Hi all,

I'm chasing an eractic fuel economy issue. Although the trip computer always shows "generous" figures (between 16-25mpg which is much better than I actually get), my actual economy seems to wonder greatly.

I've also experienced some hesitation so I decided to plug in my OBD2 scanner and view the readings from the TPS as reported by the ECU.

Do these sound correct?

At idle - 15.3%
At full throttle (via pedal or throttle body) - 78%

Surely the max throttle should be 100%, but my main concern is that 15% seems high at rest.

Does anyone have a reading from their 4.0 please?

NB: This is a 1998 4.0 Auto.

 

Anyone?

Someone most have viewed their OBD data to see the throttle percentage?

 

I'll update this thread myself, in the hope that this helps someone in the future.

Previously, by using an OBD scanner, the TPS was showing 13% at idle and 78% at full throttle. I was getting occasional hestitation and aweful MPG.

I have replaced the TPS and now have 17% at idle and 99.8% at full throttle. I have LOTS more power (massive difference) and I hope this helps my MPG. Time will tell.

 

not to hijack this thread, but how do you know when your tps is bad?

I kinda like the sound of more power and better mpg...but i dont know how to tell if mine is working or not working right

 

Try searching for "tps adjustment"...... Cruiser has an excellent write up for it. I think in 96 it got changed to where you can't adjust it but, in said write up it will give you specific instructions on how and where to get the volt out put from the tps.
I do know that it could cause issues with your engine and tranny if it's failing. I would also advise you to get one from the dealership instead of one from any parts store. I think you can get one from Quadratec that's an oem unit too.
Hope I helped.

 

+1 on cruiser54's writeup. A few changes to your '98 though, its not adjustable and the output voltage at full throttle should be 4.5 volts. The TPS plays an important role in helping the AW4 shift or lock up so this could impact your fuel economy.