Horrible Gas Mileage, How Much to Replace...

[dereileak]

yea to get stft and ltft you need to have run the car till it goes into closed loop operation. if that sensor is easy to get to then check the voltage at the sensor because .3v is to low. check the ground at the pcm also. and there should be a freeze frame data on when you look at the scan tool. look at the data and if you can record what some of that stuff is.

the scan tool I am using is an android app called torque and a 35 dollar bluetooth elm327 1.4version module for the obdII, it all depends on the car so far if it supports certain features, so idk if it will allow me to get the freeze frame data, the weird thing is earlier today the app was reporting my vehicle as going into a closed loop, so idk what to think, but I still had the engine cold, do you think this could be related to the extremely cold weather we are having lately?

I do have some pc applications that look like they can look at more stuff which I will have to try out tomorrow, as it is 4am, and freezing cold, thanks for the help so far man

[dereileak]

alrighty, I got a vehicle wiring schematic, and it looks like the o2 sensors are fused, but from what I can see is that all the fuel injectors are on the same fuse, number 17, so there is no way that can be it, unless it is dirty and getting low voltage or something. I will have to clean the fuse inserts and see what is going on , that fuse isnt blown of course or it wouldn't run at all from what I can see

[JaM Customs aka mprete]

ok well i got some more stuff on your codes and procedures you can do to test it but you might need a little better scan tool to do them. but there are some more simple procedures like testing the resistance of the sensor. should be the white wire. put it to the white wire and to a good ground. should be between 4 and 7 ohms. if not its a bad sensor. which could happen. let me know what you get with that and ill put a couple other things up in the mean time that you will be able to test.

[JaM Customs aka mprete]

oh also check that automatic shut down relay. i think that would shut down the fuel injectors to but check it anyway. also i think your o2 might not have a white wire. should be black/ dark green and black i think. your power and ground. put the dmm between those 2 wires and you should get your reading, not a good ground like i said above. but yea, check that out, that will tell you if its a good or bad heating element which is a bad sensor. if thats good we will go from there.

[dereileak]

Alright, I will try and do that, I have to wait till I get to a shop at work to get and do those things probably. I did notice something. So I did my big 3 about a couple months ago, and I forgot to hook up this thinner ground wire that goes to the engine block. Now idk if its related, but it goes into the loom of the vehicle so I cant see where it goes, a wire comes out by the battery again that is about the same, but it doesnt make sense why they would run a heavy gauge to the engine block and that thin one to the same point. Another weird thing is when I tap it to ground, it sparks a bit, telling me something is trying to complete a curciut through it, what I will do is take the one off the battery and see if it still sparks a bit, if it does, then its not the same cable. I was curious where they grounded these sensors because in the wiring schematics they show it being grounded to the chassis, it is about maybe 2 feet away from the wiring, probably even less, 1.5 feet or so from the front o2 sensor that is causing all the trouble. I will see what I can do with this guy, that would explain the o2 sensor heat malfunction, cause it may be able to read, but not when its cold, and the heater cant heat it up if there is no ground, so we will have to see, thanks again, I will keep looking, I also cleaned the fuse that was related to that o2 sensor line.

[may03LT]

I replaced it with the same brand that was in there for oem and I am still getting the code p0135

Did you ohm out the heater element on the old one prior to replacing it?

I dont know what to do, I dont want to pay all this money to have a dealership hook there big machine up to it, but I am kinda stuck, and input would be good.

For the p0134 - unplug pcm and upstream o2. Ohm out the b/dg wire from pcm pin 30 (according to your diagram) to the same color wire in the o2 connector (first), do the same with b/lbl pcm pin 43 to same color wire in o2 connector (second). One of these will not have continuity. My guess is is the first. Report results.

For the p0135 - pcm plugged in, o2 unplugged - turn the key on - in the 02 connector, the dkg/o should have 12volts, the black should have ground. Report results.

Its really hard to get to the harnesses for this thing so I am not sure.

Yes, that particular job sucks 30,000 dicks. I test them from underneath, removing the cowl isn't much help to get access from up top.

[JaM Customs aka mprete]

that could be the ground to the sensors, it could even be the ground to the pcm... which could cause all these problems. bc with the key off nothing should be trying to pull a ground other them the pcm if it has not shut off yet which is not right when you turn the key off, it could be up to 20 or 30 minutes before the pcm shuts off. or it could be 5 seconds. all depends on the car.

[dereileak]

interesting stuff here, so I unhooked that ground to my battery that looked like it went to the engine block, the very thin one, well it doesnt go there, because the other side still sparked when I touched the engine meaning it was trying to pull a load. Weird thing too, I had also lost my cruise control, well guess what started working when I reattached that ground to my engine block, the cruise, and I cleared my mpg in my car, and driving around I was getting between 14-15 on ethanol, wow, so I hope that was the cause of all this, having new o2 sensors doesnt hurt either since the ones in there had 108,000 mile on them, we will see how the fuel economy is longterm over a few days

Also the that cable that went to the battery neg did some weird stuff, when I took it off my alternator shot the voltage up to 16volts, I was like holy shit, I better not have it sit there to long, and putting it back immediately brought it back down, kinda cool if you want higher voltage, but I dont know the sideeffect of that at all, I have yet to test the resistance, but I have to wait to get to work to use a good fluke meter we have there, thanks again guys!

[JaM Customs aka mprete]

glad to help.