I have a 4.8L engine I am running with a 2002 LS1 pcm in my 93 c1500 truck. The thing is running pretty lean, 14.8+ AFR. I have tried everything I can think of to change the closed loop AFR but it will not change. I need to get it about 14.0 since we have nothing but 10% alcohol fuel year round here in the Dallas area now. Anyone have any suggestions or willing to tweak this tune so I can try it? Open loop, speed density is my last resort.
Thanks,
Greg
Why is the stoich AFR set to 13.0???
Just set it for what fuel you run, so E10 gas, just set it to 14.1ish.
Regular fuel is around 14.7, so seeing 14.8 to 15.5 is not considered lean at all. It's impossible to get a vehicle to run directly at the stoich afr set in the PCM, the o2 sensors continue to bounce back and forth from lean to rich causing the jumps up and down in the air fuel ratio seen on a wideband.
I wouldnt really worry about this small thing, it's just going to always bounce around from 14-15.5 while at idle and cruising down the freeway.
I also noticed that you VE table goes far above 100 kpa, are you even running a 2 bar map sensor??
2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.
If you don't post your tune and logs when you have questions you aren't helping yourself.
so i can't remember where i saw it as a cheat until u run full open loop and tune w wideband. but its a late night couple beer try to remember.....fuel tab / open &closed loop 02 rich lean vs. airflow. change the airflow switching to uuuhhhhh this is where i get dumb. switch it higher? if you are looking for power play with spark it makes huge gains i found most of these truck cals were never tuned for power enrichment like yours your pe delay is set to 5000 rpms still. make sure under view it is advanced and also i have found tuning pe is semi complicated and the truck i was dealing with was faster without pe. this is the thread not a 4.8 it's a 6.0 lq40.....but sameish principles though. please post back what is working for you. I have a 4.8 going in my 85 cj7 this winter and it's obviously getting tuned.
Last edited by Howes; 05-20-2015 at 09:06 PM. Reason: additional info
it was set at 13.0 to see if I could fatten it up a little but it did not change at all. I am not sure why the map range is so high, I am running a single bar map. The reason I need 14.1 or a little richer is with it running lean I get high NOX output and cannot pass a vehicle inspection here in TX due to high combustion temps.
don't know the details of your build but your egr is disabled is it equipped w an egr? that would lower them quick to get through thenndelete it again.Originally Posted by redheartbeat
Nope, no EGR. It's a 2006 4.8L truck engine except the PCM.
Like Howes said - To richen it up raise your O2 airflow settings up to 550ish mv then set your min max settings 25 above and below that - if I'm thinking of the right ecm here? Then set stoich to 14.4ish would be more than rich enough - tune MAF and VE for that. Should get your a/f bouncing pretty close around 14.6 to 14.7. If your running long tubes and have the ability in the tune to do so, then you can adjust your O2 integrator delay and O2 proportional airflow tables to get your a/f closer to what's being commanded without it bouncing around so much too. That's only if you have those tables to adjust. If do multiply the proportional by .8 or .9 and your integrator delay by 1.2 or so....
2010 Vette Stock Bottom LS3 - LS2 APS Twin Turbo Kit, Trick Flow Heads and Custom Cam - 12psi - 714rwhp and 820rwtq / 100hp Nitrous Shot starting at 3000 rpms - 948rwhp and 1044rwtq still on 93
2011 Vette Cam Only Internal Mod in stock LS3 -- YSI @ 18psi - 811rwhp on 93 / 926rwhp on E60 & 1008rwhp with a 50 shot of nitrous all through a 6L80
~Greg Huggins~
Remote Tuning Available at gh[email protected]
Mobile Tuning Available for North Georgia and WNC
Thanks for the replies. BTW, this engine has long tube headers going to 3" dual cats and then to a dual in/out muffler and out the back. No full on racing engine here, bone stock.
Well then... On top of the above you need to modify your O2 proportional and O2 integrator delay airflow tables for the relocation of your O2 sensors. Multiply proportional by .8 or .9 then integrator delay by 1.2 to 1.4 something until your air fuel - with air fuel stoich set somewhere arount 14.55 to 14.6 - matches your actual air fuel ratio being commanded. Don't think I would go super rich due to the fact I think you would then fail your ppm hydra carbon count.
