Black04SSS Posted April 17, 2011 Report Share Posted April 17, 2011 (edited) Hello everyone. I'm a new member to the SilveradoSS.com forums, but not new to tinkering with LSx powered vehicles. I found the forum while doing some searching for a few things on my SS. A few weeks ago I traded in my 2000 Z71 for a Black 2004 SS AWD with leather. I'll post some pics soon, but it's filthy right now since winter has returned to MN again..lol. It is stock for the most part though. I did replace the gold Bowtie in the grill with a polished AL one, and it has ventshades and a rollup tonneau cover on it. The truck had a drop in K&N filter, ungodly loud dual exhaust with Thrush mufflers, and since it pinged like crazy on 87 octane, I suspect somebody messed with the tune. I had a K&N FIPK on my Z71 that I took off and made work in the SS. I had to tweak the metal heat shield to make it work, but the rest was the same. I guess the core support is different - possibly for a bigger radiator on the 2003+ trucks? Anyways, I am running 92 octane for now until I can mess with the tune. I don't care to spend the extra money on gas for a daily driver vehicle. The exhaust was just too much for me and a friend happened to have a freebie stock cat back from an SS so I had that put on. Unfortunately the muffler had a loose baffle and rattles like crazy, so I am back to needing to mess with the exhaust some more. I like the stock tailpipe look, and I want something just a little louder than stock, but not too loud. So after looking around on here, I just ordered a Magnaflow 12599 muffler to replace the damaged stock one with. I don't plan on anything too crazy with it (haha, that's what everyone always says in the beginning, right!). Like I mentioned, it's a DD for me. I've got a 99 Trans Am WS6-clone with cam and heads and lots of other stuff, my wife has a 98 Trans Am WS6 with bolt ons, and then we have an 87 Trans Am GTA that is a drag car project and we have done all our own work including the tuning on all of them. I included plugs and wires in the muffler order from Summit and then I will be doing brakes all around and flushing and changing all the fluids as well soon. So anywho... hello! Edited April 17, 2011 by Black04SSS (see edit history) Quote Link to comment Share on other sites More sharing options...
USS SS Posted April 17, 2011 Report Share Posted April 17, 2011 welcome Quote Link to comment Share on other sites More sharing options...
eeekroar Posted April 17, 2011 Report Share Posted April 17, 2011 Welcome! You should look into the Corsa Touring exhaust if you want something a little louder than stock without drone. My SS only drinks premium. I figure it's the least I could do for her. With gas prices steadily rising, my ladies jewelry may go missing. Quote Link to comment Share on other sites More sharing options...
Black04SSS Posted April 17, 2011 Author Report Share Posted April 17, 2011 Welcome! You should look into the Corsa Touring exhaust if you want something a little louder than stock without drone. My SS only drinks premium. I figure it's the least I could do for her. With gas prices steadily rising, my ladies jewelry may go missing. Yeah it isn't so bad running 92 octane for now until I can tune it, but when you do the math it adds up in a hurry if you drive the truck a lot. I just don't have the right cable and software for tuning this thing and will have to borrow from a friend that has it when he gets back into town. I listened to a bunch of clips online of different exhaust systems and I really didn't like how raspy the Corsa sounded. It sounds great for a performance car or truck, but I want something a little more mellow sounding - just a little louder and much better flowing than stock. The clips I watched of the Magnaflow stuff seemed right where I am wanting my truck to sound. It still has stock manifolds and cats on it, so if I want louder and more performance in the future, a set of LTs and high flow cats (or no cats) would give it more exhaust note as well. I have to admit that going from that obnoxious Thrush stuff to the stock cat back did make it too quiet for my taste though . Even on a DD. Quote Link to comment Share on other sites More sharing options...
weehousz Posted April 18, 2011 Report Share Posted April 18, 2011 Welcome Mine also drinks 93, doesn't like anything else unfortunately. Quote Link to comment Share on other sites More sharing options...
Black04SSS Posted April 18, 2011 Author Report Share Posted April 18, 2011 Welcome Mine also drinks 93, doesn't like anything else unfortunately. Thanks! This site has really been helpful for me. Got the muffler situation all sorted out quickly and now I am getting a set of center cap stickers to cover up my corroded stock ones! On the octane topic - if it actually has problems with 87 octane, I would suspect it either has a problem of some sort or somebody messed with the tune. GM did not tune these trucks to require 92+ octane fuel at the factory. Quote Link to comment Share on other sites More sharing options...
eeekroar Posted April 18, 2011 Report Share Posted April 18, 2011 I know the gas cap says Premium only, but you should defiantly be able to run 87 without pinging.I think it is suppose to give us a little better performance and mpg. I always heard premium doesn't make mpg any better unless the vehicle is designed for Premium. I have not calculated mpg with different octanes, because it has never had regular in my presence. I drive like a granny so I do fairly well. When the BMW was in the shop, my girl was driving the SS to work and would leave with full tank and show up on a quarter tank. I would tell her she didn't have to drive like she was being chased by a rapist. Quote Link to comment Share on other sites More sharing options...
