[302SS]

Started happening about a month ago on cold starts I'd get a kind of choppy/rough idle, then it would clear up and run strong & normal. That month ago I got a few conditions where I was going 60+ mph and my car just wouldn't rev any higher and acted like it was fuel cutting, then it went away.

I thought it was bad fuel or spark plugs/wires. I replaced plugs/wires with NGK & MSD respectfully. I thought I had it sorted, until this Sunday the problem came back: and this time it flashed "SERVICE STABILITRAK" then revved high, and went back to normal 5 seconds later. No CEL. I tried to log the issue with HPTuners, but never got it to replicate it happens at complete random times - mostly on cold starts.

My battery is the original from 2017 - so I just ordered a new one thinking that maybe the battery isn't sending correct voltages to the coil packs. I have 0 CEL or anything to work off from the hptuners logs, as I sent logs to my tuner and there's nothing that pops out.

Any suggestions would be awesome.

68K Mile 6th gen camaro. It's heads/cam/intake build that's been running great cammed for the last 8,000 miles.

[p47dman]

If you have an A10 tranny, is the shift module at fault? Just read a post about a recall.

[Patriot Motorsports USA]

Most likely the battery... replace that and see if you still get the issues. I had the same thing happen to me.

[bishopts]

Sounds like a headgasket

[bishopts]

Ah I'm just kidding lol. What's your fuel trims looking like?

[302SS]

I have an A8, just replaced the battery it was the factory one from 2017. Still monitoring it’s been running ok, I think I heard a brief cutout today but not 100% nothing as bad as before. Fuel trims look ok I sent it to my tuner and he said it looks good. It’s coming and going and it’s only for a few seconds and clears up. So I’m completely lost.

Edit: it’s back after two days with a new battery… worse this time.

[302SS]

Originally Posted by bishopts

Sounds like a headgasket

I check the oil almost everytime I start it, it’s not milky at all ��

Currently threw a P0172 system too rich. It’s saying multiple injectors are having low voltage / shorted. Then you clear it and it said the coil packs are malfunctioning… running extremely rich.

[302SS]

Still happening and can't figure it out. Found an intake leak & replaced the throttle body - still having the same issue. It will idle rough on cold starts randomly and sound horrible. Then go away. Will also randomly smell fuel on cold starts / hot starts. I'm inbetween injectors & cats at this point does anyone have any suggestions? Only code I get is a "too rich" code.

[RIPws6]

I agree with the battery being the most likely culprit.
A weak or failing battery can cause inconsistent voltage to critical systems like the ignition coils, fuel injectors, and electronic throttle control, leading to rough idle, rev limitations, and Stabilitrak errors. The Stabilitrak system relies heavily on stable voltage and sensor inputs.

[Patriot Motorsports USA]

Originally Posted by 302SS

Still happening and can't figure it out. Found an intake leak & replaced the throttle body - still having the same issue. It will idle rough on cold starts randomly and sound horrible. Then go away. Will also randomly smell fuel on cold starts / hot starts. I'm inbetween injectors & cats at this point does anyone have any suggestions? Only code I get is a "too rich" code.

Remove the aftermarket coilpacks and install the OEM coilpacks for better performance.

The myth on buying "High Performance" coils is their claim of higher outputs of energy such as 45kVolts versus the OEM spec of 33kVolts is an advantage. The myth bust on this claim is to obtain such a gain, you are giving up dwell time which is the amount of spark energy being delivered over a TIME rated in milliseconds through a period of piston travel. When you add a coilpack that one, has a higher rated PEAK voltage output, it takes that coilpack longer due to the windings being increased, the impedance going up which affects how the engine's ECU is communicating to to coil to remain open or closed.

It is this direct failure of the ECU to communicate with your ignition system that can cause the issue you are having. It doesn't help that the OEM designed LT4 cooling system is being taxed with cooling the oil and it is being dumped on the driver's side of the block, while the passenger side is getting 100º cooler fluid to add into the overfueling of the driver's side.

