EVAP issues

had the SES light come on last week, scanned it, got some codes

-EVAP MALFUNCTION. and -LARGE LEAK, LOW SYSTEM VACUUM.
possible causes?: (gas door open, unplugged charcoal canister, broken purge solenoid)

-P0420:Catalyst Efficiency Below Threshold. or -P0431:Warm Up Catalyst Below Threshold. it's either one i forgot which hha
possible causes: (bad o2's or cats) ihad a "running rich" code for months untill i got a re-tune, so maybe I slightly messed-up/melted the cats.. idk how possible that is, maybe it needs to be lean not rich to do that

-RANDOM/MULTIPLE CYLINDER MISFIRE
causes?:(i would say the likely cause is from the problem with the cats or o2's or maybe a header leak) I don't think it's a plug or a wire b/c it's random/multiple cylinders not the same one over and over) the misfire must be slight b/c i don't think it drives different or hesitates


When i got the light it said "tighten gas cap", the cap was tight so idon't think it's the problem. Im guessing it's a loose hose. soo.. MY QUESTION IS SHOULD I JUST DITCH ALL THAT EVAP STUFF?



& my rear O2's are off and have been off
also i think it was the STFT's, but lowest it was reading was (5% - 7%) at idle completely warmed up after sitting for a while ...if somebody knows somthin bout that tell me.

thanks for all the opinions and info guys! lol

decided to just turn all the codes off in the tune and remove it

Quote:

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Originally Posted by lukecibilich

had the SES light come on last week, scanned it, got some codes

-EVAP MALFUNCTION. and -LARGE LEAK, LOW SYSTEM VACUUM.
possible causes?: (gas door open, unplugged charcoal canister, broken purge solenoid)

-P0420:Catalyst Efficiency Below Threshold. or -P0431:Warm Up Catalyst Below Threshold. it's either one i forgot which hha
possible causes: (bad o2's or cats) ihad a "running rich" code for months untill i got a re-tune, so maybe I slightly messed-up/melted the cats.. idk how possible that is, maybe it needs to be lean not rich to do that

-RANDOM/MULTIPLE CYLINDER MISFIRE
causes?:(i would say the likely cause is from the problem with the cats or o2's or maybe a header leak) I don't think it's a plug or a wire b/c it's random/multiple cylinders not the same one over and over) the misfire must be slight b/c i don't think it drives different or hesitates


When i got the light it said "tighten gas cap", the cap was tight so idon't think it's the problem. Im guessing it's a loose hose. soo.. MY QUESTION IS SHOULD I JUST DITCH ALL THAT EVAP STUFF?



& my rear O2's are off and have been off
also i think it was the STFT's, but lowest it was reading was (5% - 7%) at idle completely warmed up after sitting for a while ...if somebody knows somthin bout that tell me.

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Well, as far as the EVAP stuff, I would just disable or turn the EVAP stuff off in the tune. I really don't think there is a need to try and screw with it.

For the P0420 code, if you still have cats--they are bad by now, so I would just have them removed. I would just go ahead and throw some LTs and an ORY in there. I would also get some new O2 sensors just for good measure.

The Random Misfire could be a bunch of things. I would start with replacing the plugs with NGK replacements. Nothing fancy, but I recommend NGK TR-6 plugs from O'Reillys. Make sure to set the gaps properly. Then if the code still exists, look at the fuel system...FPR, fuel filter, overall fuel pressure, etc. Dealing with a Random Misfire code is so general that I could type for hours about the things you could do to correct it...

thanks, im goin to my tuner this weekend and getting that taken care of ,should i physically remove everything or leave it on

i put the tr-6's on there about 6 months but wasn't able to gap them:ugh2:

....lt's are on the list:devil: