CarTalk.com Blogs Car Info Our Show Deals Mechanics Files Vehicle Donation

2006 Pontiac torrent Rough Start & Popping Noise

Hi all,

I have a 2006 Pontiac torrent that has been occasionally having a very rough start. It sounds like an explosion in the engine and then after starting I typically hear a couple popping noises. Due to this I had changed out the spark plugs and wires, as I thought it might be a spark plug not firing as they were fairly rusted and looked original to the car that had 130,000 km on it. After changing over it seemed to be fine for a bit and running a lot smoother, but now I am having the same rough start and popping noises every now and then( I should mention that I have also cleaned out the MAF recently as well and replaced the air filter).It hasn’t activated a check engine light, so I am not sure if it’s just a fuel injection issue or not. If you guys have any ideas on it, I would be really grateful!

Cheers!

It sounds like the timing is off. Is the check engine light on?

No.

Tester

No check engine light. I believe the last one was for the EGR and I had replaced it.

Should also mention that I was having flooding issues prior to changing the plugs. Had to typically give it some gas to start periodically, but the issue has gone away since changing the plugs and wires

Remove the oil dip stick and sniff if the oil is contaminated with gas.

Tester

I tried that as well. The oil seems fine. No real smell of gas. That’s why I’m pretty stumped on this one.

I only run synthetic, so it’s usually that sweet oil smell. Also just changed it about 1k km ago though

06 torrent has 3400 v6. They have plastic ribbed intake plenum gaskets that fail due to heat cycles. Maybe you have changed them? A failure can cause vacuum leaks and burning coolant which could cause a rough idle. Next is bad headgaskets which fail in a slow gradual decline in motor performance.

It could be the head gasket actually. The last mechanic I took it to about 15k ago said it had a really slow leak. Haven’t noticed a huge reduction in oil at changes though. Coolant level has also been consistent for the last year, so that isn’t a concern to me. I haven’t smelled the burning coolant smell either, so I don’t think that’s the issue.

So just an update. Took it into a mechanic and they still weren’t able to diagnose the issue. They tested the fuel pressure, spark, cleaned the MAF. They did a Terraclean fuel service to Decarbonize the system, so hoping that solves the issue.

Hmm, describe “give it some gas”? You don’t have a carb. Pumping the gas pedal with the ignition off does nothing. Computer does not know you are pumping pedal. You crank motor, it starts. Holding the pedal at 1/2 depressed supposedly richens the mixture. Holding pedal to floor is supposed to lessen gas flow and remedy flooded conditions. If you have leaky injectors, you may have a rich condition at a warm start. Does it start the same when it sits overnight vs restarting after you go to store and motor is warm?

What I mean by give it some gas is that it struggles to start so I have to push the pedal while turning it over in order for it to start.

I have noticed that it typically happens on colder mornings and usually only if the car has been sitting for a bit. If I was to start after it just ran, I typically have no issues.

Colder mornings with dew? I would be looking at plug wires and distributor cap, distributor gasket and rotor if applicable.

It has single coil pack. Like gm has used for 20+ yrs. no distributor. The rear bank plugs are a major pita to change. But OP says they were just done with new wires. Maybe wires were misrouted? I would manually clean the throttle bore. An induction cleaning service is not effective at that. The throttle is drive by wire so care should be taken to prevent the stepper motor from getting out of whack. Crud in the bore can affect starting performance.

I looked at parts available, listed was rotor distributor cap and wires, guess that happens on the internet.