P0304 And P0308 Codes - '03 Gt

[IIGood]

My 2003 GT was sitting for about 10 days while I was out of town and today I fired it up for the first time since then. I noticed upon taking off that the car was bucking a bit as I accelerated and shifted, so I just initially thought it was me being "out of practice" with the clutch (LOL). But as I got out of the neighborhood and down the road, the stumbling persisted while just accelerating.

I get out to the highway and try to open it up, but it just fell flat. No power and the stumbling got a bit worse as I accelerated from 60 to 70 mph. Then the SES light started blinking, about 10 times. Then it went away. I got to where I was going, went in the store, and came back out. The problem persisted and then the SES light came on and stayed on. So now I'm thinking the fuel went bad (it's been in the tank for about 2 weeks and I only used a little less than 1/4 tank before parking it) and stopped by Advance Auto to pick up some fuel treatment to dump in the tank to see if that helps. They were out of Seafoam so I grabbed some Gumout, and while I was at it, borrowed their scanner to see what code the car was throwing.

I dumped the Gumout in the tank and plugged up the scanner for it to find a P0304 and P0308. Misfiring #4 and #8 cylinders. Great. I returned the scanner and got back in the car and headed home. As I was on the highway again, the SES light flashed 3 times then stayed solid after that. It's still hesitating on acceleration, particularly up to 20 mph, then from 60-70. In between it seems to be running smoothly.

Should I run this tank of gas out before trying to take it somewhere and see if a fresh tank "fixes" it, or should I just get a shop to look at it now? It was apparently in the 30s and 40s here while I was out of town and the car sat so I'm hoping it is just the fuel.

 

[IIGood]

Well, this morning I decided to drive it to work to help get some more fuel out of it. Pretty much followed the same route as yesterday but today the car ran fine. No hesitation, it's power was back...but the SES light is still on.

 

[wmburns]

The flashing DTC light indicates that a misfire is actively occurring.

If this were my car, I would first look for moisture in the spark plug holes.

 

[restomod66]

10 days isn't long enough to create an issue with the Gas in the tank. My car often times sits for periods of time this long & I've never had a problem. I'm going +1 on moisture in the spark plug holes which wreaks havoc on these cars. When my plastic Intake Manifold finally popped it sprayed coolant down into some of mine & the car would hardly run so we had to replace a few of my coil packs. Moisture is the enemy.

 

[IIGood]

Well, today I took it out for the first time in a couple days...the weather's been less than optimal around here so I've had it parked for a few days. When I started it up, the SES light was gone. I drove it a good 50 miles round trip and never saw the light. Hoping it stays that way now, fingers crossed.

Although it is going to be sitting for a few more days potentially. They're forecasting more bad weather so if that's the case, I'm gonna let it sit until that subsides. Thank goodness I picked up a 4WD before winter came on.