My wife took my 2003 Trailblazer out and it ran out of gas. I take full blame for not telling her it was low. I rescued her quickly (and my wife, too), but now it is missing terribly. It shakes badly at idle and seems to labor on acceleration. The CEL is blinking (alternating to solid when I hit 'cruising speed'). I am hoping you all can give me a checklist of things to check from easy/cheap to 'take it in'. There seems to be a strong odor of fuel in the cabin, but that could very well be from the lingering effects of gas can I had sitting in there during the aftermath. It hasn't stalled or refused to start; only rough-idles and labors. I also notice the fuel econ is plummeting from 16.1 pre-flameout down to 14.5 and falling fast.

Thanks for any tips to diagnose.

2003 Trailblazer LT EXT 4WD 4.2L

 

Could have damaged the fuel pump, or could be a coincidence, or maybe you got some bad gas. Good thing the CEL is blinking. Take the truck to Autozone and they will scan it for free and tell you what the error code is so you don't have to go taking stabs in the dark.

 

The code came back P0302 - misfire on cylinder 2. The tech suggested it's possible gunk got in the injector and suggested I first try a fuel additive and if they doesn't work, I may need to take it in.

 

BTW, does that indication rule out fuel-pump? Wouldn't all cylinders be affected if the fuel pump fried?

 

Right, a bad fuel pump wouldn't give you a cylinder specific code. I don't know what "gunk" would have gotten into the injector, other than a slow build up of varnish over the years. If it's a mechanical issue with the injector, that can show as an error. But a fuel flow issue isn't going to give a cylinder specific misfire, as that is monitored by the 02 sensors, left bank of cylinders for one and right bank of cylinders for the other.

 

yea, check and make sure the wire isnt off #2 cylinder, pull the plug to see if it is ruined. multiport so you have used NOID lights to see if the injector is firing. If your mileage dropped from 16.5 to 14.5mpg, I think your plug isnt firing which is why you have the fuel smell in the car; the raw fuel is ejected into the cat.converter and out the tailpipe never being burned.

 

I will pull the plug and see if ruined. I should've done that just now because I was just in there. What I did is I swapped the ignition coils of 2 & 3 to see if the problem moved. I took it back to Autozone to read the code hoping it returned a 0303, it returned the non-specific misfire 0300. Could this be because the problem DID move and since it now had both 2 & 3 in memory, it returned 00?

 

FYI: I took the truck to Auto-Zone this morning and had them check it again. This time it returned a 0303. So the problem did follow the ignition switch. I installed a new one and no more missing. Thanks to all that helped. $73 repair when all said and done.

 

you replaced the ignition coil not switch.

 

same thing just happened to my 2003 gmc envoy now i put gas back in it its misfire bad shakes as puch gas petle my dad is a mecianic and told me to check fule pump and fule filter and make sure its not clogged up from running it out of gas if u figure it out let me know please