Need to adjust TPS QX4

[don5154]

Can anyone advise as to how to adjust the TPS on a 98 QX4. I just ordered an new one and will be installig it. Thanks in advance.

[don5154]

Well not response so i just put it in. Apperenly adjustment is not critical. Shift points can be adjusted by rotating it. It does not seem to contain a micro switch to signal idle position to FI.

[Q45tech]

Adjustments are critical because the ecu must know the exact position of the throttle to decide which of the 10 look up tables you want.

[forecast]

What Q45tech means to say is:

the cars' computers need to know what you want (indicated by what you do with your foot) in order to deliver the best possible driving experience.

If the TPS is way off and the computer thinks you have a lead foot when you don't, it will be keeping the mixture rich and the transmission computer will be delaying shifitng as both are trying to accomplish the powerful acceleration you seem to be asking for. The MPG will be hit as a result - especially in the city.

The inverse is you'll be wondering why the power seems a bit off.

get it set by someone who has the equipment to do so, this shouldn't be more than a 30 min job if you already have the new TPS installed.

dan

[juiceman]

Can't the TPS be adjusted using a multimeter and adjusting the resistance to the mid range?

I have used Paperclips to get into the contact when it is connected (from the back thru the seal). Loop the end so the probe will stay put so that you can have both hands free to adjust

I do not know Q specs so maybe someone can tell you the resistance

[Q45tech]

Usually the ecu wants to see, expects to see between 0.4 and 0.5 volts with the throttle closed after warmup.Also the ecu expects to see 4.00 volts or greater at WOT.Some Nissan also have a backup WOT switch.The ideal steps are around 0.4 volt increments to develop 10 throttle positions...........this voltage is sent to tcu [also] to determine the road speed at which up and down shifts occur.

Any more than 0.55 volts at idle will confuse it [but that is the reason many TPS have a closed throttle switch as a back up].

All fully explained in the service manual that came with your J/Q/G.

[don5154]

This is a QX4 no service manual like on the old Q45s' I have a G35 and did not get a service manual with that. Should I have? Can the TPS be adjusted without special equipment. I have mulitmeters and a dual trace scope. :ylsuper :help

[Q45tech]

What's wrong with buying a service manual? Just because Nissan decided to save money by not including one.Since yours is OBD2 you only need an inexpensive scanner or software for a computer and adapter to emulate a scanner $200

Read the above [previous posts] voltage to ground from the center wiper of the TPS potentiometer.You test closed and WOT, fine tuning on the exact spot that gives you both extremes...........have a helper do the WOT from inside unless you have 3 hands

[Q451990]

The service manual also has a test for ohms (since it is just a variable resistor) so that you can adjust it without the sensor being plugged in. I'm not sure if that works as well as what Q45Tech mentions or not. I sort of like the voltage output test - I guess you just probe from the back of the plug when it's conected?

Just don't do what I did and decide to tighten the throttle cables for better response - they'll bind - and NEVER adjust any screws on the throttle body! Also, you need to check everything after the car is hot - the fast idle cam will set the idle artificially high if not.

All of this is Q45 advice, but it'll probably carry over to the QX4.

Heath

[don5154]

Thanks Guys I can do it now.