03-24-2014, 07:33 AM
sorry the scan tool lets us know the engine is running in closed, loop, if its not, that will explain the misfire. Even a $9 tool works.
and the LTFT this tell you , (scantool) the long term fuel trim, this is parameter is for how far off the fueling , at idle if done at idle. If way off that too explains, misfire, (too rich or too lean)
The EGR cloud and PCV clouds, of gases. collide and form gunk inside the plenum on this engine all the time, it a service issue for sure.
just make the valve free, is all.
lots of things can go wrong on such and old car. Even air leaks, or just a dirty MAF sensor.
EGR leaking? both it and its piping , or missing EGR gaskets, (causing side air leaks) in 3 places.
The 0xy sensor must work
LTFT, runs PLUS or minus around 0. 0 is perfect.
most good cars run -5%, that means the Air fuel ratio is naturally rich a tad (safe side ) and the EFI oxy readings correct it to perfect Air fuel ratio. AFR.
if it reads like -30%, that means its grossly over fueling and correcting it best it can.
if it reads +30% (lean) (that means 1 of 2 things, the MAF is dirty, or there is a huge air leak in the intake and great danger for engine if ran at full power lean. "ping or knock damage"
the CEL only tells you, the car is failing for smog, it is not a status light, that the EFI is and running right. In fact I ignore it , and just scan all cars.
and the newer the car, the more you must do that with 100s of errors possible.
no matter what its a runner... good luck with it.
and the LTFT this tell you , (scantool) the long term fuel trim, this is parameter is for how far off the fueling , at idle if done at idle. If way off that too explains, misfire, (too rich or too lean)
The EGR cloud and PCV clouds, of gases. collide and form gunk inside the plenum on this engine all the time, it a service issue for sure.
just make the valve free, is all.
lots of things can go wrong on such and old car. Even air leaks, or just a dirty MAF sensor.
EGR leaking? both it and its piping , or missing EGR gaskets, (causing side air leaks) in 3 places.
The 0xy sensor must work
LTFT, runs PLUS or minus around 0. 0 is perfect.
most good cars run -5%, that means the Air fuel ratio is naturally rich a tad (safe side ) and the EFI oxy readings correct it to perfect Air fuel ratio. AFR.
if it reads like -30%, that means its grossly over fueling and correcting it best it can.
if it reads +30% (lean) (that means 1 of 2 things, the MAF is dirty, or there is a huge air leak in the intake and great danger for engine if ran at full power lean. "ping or knock damage"
the CEL only tells you, the car is failing for smog, it is not a status light, that the EFI is and running right. In fact I ignore it , and just scan all cars.
and the newer the car, the more you must do that with 100s of errors possible.
no matter what its a runner... good luck with it.
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