TPS voltage drop

[Fordmikeyranger87]

Looking for some insight on a voltage drop on TPS. Truck is 87 ranger 2.9 v6, I’m currently getting a bit of erratic idle and acceleration. I read to check tps , and at about half way to WOT my voltage drops when I get around 1.98, drops to 0.00 and then back up to 2.1. Head scratcher at this point is I ran codes before replacing and no codes popped up for the TPS on Koeo or koer. I put new TPS on and still getting the same reading. Thinking it might of been bad part I just ended up ordering another just to see and the second one I purchased had the same reading so I’m not really sure if it’s with the wiring/pig tail which from what I can see looks to be in order but I can’t imagine both new tps would be faulty. Any insight or other tests/checks I can do to track this down is greatly appreciated.

 

[Uncle Gump]

Are you using an analog meter?

 

[Fordmikeyranger87]

Are you using an analog meter?

No, Digital multi meter

 

[Fordmikeyranger87]

Took a video but not sure how to post a video on here but here are screen shots, closed throttle reads .848 and then it has a steady increase up until 1.985 then drops to 0.00 and then up to 2.31

 

[Uncle Gump]

I always use an analog meter. DMM's have funky update rates and its near impossible to watch voltage sweeping from idle to WOT. An analog meter will show you a smooth transition Flat spots are easy to see.

I would put an analog meter on it and ensure you get the same results before going any further.

It is a bit confusing you get the exact same results with two different TPS sensors.

 

[SenorNoob]

That makes it even more likely it something to do with the meter, imo.

 

[Fordmikeyranger87]

okey, I’ll pick up an analog one today and see what I get. Yeah was a lil dumbfounded when the original tps and 2 brand new ones dropped to 0 at same spot. Just curious, could a bad ground cause something like this?

 

[Uncle Gump]

Doubtful...

 

[Fordmikeyranger87]

Doubtful...

Thanks, appreciate the quick reply’s, let ya know what the analog meter gives me later today.

 

[Fordmikeyranger87]

Okey well, analog meter telling me all is good! Voltage went up nice and gradual with no flat spots.

So now I’m wondering where I need to look for this idle and acceleration issue. Few weeks ago I was having misfire issue on 4 and 5. ended up cleaning injectors, for the last few days truck seemed to run better and the slight engine shake went away and Now 4 and 5 cylinder change idle when wires are pulled which they did not before. Currently when I start the truck it starts up great and does its normal high idle around 1500 rpm and comes down to 800 and will idle good for another minute and then drops to 500 and just fluctuates between there and 800 and seems like truck is about to die. When it gets up to running temp the idle smooths out and I don’t have any major fluctuations there but when im driving I’ll have some hiccups in acceleration like the truck falls flat and then will have a jolt of acceleration and will run good, this happens randomly through out driving. Some times it will be only once and then I’ve had it happen 3 times. Has a new CTS and IAC (Motorcraft) and vacuum hoses, I’m getting in spec numbers on compression, fuel test and injector check out good with noid light, Which I did about 2-3weeks ago

 

[Fordmikeyranger87]

Also just checked for any codes and koeo is good im getting 11 and im now getting code 42 R on koer ( hego sensor indicates system rich)

 

[SenorNoob]

Do you have an exhaust leak before or close to your O2 sensor(s)? That could it.

Mine has a problem after idling just a few seconds when warm. It'll go lean enough on take-off that I have to be careful not to stall it. The longer I idle the worse it is.