Minor misfires?

[DoMiStIc_RuSh_06]

These parts still haven't showed up. Hoping today or tomorrow. Anywho, I made a custom config so I can log misfires in each cylinder and knock per cylinder along with a bunch o other stuff. Gonna log tomorrow after work. See if I can narrow it down to which cylinder the misfires are occurring and maybe I'll do some more trouble shooting such as swapping plugs/ coil packs. I'll keep you posted to see what I find.

[DoMiStIc_RuSh_06]

Ok, they finally showed up today. I installed the evap purge solenoid today. It made the cars response seem a bit better. The ltfts are steady at 0.8 and the stfts are still all over the place. The knock is still there, worse in some cases. I will be swapping out the o2 sensor on Sunday. I'm praying this gets rid of the knock and I will also be putting my original plugs in to see if that will help with the knock as well as swapping pedals with my buddy this weekend. After All this is done and if it doesn't fix this issue, I don't know what I'll do after that.

[jebsmith]

Following this, I have many misfires in cyl4 and weird kr that goes away with an ecu reset but creeps back in. I replaced my evap valve a few months ago, it was stuck open. Maybe now the wb02 is bad. Ill check back with results of the change.

[Oncebefore]

I might have the same problem with my 07 Solstice GXP. I reverted back to the stock after not being able to get rid of knock and rough idle. It's still there up to 3* on stock tune and light misfires loged, You can feel it at idle. I was wondering if it could be a bad turbo seal. Here's a short log I took this morning messing around.

[DoMiStIc_RuSh_06]

If itwas a turbo seal, shouldn't it be smoking?

[Terminator2]

Your misfires are gone on the last 2 logs. STFTs are much better now they dont bounce like they did. LTFT was 0.0 the whole last log. KR is the same no matter if I run 12*peak timing or 17* of timing. Car is actually pulling timing on the logs so if I command 13* it sees 10*. If I command 17* it sees 14*. Still have no clue what is causing the KR unless the cat is clogged/melted.

[DoMiStIc_RuSh_06]

I'm also working on trying to get the catless dp from my buddy. The knock is wierd, kinda makes me think it's false but it's hard to figure out. At certain times I can actually hear what sounds like spark knocking. I will load that tune into my car later today and do a log for ya.

Thanks for all the help your giving me term. Hopefully we can get this knock issue figured out.

[Terminator2]

I'm also working on trying to get the catless dp from my buddy. The knock is wierd, kinda makes me think it's false but it's hard to figure out. At certain times I can actually hear what sounds like spark knocking. I will load that tune into my car later today and do a log for ya.

Thanks for all the help your giving me term. Hopefully we can get this knock issue figured out.

It is pulling timing for real but the idiotic part is no matter what I do with the timing and A/F it knocks 3-4* sometimes 1-2* other times. MAF tables are nearly perfect now. Cat could be clogged. You had 3* of KR at 20 psi, 0.88 lambda and stock timing which is not normal at all even on 91 octane. How is it running now compared to when I started tuning it?

[DoMiStIc_RuSh_06]

It seems to be running decent....like I said, some times it's pulls good and other times it doesn't. I'm Assuming that's when the knock happens. It doesn't pull as hard as it's capable of.

[Gremlin85]

I don't know what else you've tried, but never rule out a good compression test and leak-down test.

Worth a look.

[DoMiStIc_RuSh_06]

Yeah, I pulled the plugs and they are clean, a little bit carboned up but looks good. The car doesn't smoke besides black and the odd puff of Greyish here and there. Atleast it's not blue.

[Terminator2]

It seems to be running decent....like I said, some times it's pulls good and other times it doesn't. I'm Assuming that's when the knock happens. It doesn't pull as hard as it's capable of.

The ECM will also randomly pull up to 15* timing even when you have no knock. I will have 10-12* commanded and it will drop to -3* sometimes even though there is no knock at the time. It happens to all LNFs including my car when pushed to the limits as far as airflow (airloads of above 255%) car senses to much airflow and pulls spark. I am assuming it is for torque management (possibly piston protection).

[DoMiStIc_RuSh_06]

Yeah, it even did the same thing on gms1. It's wierd and it's stressing me out lol. What would cause knock besides whacky maf, bad fuel. Probably all kinds of contributing factors.

[Terminator2]

Yeah, it even did the same thing on gms1. It's wierd and it's stressing me out lol. What would cause knock besides whacky maf, bad fuel. Probably all kinds of contributing factors.

Clogged cat could be the whole problem. Going catless would definately be worth it at this point. If nothing else it will add a few more hp. Also you seem to get more KR on cylinder 4 I believe. The other cylinders have less knock or no knock. Your MAF is fine and you tried a different brand of gas already.

[Gremlin85]

The ECM will also randomly pull up to 15* timing even when you have no knock. I will have 10-12* commanded and it will drop to -3* sometimes even though there is no knock at the time. It happens to all LNFs including my car when pushed to the limits as far as airflow (airloads of above 255%) car senses to much airflow and pulls spark. I am assuming it is for torque management (possibly piston protection).

I experienced that today, actually. Dropped froma commanded 12.5* to 3* on a pull for no reason. Now I know what it was. Thank you.

[DoMiStIc_RuSh_06]

Clogged cat could be the whole problem. Going catless would definately be worth it at this point. If nothing else it will add a few more hp. Also you seem to get more KR on cylinder 4 I believe. The other cylinders have less knock or no knock. Your MAF is fine and you tried a different brand of gas already.

Would a bad plug be the cause of knock on #4. I'll try to get my cat gutted real soon or get a catless dp.

[Terminator2]

Would a bad plug be the cause of knock on #4. I'll try to get my cat gutted real soon or get a catless dp.

I doubt it. A bad plug will cause misfires on cylinder 4 normally. You don't have any misfires as of the last 2 logs so I doubt you have a bad plug.

[DoMiStIc_RuSh_06]

I may look into getting a compression test. Also would a bad fuel injector cause this?

[Terminator2]

I may look into getting a compression test. Also would a bad fuel injector cause this?

Yep a bad injector would cause lots of KR on the cylinder with the bad injector.

[T-Man]

I remember reading about cia's flexpipe collapsing on people... Might be the dp giving you headaches?