Hankg42 Posted April 18, 2011 Report Share Posted April 18, 2011 Welcome to the site! Quote Link to comment Share on other sites More sharing options...
diggerdan11 Posted April 18, 2011 Report Share Posted April 18, 2011 Welcome to the Site Quote Link to comment Share on other sites More sharing options...
weehousz Posted April 19, 2011 Report Share Posted April 19, 2011 (edited) According to my mechanic who's is also an SSS guy, the truck should adjust for whatever type of gas you put in it. If it senses a ping it should compensate. However you will lose some performance, that's really the only downfall to less than 92+. If its not correcting for the lower octane then it's possible that it was tuned wrong if someone messed with it. Edited April 19, 2011 by josh03ss (see edit history) Quote Link to comment Share on other sites More sharing options...
Black04SSS Posted April 19, 2011 Author Report Share Posted April 19, 2011 (edited) Well pinging and how GM ECMs and PCMs deal with it are nothing new to me, so let me share a little of what I know on this... I have tuned my own LS1 Trans Am as well as my Wife's LS1 Trans AM and I cut my teeth on tuning the old 165 MAF and 730 Speed Density Tuned Port Injection systems in the late 80s/early 90s Camaros and Trans Ams (that required modifying the Memcal and soldering on a EEPROM and manually removing and installing the "chip" each time I changed the tune!!! How archaic!). Octane is a measure of a fuel's resistence to detonation. That is it. It means nothing about how good of mileage you will get or how much power you will make. The octane rating plus the appropriate tune for that octane level in a given engine is what decides how well the engine runs and how much power it makes. GM desires engines to run forever and not cost them anything for warranty costs first and foremost and to make adequate power and decent mileage second. This means low octane fuels with rich air fuel ratios and low overall timing advance are the way to go as it reduces stress on the engine. Reducing stress also means less power and mileage than you can get if you take the time to analyze and tune what your particular engine desires. This is why having a custom tune even on a stock vehicle can often yield impressive power and mileage gains - and is a MUST when you heavily modify the engine (ie. cam swap, forced induction, etc.). But it has to be done right or messing with the tune can/will damage the engine over the long run (or short run if you F it up badly enough). So anyways... Our trucks, like nearly all fuel injected vehicles, have a knock sensor. That sensor senses when "knock" (aka ping, detonation) occurs, which the PCM recieves and then, since retarding timing lowers the cylinder pressures and temperatures during combustion, adjusts the timing downward accordingly to attempt to avoid the knock situation. Knock is recorded in the PCM and visible via a scantool as Knock Counts. There are thresholds programmed into the calibration file loaded into the PCM for each vehicle and those calibrations will decide how much knock is allowed before it triggers a timing retard routine and some systems will up the fuel trim to try to richen the air fuel ratio as lean conditions can cause or aggravate knock conditions. So your mechanic is partially correct. The PCM attempts to remedy the situation, but it has its limits - and especially when somebody messes with the tune that doesn't know what they are doing or you get a POS off the shelf "tune". If there is a massively lean condition or far too much timing advance programmed into the calibration file loaded into the PCM, it will be unable to deal with the problem and audible ping occurs - this is most likely what my truck was doing and it is likely because somebody tuned it for higher octane fuel. The end solution is to get a look at the tune and compare air fuel tables and timing tables to a stock tune to see if it was messed with. The actual knock threshold parameters and knock retard value can also be manipulated in the tune so I will be looking at that as well. Knock often occurs without a driver even knowing it. While it can be fairly audible and obvious to a trained ear, sometimes it can be inaudible or missed, so the only way to know 100% that an engine is not pinging at all is to review the knock counts from the PCM (assuming the PCM and knock sensor system is fully functional of course). But my truck was very loud, and not just a little bit here and there. WOT above about 3k RPMs equaled lots of pinging. I do not believe the cap on mine says Premium Only, but I will double check in the morning. I really cannot see GM making Silverado SS owners run premium. They almost never design vehicles to run on 92+ octane (unlike lots of other makes). Thanks for all the welcomes! Edited April 19, 2011 by Black04SSS (see edit history) Quote Link to comment Share on other sites More sharing options...
jddmj Posted April 19, 2011 Report Share Posted April 19, 2011 welcome to the addiction! Quote Link to comment Share on other sites More sharing options...
Black04SSS Posted April 25, 2011 Author Report Share Posted April 25, 2011 Hmmm... Well I stand very corrected. The inside of the fuel door of my SS does say "Premium Unleaded Fuel Only". I really didn't see that coming from GM on a truck like this. Well then maybe the tune is still stock on mine. I will still probably play with the tune some eventually... Quote Link to comment Share on other sites More sharing options...
Black04SSS Posted May 3, 2011 Author Report Share Posted May 3, 2011 (edited) Finally got some pics. Pretty much your standard SS: I just washed it, thus the water dripping off and running down the driveway. Edited May 3, 2011 by Black04SSS (see edit history) Quote Link to comment Share on other sites More sharing options...
eeekroar Posted May 4, 2011 Report Share Posted May 4, 2011 Sweet! Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.