2G Correct Diagnostic? Multiple Codes

[Oakley792]

Hello!

Well the past few days my car has been getting bad gas mileage, running rich and thrown the following codes.
P0136, P1104, P0300,

P0136. ( O2 Sensor Circuit Malfunction (Bank 1 Sensor 2) )
I did some research on the P0136, everyone seems to say that is the rear o2?
The rear o2 sensor doesn't effect fuel, but the front one does correct?

I just wanted someone to clarify that the P0136 is the rear sensor or front?
I do have full Megan exhaust and high flow cat.

P1104. ( Wastegate Malfunction)
The car has a EVO III 16G. Can someone explain to me what all the wastegate solenoid actually does and what problems arise. Also my car has a Turbo XS MBC.

P0300. ( Multiple Misfire )
Again if the P0136 code is the front O2 and it is bad this would cause misfire correct?

On my pocket OBD II Scanner is shows the following codes. After I reads the codes I scroll down and it says the following " 02 HTR " and " EGR ".
Anyone have input on this. I will check tomorrow but I am not sure if the car still has a EGR valve or the previous owner installed a block off plate.

Thanks!

 

[blakkat]

A o2 sensor code usually comes from a slow response. Which would indicate a bad sensor.

Your misfire code could come from many things. Check your compression, check your injectors and coil packs / wires.
Can you feel a misfire?

As for the wastegate solenoid on most cars it is basically a boost controller that runs off Ecu inputs to control boost, if you have it bypassed and you're running a manual boost controller that may be the cause. Did you disconnect the solenoid completely or just loop the vacuum lines?

 

[Tyeler18]

Fix that random misfire first of all. That's your biggest problem. The P0136 is for the rear o2 so, it won't effect fuel trims at all and can be ignored for now. For the wastegate, do you have the BCS hooked up? Or plugged in for that matter?

A o2 sensor code usually comes from a slow response. Which would indicate a bad sensor.

I disagree completely. 95% of the CEL's that come into our shop relating to the o2 are not actually the o2. Generally they're an underlying problem from an issue with the engine (in this case a multiple random misfire).

 

[blakkat]

Yes you have a good point,

Do you still have a cat? If you have a bad enough misfire I would be really worried about it.

 

[fierosail]

the miss fire will toss up a o2 code do to it not firing and burning right .
Like what people are saying fix misfire fix the o2 prob most likely

 

[Tyeler18]

I doubt fixing the misfire will fix the o2 code as the upstream sensor would catch it before, and it's a circuit malfunction code not a lean/rich code. Fix that misfire first though and then report back. I wouldn't worry about the o2 sensor until you have the driveability part fixed.

 

[blakkat]

Disregard previous post.
It's definitely a failed sensor or there's something damaged in the wiring leading to it.

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[fierosail]

my bad miss read the code thought it was front not back

 

[blakkat]

The crank/cam sensor will trigger the misfire code, it looks for the crank to slowdown momentarily when a cylinder fails to fire.

I would inspect the rear o2 circuit for damage. The o2 sensors wouldn't do anything for fuel in this instance because the car will be in constant open loop when a misfire is detected and the ecu will turn off o2 feedback based fuel control.

In summary things to check
Compression
Spark (coil, wires, plugs, igniter )
Fuel ( injectors, fuel pressure regulator, fuel pressure in general)

 

[Tyeler18]

The crank/cam sensor will trigger the misfire code, it looks for the crank to slowdown momentarily when a cylinder fails to fire.

It'll trigger it, but it isn't the cause of the misfire. Could be anything from ignition, to fuel, to compression causing it. Seeing as how we have a waste spark ignition system, I'll put my money on only 2 cylinders causing the random. Just have to find out which set is causing it and narrow it down from there.

 

[blakkat]

Yes I know, just edited my above post. I'm tired

Can you explain to me what else could cause an o2 sensor code besides a circuit malfunction. Because I'm a deans list student in my school and basically the way we have been taught is that the ecu watches for response time on the primary o2 sensor between the short term bouncing rich and lean. And that's how it determines slow response. The secondary has minute voltage fluctuations as well that the ecu monitors.

