2002 V8 -- Vibrating, Shaking, Rough Idle Right After Getting Gas

[hpman247]

I was on my way home tonight, about 70 miles away and I stopped to get some gas. I only use 93. That tank has never seen anything less.

Anyways, I only put 5 gallons in, and I pulled out. About a mile up the road when I would barely touch the gas just enough to keep a constant speed or when going up a hill (but not enough for it to gear down) the car would vibrate/shake. When I got into the pedal it was fine -- only did this when I had to hardly touch it to keep a constant speed.

The CEL started blinking after 3-4 minutes of this. When I pulled into my driveway and put it in Park, there was an extremely rough idle. It was sluggish and seemed not to have a lot of power most of the way home after getting that gas. I'd had no problems with it the first half of that trip.

Do you think it's bad gas? I know many people will say it's the coils, which it could be, but it seems strange that this happens just after I get gas. BTW, it had 5-6 gallons in it, and I put 5 gallons in it. I don't know if that will help the diagnosis or not?

 

[regiment1]

I was on my way home tonight, about 70 miles away and I stopped to get some gas. I only use 93. That tank has never seen anything less.

Anyways, I only put 5 gallons in, and I pulled out. About a mile up the road when I would barely touch the gas just enough to keep a constant speed or when going up a hill (but not enough for it to gear down) the car would vibrate/shake. When I got into the pedal it was fine -- only did this when I had to hardly touch it to keep a constant speed.

The CEL started blinking after 3-4 minutes of this. When I pulled into my driveway and put it in Park, there was an extremely rough idle. It was sluggish and seemed not to have a lot of power most of the way home after getting that gas. I'd had no problems with it the first half of that trip.

Do you think it's bad gas? I know many people will say it's the coils, which it could be, but it seems strange that this happens just after I get gas. BTW, it had 5-6 gallons in it, and I put 5 gallons in it. I don't know if that will help the diagnosis or not?

I got fuel with water in it one time, and had some of the same symptoms you describe - Just no CEL and the idle was OK.

 

[LS4me]

I was on my way home tonight, about 70 miles away and I stopped to get some gas. I only use 93. That tank has never seen anything less.

Anyways, I only put 5 gallons in, and I pulled out. About a mile up the road when I would barely touch the gas just enough to keep a constant speed or when going up a hill (but not enough for it to gear down) the car would vibrate/shake. When I got into the pedal it was fine -- only did this when I had to hardly touch it to keep a constant speed.

The CEL started blinking after 3-4 minutes of this. When I pulled into my driveway and put it in Park, there was an extremely rough idle. It was sluggish and seemed not to have a lot of power most of the way home after getting that gas. I'd had no problems with it the first half of that trip.

Do you think it's bad gas? I know many people will say it's the coils, which it could be, but it seems strange that this happens just after I get gas. BTW, it had 5-6 gallons in it, and I put 5 gallons in it. I don't know if that will help the diagnosis or not?

Got gas once and had the same symptoms; rough idle and a little hesitation. It smoothed out on it's own and has never returned so I blamed the gas.

 

[Telco]

Change the fuel filter and cut it open. Sounds like you got some dirt as well as water in the tank. When the big truck fills the station tanks it will stir up any debris in the tank and cause it to be pumped out into your tank. The filters the pumps have on them don't always work either. You can try topping off with fresh fuel and hope the crap in there now dilutes enough to run through OK, but the best thing to do would be to drain the tank and clean it out rather than run that crap through. You can use the stuff you take out for your lawn mower, or with some patience you can store it for a couple of weeks to let the crap settle out, then carefully pour the gas out of the store tank back into the car.

BTW, it only takes one bad tank to completely plug the fuel filter so it'll need changing regardless of what you decide to do.

 

[hpman247]

Well, it turns out the problem was an ignition coil. The mechanic replaced it and I'll be picking it up tomorrow. This is only the 2nd coil replacement that I've had to do in 122,000 miles. I'm guessing more are about to come.. I'll ask the mechanic if he noticed any oil in the well when he took out the coil. If so, I know what I need to do next.

I need to learn how to fix this myself.

 

[joegr]

Well, it turns out the problem was an ignition coil. The mechanic replaced it and I'll be picking it up tomorrow. This is only the 2nd coil replacement that I've had to do in 122,000 miles. I'm guessing more are about to come.. I'll ask the mechanic if he noticed any oil in the well when he took out the coil. If so, I know what I need to do next.

I need to learn how to fix this myself.

I really hope he replaced the plug too. (Bad coil > kills plug, Killed plug > damages new coil, repeat)

You would be really wise to replace all the coils and plugs now. It is likely that some of your other coils are already marginal. This causes damage to your very expensive catalytic converters.

Coils and plugs are really easy to replace yourself on the 3.9.