Rough Idle/Hesitation when Accelerating

[Caveman_SS]

I tried the fuse pull last Friday night. I let it sit overnight and most of the day Saturday while I was mowing, and I couldn't tell much difference if any that evening when I put them back in and drove around all night at a car meet with some friends. That's not to say that the fuse pull doesn't work. I guess my car was already happy with the fuel tables how they were.

Just thought I'd share the results.

[1JEWLDSSRS]

Cool. Thanks for getting back. Enjoy your ride!!

[Nenous1]

I'd check the throttle body and i'd check the carbon buildup on that engine, it's a GDI.
If that doesn't seem an issue, check the high pressure fuel pump, because the problem you described is similar to what happened to my car some time ago.

[hesster]

Sounds like you got it sorted out mostly.
Your injector's leak down was prob a key issue, as my recent leak down test showed a whole lot less over time, 12 lbs over a hour, and still at 38psi the next morning. All I can find on the web is if it drops "rapidly" after shut down, then they are leaking, and you would be contaminating the oil with gas. Not good for engine wear.
Running less than 93 octane on a LS3 is never good. And preferrable, use a Top Tier Gas. There are methods to drain the gas in these cars after all, as you can not siphon it from the fill neck.
With that many miles on the car, I imagine the Throttle Body is "Coked" up, read up on how to safely clean it.
If all is fixed, the car will relearn by itself and will clear most codes, including permanent codes, on it's own.


https://www.consumerreports.org/cars...e-a7682471234/

[102SS]

Shell now sells oxygenated 93 in Canada it started about two days after my previous post in this thread ironically.

The link you posted is about new fuel standards and does not relate to octane as all major suppliers now sell "Top Tier Fuels" in all grades.

Quoted from your link{

"Keeping things simple for consumers, when a participating retailer sells Top Tier fuel, all octane grades from regular to premium gasoline and diesel must adhere to the Top Tier standards. So it is not necessary for drivers to upgrade to premium to gain the cleansing benefits"

Car and Driver magazine did an octane test a few years ago and used a chassis dyno to verify results and it showed some surprising results.

here is the link:

https://www.caranddriver.com/feature...dodge-charger/

[Badbubba]

As others have said, 93 octane. You have 2 tables, a "high" and "low". If the engine has bad fuel or knock, from low octane, it will drop into the low table, retarded timing. And it may stay in the low table even after a few fills with 93. So as 1JEWLLD stated, the 5, 20 fuse pull to reset into the high table. If there is a 93 tune. A few tuners will copy the 93 tune into the low octane table. So the 5, 20 would do nothing. I prefer having a high and low table, just in case of bad fuel. If it were me, I'd just run 93 and if you do mods later, then get a tune. Not sure why the manifold bolts would be loose. Are there headers installed? Maybe there were and taken off, not too hard to install. I'm guessing the gasket was a multilayer, which is oem. I've reused mine when I installed headers. They are robust, can be reused and should hold up. If they're are aftermarket, fiber, you may, should, end up changing the to oem. If they are fiber or not multilayer, someone had there hands into something. If so, maybe they left a header and possibly intake tune installed.

[Caveman_SS]

Originally Posted by Nenous1

I'd check the throttle body and i'd check the carbon buildup on that engine, it's a GDI.
If that doesn't seem an issue, check the high pressure fuel pump, because the problem you described is similar to what happened to my car some time ago.

I actually cleaned the throttle body before I replaced the injectors. Forgot to mention that. The throttle body was actually very clean before I cleaned it. Is there another fuel pump besides the one in the fuel tank? I wasn't aware of that if there is. The only car I've messed with that has a "high-pressure fuel pump" on it is my wife's Hyundia Sonata 2.4L. Hers is right on top of the engine.

Originally Posted by hesster

Sounds like you got it sorted out mostly.
Your injector's leak down was prob a key issue, as my recent leak down test showed a whole lot less over time, 12 lbs over a hour, and still at 38psi the next morning. All I can find on the web is if it drops "rapidly" after shut down, then they are leaking, and you would be contaminating the oil with gas. Not good for engine wear.
Running less than 93 octane on a LS3 is never good. And preferrable, use a Top Tier Gas. There are methods to drain the gas in these cars after all, as you can not siphon it from the fill neck.
With that many miles on the car, I imagine the Throttle Body is "Coked" up, read up on how to safely clean it.
If all is fixed, the car will relearn by itself and will clear most codes, including permanent codes, on it's own.


https://www.consumerreports.org/cars...e-a7682471234/

Yeah, it seems to be running just fine now. I think most of it was solved by fixing that exhaust leak and the injector replacement finished it off. I plan on only running 93 in the car from here on out. Thanks for sending the link and your results from your leak down test. I'll read up on the top tier fuel stuff.

[Caveman_SS]

Originally Posted by 102SS

Shell now sells oxygenated 93 in Canada it started about two days after my previous post in this thread ironically.

The link you posted is about new fuel standards and does not relate to octane as all major suppliers now sell "Top Tier Fuels" in all grades.

Quoted from your link{

"Keeping things simple for consumers, when a participating retailer sells Top Tier fuel, all octane grades from regular to premium gasoline and diesel must adhere to the Top Tier standards. So it is not necessary for drivers to upgrade to premium to gain the cleansing benefits"

Car and Driver magazine did an octane test a few years ago and used a chassis dyno to verify results and it showed some surprising results.

here is the link:

https://www.caranddriver.com/feature...dodge-charger/

Thanks for sharing the link, I'll read up on that too.

Originally Posted by Badbubba

As others have said, 93 octane. You have 2 tables, a "high" and "low". If the engine has bad fuel or knock, from low octane, it will drop into the low table, retarded timing. And it may stay in the low table even after a few fills with 93. So as 1JEWLLD stated, the 5, 20 fuse pull to reset into the high table. If there is a 93 tune. A few tuners will copy the 93 tune into the low octane table. So the 5, 20 would do nothing. I prefer having a high and low table, just in case of bad fuel. If it were me, I'd just run 93 and if you do mods later, then get a tune. Not sure why the manifold bolts would be loose. Are there headers installed? Maybe there were and taken off, not too hard to install. I'm guessing the gasket was a multilayer, which is oem. I've reused mine when I installed headers. They are robust, can be reused and should hold up. If they're are aftermarket, fiber, you may, should, end up changing the to oem. If they are fiber or not multilayer, someone had there hands into something. If so, maybe they left a header and possibly intake tune installed.

Thanks for explaining the tables. That was helpful. I don't know what kind of intake manifold gaskets are on the car now, I didn't pay attention to that at the time. I plan on doing headers on it in the near future. When I do that, I'll make sure to use a multilayer gasket. I'll also get a tune when I install the headers. So, I guess I'll get a 93 tune at the same time.

[Badbubba]

No other fuel pump for the LS engines. The V6 LLT and LFX are direct injected and therefore prone to buildup on the intake valves. The Gen 6 Camaro's LT1 engine is DI.