Minor misfires?

[DoMiStIc_RuSh_06]

Hey,

Just wondering what causes minor misfires. Is it a maf issue or a spark issue? Currently being tuned by term and hes done all he can do for my car (somethings whacky) and he says that the reason my car seems to work good sometimes and sometimes not is due to the minor misfires.

P.S term seems to think my evap solenoid is going bad so i have one coming as well as an upper o2 sensor.
Attachment 27867
Attachment 27866

Wondering if cleaning the maf sensor might help.

Thanks in advance

[mrvedit]

Misfires will only occur if your AFR is less than about 9 or more than about 18, i.e. way out of normal range. A good tune should never let it go that far out. IMO it would take a crazy dirty MAF to cause such problems.
(I'm just a novice taking a stab at it.)

[DoMiStIc_RuSh_06]

I cant actually hear these misfires just that they are picked up on the scanner. LAst bnight when i started my car up after letting it set for a couple hours, the car had a wierd idle and at the same time the scanner showed 10 misfires.

[1080112520]

Dang last time i tuned my car it was 30* outside, today it was 87* you wanna know how far out my tune was, umm -18 lmao i was like wtf.... But yeah if your tunes out itll cause the misfire but so will plugs.... And so will the 02 sensor it cant keep up with commanded lambda ect.

[gmtech16450yz]

Originally Posted by Terminator2
The car really needs a skilled tech to look it over.

Absolutely. (posted by gmtech)

Dude, don't want to be a d1ck but stop it!

Your mixtures are whacked out, first it goes too rich, then too lean. More than likely your maf cals are messed up with the intake stuff you have on there. Who knows what else is whacked on this thing, haven't you been messing with it for like a year? You really either need to just stop messing with it and drive it, or take it physically to someone so they can diagnose it properly. Posting these logs and symptoms and then having a dozen guys give you different guesses on what it might be is wasting everyones time and not getting anywhere. Yeah, it could be a dozen different things, and even if you changed a dozen parts you'd probably create a dozen more problems.

Seriously, either just leave it alone or take it to someone and pay to have it properly diagnosed.

[DoMiStIc_RuSh_06]

Taking it to someone who's a skilled mechanic isn't an option. Know one around my area has a clue about how to deal with an Lnf and they won't even look at it until it throws a code which it hasn't done. The reason I post is so I can get ideas on which direction to go. I have ordered a couple things that people have suggested. I'm taking it one step at a time. Also, someone else could have the same symptoms and found a cure. Not trying to be a dick but if you don't have something constructive to say to help me out please don't post. I'm perfectally capable of working on vehicles so stop acting like I'm not.

I was in contact with Gm head office and they claim there is nothing wrong with the car but the logs and myself say otherwise. Even if I go back to the dealership and try and explain it to them, they'd be like huh? What's that do! For Christ sakes they can't even install gms1 right.

[Terminator2]

Dude, don't want to be a d1ck but stop it!

Your mixtures are whacked out, first it goes too rich, then too lean. More than likely your maf cals are messed up with the intake stuff you have on there. Who knows what else is whacked on this thing, haven't you been messing with it for like a year? You really either need to just stop messing with it and drive it, or take it physically to someone so they can diagnose it properly. Posting these logs and symptoms and then having a dozen guys give you different guesses on what it might be is wasting everyones time and not getting anywhere. Yeah, it could be a dozen different things, and even if you changed a dozen parts you'd probably create a dozen more problems.

Seriously, either just leave it alone or take it to someone and pay to have it properly diagnosed.

I have a good idea that the purge solenoid needs to be replaced as maybe does the WB O2 sensor. His A/F bounces a lot even with a ton of MAF tuning it will bounce up and down randomly sometimes like a sine wave. The car did this even on the stock intake so it is not the intake. Every LNF I have ever tuned (50 total now) that has had a bouncing A/F issue was due to a bad purge solenoid and often the bad purge solenoid causes the WB O2 to become encrusted with excess carbon buildup and it needs to be replaced as well.

[BackyardTurbo_FTW]

Everyone Ive seen with the sine wave look has been the O2. The Purge has helped random KR issues when Ive seen them.

[DoMiStIc_RuSh_06]

They should be here by then end of the week term...praying this is the issue..... I wanna thank you for all the help you have given me since I have had the Lnf. Much appreciated. As soon as I get this issue figured out, I know of atleast 2 if not 3 guys that wanna get tuned. Thanks again.

[DoMiStIc_RuSh_06]

Everyone Ive seen with the sine wave look has been the O2. The Purge has helped random KR issues when Ive seen them.

I seem to have both of those issues byt. Random knock and the bouncing afr. I'm keeping my fingers crossed. The car still pulls decent at times, to the point that it'll even break free at the bottom of third, then it has times where it can get outta it's own way.

[Terminator2]

They should be here by then end of the week term...praying this is the issue..... I wanna thank you for all the help you have given me since I have had the Lnf. Much appreciated. As soon as I get this issue figured out, I know of atleast 2 if not 3 guys that wanna get tuned. Thanks again.

Your welcome. Playing both tuner and tech from 3K miles away is not easy sometimes LOL.

[DoMiStIc_RuSh_06]

I would imagine. I have been doing tons of research and scratching my head/ stressing lol.

[DoMiStIc_RuSh_06]

So from the research I have done, if both the evap solenoid/ o2 sensor are not working properly, that would explain the wierd stfts which in return would explain the lack of throttle response at times?

[Terminator2]

So from the research I have done, if both the evap solenoid/ o2 sensor are not working properly, that would explain the wierd stfts which in return would explain the lack of throttle response at times?

Yes.

[DoMiStIc_RuSh_06]

How hard is it to change out the o2 sensor. Looks like I could get at if from the top of the car. Is thiscorrect?

[Iam Broke]

You can get it from the top. Use the Force, Luke.

[DoMiStIc_RuSh_06]

Lol....will prob need some penetrating oil because I can imagine that son beach is in the.

[Iam Broke]

If you can stand it, break it loose when it's hot. It'll be easier to get it loose but you will get cooked.

[DoMiStIc_RuSh_06]

Uh oh lol..... Not liking that idea but I will try it.

[Terminator2]

Lol....will prob need some penetrating oil because I can imagine that son beach is in the.

Both pieces are stainless as far I I can tell so there should be little to no corrosion on either part.