Hello all,

I have a few questions about TPS diagnosing. The first one is in relation to The '92 4rnr (3vze)I have. I have a new sensor and have adjusted over a dozen in the course of a couple of months trying different methods and settling on one on 4crawler's page...courtesy of Frankentyota. I ask because I still can't get the truck to go in to base timing.

The first method I tried was out of the FSM for '93 trucks online. The second was by hand, recommended by a fellow at YT. He suggests, with the motor running, adjusting it by hand, setting it at the high RPM just over the low/high RPM range threshold. Well, it all sounded good, but with that method I still couldn't get base timing. Then, with Frankeyota's method I set it with the meter, but still no base timing.

First, how do these two methods compare? What I'm wondering is if I'm interpreting Frankenyota's suggestion incorrectly...setting it at or just under 2.3k ohms. More specifically, would that setting be on the high end of the RPM, as the YT member suggests setting it at, or the low side?

Here is the post from YT:

"Here is what you should try now:

0. Adjust the high rpms down to 800, with the TB idle adjust, while the TPS is disconnected.
0.5 Reconnect the TPS
1. Make sure you have it mounted correctly. (lots of posts on this)
2. Adjust the TPS while the motor is running. You want the higher rpm case as the idle detect (now set to 800rpm). It should be just detected, meaning you want the setting very close to switching to the lower rpm, but set to the HIGHER, 800rpm case. That is the ECM detecting the physical throttle idle position. The lower rpm case is the ECM NOT detecting the idle position, and therefore forcing the lower rpm case."

Second, in relation to the '92, is there any other reason, besides a misadjusted TPS, the motor would not go into base timing? I would, of course, think that it would be the ECU or the TPS cable leading to it. However, the ECU is not detecting a short and the RPM shifts up when I disconnect the TPS harness. One time, the RPM actually shifted down, which I thought was strange as I don't have any explaination for that.

Now, I also have an '86 4rnr(22re)that has been hesitating/missing. One of the suggestions from the FSM is to check the TPS. I went to test it, but I could not get a reading other than 1.000k ohms on a 20k setting (Is that "open"...1k ohms?) at the IDL-E2 terminals even with the other terminals' values being within their respective ranges. Would this mean it is bad on the IDL-E2 circuit? I had even tried using different feeler gauge sizes just below and above the appropriate size wondering if this was a case of factory tolerances.

BTW, I have asked and searched...lol!

Oh! And one last thing...out of curiosity. Does it matter on the 3vze if the TPS terminals, while the sensor is mated to the TB, are facing out and away from the plenum or does it have to face in towards the plenum? In the former scenario, it should would make for easy adjustment and/or testing on the TPS. But, whatever way it should be!

Thanks!

It all comes down to "does the ECU see the IDL setting and does it see the timing set jumper?". So if you can get the setting at the TPS to read properly, then you need to check if that same reading is getting back to the ECU connector. If not, there is a wiring problem between the two ends. Same with the timing check connector.

As far as what does "xxxxK" ohms mean on a given meter, the best bet is to stop by your local electronics store (like Radio Shack) and pick up a few resistors to practice with. For example, get a 1000 ohm resistor and then make sure you get get a reading that you can interpret as 1000 (+/- whatever tolerance that resistor has) ohms. I have some tips on using digital meters on my web page:
- http://www.4crawler.com/4x4/CheapTricks/TPS/index.shtml#HowToUseAnOhmMeter

Nope, 20K is "open" if you are on the 20K setting (that's almost always true, although if you are hooked up to something with more than 20K of resistence, you need to go to a highr scale)

When I set up my 22RE TPS I found that conventional flat feelers couldn't be inserted straight enough to be accurate. I used a piece of 24 gauge wire ( most telephone wire is 24 gauge) it measures .0201" in diameter & can be bent to get where it needs to go easily.

Dave

Thanks to the both of you. I'll do some testing on the suggested connections. <img src="/forums/images/graemlins/cheers.gif" alt="" />