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TPS question


JeenyusVR4
08-11-2010, 02:15 AM
ive been having this problem where my car feels like it falls on its face almost as if theres not pedal response intermittently. I hooked up my datalogger and my tps percent was pretty much flucuating like crazy from 20% to 80% and everything inbetween. The car has a very smooth idle so i feel like im narrowed down to a couple options.
I just replaced my tps and for one i adjusted it to be around 12% at idle but it still kept jumpin around. I tried adjustin it a couple more times and still the same result. i also recently had my ecu's leaky capacitors repaired.
my questions now are could it still be the ecu by chance? or is there something that im overlooking? all help is appreciated thanks.

91STT
08-11-2010, 03:45 PM
it is possible that it is the ecu that is the problem.
first you will have to check the resistance value for the tps across terminals 1 and 4.
the total resistance should be between 3500-6500 ohms.
than measure the resistance between terminals 2 & 4; the resistance should change smoothly between 3500 & 6500 ohms as the throttle valve moves from closed to wot.
it those 2 tests prove good, you need to check the wiring harness.
with the key on engine off, the voltage between tps harness terminal 1 and ground should be between 4.8-5.2V.
if it is not within specs repair the harness.
check continuity between tps harness terminal 4 and ground with key off.
repair harness if you have high resistance or an open
unplug your ecu, etac, ecs control unit, and cruise control unit;
check for short to ground with a meter between tps harness terminal 2 and ground.
the ohmmeter should not give you a resistance reading; if it does, locate and fix short.
check for open circuit by grounding pin #84 and measure continuity between tps harness term 2 and ground; you should get almost zero resistance.
if you get high resistance or no reading, locate and repair open.
if the above checks all come out good, than i would suspect your ecu.

JeenyusVR4
08-13-2010, 02:59 PM
so i went through all the checks one by one and everything checked out good until the last chack for an open and im not gettin any reading on my ohmeter so im goin to start chasin the wire! thanks for all ur help ill let u know how everything works out.

JeenyusVR4
08-13-2010, 03:33 PM
u know what i just checked again and i didnt have a good ground on pin 64 (92 vr4). i checked again and its givin me 1.6 ohms.

JeenyusVR4
08-13-2010, 04:57 PM
ok after i tested pin 64 and terminal 2 i am for sure getting 9 ohms, so then i started testing sections of the wire and its only showing 1 to 2 ohms max if not 0. how can this be if i checked every section of the wire but when i test the whole thing it shows 9!?

91STT
08-16-2010, 01:50 PM
u know what i just checked again and i didnt have a good ground on pin 64 (92 vr4). i checked again and its givin me 1.6 ohms.

ok after i tested pin 64 and terminal 2 i am for sure getting 9 ohms, so then i started testing sections of the wire and its only showing 1 to 2 ohms max if not 0. how can this be if i checked every section of the wire but when i test the whole thing it shows 9!?

do you mean pin # 84?
did you disconnect the etacs, ecs control unit, and cruise control unit?
you can get erroneous readings if they are plugged in.
also what is the reading you get when you touch the two test leads together?

JeenyusVR4
08-17-2010, 01:50 AM
I looked up the pin chart for a 92 vr4 and there is no pin 84 but it had 64 as tps so i checked out a newer model and it had 84 as the tps so im figuring that its the same thing.
but i definatley forgot to unplug my ecs! im gonna recheck it again tomorrow nd see what i come up with.

I was using a cheap 20 meter that was really odd to read so i brought homw my nice one from work and rechecked my brand new tps. the resistance between terminals 1&4 moved smoothly but it starts at .5 Kohms and at WOT its at 5.6. so im thinking a got a bad part possibly. i mean it is a napa part i got a good deal on :nono:

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