 and recently had to retorque these bolts. A couple were not even hand tight.

As I think of of it - you get a left lean code but the plugs are telling it is really rich. This makes sense that the O2 sensor is bad and the PCM is trying to correct. This is exactly what happened to me and drove me batty for 2 years.

Since the only thing that controls the 3 right and 3 left clyinders, as completely independent banks tying all 3 clyinders together in each bank, are the O2 sensors, if you get 3 normal on one side and 3 rich or lean on one bank - the O2 sensor is the only logical culprit. Absolute!

Now it is unclear from your post if all 3 left/drivers plugs are black. If just one is - I don't know where to start. BTW - have you changes the plug wires? this will only help overall performance and of course eliminate any engine miss's as a result of bad wires.

 

all 3 where black. if the bolts are loose how is the fuel making its way up the intake manifold? doesnt it inter right by the intake valves? so the next thing would be to clean the plugs, then switch the sensors run it for a little bit then check the plugs again. if the right side is then rich it is that sensor that is bad. i am wondering if maybe some wires got pinched when installing the engine? could this cause a short before the o2 sensor connector and cause the pcm to read it as a rich signal?

 

I don't think so. You are getting a reading which means the sensor is communicating with the computer. If it was grounded or open, there are codes for those and it wouldn't say lean. I'm fairly sure your left O2 sensor is bad. You can switch then to find out for sure before you buy a new one.

As far as where you're finding various leak - I am only speculating on cause. I can't see your car so it's difficult to analyze what you are seeing. I find it hard to believe you find raw fuel sitting on the engine anywhere. It would evaporate almost immediately. If not, then it is coming out at a rate that it would probably catch on fire.

We need to get the right and left banks reading the same - lean, rich or OK. Latter perferred of course. Again, only O2 snsors can cahnge a complete bank of cylinders. If you get a new O2 in left, and now it reads lean just like the right, then you probably have a dirty MAF sensor. That can be clean in 5 minutes.