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Throttle Position Sensor

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Old 10-20-2007 | 01:31 AM
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thxone's Avatar
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Question Throttle Position Sensor

Ok...so I have been driving my 79 N/A for a bit again and I have been trying to use the throttle in different ways. What I have found is that for the most part if I roll on the throttle slowly the car will accelerate almost like it should and doesn't bog nearly as bad as it does if I just floor it or give it more than half the throttle quickly.

I still think the car is either getting too much fuel or too little fuel with more than half throttle and I think the TPS may have something to do with this. I admit that I messed with the TPS when I first got the car a long time ago and tried to adjust the inner workings of the TPS...the problem is, I had no idea what I was doing. Now, I didn't break anything inside of it but I am not sure if the contacts are being contacted correctly if you know what I mean.

Does anyone know how this should be adjusted or at what point the contact thingy is supposed to move and to what position depending on the throttle position? Any pics? I can't buy books or anything like that, I am BROKE so no buying of special tools either...I just need some knowledge and personal experience from ye old wise ones here in this forum...and no that does not mean Mr. Wet Behind the Ears "Snw" unless you really know.

I am leaning more on the side of too much fuel going in because if I roll on the pedal slowly the pole in the TPS is staying in one position longer right which should tell the ECU to not dump so much fuel in and by the time I hit the upper rpm's like above 4,500 the pole has moved and the ECU says dump more fuel right? I also noticed that sometimes above 4,500rpm the car wakes up and screams but very shortly after it is time to shift.

Yes, sometimes there is a dark smoke from the rear when I get on it...not blueish or white but more blackish grayish...IT'S NOT OIL!!! So, any ideas, suggestions or for sure fixes for this?
Old 10-20-2007 | 03:57 PM
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Ok, here are the pics of the TPS, I adjusted it the way it makes sense. Notice the positions at the red arrows

Not Adjusted:

Closed Throttle


Half Throttle


Adjusted:

Adjusted Closed Throttle


Adjusted Half Throttle


Adjusted Full Throttle
Old 10-20-2007 | 04:23 PM
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WOW, yeah the TPS is definitely "part" of the problem...it is adjusted now and it made a big difference. I think however as soon as it hits the last contact is when it bogs so I am at a loss...I am going to bend it out of the way so it makes contact even later but first I am going to clean the connection...if that dont work I will ben that last pole inside the TPS out of the way a bit.

It bogs at a higher rpm now so this tells me that yes, when it contacts that last pole inside the TPS, something goes wrong. What could be going wrong? What does this last pole do?
Old 10-21-2007 | 03:04 AM
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the last pole richens the air/fuel mixture about two points ie from 16:1 AFR to 14:1 AFR when everything else is working right.
Old 10-22-2007 | 11:10 AM
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Your adjustment looks fine. Don't bend the contacts. The TPS just gives its basic signal. Your AFM is likely the main problem.
You either adjusted it and its too rich or you just need a different one. Maybe you have have a vaccuum leak.
Old 10-22-2007 | 04:40 PM
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Originally Posted by Bleach
Your adjustment looks fine. Don't bend the contacts. The TPS just gives its basic signal. Your AFM is likely the main problem.
You either adjusted it and its too rich or you just need a different one. Maybe you have have a vaccuum leak.

Ok So I won't bend the contacts then. I think, but I am not sure, I may have swapped my '82 N/A AFM onto this car...I will put my '79 AFM back on it if that is the case. I have not adjusted either AFM though. At least I am getting somewhere with this.
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