Porcelain white but AFR shows 12.5-12.8 at WOT??

[5.3LS10]

thank you for all of the replies everyone. I will be ordering a new wideband this week. I will also get a new set of plugs to baseline with. Should I be changing heat ranges or anything or too soon to tell with the lean issues?

I have multiple VE cells over 100%. IS that normal for an NA engine? Some at WOT are 115+ or is this a sign of a fuel volume issue?

[turbo conversion]

There is a big difference in AFR between the first and the second data logs, what if anything did you change?

The first log is consistently lean while the second log is much closer to target.

David

EDIT: what is your shift rpm target?

[dontz125]

It's not uncommon to see WFO at max torque a little over 100% VE. It's actually possible to see a NA engine pushing 110kPa MAP, depending on the pipe and intake characteristics.

Some people actually play with their req_fuel to increase their VE into the 200+ range, as this improves their granularity down in the idle zone.

[jsmcortina]

Some people actually play with their req_fuel to increase their VE into the 200+ range, as this improves their granularity down in the idle zone.

But it isn't advised because it cocks up other things that use ReqFuel.

James

[5.3LS10]

There is a big difference in AFR between the first and the second data logs, what if anything did you change?

The first log is consistently lean while the second log is much closer to target.

David

EDIT: what is your shift rpm target?

Sorry I missed that.

I am shifting around 6500. I was more or less trying to get the car to launch the other night and make sure it stayed together after a couple passes. Eventually I will probably put in a shift light and target a specific rpm to help be a little more consistent.

I pulled out (what I thought to be a little fuel) because the AFR was low 12s. Apparently it was too much... but apparently I should have left the fuel in there.

[turbo conversion]

I asked because your VE AFR and Ignition maps are all different for the rpm bins.

I took the liberty and reset your rpm bins, this will give you a little more resolution.

This will require a little retuning but you are not done yet so.

David

[5.3LS10]

I asked because your VE AFR and Ignition maps are all different for the rpm bins.

I took the liberty and reset your rpm bins, this will give you a little more resolution.

This will require a little retuning but you are not done yet so.

David

Great thanks David! You are correct I do have a lot more work to do and I still would like to run it on the dyno at some point to fine tune WOT but want to get it more stable before I put the money up to go to the dyno.

Do you think I should be looking into a fuel issue?

I just find it strange that it is obviously lean but the VE is already over 100?

Or get the new wideband installed and get it reading correctly and then prove it with the AFR reading that as I add fuel it does not richen up then I know for a fact I am having a fuel delivery issue?

[turbo conversion]

I think it was the second log that looked decent, no major lean or rich numbers.

What ever tune you used there go back to it and go from there.

The first log was way lean, probably what started to melt your plugs.

For sure you need a accurate o2 sensor.

VE over 100 should not be an issue, as the injector duty cycle in your second log looks okay.

David










David

[5.3LS10]

I think it was the second log that looked decent, no major lean or rich numbers.

What ever tune you used there go back to it and go from there.

The first log was way lean, probably what started to melt your plugs.

For sure you need a accurate o2 sensor.

VE over 100 should not be an issue, as the injector duty cycle in your second log looks okay.

David


David

I just ordered the 30-4110NS. I have a brand new 17025 bosch sensor in the box so did not need to order a new one. Hopefully by this weekend I will get it and be able to install it.

Do you think the preignition was from the overly lean condition or from too much timing?

Thanks again for all the help everyone!

[turbo conversion]

Hard to say but it could be a little of both.

David

[Yves]

I think it was the second log that looked decent, no major lean or rich numbers.

What ever tune you used there go back to it and go from there.

The first log was way lean, probably what started to melt your plugs.

For sure you need a accurate o2 sensor.

VE over 100 should not be an issue, as the injector duty cycle in your second log looks okay.

David


David

I just ordered the 30-4110NS. I have a brand new 17025 bosch sensor in the box so did not need to order a new one. Hopefully by this weekend I will get it and be able to install it.

Do you think the preignition was from the overly lean condition or from too much timing?

Thanks again for all the help everyone!

Remove timing is the first thing you should do and get rid of the black specks. If it keeps continuing to melt the electrode, there is something in that chamber that gets very hot and ignites the mixture.

Going a couple of grades colder wouldn't hurt in first instance, at least until you have sorted it out. You need to find where the line is forming at the ground strap. Ideally it should be half way if the heat range of the plug is good.

A borescope is helpful checking your piston condition. Pre-ignition is a silent but fast killer.

[5.3LS10]

Hey everyone quick update. I have the wideband installed and I fixed the rearend (cracked one of the welds for the lower control arm mount). I am hoping to put the rearend back in the car tonight. Hopefully I will have time to take it out real quick and do a couple pulls and see where the fuel is at with the new wideband.

[5.3LS10]

So the new wideband definitely added a lot of fuel to the VE table while using the autotune function. Plugs still look a little white to my liking but AFR is only 12.8-12.9. Might try adding a little more tomorrow get it closer to 12.5 and see if it likes it. Here are some datalogs and the current tune. Also last time I filled up I had put 91 octane in the car and not 93 which I usually do. I ran the tank down today while I was driving around and filled it back with 93. Hopefully that will help.

[benckj]

Sounds like your getting on top of it now. Strange how the O2 sensor was so far out.

One thing my Tuner did while checking my car was to lower the VE (raise AFR) at idle until he heard a slight miss. This occurs around 15.3AFR and is a good independent check of the O2 sensor. After setting up cal values mine agreed with his one placed in exhaust pipe and started missing around 15.2.

[5.3LS10]

Sounds like your getting on top of it now. Strange how the O2 sensor was so far out.

One thing my Tuner did while checking my car was to lower the VE (raise AFR) at idle until he heard a slight miss. This occurs around 15.3AFR and is a good independent check of the O2 sensor. After setting up cal values mine agreed with his one placed in exhaust pipe and started missing around 15.2.

Its funny you mention that because I always had very erratic lean AFR readings at idle and I sort of wrote it off to a large cam with lots of overlap. It never ran great at idle.

When I put the new wideband I thought for fun let me double check the MAP and AFR at idle. I added a bunch of fuel at idle, brought the MAP down about 8 kPa at idle and now gauge shows around 14.0-13.5:1 at idle. I have not rechecked since the autotuning yesterday but it should still be pretty close.

I am going to add some more fuel tonight and see if it likes it or not.

Would like to see some more color on the plugs and I did probably about 8-10 pulls last night so figured I would see something more. No more black specs though!

**EDIT** I also noticed I am getting close to low 80s% on duty cycle at WOT. Can someone else confirm that and validate that I am basically starting to max out these injectors?

Thanks,
Shane

[5.3LS10]

One other thing I was thinking of. In theory I can up the fuel regulator pressure and I can get more out of the injectors but doesn't the power draw on the pump incrrease and also the pumps flow decrease when you increase pressure?

[nathaninwa]

What pump are you running? Most are efficient to about 70psi so upping to 50 to 55psi would be alright most likely if your running around 20psi boost

[5.3LS10]

What pump are you running? Most are efficient to about 70psi so upping to 50 to 55psi would be alright most likely if your running around 20psi boost

It is a Walbro 255 intank pump. Base pressure on the LS engines is 58psi which is what it is at now. No boost just NA.

[nathaninwa]

Gotcha. You won't gain much in raising base pressure when your hat high already

But those pumps do run around 70psi safely

[5.3LS10]

Should I be concerned about the duty cycle or only once it gets closer to 90% Or is that a personal preference/comfort sort of question?