Hello everyone,

I am 2 weeks away from another dyno session that includes the addition of the GPI rod modded intake manifold on my build and I need to get this issue figured out.

Build
Ported Heads
Spinmonster Cam
Texas Speed LTH w/ x-pipe
MF103 Intake
Vmax Ported TB
GPI Rod Mod Intake Manifold.

So I ran the texas speed headers on my car for about 10k for the past 2 years without ever blowing the o2's so please keep that in mind. This year I did heads/cam which was back in April. About 2 months ago I threw a few codes and they ended up being P0030, P0050, P00135, P00155. So naturally I went and got brand new OEM AC Delco o2's and swapped out both sides. I noted that the o2 wiring harness extensions were looking a bit rough but I didn't change them out at the time. Around 400 miles later....boom the codes pop up again. So this time I bought new o2 wiring harness extensions and o2's. Went ahead and installed everything. I made sure the wiring harnesses were tucked nicely away from the headers and nothing was touching. I also checked the o2 fuse #6 15 amp and it was not blown. So now it is 400 miles later again and driving today I threw the same 4 codes. Any ideas guys? My tuner/engine builder says hes going to look at it in a few weeks...I'm thinking its in the tune?

So far what I have changed/checked
Brand new AC Delco o2 sensors (400 miles ago and already bad according to my scanner)
New o2 wiring harness extensions from Michigan Motorsports.
Checked #6 fuse (15 amp) not blown and swapped it with another 15 amp.

Any info would be helpful guys. Thanks

Update: Issue Solved, it was the Texas Speed Long Tube Headers and their o2 bung location being too far down stream.

 

Sorry to hear of your O2 heater circuit issues...this would not be related to the tune since it is the heater function of the O2 sensor !!...all these DTC's are related to your front O2 sensors. With the heaters unplugged you should read between 3-15 ohms (B1S1 is pink and gray white on the harness side...we are checking the O2 side...heater circuit wires are usually the same 2 colors on sensor side) if the heater itself is OK. We can do a DC voltage test first. With your DVOM connected to a GOOD ground you should see 12 volts KOEO probing the pink wire...if good now switch the red DVOM lead to the gray/white wire...with engine RUNNING and warmed up you should see .05- .1 volts on the ground side...we are basically doing a ground to ground voltage drop check...since the heater ground is PWM (pulse width modulated...ECM provides the ground and modulates it to maintain the heater at a constant temperature). You can check for this "pulsed" ground by taking a 12 volt test light connected to battery POSITIVE (or connect the test light between the 2 wires which is a little more dangerous) and with the sensor unplugged probing the gray/white wire while the engine is running and the DTC's cleared (if DTC's are present the ECM may inhibit the heater circuit function !!) see if the test light flashes...if it does not you may have to check at the ECM...you may have a broken wire between the ECM and the sensor...perform the same check on the other O2 sensor...heater ground is the light green wire on Bank 2....if missing ground on one or both ECM ground circuits you may have a bad ECM !!...since this is happening at 400 miles you may have high resistance in the wiring once it heats up...hard to know for sure !!...since you are using extensions I would check for pin fitment !!...no loose connections !!

 

Thank you I will show this to my tuner today!

 

Just to let you know this is something a “tuner” will not be able to “tune” !!...I hope he is good in electrical diagnosis !!

 

Update/help requested. So the shop I have been wanting to get the car two for atleast the past month or so keeps pushing my date back so I am trying to figure this issue out myself.

I bought a volt meter to check the o2 connector off the engine wiring harness for the voltage output. I used the fuel rail as a ground. I am not electrical friendly at all so bare with me.

Car guy, engine not running

Passenger Side Connector
(Pink Wire) Top Left Pin: 11.94 Volts (20 V setting)
(Green Wire)Top Right Pin: .033 Volts (2 V setting)
(Dark Brown Wire) Bottom Left Pin: .207 Volts (2 V setting)
(Tan Wire) Bottom Right Pin: .016 Volts (2 V setting)

Driver Side Connector
(Pink Wire) Top Left Pin: 11.85 Volts (20 V setting)
(Green Wire) Top Right Pin: .030 Volts (2 V setting)
(Dark Brown Wire) Bottom Left Pin: .208 Volts (2 V setting)
(Tan Wire) Bottom Right Pin: .016 Volts (2 V setting)

I am not sure what these outputs are suppose to be so I was hoping someone could chime in...and give me the next test? Does it appear I have a short in the wiring or? Maybe the issue lies elsewhere?

Thanks!

 

Just follow what I posted in post #2...I don’t know what top left, bottom right refers too as to wire colors !!...there is a 450 Mv bias voltage on the O2 signal wires but not on the 2 heater circuit wires !!

 

Just updated it with wire color...

Tracking sorta...but not sure what that means? Are two wires suppose to be showing 450Mv? looks like right now there are two that are close are .033 and .207?

 

With voltmeter across the 2 sensor wires you should see 450 Mv...if you measure each of the signal wires to a good ground if you subtract those 2 millivolt readings it will equal 450mv !!...I can’t remember what my voltage readings were