TPS setting 1989 4.0L

installed an new TPS today was going to set it like described in here. with key on motor not running have 5.41 Volts to sensor was going to set it to 88% of that which would be 4.76V or so but any attempt to get it lower than 5.04 V ends up with extreme high idle 3000 rpms. at 5.12 volts its normal idle
what gives? should I leave it there or?

There is no way you should have 5.4v. What is the supply voltage on the sensor. That voltage is regulated to 5.0v and comes from the ECU I bet you have a ground problem somewhere on the engine. Measure from the negative post on the battery to the ground lead on the sensor. You should have close to zero volts.

set it to 12% not 88, and it should be ok.

Is it a manual, or an automatic, they are different.

Fred

the setting is still 12-14%

measured from the ground post of battery to reference of square terminal on sensor have 5.41 volts this is an twin lead automatic version then measured to the return with it at about 5.09 at idle position then at full thottle its about 2.2 volts the tranny works right now and idle seems ok at about 700 rpm and fixed the stubble from idle when it was cold so any reason not to leave it like this?

JNEARY --- Good one! 12% / 88% ---6 one way half a dozen the other!

The reading should be 10 - 12 % less or 88 - 90 % of the first reading!

CrazyRay -- are you shure it wasn't 4.5V? Now that is a difference from 5.4V!

Sorry -- it is really late!

no its 5.41 at least on my meter but like I said its running much better just wondered if should leave where its at

sjx40250 said:

JNEARY --- Good one! 12% / 88% ---6 one way half a dozen the other!

The reading should be 10 - 12 % less or 88 - 90 % of the first reading!

CrazyRay -- are you shure it wasn't 4.5V? Now that is a difference from 5.4V!

Sorry -- it is really late!

Click to expand...

if you adjusted it from the wrong wire connector and got 88% it is wrong, therefore giving you a high idle. if you adjust it on the other connector and get 88%, it is probably ok.the two connectors are opposite.

told to set it by the square plug and to probe back of it not unplug it
is this correct infro?

I am interested in this as well. I tried to put in a new tps yesterday and I am only getting 4.32 to the tps , adjusting the tps has no effect.. What is it suppose to be?

Okay, here it is direct from the Jeep Renix (1987-1990) Fuel Injection Manual.
Manual Transmission:
1. Turn on ignition.
2. Insert negative test lead into the back of terminal B. Insert the positive lead into the back of terminal A. Make sure the throttle is closed and note the input voltage.
3. Remove the positive test lead from A and insert into the back of C, and note the output voltage.
4. Divide the ouput voltage by the input voltage. The correct ratio is .17. For example, it the input voltage is 5.0, the output voltage should be .85, .85/5=.17.

Automatic Transmission

1. Turn on ignition.
2. Use the four plug connector. Check the input voltage by inserting the negative lead into the back of terminal D and inserting the positive lead into the back of terminal A. Note the input voltage while insuring that the throttle plate is closed.
3.Remove the positive lead from terminal A and insert it into the back of terminal B. Note the output voltage.
4. Divide the output voltage by the input voltage. The correct ratio is .83. For example, if the input voltage is 5 volts, the output voltage should be 4.15 volts. 4.15/5.0=.83.

That's what my book says, I know that the information is correct for the manual, as I've done it and it works well.

Fred

i always use the drb2 scan tool, but if that is the correct procedure, ok. however for optimum idle quality and performance the manufacturer's recommendation is 12-14%. it looks as if your manual is saying jeeps original setting of 17 to 18%.

Fred said:

(...snip...)

Automatic Transmission

1. Turn on ignition.
2. Use the four plug connector. Check the input voltage by inserting the negative lead into the back of terminal D and inserting the positive lead into the back of terminal A. Note the input voltage while insuring that the throttle plate is closed.
3.Remove the positive lead from terminal A and insert it into the back of terminal B. Note the output voltage.
4. Divide the output voltage by the input voltage. The correct ratio is .83. For example, if the input voltage is 5 volts, the output voltage should be 4.15 volts. 4.15/5.0=.83.

That's what my book says, I know that the information is correct for the manual, as I've done it and it works well.

Fred

Click to expand...

Going off of some scans from the factory manual (not the fuel injection manual) I've been setting my TPS output voltage to 4.2 volts, period. Today I set it using this "math method" and for the first time in a long time my '90 Laredo runs normally.

input (A) voltage = 4.70
4.70 x .83 = output (B) voltage = 3.90

Before, my shift points were a little low (the AW4 would shift into OD @35-40mph unless I had the accelerator pedal pressed good climbing a hill or something) and my idle was a little high, around 1000rpm, especially when started cold.

Now the thing runs like it did when I first got it, idling at 500-700rpm and shifting into OD @±45mph. I'm so happy I could go drink a beer.

Hey... :idea:

:revolver

i would still set it at 12%.