PCM Diagnostics & Tuning - my eyes are watering! is my car running rich? it may be a stupid question!




poltergeist 02
10-11-2010, 06:57 PM
i'm posting this here because i think it's tune related and not just a fueling problem. just a quick maybe stupid question. do you think my car is running rich? if i have my car pulled in the garage (with the door open and back of the car facing out of course) and idling my eyes start to water from how thick it is. do you think it fumes building up or should it not be that bad? i am new to ls1's and i have only built carbureted cars prior to this one. i don't remember having this issue with any of those unless they were over jetted.


MawneeC5
10-11-2010, 09:00 PM
no cats?

poltergeist 02
10-11-2010, 09:06 PM
no cats


jimmyblue
10-12-2010, 10:15 AM
If it stings, it's more likely NOx. Which comes from lean
and excess timing.

Slow sensors can make you swing wide, and put you
alternately rich and lean while maintaining average
that reads right, but sucks for chunky soup.

An open loop car (like carb) will just sit in one spot.

poltergeist 02
10-12-2010, 07:37 PM
so this is normal?

tsench
10-12-2010, 08:04 PM
no cat = tears and gas smell to your clothes

jimmyblue
10-12-2010, 08:27 PM
That's only true for no cats and a bad mixture. An engine
that's running right doesn't stink or sting.

digitalsolo
10-13-2010, 02:21 PM
That's only true for no cats and a bad mixture. An engine
that's running right doesn't stink or sting.

This ^

Though I can generally "smell" if a modded car has cats or not.

That said, stinging eyes can be dead rich or lean, but either way it's not generally a good thing (unless you're a wimp and have sensitive eyes ;)).

Frost
10-13-2010, 03:00 PM
It's more often a little lean or the base timing is high... NOX burns.

CalEditor
10-13-2010, 05:33 PM
It's more often a little lean or the base timing is high... NOX burns.

2X

LEAN LEAN LEAN and a lean cause high HC's if you don't know.

If you are old like myself and you worked on carbed car you would know. Back in the day we may have close the choke partially while running the car and it never I repeat NEVER smelled as bad as a LEAN car

poltergeist 02
10-13-2010, 09:29 PM
thanks, thats all i needed to hear. i will get the car re tuned asap.

Mike454SS
10-13-2010, 10:58 PM
Also...if you have shitty O2 sensors and a cam that isn't as tiny as stock...as jimmyblue alluded...it will swing rich/lean VERY slowly in closed loop compared to fresh O2's and a stock cam...when the cam is bigger than stock, you need to be better about sensor maintenance...and if you're daring, you can futz with the closed loop PID stuff in the tune...but you should have some servo tuning background, or other Laplace transform (controls with closed loop feedback) background (or a LOT of time behind a laptop and EFI tuning software) before you delve in there.

Old Geezer
10-14-2010, 07:11 AM
Too many/too quick hits on the bong mite do that!!

poltergeist 02
10-14-2010, 05:32 PM
Also...if you have shitty O2 sensors and a cam that isn't as tiny as stock...as jimmyblue alluded...it will swing rich/lean VERY slowly in closed loop compared to fresh O2's and a stock cam...when the cam is bigger than stock, you need to be better about sensor maintenance...and if you're daring, you can futz with the closed loop PID stuff in the tune...but you should have some servo tuning background, or other Laplace transform (controls with closed loop feedback) background (or a LOT of time behind a laptop and EFI tuning software) before you delve in there.

well, the car only has 25k on it and the cam has only been in for 800 of them. unless age has something to do with them going bad, i'm not sure that o2 are my problem.

jimmyblue
10-15-2010, 10:45 AM
Almost any car with headers makes the sensors colder
than they should be. Most "get by" with it. But it still
has that effect.

turbolx
10-15-2010, 01:04 PM
Hrmm... bigger cam, unknown state of tune (VE, MAF models), smelling fuel and burning eyes... I'll take incomplete combustion for $1,000 Alex.

Injection timing may have some impact here, depending on your overlap and port velocity near idle. If you're tuning yourself, I'd start there then go back and revisit the VE surface (and MAF transfer) next.