post tps replacement problem

[ColLateralus]

i have recently replaced my tps , but somehow, sh1t hit the fan during the 5 minute swap and now when i start her up she'll redline for like 5 seconds and then drop down to 1k rpm and jump up and down between that and about 2k rpm. i put the old tps back on and it does the same thing. playing with the throttle manually while the engine is running(if you can call it that) does absolutely nothing. Something tells me the computer is trying to memorize the new tps, but i've let it run for like 10 minutes and it just keeps jumpin, does anyone know whats goin on?!

[Southern Comfort]

Make sure you put it on correctly. Look at the wires closely, they may be broke in sid e of the insulation. Also remove your battery post for about 10 minutes or so. See if the computer goes to relearn mode. Let it run for a while to relearn.

[xavier3jr]

u might also have to change the IAC

[david-b]

Check the IAC. It may have been damaged, or not hooked up right again. Maybe a short then too.

[ez1286]

Are you sure it's on right? Could potentially be reading 100% open, which may cause some slight problems...

[ned032002]

It's probably not set at the right voltage which should be between 0.48-0.52 Volts. Try getting your hands on a Chiltons manuel, it may help alot of situations.

[Shpyder]

Okay, this belongs in the adequately labelled "PROBLEM DIAGNOSIS" sub-forum. ahem ahem...

[Nayr747]

I don't know if you have a 1g or 2g but it's completely different for each. Here's all I have on TPS's. It's mostly for 2g's, but there's info for 1g's in the links. Maybe sticky this?


It is due to a TPS (Throttle Position Sensor) code and it has done that ever since the car was first obtained. The code is invalid though and I have a copy of the Mitsubishi service bulletin that explains how to fix the computer from throwing this erroneous code.
http://www.dsmtalk.com/forums/showth...&highlight=tps

Buying used TPS: Make sure 2g (all four pins). 1g’s have space for 3rd pin.

Chiltons: 4-28

Closed TP Switch and TP Sensor Adjustment [2G]
1. Disconnect the connector of the TPS.
2. Connect ohm meter between terminals 3 and 4.
3. Insert a feeler gauge with thickness 0.45mm (.0177 in.) between the throttle stop and the throttle lever.
[Fold a piece of paper in half 4 times if you don't have the feeler -Ed.]
4. Loosen the TPS mounting bolts. Turn the TPS all the way counter
clockwise.
5. Check for continuity in this condition.
6. Slowly turn the TPS clockwise until the point where continuity and
non-continuity is found (pins 3 and 4).
7. Tighten the TPS mounting bolts.
8. Check the voltage between pins 2 and 4 of the TPS with the ignition
switch on, but the engine not started.
9. Standard value: 400 - 1000 mV
10. Remove the feeler gauge.
http://www.roadraceengineering.com/2gtbswap.htm

Detailed 2g tps adjustment procedure:
http://www.dsmtuners.com/forums/show...tps+adjustment

2G's seem to scale (report the lowest voltage seen as 0 and the highest as 100) the output of the TPS that is sent to the datalogger, or the datalogger software is doing it. Doesn't matter too much since the only thing your adjusting a 2G TPS for is the point where the internal IPS is opening. The actual voltage output from the TPS on a 2G at idle is quite large.

On a 1G you adjust the TPS for about 0.5v at idle (0.48 to 0.52v) What the TPS reads at WOT is largely unimportant.

With both generations, as long as the physical butterfly opens all the way, then whatever the TPS reads is what it reads. The ECU is usually looking at the change in voltage from the driver moving the pedal and not some magical voltage.

This all assumes a good TPS. If your TPS drops out or spikes in voltage as the throttle moves it's bad.


For the most part the ECU only cares about relative movement of the throttle, not absolute position. But there are a couple things that still depend on TPS. 2Gs use the TPS for the closed throttle switch as well, which the ECU needs to see closed before it will go into closed loop idle speed control (this applies to 1Gs as well, but they use a seperate switch). You need to be sure that input is switching. On every car I have worked on that happens around 1%, so it makes sense to set the TPS so that it is just barely on zero with the throttle closed. Anything over about 90% the ECU will consider WOT, and most cars end up over 90% with the zero point set properly.

The 1g ECU may not care where TPS is at idle since it will still get the throttle closed signal from the switch. If the ECU goes into closed loop idle speed control it is probably fine. But it still makes sense to be close to zero. WOT should be fine as long as the throttle plate gets the full range of motion (cable tension set properly).

Since cable setup is important to getting the TPS set up properly, we might as well mention something about that. The easiest and best way I have found is to loosen the bolts holding the bracket, have a friend floor the throttle pedal, pull on the cable until the throttle plate is opened hard against the stop, then tighten the bolts. This will assure full opening range and maximum slack at idle to prevent idle issues when the cable warms up and expands.
http://www.dsmtuners.com/forums/show...&highlight=tps

On a 1G you adjust the TPS until it outputs about 0.5v on pin 2 (spec is 0.48 to 0.52v). That's the same as reading 10% on a datalogger. The IPS shouldn't be adjusted unless somebody have messed it up. You should check that it has continuity to ground when the throttle is closed and not when the throttle is slightly opened.

On a 2G the TPS is adjusted by where the internal IPS opens and closes not by any specific TPS voltage.

If you search you find a post where I explain why you can't set the TPS by resistance as suggested by the aftermarket manuals and the VFAQ site.

The ECU really doesn't care much if it reads 100% at WOT or 90%. There are very few checks for any absolute voltage and most of those are in the fault routines for the TPS.

On a 1G the correct adjustment is so that the TPS outputs 0.48v to 0.52v when the throttle is closed. This will show up as about 10% on a datalogger.

On a 2G the TPS output voltage has a wide specification because the critical adjustment is where the IPS internal to it opens and closes.

The specifications for the TPS also allow for a wide range in total resistance. This is one of the reasons you can't set the TPS to some fixed resistance contrary to some aftermarket manuals. The correct resistance with the throttle closed will depend on the total resistance of the TPS, so unless your old and new TPS are identical they may be in different positions when adjusted.

You can change the TPS without out removing the fuel rail but it's a real PITA. Reaching the bottom screw is a problem.
http://www.dsmtuners.com/forums/show...ighlight=p0120


“Just take it off and use electrical contact cleaner to clean all moving parts and contacts and reinstall and adjust per specs on the page.” -dsmtalk