Brand New O2 Sensor from Oreilly's bad????

[EagleTalonTim]

I just bought an OEM replacement O2 sensor with the plug already on it for my 93 A/T TSI AWD Talon and I am still getting 13 mpg!!! There is one VERY small boost leak around the TB which I am hunting down and going to fix. I just put brand new exhaust on the car.... 2 1/2", no CAT, Turbo muffler, and standard 2 1/2" tip thinking thinking the CAT was the problem with the gas mileage. There are no vacuum leaks. The turbo spools fine. No CEL. Coolant Temp Sensor was replaced 200 miles ago. Brand new K&N fuel filter and MAF tested out fine. The tires are properly inflated and all the same size.

Why am I still getting 13mpg?? Is the O2 sensor that Orielly's calls for not the right one?

 

[big_d]

theres a test at the bottom...might help..big_d


http://www.mr2.com/TEXT/O2_Sensor.html

 

[EagleTalonTim]

ok, the O2 sensor tested perfectly fine....now what?

 

[Twinturbo2800]

once i hollowed my cat i got similar MPG.

 

[EagleTalonTim]

how can hollowing out your cat make you get that much worse gas mileage?? I have a 2.0 N/T talon that I ran without a cat since I got it, and it was getting and average or 33 to 36 mpg. When I put a cat on it, the mileage went down to 25 to 28 mpg.

 

[EagleTalonTim]

I just put a brand new fuel filter on the car since the other one had been on there for 2 years while the car sat then I took it for a test drive. Now, the boost is kicking in at 2500 rpm's and the exhaust still smells rich as hell.

 

[kenamond]

Your profile lists no aftermarket boost gauge. When you boost leak test, do you have a pressure gauge in the mix somewhere to know how must you're pressurizing the intake? If so, how high do you pressurize and how quickly does it leak down when you stop adding air (how long does it take to drop from, say, 20psi to 19psi)?

Is the car misfiring or backfiring? Is the car running on all 4 cylinders? What do the plugs look like? What plugs are you running, what are they gapped to, and when were they last replaced? How old are the wires?

Anyway, I'd make sure you have fixed the boost leaks. It should hold 20psi and leak down 1psi every few seconds or better. If that's already the case, post more info about the ignition status.

 

[EagleTalonTim]

I just use the boost gauge as a reference to how much pressure is in the intake when I am doing the boost leak test. I only pressurize it to 15psi. It drops 1psi every 1 second. When it gets to 5 psi, it takes longer to drop. The plugs look like they have been running rich. Black, with a slight brown on the tip.

I posted another thread in the Problem Diagnostics because no one in this area could think of anything better than the O2 sensor or Coolant Temp Sensor.

http://www.dsmtuners.com/forums/showthread.php?t=266830

I am working on trying to find an AFPR, injectors, and SAFC. Found nothing yet that fits my budget or will bolt right up perfectly.

 

[kenamond]

That's not too bad of a boost leak, but you should be able to do better. Is much air leaking out of your oil cap or VC breather when you test?

All of the plugs looked the same?

I get 21mpg city (lower if I get on the gas more) and 28mpg highway.

Update your profile.

 

[FL_TalonTsi]

once i hollowed my cat i got similar MPG.

eagletalontim you should just eliminate your cat, u live in Texas, there are no emission tests.

 

[EagleTalonTim]

All the plugs look the same. I did not just hollow out my cat, I put a "fake" cat on it. It is the outer shell of the cat with pipe run down the middle of it. Texas does have emission laws, but all they check here is if you have something that looks like a cat on the car. There is no air leaking out of the VC during a boost leak test....just the one around the TB. I think it is the TPS. Probably time for a TB rebuild or upgrade.

Newest Update. probably the entire cause of all this....

I found that the ECU in the car is for a 92 2.0 N/T FWD talon. Not quite the right one I just bought a computer for a 92 AWD Turbo eclipse 5 Speed and some 450 injectors. Hopefully they will work since my car is an automatic. I did some research and found that it is does not matter if it is auto or manual. Hopefully this is right. If I am wrong, please tell me!

 

[FL_TalonTsi]

Texas has emission test?? haha sorry about that, guess you learn something new everyday.