So, this has been driving me crazy for some time now. (Don't mind the pun). I've spent days trying to get the bottom of it but I'm reaching the end of my knowledge about the specifics of the engine management system. The problem is I get regular highway mileage but terrible town mileage. I know everyone says these things get bad town mileage but I've had it for six years so I know what I used to get. I'm in the 15 mpg (16L/100km) range on the highway but getting 7 or 8 mpg around town. Also, I can smell all the fuel coming out the exhaust when it's idling. It seems to me it's in limp mode and the computer isn't running the fuel the way it should. I have replaced in the last year the thermostat and the O2 sensors. I have tested the coolant temp sensor, vaf (repeatedly), tps (set up and tested repeatedly) and the rpm sender in the distributor. On to the ecm. I've been following the testing procedure in the fsm.
Here are some numbers...
The first four test (batt, mrel, igsw,+b to e1) check out.
Then things get sideways.
IDL to e2 throtle open is only 0.2 to 0.6v. It should be 9 to 14
vcc to e2 is in spec
VTA to e2 throttle closed is in spec
vta to e2 throttle fully open is less than 1v. It should be 3.2 to 4.9
vs to e2 plate fully closed is 2.25v. It should be 3.5 to 4.5
vs to e2 plate fully open is within spec.
Now when I try and measure vs to e2 while the truck is idling it either stalls or coughs and sputters like crazy because the air fuel ratio becomes super rich. (Much more that it is already.)
I haven't done the full second page of voltage tests yet but the ones I have check out. So far the issue seems to relate to the information the tps and vfa are providing the computer. The emc ground is solid, the vs wire is solid and so is the idl wire.
Should I run every voltage test possible along with the resistances before these numbers will be of any help to someone with knowledge about testing the computer? Also, I should add that I have a parts truck. I have tried another ecm, vaf, tps, all yielding the same results.
Some fresh ideas or info on the subject would be appreciated.
Thanks
Here are some numbers...
The first four test (batt, mrel, igsw,+b to e1) check out.
Then things get sideways.
IDL to e2 throtle open is only 0.2 to 0.6v. It should be 9 to 14
vcc to e2 is in spec
VTA to e2 throttle closed is in spec
vta to e2 throttle fully open is less than 1v. It should be 3.2 to 4.9
vs to e2 plate fully closed is 2.25v. It should be 3.5 to 4.5
vs to e2 plate fully open is within spec.
Now when I try and measure vs to e2 while the truck is idling it either stalls or coughs and sputters like crazy because the air fuel ratio becomes super rich. (Much more that it is already.)
I haven't done the full second page of voltage tests yet but the ones I have check out. So far the issue seems to relate to the information the tps and vfa are providing the computer. The emc ground is solid, the vs wire is solid and so is the idl wire.
Should I run every voltage test possible along with the resistances before these numbers will be of any help to someone with knowledge about testing the computer? Also, I should add that I have a parts truck. I have tried another ecm, vaf, tps, all yielding the same results.
Some fresh ideas or info on the subject would be appreciated.
Thanks