Bought a 78 trans am with ls 6.0 ltr noticed doesn?t have the power it should. So I bought a mpvi3 and download the file and noticed that my long and short term fuel trims are disabled and my oxygen sensors read.3 all the time and my ect is set to 285 I assume they don?t want closed loop involved or they never enabled them after tune or is this a type of tune they used any help would be appreciated
Determine what generation ECM is being used and post a tune and log in the appropriate GM generation V8 section.
P59 platform
and post a tune and log in the appropriate GM generation V8 section.
Did Kingtal0n tune it?
Don?t know who tuned it the previous owner just said it had a bad ass tune which I think it?s junk I have a log and tune file getting ready to post on the site for help
Just posted the log and file thanks
LOLOL Don't need no stinkin O2 sensors or catch cans LOLOriginally Posted by 2xLS1
EFI specialist
Advanced diagnostics, tuning, emissions
HPtuners dealer and tech support
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If everything is super funky you may want to have it SPS programmed back to factory settings. Reason is there may be some tables, or settings that have been modified that are not visible with HP Tuners. This way you won't be chasing your tail trying to fix a problem that is un-fixable.
The only way a tuner would do that is if you bring him the car and he tells you to fix the oxygen sensors and the wiring for them, and you didn't want to do that. So then he offers to tune the car without them.
No tuner would disable the closed loop narrowband feature and then hand the vehicle to somebody without a good reason. Open loop tuning as I have said many times is only for when you are the tuner and you need full control over the air fuel ratio at all times. No tuner would ever let the ECU target 14.7:1 for their own car, that would be pretty silly as it is neither optimal, nor necessary for any reason other than a cat converter where the 14.7:1 ratio is said to help them do their jobs effectively. If you don't have a cat and are tuning yourself you would always desire open loop to avoid using 14.7:1.
These are advanced target initial example air fuels for you would target as a tuner for your own vehicle.
depending on the engine of course. Here are targets for a 13:1 compression 427 I tuned a while back on Holley.
Here are the targets from my Nissan Skyline on a Haltech
These targets are only possible on the OEM Ecu using open loop so it is an advanced way of tuning for specific air fuel ratios to enhance the longevity of the engine with superior fuel economy. Using Holley or Haltech they have a closed loop WIDEBAND feature which makes narrowbands obsolete, but in the OEM GM ECU there is no wideband support so you are stuck with open loop tuning if you want the performance of a aftermarket stand-alone ECU.
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