GMTheOnlyWay1

iTrader: (1)

Hello guys my problem is I live in Colorado and 99.9% of the gas stations only have 91 octane fuel and a heavy ethanol mixture. Here in junction 91 is the only thing you can find unless I go out to the airport for some c16. I always fuel up at only conoco/shell stations from what I hear they have better gas but regardless my car still pings loud under WOT from about 5k/5200- redline and I can clearly feel the difference in power.

Some of the things I've Tried-
NoS Brand/Torco Octane booster: It works but I feel like after a few days it goes right back down to normal octane and starts to ping again. Im not adding more fuel or anything. but at 12$ extra for 10 gallons its been a hassle on the pockets. Plus I worry about these additives creating increased wear and tear.

Mixing in x amount of c16 usually 4-5 gallons for a full tank. This really helps and makes my car feel and sound extremely healthy but isn't very cost effective at 6 bucks a Gallon plus I cant put the fuel directly in the car out at the airport so this makes it even more inconvenient on top of the drive out there.

I've read around the site and found things for mixing chemicals such as Toulene and Xylene for an octane increase So I went ahead and checked around at my local paint shops but everything is extremely expensive 120+ for a 5 gallon supply.

I was also wondering, I have a few mods ready and plan on getting a tune by frost after installation (mail order), Can he richen up my wot fuel mixtures? maybe making it okay to just run 91? Im thinking this is probably my best bet.

Any opinions/ suggestions are Greatly appreciated. This problem is extremely annoying especially for random fun runs.

RPM WS6

iTrader: (3)

These cars only require 91 octane to operate properly in stock form (meaning no pinging at WOT). They also have knock sensors which detect knock and reduce timing to compensate. If you are hearing audible knock then this is significant because the issue has exceeded the PCM's ability to compensate.

For a stock LS1 with stock tuning, you should never need to add 4-5 gallons of C16 to 91 octane just to keep detonation away. There is either significant carbon buildup in the combustion chamber casing hot spots and/or increased compression leading to detonation, or some part of the fueling system (sensor, injector, etc.) isn't working optimally leading to poor A/F and thus detonation.

The problems you are having are not normal for your mod level and vehicle, based on the information given. I'd suggest looking at O2 sensor data as well as logging LTFT (long term fuel trim) and KR (knock retard) data if you have access to a comprehensive OBD scanner. A Seafoam (or other top end engine cleaner) treatment would also likely be in order, plus an MAF cleaning. Catch up on any other general maintenance that may have been neglected as well.

redtan

iTrader: (5)

Was the car ever tuned? Can't imagine a stock compression LS1 pinging badly enough that it requires a mix of C16 fuel. That ****'s for boosted applications or people running 12+ compression ratios, not a nearly stock LS1 with 10.0:1 compression.

I agree that there's an underlying issue somewhere causing this rather than not enough octane. Have you actually scanned the car to verify this knock, both with straight 91 and then with your mixture to verify that it indeed goes away with the higher octane. Or are you just going by sound and feel of the car?

NC01TA

I totally agree that some maintenance may be needed. You didn't mention if you have done anything during your ownership.
I HATE pinging and I'll just pass on my experience to you. Even with 93 octane (no ethanol) here in NC I was having some pinging issues once the car was warmed up. Not severe, but you could hear it with heavier acceleration. With about 40k miles on my 'stock' T/A, my mechanic cleaned everything out, replaced the original plugs with AC/Delco iridium, and the pinging problem was gone. It was that simple. I'm not a mechanic and can't explain the 'whys' but it worked for me.

GMTheOnlyWay1

iTrader: (1)

All the general maintenance has been done. car has 78k
plugs and wires less than 1k miles ago
new fuel filter/oil change less than 3k
maf cleaned 2 weeks ago even though it was still clean
Ive checked pressure at the rail and its slightly above the norm.
Car has never been tuned, I've even reset the tune by pulling the fuses etc.
All the general maintence stuff has been taken care of sooner than regularly since I got the car a little over 2 years ago.
I had the dealership run fuel trims on it when it first started and all they could come up with was that my car was running lean. They blamed it on the lid lol.
Im not very smart when it comes to scanning and all that but im sure they would have told me if i had a bad o2/knock sensor.

GMTheOnlyWay1

iTrader: (1)

I am running the Ngk tr55 combo with the msd wires. I might just try and switch back to the AC delco iridiums and see where that gets me but I had the same problem prior to the change. I've even ran some Amsoil Fuel treatment thats suppose to clean everything up id say 5k miles ago or so.

GMTheOnlyWay1

iTrader: (1)

Also No I haven't had the car looked at on any of my mixtures to verify that it actually goes away the car just feels much more awake and the pinging noise itself is gone. The power difference is definitely big because I've even had friends notice it.

RPM WS6

iTrader: (3)

Then this is where I would start. You'd need a comprehensive OBD scanner to monitor LTFTs and see just how elevated they are. Stock O2 sensor data isn't as precise as aftermarket wideband info at WOT, but it's still worth looking at just as a reference point.

You can also hook the fuel pressure gauge back up and tape it to your windshield, then check fuel pressure at WOT where the issue is. Good pressure at idle doesn't always guaranty good pressure under heavy load.

The Seafoam/top engine cleaning I mentioned above is still in order, as carbon buildup could definitely be a factor casing the ping. A fuel system detergent (again, Seafoam or Red Line, for example) or bench cleaning of the injectors may also be in order.

An air lid isn't causing this problem, many of us have had these on otherwise stock cars without ever having pinging. So the dealership may have pointed you in the right direction (lean), but their reason as to why (lid) is incorrect.

GMTheOnlyWay1

iTrader: (1)

Alright Ill go ahead and check pressure at WoT and seafoam the car. Where can I pick up a comprehensive OBD scanner? aren't they pretty pricey? on a tight budget right now unfortunately.

by the way thank you guys.

RPM WS6

iTrader: (3)

I'm not sure if any of the "cheap" OBD scanners will show the data that you need. I think most of those are just code readers or maybe some basic sensor data as well. What I'd want to look at would be LTFTs (looking for patterns in respective fuel cells), KR data, and O2 sensor data at WOT (again, not great for tuning purposes but helpful for rich/lean macro-data).

You wouldn't really need any super new fancy tuning suite software, I just use an old AutoTap program from the early 2000s and it works just fine for this stuff. You might be able to find a used cable and software for relatively cheap, then all you'd need is a laptop.

Orange Juice

iTrader: (3)

You could try checking your local forum and see if someone close by has HP tuners for your year and would run a scan for you.

GMTheOnlyWay1

iTrader: (1)

Yeah I tried calling around a few places here but no luck on HP tuners. Im going to try and get a hold of that auto tap and use my buddies laptop. Thanks again.

thunderstruck507

iTrader: (18)

You need to check fuel pressure at WOT as well, it could be going lean under load.

Could also be a vacuum leak or something similar.

There is some kind of mechanical or electrical problem (or perhaps the station you are getting fuel from is selling 87 as 91? even then the PCM should compensate prior to pinging)

RockinWs6

I had bad pinging troubles twice with my Ls1, 1st time it was a dirty fuel filter. 2nd time it was carbon build up in the intake and heads from the pcv system.