Finally my car is throwing some codes after its been running like crap forever. It is throwing 7 codes:
48 MAF Sensor Error
P135 Oxygen Sensor Heater (bank 1)
P134 O2 Sens CKT Inactive
P1133 HO2S Switching Fault
P174 Front fuel trim lean
P171 Fuel trim lean

I got these codes.. and when i checked out my O2 values my right O2 values were goin nuts from 35 to 900. Is there anyway to diagnose and see which o2 sensors are messed up or what part of the harness is?

 

Odd... you have a combination of OBD-I and OBD-II codes. What PCM are you running in your 94? Got to be a very unusual setup.

It is completely normal for the O2 sensors to swing back and forth rapidly over the full range of 0xx-9xx mV's. That's the way both sides are supposed to respond in closed loop.

 

its a stock PCM so i believe OBD1 I never messed with the PCM but then again i am not the first owner of the car. It jumps between closed loop and open loop. Also the right side injector is registering as its pumping more fuel than the left constantly.

My car is running very rich and is stumbling a little as im driving. It also bogs down when i let out the clutch to take off and stumbles. I can smell raw fuel when it is doing this. Every once in a while it will stop and run perfect so this is confusing the crap out of me.

 

Did you check your MAF sensor readings to make sure they are legit? Do they correlate with engine speed and throttle position? If there are irregularities coming from the MAF sensor, then the computer could be using these values to calculate rich/lean conditions. ...and same with your O2's (but it sounds like they are doing what they should be doing). Try unplugging your MAF and see if the car runs any better.

Wait a minute, in your signature, you list "CAI, MAF..." Do you have an aftermarket MAF sensor? If so, try swapping the stock one back in there (if you have it, or if you know someone who will let you borrow his for testing purposes). It wouldn't be the first time I saw an aftermarket MAF make a car run less than optimal.

 

Yes i do have an aftermarket MAF sensor. I tried cleaning it a couple weeks ago to see if that would fix the problem but it didn't. I do not have the stock one but i guess i'll try to find someone who has MAF that i could possibly borrow. I looked up the codes more clearly (somehow they are OBD-II codes, i don't know how that happened) and all of them seem to correlate with each other and seem to be pointing the fingers at the right O2 because all the codes are from bank 1 which i forgot to mention.

Say i unplug the MAF and it runs better, does that mean it was a faulty MAF causing the problem?

 

I would say that is a good assumption. Make sure your MAF wiring harness is in good shape too. if you have a datamaster log or even something from free scan you could email it to me at mkent93@yahoo.com
Problems don't ALWAYS show up in the scans but many times they do.

The irritating thing is, all things everyone else has already suggested could also be the problem.

 

yes i agree but ruling out the MAF first would be a lot easier and cost efficient. I just disconnected the MAF sensor and it sputtered then ran the same as it did with it plugged in. The weird thing is that my check engine light came on this time when it was unplugged when all this time i thought my check engine light wasn't working because it was throwing those seven codes without any light coming on. But as soon as i unplug the MAF the light came right on.

I don't have a datamaster log (or really know what exactly it is) but the scan tool i used can take a snapshot of the data display as the car is running for however long i want it to. Not sure if that is the same or how i would get it online.

What i also don't understand is why it is throwing the OBD-2 codes.. does that mean i have the OBD pcm somehow?

 

What is the scan tool you are using? I am suspect of it if it is giving a mixture of OBD1/OBD2 codes.
A snapshot of data is almost worthless since engine conditions are changing continuously. With software such as Datamaster or Freescan you can view graphs of your data versus time and see the dynamics of the engine. It is relatively cheap if you already own a laptop (if i remember right, the software was around $200 and the cable was around $80?). I used to think that was expensive since I'm in college, but it is definately a valuable tool to own. If you don't have a laptop, i think scanmaster is a good looking scan tool but I have no knowlege of logging capabilities with that tool--all i know is I get tired of driving around trying to watch my laptop for knock, timing, ect when I could have it mounted in my dash like the scanmaster will do.
Ok, so i kinda went on a tangent...if you had an OBD2 pcm in that car, someone would have had to install a crank positioning sensor, CPS reluctor ring, and a new woodruff key on the crank, along with some modifications to the knock sensor circuit or you would be seeing many more codes. This is why I am suspect of your scan tool...

