Tps only hitting 4.95V?

[Ace_gst]

Hey every one i know this is a subject that has been talked about a lot and i have done tons of searching only to find people telling other people to search. Well here is the thing. I just put a new throttle body on my 89 gst (throttle body is 90 as well) it was rebuilt, bored and half-shaft mod. I am trying to adjust the TPS and at closed throttle i can get .460 but at WOT it max's out at 4.95v. When i adjust the TPS at closed the volts jump all around but at WOT i can only get a 4.94 to 4.95 change. With the TPS set at .460 and 4.95 the car will start jump up to about 4K RPMs and then die. I can keep the car alive by bouncing on and off the gas peddle a little. Kinda at a loss here don't know what to do. Thanks in advance for the help.

 

[96 420a-t]

Tps should only ever hit 5v because it has a 5v reference going in to it.

 

[Ace_gst]

Ok but is the 4.95 fine. You make it sound like as long as it does not go over 5 your fine. Think i need a little more explanation then just that.

 

[LiquidX]

Check your throttle cable to see if it's too tight.

 

[Ace_gst]

I adjusted it with the cable off and still cant get it to 5v?

 

[LiquidX]

Try adjusting the throttle stop screw that is by the wheel that the cable attaches to. It is also the idle position switch for the 1g. You'll want to un screw it to allow the plate to close.

 

[96 420a-t]

Your tps will NEVER get 5v coming out of it. It has 5v going into it. 4.95 v is good for a tps at WOT.

 

[LiquidX]

Your tps will NEVER get 5v coming out of it. It has 5v going into it. 4.95 v is good for a tps at WOT.

Then do you care to explain why I have my TPS reading 0.63v at 0% and 5.0v at 100% throttle? Then again, this is all through link.

 

[Ace_gst]

Ok should the throttle body be open at all at idle, mine is completely shut. What should i set the closed throttle volts to.63? Will the idle switch being out of adjustment make the car rev to 4k when started then just die. I just got this TB from throttlebodys.com.

 

[DSMTyson]

Your tps will NEVER get 5v coming out of it. It has 5v going into it. 4.95 v is good for a tps at WOT.

This comment makes no sense whatsoever..

Then do you care to explain why I have my TPS reading 0.63v at 0% and 5.0v at 100% throttle? Then again, this is all through link.

Exactly.


OP, for the record. TPS Volts is supposed to be at 0.63v at 0% throttle. Not 0.46v.

 

[Ace_gst]

So what do i do about the 4.95 issue?

 

[snowborder714]

Don't worry about it. That is considered WOT to the ECU.

 

[Ace_gst]

Ok so i can check that off the list..once i get it back to .640 at closed will it help it from starting up then dieing right away.

 

[Ace_gst]

Haven't had a chance to mess with the car yet but should the throttle body be closed or cracked a little at idle.

 

[xlMcMlx DsM]

The reason you won't see a full 5v or 0v is because those are reserved for shorts and opens.

The TPS is a potentiometer, meaning that the resistance changes as the throttle changes. So that means the voltage drop changes as you open and close the throttle. At idle there should be a small amount of voltage, .63ish volts, as mentioned above. At WOT, there should be CLOSE to 5v. The voltage drop is low at idle and high at WOT.

Basically if you ever see a reading of 5v or 0v, there is a problem.

 

[Ace_gst]

Thanks every one for the info. Give it a shot after the rain stops

 

[steve]

Unless you have DSMLink you should be adjusting for 0.5v on a 1G.
What the TPS reads at WOT really is unimportant as long as the TPS isn't really hosed up.

DSMLink scales it's output values as does stock OBD2 logging. On a stock 1G the values are absolute so closed it's ~10% (0.5v).

The ECU is more interested in the change in TPS values as your driving than some magical WOT value.

 

[Ace_gst]

Thank you Steve. I have it at .46v right now. As soon as the rain stops ill set it to .5v and adjust me IPS and see what i have.

 

[Ace_gst]

Hey set the tps to get.506v and it started up and idled at like 2400 and would serge to 3000 so i have a little more adjusting to do

 

[steve]

Adjusting the TPS won't do that, what else did you "adjust"?

 

[96 420a-t]

This comment makes no sense whatsoever..

The reason you won't see a full 5v or 0v is because those are reserved for shorts and opens.

The TPS is a potentiometer, meaning that the resistance changes as the throttle changes. So that means the voltage drop changes as you open and close the throttle. At idle there should be a small amount of voltage, .63ish volts, as mentioned above. At WOT, there should be CLOSE to 5v. The voltage drop is low at idle and high at WOT.

Basically if you ever see a reading of 5v or 0v, there is a problem.

Here's why I said what I said.

But OP, what you have is idle surge. A common enough problem.

 

[DSMReviver]

I don't mean to thread jack but I am in need of 2g tps. I went to junk yard other day to look for turbo 2g tps but no turbo in the yard. Is 2g NA 420a cars have same tps I need?

 

[96 420a-t]

They aren't the same.

 

[Ace_gst]

I "adjusted" the idle switch because it was completely closed and played with the BISS before i figured out the TPS so i need to set those first. Going to mess with that tomorrow if anyone has a good link for a 90 eclipse.

Ok so i tried to set the BISS screw and could not get the idle to come down passed 900. It still serges a little maybe 200 rpms but when i touch the gas as all it revs up to 4500k and will sit there for a sec before it comes back down to its idle. It wont let me gradually rev up. Also when i first start the car it jumps right to 4000k rpm.

 

[steve]

The IPS might be holding the throttle open. It's adjustment is critical and the FSM says to leave it alone and not touch it. I don't have the spec handy for a 90, on a 91 they say if it has been disturbed, to set it to 15/16th of a turn after the tip first contacts the throttle pulley.