Quote:
Originally posted by deizel295
Bucking under load? that is not usually fuel issues. I am in an advanced engine performance class at college right now, check your MAP (manifold absolute pressure) sensor.
1st try disconnecting it electrically, the ECU will revert to using the tps and ckp sensors, if the car runs better then you found it. OR use a digital volt ohm meter (DVOM) to look at the signal at different vacuum readings.
these are just general numbers but they should look somthing like this (SOMETHING)
Volts VS Vacuum
4.5V 0" hg (inches of mercury)
3.5V 5" hg
2.5V 10"hg
1.5V 15"hg
1.0V 20"hg
Test this between the signal wire and ground. use only a high impedence DVOM or you'll destroy the ECU and the DVOM
your higher "hg readings will be at less throttle positions (toward idle or on decel - obviously you can't do this while in motion)
This may sound far fetched but it worked on shop vehicles.
Also check your MAF (mass air flow) sensor, a good check of this is to disconnect it electrically, like before if it runs better you got it! also try spraying the wire inside the air flow area with brakleen ( DO NOT USE CARB CLEANER!! TRUST ME DO NOT!! ) and it sometimes cleans it up, carbon builds up on the wire and the ECU cannot sense the air flowing past it. MAF's work by heating up a wire (hot wire MAF) and looking at the voltage drop across it to keep it at a constant temp, as the voltage drop changes the ECU computes this to a different air flow number. so try those, they may be the issue. always do the tune up stuff first, but don't throw a high priced pump at it unless you diagnos it. If you think it is the pump, do a fuel pressure gauge on the fuel rail, the try a fuel volume test, it should put out at least 1 pint in 30 seconds and have at least 40psi running pressure. hope all goes well.
TOYS RULE BABY!
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I know what your saying as im in an advanced course at a particular school and own a 94 tercel. These cars, 91-94 ,use a MAP sensor setup. Ive had similar problems and after replacing the fuel filter the problem was gone. Toyota says they're a lifetime filter but those in the know know thats bulls**t.
