TPS Voltage Help?

MyTy

MyTy

Member
Hey so I'm in need of help with my TPS I'm not sure if I need to buy a new one or whats going on but could really use some feed back.. So I recently adjusted the idle screw some to help keep the Ty running.. it helped but not much and came to find out I probably messed up the TPS voltage.. so I hooked up my datamaster and it was reading at .80 voltage with the engine off but key on.. so I started loosing the idle screw back to where it once was and got it to .75 so I kept loosing hoping I would reach .50 voltage. well with the screw completely loose to the point where the screw is no longer touching the throttle plate thing that the screw touches and it reads at .63 Voltage.

Does this mean I need a new TPS sensor? the truck has never ran proper at idle or when going into reverse at times..

How do I reach .50 voltage at idle?
Is it maybe the way I have the Datamaster program hooked up? like the settings?
 
Don W.

Don W.

Stab it and steer it
Re: TPS Voltage Help?

You're going at it incorrectly. TPS is not "adjustable". At closed throttle it should read .36 - .44. According to the manual if the TPS won't go below these numbers then replace the TPS. The book says WOT should be over 4.0 volts in one place and over 4.5 in another.

Are you getting any codes?

You can check the TPS by starting a log with the engine off and graph the TPS. from throttle closed to wide open it should progress evenly to over 4.0 volts

What the idle screw does is, in effect, adjust the IAC. Start the truck and watch the IAC "counts". With engine warm in neutral, counts should probably be in the range of 30-35. A number isn't shown in the manual that I know of. What it does say is above 60 if idle is to low and 0 if idle is to high. I read that to mean that the IAC has a range of 0-60. Making an assumption 30 would be in the middle and maybe something close to "normal."

What issue are you attempting to "fix?"
 
MyTy

MyTy

Member
Re: TPS Voltage Help?

well from what ive found on the forums and from what I'm experiencing is that the you can adjust the TPS voltage.. when I adjust the idle screw I can actually see the TPS voltage change threw datamaster. I have two ty's so after I posted the question I decided id go see what happens on the readings when I swaped them out.. rite away the TPS voltage read different at like .44 that was with the screw all the way loose not even touching. so I adjusted it to .50 which is what a lot of people on here and a mechanic I know said it was supposed to read at idle.

Thought I had it all fixed until I took it for a drive.. now it feels super sluggish almost like I had the ebrake engaged which I didn't but something now is way off.. and still stalling. Tomorrow going to put the old one back in.. and start scratching my head again.

To answer your question Don.. Since Ive had the Ty its had a rough idle and occasionally would stall when coming to a hard stop or accelerating from a stop, and almost always when going into reverse. Ive replaced the ignition switch on the steering column, spark plugs, wires, ignition coil, distributor, IAC Valve, a couple days ago took off the throttle body and cleaned it out real well, has new vacuum line kit from sportmachines, today I installed a new AFR from Fabtech...none of this has fixed my issue.. Its very annoying having to stop with my left foot in order to keep the car from not stalling when coming to a stop.. and than having to continue sitting at the light with my left foot on the brake and right foot giving it gas so it wont stall... I can even feel it flutter while I do that like every 3-4 sec it will flutter almost like a fuel issue hard to explain the fluttering.. I'm getting very close to replacing the fuel pump..
 
liquidswords88

liquidswords88

I pity da fool
Re: TPS Voltage Help?

I was having a similar problem. To go along with the Poor idle, my timing was all out of whack. I played with different timing amounts which all changed my idle quality. To much advance caused surging and inconsistent idle. My problem ended up being my cam timing retarted one tooth. I messed around with every part of the idle circuit. The timing changes had more effect on the idle than any other adjustment I made. I am new to these trucks, and turbos in general. It seems forced induction motors are much more sensitive to timing than n/a engines.
 
dgoodhue

dgoodhue

BuSTeD 4.3
Re: TPS Voltage Help?

The idle screw is not suppose to be an adjustment. It is the minimum air and if adjust too far it affects the calibration of the idle. The ECM resets the TPS closed throttle everytime you turn the vehicle on, so adjusting the voltage is done in vain.

Get the engine warm up and idling. Adjust the throttle stop screw so the IAC counts around 10-20. If the engine isn't idling properly you need to address that issue, not mask it by forcing the throttle stop so it has a high idle.
 
MyTy

MyTy

Member
Re: TPS Voltage Help?

On my DataMaster I have a spot that says IAC Position.. Is that the same as IAC count? Currently the slot on my DM that says IAC Count jumps around from 50-30 at idle.

Another question I want to ask is when I disconnect my IACV the rpms jump up to over 2k at idle.. and that is with the idle screw barely touching so I'm not going to be able adjust that unless I mess with the timing..

Does anyone know the proper idle for when you disconnect the IACV? I see someone asked this same question back in the day but no answer was given.. would it be a bad idea to adjust timing with the IACV disconnected?
 
Don W.

Don W.

Stab it and steer it
Re: TPS Voltage Help?

MyTy said:
On my DataMaster I have a spot that says IAC Position.. Is that the same as IAC count? Currently the slot on my DM that says IAC Count jumps around from 50-30 at idle.

Another question I want to ask is when I disconnect my IACV the rpms jump up to over 2k at idle.. and that is with the idle screw barely touching so I'm not going to be able adjust that unless I mess with the timing..

Does anyone know the proper idle for when you disconnect the IACV? I see someone asked this same question back in the day but no answer was given.. would it be a bad idea to adjust timing with the IACV disconnected?
Click to expand...

Yes, IAC Pos is "counts." No such thing as proper idle with the IAC disconnected. Idle is not directly adjustable.

I just looked at some old DM files and my closed throttle IAC is around 68. Take it for what it's worth.
 
D

Davemc1963

93 Ty Owner
Re: TPS Voltage Help?

When setting up my TT chip I found that I had to bend the TPS operating lever a little to get the min air and counts in the correct ranges. (The 90 degree bend in the arm, where it contacts the throttle body). It provides an adjustment of sorts and is the only way you can 'adjust' the TPS. I suspect that there is either a dead band at 0 throttle or just wear.
The TT is particularly picky with those settings as is made clear in the instructions. (I realise that you have no mention of a TT chip, but the principles still apply).
Everything is fine now and running sweeter than it ever has!
I found that I needed to switch off and allow the IAC to 'reset itself' after I made an adjustment.
 
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