2010 Vette Stock Bottom LS3 - LS2 APS Twin Turbo Kit, Trick Flow Heads and Custom Cam - 12psi - 714rwhp and 820rwtq / 100hp Nitrous Shot starting at 3000 rpms - 948rwhp and 1044rwtq still on 93
2011 Vette Cam Only Internal Mod in stock LS3 -- YSI @ 18psi - 811rwhp on 93 / 926rwhp on E60 & 1008rwhp with a 50 shot of nitrous all through a 6L80
~Greg Huggins~
Remote Tuning Available at gh[email protected]
Mobile Tuning Available for North Georgia and WNC
GHuggins, is that for enriching the closed loop? To multiple by those values? If you wanted to lean out, would you go the opposite way? Same for the O2 rich/lean vs airflow table? I see 450 is recommended as the normal switchpoint, but I've seen folks recommend 300mV to try and get a lean cruise.
He was asking about enriching closed loop which is why I said to set O2's to 550. He's already got them at 500 with no real forseen benefit which is why I then stated he needed to dial in the O2's distances after he stated he only had long tube headers. There's no point in going richer than 550 as it doesn't usually do much more plus you don't want to get your O2 settings too far into their less efficient areas. Yes if you want to run leaner, you can go leaner via O2 mv vs airflow settings.
As for the O2 tables. This is to adjust for the new O2 distance from exhaust valve. He was trying to richen up his tune to no avail, this was because his fuel trims were just being pulled back or I guess the best way to describe this is that his oxygen sensors were correcting his fueling incorrectly based on exhaust pulses being seen at the wrong time? This is to get the commanded air fuel to match actual air fuel ratio. You can only typically set stoich down to around 14.5 to 14.6 without causing counter issues with the O2's or in other words you can only typically go as rich as 14.5 to 14.6 before your O2's start pulling fuel back out.
Once the O2 distances are dialed in and stoich is dialed in for your O2 switch points what you'll usually find is a very, very steady air fuel ratio at idle. In other words no longer bouncing around and staying withen .3ish or less of what's being commanded... Makes for very stable idles, smooth cruising and great driveability. When things are dialed into that "working together" sweet spot things seem to work together much better as a whole. Of course there's a lot of timing tables and air flow tables that all correspond to this, but once your able to adjust fueling correctly, all the rest just seems to come in like it needs to.
Hope that wasn't too confusing. Think I mighta confused myself typing it.
Just a couple of problems caused by incorrect fueling causing other underlying problems. Fueling ranging up and down too much via not having fuel trims dialed in close enough (fuel trims going from +5 to -5 long terms) = pulling 5 degrees timing durring wot pulls at 2500+ rpms on twin turbo porsche resulting in less boost, very bad dyno graph and around 30 less hp. O2 distance wrong = lean idle, lean cruise, surging while cruising, surging while holding steady elevated rpm, surging at idle, timing bouncing around.
Fueling is the most important thing about a tune. This is why you'll see me recommending fixing injection timing, O2 settings, stoich settings and air flow tables more than anything else on a regular basis on here. AND you will almost always see benefits with getting what ever problem there may be sorted out by doing this. Heck just by getting fueling right, I got an extra 50hp and nearly 80lbft torque out of twin turbo vette, because I was finally able to add timing without it being pulled plus for whatever reason when things are right on turbo cars, they don't seem to have turbo lag or sudden boost spikes - just constant pin you back in your seat and take off power and torque. When things are right with turbos, there like missiles. Hard as hell to tune right, but worth every bit of the frustration in the end...
OK, I'm rambling again and somehow got a little off, but somewhat still on subject? Sorry.
Back to issue - fix tables suggested, should see it running as commanded and at a richer air fuel ratio than it was when right.
2010 Vette Stock Bottom LS3 - LS2 APS Twin Turbo Kit, Trick Flow Heads and Custom Cam - 12psi - 714rwhp and 820rwtq / 100hp Nitrous Shot starting at 3000 rpms - 948rwhp and 1044rwtq still on 93
2011 Vette Cam Only Internal Mod in stock LS3 -- YSI @ 18psi - 811rwhp on 93 / 926rwhp on E60 & 1008rwhp with a 50 shot of nitrous all through a 6L80
~Greg Huggins~
Remote Tuning Available at gh[email protected]
Mobile Tuning Available for North Georgia and WNC
I can't believe no one had mentioned this... but if you're running e10 then the stoich for that fuel is 14.12ish. If you're seeing 14.8ish on the wideband then your actually running 14.2ish. It's a lambda sensor that is converted to afr. So seeing 14.7 is stoich for the fuel you're using.
