1997 Pathfinder SE - TPS Issue

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LumpyHumper
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1997 Pathfinder SE - TPS Issue

Postby LumpyHumper » Tue Mar 21, 2017 6:02 pm

I recently replaced my Pathfinder's VG33E and I can't seem to get it to run correctly. I am getting a P0300 (random misfire) code but that's it. My main concern is not the misfire, but rather the TPS. In order to get my vehicle to run semi-close to what it's supposed to, I have to turn my TPS sensor completely to one side. I know that there's a specific procedure to follow for adjusting the TPS, but I have no option. If I even slightly turn the TPS towards the opposite side that it's clocked to, the RPMs will jump to 3000+ from the already high 1500 RPMs. To add to that, while driving the car's recognition of the pedal is intermittent. What I mean by that is sometimes the pedal is recognized, but then the vehicle stops recognizing that I'm still depressing the pedal. The only way to go around that is to put the pedal to the floor for a second and then let off once I'm at the desired speed. I should also mention that when first adjusting the timing, the only position to get it to run correctly was to again, clock it to one side but instead of the TPS it was the distributor. I have heard about a closed throttle position relearn procedure, could this be the solution? If so, please let me know where I can find it. Any insight is greatly appreciated! I am pretty desperate to get my Pathfinder running well again.

I have made an Imgur album to show you where the TPS is currently set at, as well as what my diagnostics tool has picked up. Since I can't insert a link, please put "/a/1Hbh8" into the address bar following "Imgur.com"


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smj999smj
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Postby smj999smj » Tue Mar 21, 2017 6:37 pm

If the closed throttle position isn't relearned correctly, the idle will be higher than normal First, I would get the distributor straightened out. If you have to move it all the way over the the end of the adjustment slot, then, either the distributor is installed a tooth or two off or the timing belt is off a tooth...which could also cause the random misfire. When you replaced the engine, did you replace the timing belt?

Once you are sure the engine timing and distributor timing are correct, then adjust the ignition timing and base idle (which is done with the TPS unplugged). Once that is set, then tackle the TPS. Make sure the end of the spring is installed on the correct side of the pin. If I remember correctly, I would install the TPS initially with the plugs in the upward position and then turn it counter-clockwise, or the plug side downward, until the adjustment slots line-up with the mounting holes and the bolts can be installed.

Review Nissan TSB # NTB99-053b for the TPS adjustment procedure as well as the closed throttle position relearn (or, as they call it: reset TPS idle position memory). This involves a series of turning the key on and off and you really need a scan tool to see if the closed throttle position switch has been re-learned, but, generally after cycling it 12 or 13 times as per the TSB, it's usually a done deal.

Also remember that any time you re-adjust the TPS, you'll need to relearn the closed throttle position.

LumpyHumper
Posts: 8
Joined: Thu Mar 16, 2017 4:55 pm
Location: Nebraska, USA

Postby LumpyHumper » Wed Mar 22, 2017 1:38 pm

Okay, thanks for the help. I was able to find the relearn procedure. I will take your advice and I'll let you know what happens.

LumpyHumper
Posts: 8
Joined: Thu Mar 16, 2017 4:55 pm
Location: Nebraska, USA

Postby LumpyHumper » Sat Mar 25, 2017 6:55 pm

I didn't measure the voltage on my TPS because I didn't have an ommeter, but I rotated it more towards the middle. I then did the relearn procedure and that helped dramatically! It idled at around 1000-1500 rpms but then today I went ahead and tried to adjust the FIC and the throttle stop. I know the throttle stop screw is preset at factory but it was already tampered with so I had no choice. I have gotten the idle down to about 800 rpms which is where it should be, so that's good! This is the most progress I have made in a while. However, I still have a lack of acceleration. I'm not sure what the problem is as I was hoping this would fix it. Perhaps all I need to do is just properly set the TPS with an ommeter and that will fix it. Another thing I have noticed is that the little pin on the throttle doesn't rub on the FIC; there's a gap between is. From what I have found that isn't correct, but I can't get my throttle to go down that far without completely having the throttle plate closed and thus not starting because of no air. If you have some input on how to fix that, that would be greatly appreciated. I also suspect that the throttle lever's spring isn't tight enough, as I can move the spring with my finger fairly easy. Not sure if that's a big issue but I figured I would mention it. Thanks for the help so far.

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smj999smj
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Postby smj999smj » Sat Mar 25, 2017 11:51 pm

You don't measure voltage with an ohmmeter; you measure resistance. You use the ohmmeter with the appropriate feeler gauges to properly adjust the TPS, followed by the closed throttle position relearn.


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