Start up tune running extremely Rich
TECH Senior Member
Joined: Jun 2016
Posts: 22,306
Likes: 3,621
From: Central Cal.
Actually, it CAN be that bad. The sensor can only go by what passes it, and there is NO consistency there with open headers. It CAN be compensated for, but it is a shot in the dark. No tuner in the world can narrow that down.
Put some 2' pipes on it and be amazed at the change.
Put some 2' pipes on it and be amazed at the change.
TECH Regular
Joined: Dec 2011
Posts: 420
Likes: 115
Lots of factors could cause it. Does the 'mail order; tune really have a halfway decent injector table for whatever injectors you have. Is your fuel pressure right. In general, cams (and thats a healthy cam for a 6.0) will make the low RPM much less efficient, so you usually have too much fuel, sometimes by a lot, in the ranges below 2 or 3k rpm.
A few people are not understanding correctly. You can NOT run O2 sensors with OPEN headers. It will always add fuel. You can run O2 sensors with headers IF you have exhaust or atleast 2-3 feet of pipe off the headers. A car can be tuned for OPEN headers, it will run in open loop and ALL the O2 sensors will be turned off in the tune. My guess is the mail order tune was NOT done for open headers and the front O2 sensors are still turned on. We do hundreds of mail order tunes a year and some combo especially swaps are really hard to get the fuel right due to all the extra variables so the fueling in the tune could be off also on top of that.
TECH Senior Member
Joined: Jun 2016
Posts: 22,306
Likes: 3,621
From: Central Cal.
a few people are not understanding correctly. You can not run o2 sensors with open headers. It will always add fuel. You can run o2 sensors with headers if you have exhaust or atleast 2-3 feet of pipe off the headers. A car can be tuned for open headers, it will run in open loop and all the o2 sensors will be turned off in the tune. My guess is the mail order tune was not done for open headers and the front o2 sensors are still turned on. We do hundreds of mail order tunes a year and some combo especially swaps are really hard to get the fuel right due to all the extra variables so the fueling in the tune could be off also on top of that.
TECH Regular
Joined: Jun 2021
Posts: 497
Likes: 148
From: Shlumpt, TX
Lol?? I already said I understand. It’s in the tune. You CAN tune for open headers it is just hard. Guy above you literally said you can.
Do I need to be simpler for you to show you I understand?
Do I need to be simpler for you to show you I understand?
a car can be tuned for open headers
After some reading it most likely is not so much the tune but more that he's running 02s dumped and without pipes there's too much oxygen getting into the collector causing the ECM to dump excessive fuel
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Thread Starter
Teching In
Joined: Dec 2017
Posts: 44
Likes: 3
From: Myrtle Beach S.C.
Thanks for all of the replies ! Shakenfake all 8 plugs looked that way. It is set up for Speed Density. I have open long tube headers with both 02 sensors installed about 8 inches from the end of the pipe. No Y pipe and no mufflers. Sounds like the mufflers do need to be installed even for a "Start Up Tune" I will get the exhaust done before i proceed any further and then see how it runs.
TECH Senior Member
Joined: Jun 2016
Posts: 22,306
Likes: 3,621
From: Central Cal.
Thanks for all of the replies ! Shakenfake all 8 plugs looked that way. It is set up for Speed Density. I have open long tube headers with both 02 sensors installed about 8 inches from the end of the pipe. No Y pipe and no mufflers. Sounds like the mufflers do need to be installed even for a "Start Up Tune" I will get the exhaust done before i proceed any further and then see how it runs.