This is why I love lambda! It eliminates this kind of confusion.
Changing stoich is going to affect wide open throttle for the most part. The o/2 sensors are going to keep you at stoich. Maf sensor is is what you need to calibrate to richin it up to decrease nox.
so it doesn't matter what fuel I am running, just tune for 14.7 on my wideband and all is good? Man was I confused, I thought we had to tune for the fuel so as not to burn up the engine. Believe me, I only play around with this tuner every once in a while when I must and that piece of knowledge will come in handy, for sure.
All wideband sensors are actually lambda sensors. They convert the lambda reading into an AFR reading based upon a predetermined stoichiometric transfer function. For the NGK/AFM AFX it's 14.57, for your wideband it will say in the owners manual. This is why I, and anyone else who knows what they are doing, encourage people to learn lambda. It's much easier concept and and if you set transfer function correctly in hptuners you'll almost never have to worry about afr again.
This is all true, BUT air fuel sensors will and always have read richer or leaner than stoich. In fact they have ranges that describe how rich or lean they read. PLUS you should never see one "when tuned correctly" bouncing around with great deviations especially up into the 15's at idle unless tuned purposely to do so. This just shows that there is incorrect fuel control. Use a OE for comparison - Air fuel always stays withen .2 to .3 of what it's supposed to be...
I and others out there don't particulary like to use lambda simply because you can have lambda out 1% and have an actual air fuel ratio off .4 or .5... This is why OE's like Ford or others that use lambda have the decimal set up as .000 accuracy corrections to keep air fuel where it's supposed to be for emmission, driveability and so on. This is also why lambda can be a pain to tune with sometimes... BUT, I guess there's tricks and work arounds for that.
OE's use lambda for setting up their ECM's fueling from factory - don't get me wrong, but ever wonder why a lot of those newer vehicles come from factory with +-8% fuel trims?
Bassically if things are right fuel wise - injector settings and so on - things will work correctly tune wise. Ever wonder why Banish and others always say to verify injector settings and how they only use certain injectors and so on. It isn't to waste time typing or because they have nothing better to do... AND yes, most of these guys use lambda for tuning. I just personally like air fuel. Personally gives me a better perspective on things and is easier for me to tune with. I don't like having to spend so much time "finely" tuning in lambda to get correct air fuel readings. I guess if you know the tricks, lambda can be made easier?
Greg also stated earlier in the post that he's only running long tubes. O2's moved = incorrect fuel corrections = incorrect fuel control. Just because he's running some sort of ethanol percentage in his fuel - we all are / don't care if you are buying so called 0% ethanol / it's still got it because all fuel must have atleast 3% to 5% now / ever tested ethanol content on the so called 0% fuel / real let down - doesn't mean that he should have bouncing around air fuel ratios. Think everyone really got off subject onto the lambda vs air fuel vs ethanol percentage band wagon there. This is all still besides the fact that he's got a problem that needs to be addressed......
Greg, you want to fix your fuel control problem, address the O2's as previously posted then you can use lambda, air fuel, whatever to fix your fueling.
Sorry for the long post, just trying to clarify some things here.
2010 Vette Stock Bottom LS3 - LS2 APS Twin Turbo Kit, Trick Flow Heads and Custom Cam - 12psi - 714rwhp and 820rwtq / 100hp Nitrous Shot starting at 3000 rpms - 948rwhp and 1044rwtq still on 93
2011 Vette Cam Only Internal Mod in stock LS3 -- YSI @ 18psi - 811rwhp on 93 / 926rwhp on E60 & 1008rwhp with a 50 shot of nitrous all through a 6L80
~Greg Huggins~
Remote Tuning Available at gh[email protected]
Mobile Tuning Available for North Georgia and WNC
I appreciate everyone's input. Thanks
The problem is he is looking at his wideband thinking he needs to see 14.1ish. What he needs to see on his wideband is stoich. This is what I meant about preferring lambda. If he was using lambda he'd just look for 1 and it'd be all gravy.
As far as the rest of your post...my wife is after me too get off the phone, so I'll post my reply later.
We are also assuming that his wideband is installed and/or calibrated correctly.
lambda lambda lambda. get off afr.
get a wideband that displays lambda like the NTK AFRM.
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