Idle issues and lean surging on decel at highway spees

[95GMC]

Finally got the open loop idle to work by using one of the bin files from the thread tayto linked and doing the exact same thing I already tried with raising the temp qualifier... I guess somehow the bin I was using was corrupted or something? At any rate I transferred all my VE tables etc. over to that bin and I have a decent idle for now. Before I did this I tried several things and still couldn't get the closed loop idle working well, I'm not sure what's going on it's a very mild engine in comparison to some I've seen on here and other forums that idled well in closed loop. I also drove the truck again and still have the lean surge only on decel from say 30mph and above that gets worse with more speed. I guess for now I'll just drive it and do some of the WOT tuning. I guess I could always cheat and enable the DFCO earlier so it can't physically run lean since it's not technically running but I really want to fix this the right way, whatever that entails.

[ralmo94]

Finally got the open loop idle to work by using one of the bin files from the thread tayto linked and doing the exact same thing I already tried with raising the temp qualifier... I guess somehow the bin I was using was corrupted or something? At any rate I transferred all my VE tables etc. over to that bin and I have a decent idle for now. Before I did this I tried several things and still couldn't get the closed loop idle working well, I'm not sure what's going on it's a very mild engine in comparison to some I've seen on here and other forums that idled well in closed loop. I also drove the truck again and still have the lean surge only on decel from say 30mph and above that gets worse with more speed. I guess for now I'll just drive it and do some of the WOT tuning. I guess I could always cheat and enable the DFCO earlier so it can't physically run lean since it's not technically running but I really want to fix this the right way, whatever that entails.

You might think about switching to a 4 wire o2 from like a 98 or something, and run the signal ground right to the pcm wire that grounds on the engine, and not ground that on the engine, to make sure you are getting accurate signals. Otherwise the signal ground is on the exhaust pipe.

[95GMC]

That's a great idea and heck for the price I'll definitely give it a shot

[ralmo94]

Make sure you DON'T connect signal ground to heater ground

[95GMC]

Oh yeah for sure definitely don't want to try to pull 5+ amps through the signal ground haha I imagine that'd fry the driver in the ecm pretty quickly

[tayto]

disable DFCO and see if the lean surge goes away. it is one of those things you should enable AFTER you get your VE table dialed in. Since you are running headers,.you will probably have to mess with proportional gains. A 3 or 4 wire is a good idea for headers IMO.

[ralmo94]

disable DFCO and see if the lean surge goes away. it is one of those things you should enable AFTER you get your VE table dialed in. Since you are running headers,.you will probably have to mess with proportional gains. A 3 or 4 wire is a good idea for headers IMO.

There may also be a Decel ENLEANMENT