 

[Oakley792]

Thanks for all the replies guys, I am moving into a new place so busy with signing paper work and moving boxes. Once I get done with that I will start checking the ignition system on the car and make sure all fuel systems are up to par. I will post back with updates.

To the above posters, the car has a high flow cat, which could be clogged. The car sat for over a year before I bought it.
Yes I have a manual boost controller but then again I have not taken it off or seen if the old BCS is hooked up. That is something I will have to check.

Also I might add a few months ago my balance shaft broke and took the crank sensor with it. I put in a new crank sensor and balance shaft belt and all was good. Until one day I left to go to work got on our major highway going 70MPH and I hear a bit POP!. It backfired and I lost all power. I pulled over to the side and the car ran at idle from 500-800rpm and when I reved the engine it would literally go to 2000rpm and two step. Sometimes puffing black smoke. I shut her down and a few hours later came back to tow home. I got in the car and it ran perfectly. I hooked up my OBD II scanner before I left the first time and it said Crank sensor malfunction. But after I drove it home that night it never once threw that code again and I can not remember the exact code number.

Could my crank sensor be reading wrong and misfiring? I just put on new NGJ BPR7ES along with new wires, and coil pack. Compression was good when I checked it a month ago. The car builds up boost fine and doesn't feel like it is misfiring at all. That never really crossed my mind as it runs perfectly at idle and WOT.

 

[Tyeler18]

Yes I know, just edited my above post. I'm tired

Can you explain to me what else could cause an o2 sensor code besides a circuit malfunction. Because I'm a deans list student in my school and basically the way we have been taught is that the ecu watches for response time on the primary o2 sensor between the short term bouncing rich and lean. And that's how it determines slow response. The secondary has minute voltage fluctuations as well that the ecu monitors.

It'll throw a code for o2 too lean/too rich as well as a few others which aren't of much concern. However, a random misfire (such as this) will pour fuel down the exhaust and will throw an o2 too rich code or if it's a misfire from a stuck injector where no fuel is being sprayed it will throw a code for o2 too lean. Neither of which are actually a bad o2, but most people will tell you to throw an o2 sensor in and should fix it...

I'd assume you're going to UTI from your location?

OP- I doubt if you have a newer cat on it, that it's clogged. A misfire can kill it quite quickly, but I have a hard time believing it's clogged already. If you clear the codes, how quickly do they come back?

 

[blakkat]

I get what your saying but how would a misfire result in a circuit fault code? I know the rich or too lean code but I mean in this instance. I would tend to think if there is a failure in the circuit it's probably in the wiring between the harness connector and the sensor.

And yes I am a Uti student, the school is really good and you learn a lot if you pay attention.

All of the idiots this school spits out are the ones that pass with 70% in every class and take the maximum days off. I have a 4.0 and 100% attendance so I tend to think of myself as pretty knowledgable with cars.

 

[Tyeler18]

I get what your saying but how would a misfire result in a circuit fault code? I know the rich or too lean code but I mean in this instance. I would tend to think if there is a failure in the circuit it's probably in the wiring between the harness connector and the sensor.

And yes I am a Uti student, the school is really good and you learn a lot if you pay attention.

All of the idiots this school spits out are the ones that pass with 70% in every class and take the maximum days off. I have a 4.0 and 100% attendance so I tend to think of myself as pretty knowledgable with cars.

I'm just saying that 95% of the o2 codes that come into my work aren't the o2. Yes in this instance the o2 could be the problem, or the wiring, that's to be determined though.

Meh, I ask because I went to Wyotech in Laramie and over 90% of the people that go there as well are morons that couldn't do anything else. I graduated from there with a 4.0 and 100% attendance as well, however, I'd never recommend either school to anyone with any automotive background prior to taking it. Biggest waste of $40k in my opinion.

 

[blakkat]

Yeah I hear ya, I just learned a lot more of the specifics without the wait till I actually had to fix something for me to learn.

 

[Oakley792]

Thanks for all the replys everyone, I will not be able to look at the car until this Tuesday. My only question is wouldn't I feel a misfire. The car idles fine at about 750-800rpm. and it builds up boost fine.

 

[Tyeler18]

You may not feel it, but it could be just slight enough for it to throw a code, or just random enough.