Idle hunting issue

[ivorton74]

So I've been having this idle issue since I finished the swap. I'm trying to figure out what the problem is. I just got done putting in a new idle air control valve and also cleaned the throttle body(turns out they were pretty dirty). But its still hunting at idle. I pulled some codes and they're all pointing at the O2 sensors(P0134,P0135,P0154,P0155). Can the o2 sensors cause bad idling like that? It only does it when its warm btw

[BR3W CITY]

How is your tune setup? The 134 and 154 are front o2 codes, indicating that they are not installed, but not deleted from the tune.

The other two are the same two 02 sensors heater circuit codes, which indicate the same thing.

Are you running front 02's? It sounds like the computer is still trying to use the front 02, but popping codes because no heater circuit exists to warm up (short).

If you ARE running front 02's, then they are wired wrong, the wrong type, or are not getting signal from the ECM.

If you AREN'T running front 02's, it sounds like they werent' turned off in the tune, and its attempting to correct based on NOTHING.

[ivorton74]

I do have 2 front o2 sensors. I'm waiting til I can buy new sensors and change em out. My buddy says when he checked them they weren't reading at all.

[BR3W CITY]

or just tune them out...itll probably cost the same as new front o2's

[ivorton74]

How do u tune them out?

[aknovaman]

If you tune them out you will loose all feedback from the exhaust system and run it it in open loop. This has some negative affects like when the weather changes or you drive to a different altitude there will be no feedback to correct the air to fuel mispxture the way gm designed the system to work.

Do yourself a favor and fix the problem don't ignore it and put a bandaid over it.

[Super73]

Originally Posted by aknovaman

If you tune them out you will loose all feedback from the exhaust system and run it it in open loop. This has some negative affects like when the weather changes or you drive to a different altitude there will be no feedback to correct the air to fuel mispxture the way gm designed the system to work.

Do yourself a favor and fix the problem don't ignore it and put a bandaid over it.

Tune the ve properly and... well... umm... it is almost un-noticeable unless we are talking 5k+ feet elevation swings.

[BR3W CITY]

Originally Posted by aknovaman

If you tune them out you will loose all feedback from the exhaust system and run it it in open loop.

Most folks who choose to tune them out end up running a wideband o2 for monitoring and logging. The results of that log change the way the tune is set, so in effect you DO have feedback. The difference is, you only use that feedback when making tune-level changes. Otherwise, effectively, you don't need the feedback for anything (especially in a non-emissions vehicle)

This has some negative affects like when the weather changes or you drive to a different altitude there will be no feedback to correct the air to fuel mispxture the way gm designed the system to work.

Thats actually the MAF/IAT combo that handles this, which doesn't get removed unless you decide to straight up speed-density tune the truck....like I did. The VE and PE tables handle the AF mixture, and with two fuel tables you have more than enough resolution to handle the fuel mapping just fine even with weather and altitude etc. GM actually designed the Speed Density mapping system as a way for advanced engineers and factory tuners to command what they needed/wanted without being hindered by the sensors. In effect, you are using it exactly as GM designed it to work (for that level of user).


Do yourself a favor and fix the problem don't ignore it and put a bandaid over it.

That would fix the problem, and not be a bandaid, as there would be no way for the problem to re-occur or cause further issues, making it a permanent fix.

I've addressed a few things in bold.

I didn't actually set out to advocate tuning them out above any other solution, especially since Ivorton is already setup for the sensors...but its still a usable solution, and one he's free to explore if the idea of it (or sd tuning if he wants to go that far) appeals to him. Is it beyond-needed? Sure. Is it a long way around a short path? Maybe.

[ivorton74]

ill change the sensors first and see what happens.