So, with the poor fueling and the ECU's lack of controlling it due to a change many factors, starting with the old battery kicking it off, you have a Domino-Effect causing all sorts of issues. The possible reason it works but then it comes in could be the charging or voltage regulator by not using an OEM Spec AGM battery. These cars are known to have faulty Alternators as a culprit caused by overcharging bad batteries... so when it is hitting intermittently, it can be due to the voltage regulator. My FIRST action would be to check all grounds from the battery to the chassis, both front and rear of the car and from the block to the engine.

Hope all this helps, give me a ring or PM if you have any questions!

[KingLT1]

Originally Posted by 302SS

I check the oil almost everytime I start it, it’s not milky at all ��

Currently threw a P0172 system too rich. It’s saying multiple injectors are having low voltage / shorted. Then you clear it and it said the coil packs are malfunctioning… running extremely rich.

Areas to look at for a "System too rich" condition would be the MAF, Injectors, and HPFP.

[302SS]

Originally Posted by RIPws6

I agree with the battery being the most likely culprit.
A weak or failing battery can cause inconsistent voltage to critical systems like the ignition coils, fuel injectors, and electronic throttle control, leading to rough idle, rev limitations, and Stabilitrak errors. The Stabilitrak system relies heavily on stable voltage and sensor inputs.

I replaced the battery, still having the same issue.

Originally Posted by ZLElvira

Remove the aftermarket coilpacks and install the OEM coilpacks for better performance.

The myth on buying "High Performance" coils is their claim of higher outputs of energy such as 45kVolts versus the OEM spec of 33kVolts is an advantage. The myth bust on this claim is to obtain such a gain, you are giving up dwell time which is the amount of spark energy being delivered over a TIME rated in milliseconds through a period of piston travel. When you add a coilpack that one, has a higher rated PEAK voltage output, it takes that coilpack longer due to the windings being increased, the impedance going up which affects how the engine's ECU is communicating to to coil to remain open or closed.

It is this direct failure of the ECU to communicate with your ignition system that can cause the issue you are having. It doesn't help that the OEM designed LT4 cooling system is being taxed with cooling the oil and it is being dumped on the driver's side of the block, while the passenger side is getting 100º cooler fluid to add into the overfueling of the driver's side.

So, with the poor fueling and the ECU's lack of controlling it due to a change many factors, starting with the old battery kicking it off, you have a Domino-Effect causing all sorts of issues. The possible reason it works but then it comes in could be the charging or voltage regulator by not using an OEM Spec AGM battery. These cars are known to have faulty Alternators as a culprit caused by overcharging bad batteries... so when it is hitting intermittently, it can be due to the voltage regulator. My FIRST action would be to check all grounds from the battery to the chassis, both front and rear of the car and from the block to the engine.

Hope all this helps, give me a ring or PM if you have any questions!

Hey, where should I start with the grounds? I have stock coilpacks on the car. I put on MSD Sparkplug wires, not coil packs. I did replace the battery as well. This is the only symptom I'm getting, the random misfire/fuel cut, I did get a weird "service stabilitrak" code and a too rich code a month ago+. But I haven't gotten that in awhile. Nothing else has happened electrically that would be considered weird I think.

[302SS]

Originally Posted by KingLT1

Areas to look at for a "System too rich" condition would be the MAF, Injectors, and HPFP.

How could I test the injectors / HPFP? I've been thinking injectors since the start of this, but have been trying the easy things first (battery- knew it was old. Sparkplugs - were fouled. Sparkplug wires- old. Then I found a loose MSD intake, and thought maybe that was it, and it wasn't...)

[mstgeer]

Originally Posted by 302SS

How could I test the injectors / HPFP? I've been thinking injectors since the start of this, but have been trying the easy things first (battery- knew it was old. Sparkplugs - were fouled. Sparkplug wires- old. Then I found a loose MSD intake, and thought maybe that was it, and it wasn't...)

Have you resolved this issue? My stock, except Holley CAI and oil catch can, '17 2ss with 15k miles is doing the same thing, random misfires (not all the time, but seems to be progressively more frequent), not enough to trip codes or trigger the check engine light. Runs rich on cold startup (black smoke out exhaust). Checked fuel trims and getting negative values.

Does checking the resistance of coils generally result in accurately identifying a bad coil?