Rough Idle/Hesitation when Accelerating

[Caveman_SS]

I’ve got a 2010 2SS 6-Speed manual. I just bought it a few days ago and it’s idling roughly, dies sometimes when idling, and cuts out (hesitates?) on moderate acceleration.

The first time that it stalled when it was idling, the check engine light was on when I cranked it back up. It cranked back up just fine (stilled idled roughly). The codes were P0171, P0174, and P0113. The next morning I cranked it up and the check engine light was off. I plugged in my scanner and now only P0171 was stored. I tried cleaning and then replacing the MAF sensor but that didn’t help.

My next guess was the fuel pump. I can hear it prime when I turn the ignition switch to the on position so I knew it was getting power. I rented a fuel pressure gauge and tested the pressure.

Idle: 60psi - still idling roughly, but the pressure was steady at 60psi
Key on/engine off: 28psi

I’ve been running 87 Unleaded in it for the few days that I’ve had it. I bought it used with 119,000 miles on it. I had a thought that maybe the previous owner had a 93 tune on it and I didn’t know it. I bought it from a dealership and they didn’t say anything about it being tuned. The car is pretty much stock. Just has some SLP Loudmouth 2’s on it.

I’m not sure what I want to try next. Maybe spark plugs? Maybe try 93?

Any help is appreciated.

[ZL1_Chris]

I would check injectors or possibly a intake leak otherwise it could be a number of problems. If the car was tuned for 93 and you are running 87 that would cause detonation but doubtful with your set up.

[SaReNi]

I thought all SS's were 93 required from the factory.

[ZL1_Chris]

Originally Posted by SaReNi

I thought all SS's were 93 required from the factory.

100% correct, because of the higher compression ratio premium fuel is recamended to combat detonation. While not recamended running lower octane fuel will only potentially allow for detonation or knock and the computer will pull timing effecting performance, unless knock is turned off in the tune. In conclusion running a lower octane fuel will not under no circumstances cause the engine to stall or idol erratically, unless there's moisture present.

it could be ......Bad injector, bad ground, collapsed lifter, cracked spark plug, bad plug wire, bad coil, vacuum leak, bad o2 sensor or one of many other potential causes.

It's not a fuel pump or octane issue

[xstuntman]

I would do a tune up on it for sure. Plugs, wires, oil change, air filter, etc. I wouldn't buy any of that off eBay either, local parts house so hopefully you get the real thing.

Pulling the plugs might give you a clue to what's going on and there's a good chance the plugs and wires are original and due a replacement anyhow.

[Caveman_SS]

Originally Posted by xstuntman

I would do a tune up on it for sure. Plugs, wires, oil change, air filter, etc. I wouldn't buy any of that off eBay either, local parts house so hopefully you get the real thing.

Pulling the plugs might give you a clue to what's going on and there's a good chance the plugs and wires are original and due a replacement anyhow.

I’ve got some wires ordered from Summit. I’ll get those and some new plugs in soon and see if that does the trick.

[102SS]

While your car will run on regular the computer is going to pull timing out and you will not get optimum performance or fuel economy.

I use Shell 91 with no ethanol added and she seems to run strong with no detonation.

I used to run 94 that contained 10% ethanol but Petro Canada is always has the highest price for fuel.

Its actually Sunoco but they bought all the Sunoco`s and jacked up the prices.

My fuel economy is actually better now plus I get 3 cents off a liter with my CAA card and air miles as well.

If its good enough for Ferrari its good enough for my Chevy and my Pontiac G8

[Caveman_SS]

Thank y’all for the recommendations.

Here’s where I’m at now. I changed the spark plugs (the wires are supposed to come in today or tomorrow), and now the gas tank has got half 87 and half 93 in it. I drove it like that for a few miles and it still didn’t really seem to change much. It didn’t lose power while accelerating like it had done before but that didn’t happen all the time. The idle was still pretty rough.

The next morning, before I cranked it up I thought I’d check the exhaust manifold bolts because I noticed a pretty loud exhaust leak when I cranked it up after changing the spark plugs. The rear 3 bolts on the driver side (bank 1) manifold were so loose that I could easily twist them around with my fingers. Bank 1 was the only side running lean according to the stored CEL code P0171. The other two codes (P0113 and P0174) were no longer coming up on the scanner. I never cleared the codes, they just went away. So I tightened them up good and now no more exhaust leak and it seems to be running smoother at idle.

I’ll still probably change the intake manifold gasket at some point just because. I also want to go through the ground connections on the car and clean them up and make sure they’re connecting properly.

[Caveman_SS]

Just to update anyone who looks at this later...

I think that it ended up being an exhaust leak.
The back 2 or 3 exhaust manifold bolts on the driver's side were so loose I could turn them by hand. I tightened these up and it hasn't acted up since.

I also discovered that I had a leaky fuel injector and replaced them with some stock LS7 injectors I got used for $100 and that fixed that issue. I knew I had a leaky injector because the oil smelled like fuel.

[1JEWLDSSRS]

Also since you did use 87 in the car, and it is designed to run on premium, either 91 or higher, and if it isn't tuned yet, you might want to do the "infamous" fuse pull, # 5 and 20 in the fuse box under the hood. Take them out for about an hour or so, then re install them. This will put the ECU fuel tables back into the upper fuel tables for the premium.

https://www.camaro5.com/forums/showthread.php?t=38964

[Caveman_SS]

Originally Posted by 1JEWLDSSRS

Also since you did use 87 in the car, and it is designed to run on premium, either 91 or higher, and if it isn't tuned yet, you might want to do the "infamous" fuse pull, # 5 and 20 in the fuse box under the hood. Take them out for about an hour or so, then re install them. This will put the ECU fuel tables back into the upper fuel tables for the premium.

https://www.camaro5.com/forums/showthread.php?t=38964

Thanks. I'll try that out. I've been running it on 93 since I started this thread and haven't had any issues out of it.

[1JEWLDSSRS]

Originally Posted by Caveman_SS

Thanks. I'll try that out. I've been running it on 93 since I started this thread and haven't had any issues out of it.

Cool. Most times it will NOT go back into the upper fuel maps by itself, that's where the fuse pull comes in to play. You actually "reset" the ECU mapping. So you may see some better performance after the pull.

[Caveman_SS]

Originally Posted by 1JEWLDSSRS

Cool. Most times it will NOT go back into the upper fuel maps by itself, that's where the fuse pull comes in to play. You actually "reset" the ECU mapping. So you may see some better performance after the pull.

Alright cool. I’ll try it tonight.

[1JEWLDSSRS]

Originally Posted by Caveman_SS

Alright cool. I’ll try it tonight.

Awesome, good luck!!