Low idle rpm and stalls after idling for around 3 mins

[Santimoore78]

Forum

Hello everyone. New on here. Here’s the story.

I have a 2010 camaro 2SS, l99 automatic. 86,000 miles. Bought the car used with 50,000 miles. I decided to do some basic maintenance. Car was running fine, just figured it was time, plus I love learning about engines and doing the work myself. First thing i did was change the spark plugs and plug wires. The car had headers when I bought it. So the plug wires for cylinders 5 and 6 were touching the headers. I put sleeves on just those two. Next day got a really bad misfire from cylinder 6. The sleeve slid down and the wire melted. So I bought the Hinson 8.5 mm wires with sleeves and replaced that spark plug. Car was running fine again. Next day decided to clean the MAF sensor and throttle body ( used the correct cleaners.) didn’t remove the throttle body, had a friend hold the gas pedal to open the valve while I cleaned it. I was very careful but at one point I did slightly bump the valve. After cleaning I let the sensor and TB dry for 45 minutes. Put everything back together and fired it up. Did not run right. Felt like the engine was going to fall out. Turned it off and waited 2 mins. Second time I fired it up it was a little better but still rough. So I turned it off again. About 3 seconds after turning engine off I head what sounded like one of the pistons fire on its own. Waited a few more minutes and fired it up again.

Ever since that, my idle randomly jumps from 500rpm to 250 rpm then goes back up to 500. After about 3 minutes of idling or sitting at a light, engine stalls. Bought a new MAF sensor and that didn’t fix it. Tried looking for a vacuum leak with carb cleaner and could find anything. All sensors and hoses are plugged in. When the car stalls, I get a check engine light. P0171 and P0174. Lean on both banks. After driving the car for about 30 miles the light turns off. Car seems to run smooth on the freeway. But at slow speeds it sometimes feels like it’s going to stall.


Any ideas what I need to look for?

Also, i pulled the plugs to see if they were good and found a little bit of oil on the threads in cylinder 1. And checked the gap on all the spark plugs (.04 oem ac delco)

[hammdo]

Sounds like a vacuum leak or too much air. Make sure you have the boot from the CAI all around the throttle body and the clamp is tight... Check all around the throttle body to make sure you have the CAI boot fully and firmly in place...

-Don

[Santimoore78]

I also think it’s a vacuum leak. Air intake is stock though. No CAI.checked the clamps and they’re all tight. But it if was a vacuum leak, wouldn’t the idling have changed when I was spraying the carb cleaner around? I didn’t notice any change

[Santimoore78]

I forgot to mention that when I was cleaning the throttle body I noticed the gap under the valve looked bigger. It wasn’t too dirty to begin with. I put a slight amount of pressure with my finger to see if it would close freely without forcing it. Is it possible that even the smallest amount of pressure could have cause it to lose calibration?

[Dizzy82]

The throttle body plate should never completely close.

[Rons1le]

You also may have cleaned carbon off that the computer had adjusted for you may need to unhook your battery for a little while to allow the computer to reset.

Sent from my SM-G960U using Tapatalk

[LuSINda]

Since your initial problem was your spark plug wires that is where I would begin my diagnosis. With that plug wrap melting all the time it leaves plenty of metal for crossfire. Misfire at 5 and 6 is enough to cause all your symptoms.

[christianchevell]

Well for one making sure the MAF is tight and has a gasket on the CAI tube what ever brand you have for one would be nice to make sure it runs, pushing on the throttle bodies blade is stupid it has plastic gears in it and never closes BTW... and could have been damaged but mostly I would have to change out all the plugs and wires after you touched them.... For one the stock plugs are Iridium and do not ever get gapped they come the right size or you attempt to gap them and you break the wire... most seriously could have happened...……….

And sounds like you got a backfire from excess cleaning product which could have messed say with a sensor to the engine..... there's the MAP manifold absolute pressure sitting right up top in the front area of the intake, but probably could have not really hurt a sensor...I am more inclined to think you messed up the throttle body pushing its blade and your running lean so you are not really measuring the right amount of gas to air so you have to go from there.