 

Bank 1 is the LEFT side = drivers side = Cyls 1/3/5/7. You said the right O2 was swinging from high to low.... that's what it is supposed to do. What were the left O2's doing? Your problems appear to be on the left side. If you don't understand why the O2's are supposed to be jumping around in closed loop, read this:

http://members.aol.com/InjuneerZZ/ScanMast.htm

You have "lean" codes on both the left (P0171) and right (P0174) sides of ther engine.

I've never seen a scanner produce both OBD-I and OBD-II codes. Clear the codes by pulling the "PCM BAT" fuse for 30 seconds. Run the engine for a while. Then check for codes again.

Check the pink wire in the MAF sensor harness connector for +12V.

 

it never crossed my mind about the scan tool, but now that i think of it, it is nothing like anyone elses probably. My family owns a subaru dealership and im using a scan tool probably almost as old as me that has different programs you can plug into it and im using a chip for a bucnh of GM models and once the chip is in you select your exact car etc etc and then you can check values and trouble codes. It also has a trouble code clearer (not sure if that is the same as pulling the PCM BAT) and i clear them and the car will run fine for about 20 minutes then start doing it again and throw some more codes. So i have no idea what kind of tool it actually is, it everything is so faded and worn down that it doesn't have any kind of source telling me what it is. I also didn't realize that bank 1 was left side i thought it was right. Im not sure if this means anything but the car was jumping around from closed loop to open look continuously.

** Is there anyway to check if the actual O2 sensor is bad without replacing it?

Ok now i understand why they are supposed to be jumping around i misread my manual that says it would operate down through about 10 mV if exhaust is lean and around 1000 Mv if the exhaust is rich.

I will be in the shop in about an hour to start troubleshooting and ill have my computer, thanks for your help guys ill keep you posted and im sure ill have a bunch more questions in a little bit

 

just to update, i just got here, The scan tool is a subaru brand but the program in the scan tool being used is a Domestic 1 used for all GM cars 1981-1995. It is now throwing only 3 codes from when i cleared it 2 days ago:
48 MAF Sensor Error
P134 O2 Sens CKT Inactive (bank 1)
P1133 HO2S Switching Fault (bank 1)

Checked pink wire in the MAF and it looks fine.

 

Well, assuming your codes are accurate, it looks like you need a new o2 sensor (get a AC Delco), and apparently you have something going on with the MAF. Check and make sure you didn't burn your wire going to the o2 sensor on the headers. That wire runs from the back of the driver's side of the engine and down to the bung in your header. Did you install the headers? Usually you have to buy o2 extensions unless you extended them yourself. Check out your wiring real closely and make sure its in good shape.

 

If you have an Ohm meter, check the pink wire and make sure you are getting voltage to it. Just turn the key forward (you don't have to start it) and unplug the maf and probe the connector which goes along with the pink wire. I can't remember if its suppose to be near 5v or 12v but if you have 0v then that's a problem. Someone please correct me if I'm wrong.
From what I've read the pink wire usually breaks somewhere back in the wiring harness, towards the PCM.

 

Unfortunately i don't have an Ohm's meter but tomorrow ill be able to use one. The MAF was registering at 5 grams.

I have a Carline 94 manual for my car and everything matches up except my LT Fuel TR Banks 1 and two which are supposed to be valued at 118-138 and they both register at 160.

Another thing i found strange is that last time i was paying so much attention to the right one i wasnt looking at the left. The right one was jumping from 100-900 again as it is normal in closed loop. The left one strictly stays around 400 +-50 idling and in higher rpms. Then when i shut it off it stayed at 400 and slowly went down as the temp went down while the right one went to 90 and slowly went down.

 

Well, again, replace that o2 sensor and I think that will clear up alot of your problem if not all of it. The left one is lazy...its not cycling back and forth during closed loop and that is a tell tale sign that it has quit doing its job. It is important to make sure you have no exhaust leaks before the o2 sensor too as that will also make the computer THINK the car is running lean, therefore it will dump a ton of fuel to compensate.