13 MPG?? Huh??

[SHOketer422]

Heyy...
recently got done doing my own heater core install, which took about a month, during the coldest month of winter, and the car was out of commission the whole time, so i hadn't been driving it for a while...runs ok for a bit, but now, for some reason, the car runs rough, and i get 13 mpg...why?

ran codes, got: knock sensor not sensed during test
did cyl balance test: cyl number 5 is weak

pull the intake, fuel rail, etc, to replace the sensor, cause i did the test quite a few times, with the same result every time...pull the plugs, and theyre all black and carbon fouled from idling during the tests and whatnot, except for one plug, which is basically perfect...cyl number 5...i pull the injectors, and get them cleaned...reallly cheap too, www.cruzinperformance.com the guy is great...haven't put the car back togehter yet, but the injector guy, rich sent me the bench and flow tests, and all the injectors were good, before and after the cleaning...my plugs are good, wires all have the same amount of resistance, new too, did a 60k end of last year...what could be the problem? is my injector not gettin its pulse to open up? how could i figure that out without having the intake off, or what??? ive been told its not the coil, because only one cylinder is bad, not two, which would happen, so what could it be...

 

[Mr Anonymous]

It could be something as simple as a thermostat that is stuck open, or one or both O2 sensors not working properly. You mention running the KOER codes, but don't mention the KOEO codes. Were there any? Also, which plugs and wires are you using?

 

[billyshoe]

239k may have everything to do with it.

 

[SHOketer422]

hmm...

well, only code i got KOEO and KOER was the knock sensor, i had one about the ECT sensor but i cleared that out, it was an old one...im using the autolite double platinums, and the wires are ummmm, i dont remember, BUT i checked the resistance through them all and they are all pretty much identical, the cyl that is bad actually has a little less resistance through it, but very little....once i get my cleaned injectors back in, ill run it for a lil and then check the compression, didn't have a testor but i bought one...if the compression is bad, there i go, im SOL, if not, its gotta be the injectors not getting pulse, cause the plugs and wires are relatively new, i have maybe 3K miles on them...and we kno its not the coil, so whhat else is there? OH, replaced the thermostat some time ago, maybe a couple of years, the last owner did it, i can check that i suppose, is there a code for that? also, the O2 sensors have codes too, i thought they did at least....thanks...

 

[billyshoe]

The sp wires can always be suspect of arcing a carbon track & grounding out the spark. New or old.

 

[SHOketer422]

how new are wires? last august i bought them i believe...theyre kinda ***** :-( but ive got an old set lyin around, i might try and use one of them, that i kno is good, ill check beforehand on another cyl and then run the test, annd then yea we'll see...