Zero reading at TPS, stalling issue

[jeepmjga]

Hey all, done my due diligence trying to figure this one out but I'm stumped.  Whenever I get on the throttle above say 1k or so rpms and let off (such as coming to a stop light) the truck stalls or drops RPM down to almost stall.  Replaced IAC and tried testing the TPS, but I am getting zero readings out of the TPS.  Key in ON position, Probing B and pos lead in A, reading .0L, same when trying to test pos lead in C.  Tried a new TPS, same thing happened.  I don't know where to go from here.  As far as when I'm back probing I am sticking the needles in as far as they will go.  Throttle body is clean as a whistle as well, and no vacuum leaks that I can see.  I can literally unplug the TPS while the truck is running and nothing changes.  Am I testing the TPS wrong?   Any ideas?

[scaleless]

If you are reading OL, you are trying to read resistance (Ohms) - you want to be reading voltage.  To verify your meter is working properly, try testing the battery - you will get ~12v

[jeepmjga]

Ok I stupidly had the range setting wrong, but I'm getting 4.91 as ref volts, but still zero reading when i test for output. Same thing on new tps sensor. 

[scaleless]

Most likely you're getting a poor connection with your multimeter leads.  If you have THICC leads it's hard to get a connection.  Try moving the throttle while testing as well, to make sure your TPS isn't just bottomed out, and while you're at it make sure the throttle is actually touching the TPS lever.

[jeepmjga]

Well I adjusted it completely one way or the other and still no change.  Also if I sit at a constant throttle (say 1500 rpm) the throttle will drop about 500 rpm without me moving my foot at all.  Also should mention did cruiser's tips as far as ground refreshing and moved the blower ground as well.  Have NOT added the two extra grounds yet, but that is on the list.  Also should mention just put in new plugs, wires, cap and rotor, ign coil and MAP sensor, but the problem was happening before all that went in.  

[SVPete]

To ensure you are getting good contact, use some paperclips to back probe rather than trying to stuff your multimeter leads in.

 

Ignoring the TPS for a moment.....do you still have an EGR valve installed?

[jeepmjga]

Yes EGR is still installed, haven't gotten around to messing with it yet.  

[SVPete]

Still check the TPS by back probing using paperclips to ensure you are making good contact. It is very possible to get a bad part. Happened to me with the TPS on my 1992 Cherokee. It throws you, since it's natural to think that there's no way that the new part you just installed is bad. The car would start, if I started driving to work on the 40mph road near me, it would feel like it was trying to stall about a mile down the road, then pick back up and be fine the rest of the day. If I started it in the morning, and drove the residential 25 mph street, it would die......and seem like a no spark issue. After chasing my tail for a while, I finally replaced the TPS again, and problem solved.

 

Disconnect the vacuum line to the EGR, plug the line with a golf tee (or the like). See if there is any change.

[SVPete]

And just to make sure......you are leaving the the TPS connector plugged in the TPS when making your checks, right?

 

Not meaning to insult you, just had to ask.

[jeepmjga]

14 minutes ago, SVPete said:

And just to make sure......you are leaving the the TPS connector plugged in the TPS when making your checks, right?

 

Not meaning to insult you, just had to ask.

 

No worries, yes leaving them plugged in.  I will try the EGR thing tomorrow its just the output volts that is throwing me off. 

[SVPete]

You still should confirm your readings at the TPS. If you do not have an output voltage, it's not working and can still be the problem.

[jeepmjga]

Ok well solved (thank you scaleless). The little arm was on top of the throttle control so the sensor wasnt moving with the throttle. Guess I needed a break more than I thought 🤦 thanks for the help everyone. 

[silvertwinkiehobo]

When installed and at closed-throotle position, you should still have a reading above zero volts. That's how you know if you installed it wrong (which I've done before myself).

[cruiser54]

Nicely done.

 

be sure to do Tip 5.