Ok so a few weeks ago I filled up my 99 v6 from empty to full with 87gas. and about 10-15 minutes down the road my check engine light started flashing. The oil pressure was fine, temp was fine and couldn't tell their was a problem. So when i slowed down and pulled over I noticed my car was rocking. and when gas was applied it would putter and move slowly. So i thought bad gas. worked the tank down and filled up with 97. but the problem still stayed and the engine service light started blinking right after that fill up and now continues to blink when ever the car is running. I have tested the coil pack and its not an individual cylinder. A friend of mine had a similar problem so he pulled my battery for 30 mins and reset the computer. but the problem still persists.

 

When you got the second tank of gas, did you go to a different station? Should have. If the gas station is dishonest and putting crap in the gas to stretch the supply, they're likely doing it to all the grades. Way too coincidental that your problems started shortly after a fill up.

 

have the car scanned for trouble codes at your local parts store. let us know what the codes are. could be as simple as a bad gas cap.

 

Damn, beat me to it. I agree with Craby; get the car scanned for codes and post them back here. Could be a bad gas cap, could be the evap system, could even be something with the engine, just needed the fill-up to kick in. Who knows?

 

I'm getting it scanned tonight. And no the gas was actualy from 2 different states.

 

P0171
p0174
p0303
p0420
p0303
p0420

now the place i went to said that bank 1 and 2 were too lean. which was codes 171 and 174
they said 303 was cylinder3 misfire detected
and 420 was cattalyst system efficiency below threshold bank one.

now they said they erased the codes and told me to drive around the block uppon return codes p0303, p0420, p0303, came up in that order.

 

This is the engine If that helps at all.

 

track the missfire first. check the plug and plug wire on cylinder 3, might try moving the coil around to see if missfire follows to see if coil is failing. check/change fuel filter and check fuel pressure. look for water in fuel filter. water in fuel can cause injector failure and that may be the issue.

has the exhaust been quite lately? making a hissing noise maybe. cat could be plugged but code could be caused by lean condition or missfire.

 

I pulled the number three plug cap off then re applied it securely the wires are not burnt. but the number nothing changes. um the exhaust was always very quite when i bought it. but now it sounds like its puffing. like a blowing noise. no like snake hissing noises. Idk how to check fuel pressure and i can look at fuel filter.

 

how old are plug wires? pull that number 3 plug and make sure its ok. could be burnt or just wore out. and yah like a woosh sorta noise. you may have a plugged cat. been smelling a hot smell after driving it for a while and stopping and getting out.