You bought a MAF you most likely did not need, and throwing money around you may want to get a CNC vmax ported throttle body just for kicks, but frankly you attempting to check the gap of the plugs is a red flag to me and the nice internal backfire which in old chevy days was usually a fart out the carb which usually hurt nothing but then again you have messed with the plugs and the throttle body...….and you think your gap is .04 frankly its what the plug comes with.... don't ever touch the wires again if smart ….
https://www.ngk.com/learning-center/...g-instructions

Frankly I use the ngk trx 6 ix as I am built and its a little different heat range and its gapped from the factory at .039, you should have a good as in elite engineering catch can to help reduce crap in the pcv system as its like the number one mod done by people.

Frankly you sprayed crap into your intake, you most likely loosened carbon oil sludge and that's not good, me I carefully do that if ever and if it had heavy contaminants I would use a engine cleaning service, And yes I occasionally use some Lucas fuel system cleaner to clean the injectors but avoid cleaning the throttle body or its blade as it should not get much filth on it with regular cleaning of my CAI filter, and most used sea foam instead of a service to clean their engine.... You may want to try seafoam and change out the wires and plugs checked and make sure the tubes tight and the Maf is tight.

But Ultimately My best guesstimate is your monkeying around with the throttle body screwed up the https://www.yourmechanic.com/estimat...or-replacement Throttle position sensor and here's a article on that so good luck to you, actually the guy who said you should unplug and replug after a while the battery may be the best and quickest fix if it can reset the brain fart the TPS is having...IMO SO good luck to you best guess is tps, after that the plugs you checked the gap on and wires.... but the symptoms match a problem with the tps which is not easy peeesy …...

[Santimoore78]

Replaced all plugs again and put on new OEM throttle body. Unplugged battery. Runs the same.

Found another issue. I noticed the EVAP purge line that is next to the fuel line on the passenger side is pinched. It came off the clip near the purge valve. I’ve been hearing a hissing sound right behind the throttle body. Sprayed carb clean and nothing happened. I pinched the line with my fingers to see if i could feel it cracked inside the heat cover and noticed a lot of carbon build up on exhaust tips the day after.

What problems could the purge line cause? I know it’s not the line that goes from the intake manifold to the purge valve because I replaced that line.

[ChibiBlackSheep]

You bought a used car with headers, and having air issues. I would get this thing hooked up to a machine that does diagnostic data and see what you are reading.

The car might need a tune. It could have been tuned with more mods that were removed before selling the car, and now the tune is completely off.

Drove the car for 30k miles, not knowing how it was running. It could have been running super rich the whole time, fouled out oxygen sensors, catalytic could be going. I would get some scanning data before you keep throwing money at parts.

[LsxDoctor]

NOOOOO!!!! I made the mistake of messing with my throttle body blade too! I looked up how to reset the TBPS but could not figure it out. Eventually I disconnected the battery for a night then just drove normal for a few days and it seems to have cleared up. I'm pretty sure that's the issue you're having.

[Acoons95]

Ok, I have a 2010 Chevy camaro v6. I just got the passenger cat replaced. All spark plugs and oil and oil filter. There is a misfire in cylinder 5. 2 Evap codes. I still have my 420 and 430 cat codes. And a po69e fuel module code. I swap plugs and coils and the code did not follow.i can relay all live data as well. The car has the constant misfire and once it reaches temp it starts to stall out. I'm at a lost.

[TheFlyingBananaSS]

Originally Posted by Santimoore78

I forgot to mention that when I was cleaning the throttle body I noticed the gap under the valve looked bigger. It wasn’t too dirty to begin with. I put a slight amount of pressure with my finger to see if it would close freely without forcing it. Is it possible that even the smallest amount of pressure could have cause it to lose calibration?

THIS.