Cam question

[jackal2000]

im experiencing major random misfires (P0300). is this normal in cam applications? i talked to milzy today and he said to delete that DTC from the PCM. on the DHP forum one guy mentioned that if i do that it might inhibit the specific misifre codes as well (i.e P0301 etc). im just trying to gather as much insight as possible to see why this is happening. its milzy's stage 2 cam btw.

[lvemy3100]

in short.. yes it is normal...

I was gonna say something on gmv6pcm.com but was in a rush earlier...

[jackal2000]

ok thanks for the confirmation. do you recommend deleting the DTC? now i just gotta figure out that surging idle im having...

[xonelith]

I deleted the DTC, however if the misfire is big enough, the SES light will flash, even though the DTC is disabled. I increased my idle rpm (it seemed to happen alot for me; particularly in cold weather) and now i don't get the flashing light. I think I set it to 950rpm. Oh, I also changed the spark plugs:)

[jackal2000]

i raised my idle RPM to 800 yesterday, perhaps it needs raised a bit more. my plugs are brand new and gapped to .050 (autolite 104s)

[jackal2000]

i just rescanned the car and found some more DTCs

P0300 (of course)
P0122
P1122
P1133

those last three i believe are due to a bad TPS. the funny part is i bought a new one months ago when i had the surging idle problem but it went away and i forgot about it. anyone know how hard it is to install??

edit: upon further review that last code seems to be an upstream O2 sensor issue. hmmm....is this because of the headers?

[Malaclypse]

In six years of working on cars every day I've seen a cylinder specific misfire code set twice... and I see alot of misfires. Don't worry about it.

Replacing the TPS is easy, two torx screws and one connector and you're done. I think they're T15s.

The P1133 - B1S1 O2 sensor insufficient switching: could be caused by the headers moving the O2 sensor farther downstream. This is why alot of programmers will play it safe on fuel trims for part throttle. It takes longer for the O2 sensor to measure exactly what the engine is doing.

It could also be caused by a bad O2 sensor so you might try replacing that and see if the code comes back.

[Sprucegagt]

I had the same code (P1133) not long after I installed my headers. Changed the O2 sensor and never had it come back.

[jackal2000]

the reason i was worrying about the specific misfire codes is because my car threw 301 codes before all of this work was done.

so i need to replace the upstream O2 and delete the codes for the downstream O2?

[Sprucegagt]

You have a Powrtuner don't you. If so then yes, stop reporting/monitoring on the rear O2 sensor and replace the front oxygen sensor. When your oxygen sensor is bad it may be causing your idle problems.

[AaronGTR]

Yes, a bad O2 sensor will definitely cause idle problems. That and the TPS sensor could be contributing to the misfire issue too. I never had any misfire codes with my cam. Granted it's a boost cam and not an NA cam so the overlap is a lot less, but it's still much higher lift and duration than stock and the idle is still a lot rougher. I would fix ANY other code and sensor issues you might be having first, and then play with the idle speed some more and see if you can't get the misfire code to go away before going and deactivating it. It's there for a reason and you shouldn't just arbitrarilly turn it off because it popped up unless you have no other choice.

[jackal2000]

yes i have teh powrtuner

thanks for the help guys