2003 Blazer xtreme (4.3 - 6 cylinder). I bought this about 4 months ago. Been slowly going through it and fixing problems that the previous owner just let go. It did have a check engine light but that was related to the previous owner removed the cat converter. Replaced that and a O2 sensor and been check engine light free for months.

I noticed that the engine isn't running smooth. Shakes even a little. At idle after warmed up you can really notice it. Also noticed the fuel mileage sucks. I go about 100 miles in 4 days and go through almost between half a tank and 3/4s. So I am down to about a quarter tank for 100-120 miles.

I am going to replace plugs and wires, cap etc... but what else could it possibly be? Before I dump money throwing parts at it. No codes being thrown....

ALSO - is the evaporator drain just a tiny hole about the size of a quarter inch at the bottom? No hose? I am leaking on my passenger floor and that is the only hole I can see... and doesn't seem to be obstructed.

Thanks!

 

1st off please don't use any electrical components like the dist, plugs, rotor etc that aren't AC Delco or Delphi. These vehicles are uber picky about that for some reason.
Has the MAF been cleaned lately? Vacuum lines are all in good condition, not cracked etc & hooked up? Air intake temp sensor is hooked up in the intake tube off the air filter? Air filter is clean? Have you ran any sort of injector cleaner through it or that Chevron fuel system cleaner our admin Kyle likes to use & recommends?
Nice extreme & welcome to forum btw!

 

+1 on all Rotti said and add a clean-up on the egr with an updated gasket with a screen.
That should keep you busy for a bit. Somebody just started a string on smelly AC and there was some stuff on cleaning the drain. Not too far back.

 

A 2003 shouldn't have an EGR. They were weeded out midway 2002.
As for the A/C I remember that post now smitty. Captain Hook told the OP how to clean it.
Check out https://blazerforum.com/forum/2nd-ge...entures-72723/ &

https://blazerforum.com/forum/2nd-ge...se-help-73252/ <--- that's the one.

 

That is a shame. I love the looks I get at a stop sign when I jump out and whack that thing with an extension and hammer for no particular reason.

 

LMAO!!!
Like when I kick my tires to "reset" the counter balance beads.

 

Chevy TSB #02-06-04-059

The plastic timing cover on the 4.3's are WARPING, throwing the crank sensor off. If your tach is going crazy then your crank is actually hitting the sensor.

12565102 is the GM part number for the 2 shims. One is .5 mm and the other 1mm. Some are requiring both spacers.

GM should mail everybody about this...this may be your problem too.

 

Well I took it in to my mech as I don't have the time lately.

He pulled a couple spark plugs and said they looked great. Wires and cap/rotor are all good too. He ran it with his computer hooked up and said everything looks normal. Says he can't find anything out of the sort, and that maybe it's just the 4.3 is kinda a fuel hog and with all the ethanol in the gas that's not helping either. So he ran a 3 stage injector cleaner. He only charged me for that - good guy.

He did note that my evap drain is fine. I have a leak inbetween the housing and the firewall, and that's where I am getting rundown. Guess I need to pull the dash to fix this?

 

Well your gas mileage isnt right for sure.. I would clean you MAF like rotti said, it doesnt take long at all, and the other thing i would look into checking is the fuel pressure because if you have a leak in the spider injectors that will cause rough idle and bad mileage as well. Pressure should be 60+ with key at run and the engine OFF and it should stay at or above 55 for 10 minutes.

 

^^^, +1 on the MAF and checking fuel pressure and leakdown.