2.5 TPS Adjustment

[TeKdo]

Hey guys just wanted to double check how people are setting the TPS on the Renix 2.5 because I've been getting less than stellar gas mileage since I replaced mine.

 

My OEM TPS died after 40 years which is a good run so I replaced it with a Standard Ignition part.

 

Right now, I have the output voltage set to 17% of the input voltage with the ISA fully retracted as it would be when idling at a stoplight. I set the output to 17% of the input because that's what cruiser recommended and what the '90 fsm recommended as well.

 

Just wanted to clarify that I was setting the TPS at the right ISA position and at the right percentage of output voltage.

 

I've been averaging about 16.8 to 17.5 mpg for 90% city driving.

 

Only major mod this truck has is an AX15 and NP231 swap (from the stock AX5 and NP207). It does have all new sensors except for a MAT sensor because I can't find on that is the right specs.

 

Other than that it's a bone stock Comanche  235/75/15s on stock wheels. Dana 30/35 combo and 4.10s. it does weight right around 3700lbs with me in it and with about 12 gallons of gas but I don't really see why I'd be getting mediocre mileage around town with this truck when it used to average 18 to 20 around town during the summer other than a weirdly adjusted TPS.

[89 MJ]

In my opinion, 16.8-17.5 isn't terrible mileage for being in town.

 

Were your previous mileage calculations with the AX-15 as well? Being that the AX-15 is a heavier duty transmission than the AX-5, it would make sense that the new transmission would take more power and reduce fuel economy. 

Is your speedometer still accurate since the trans swap? If you got a different tooth speedo gear in the transfer case, both your speedo and odometer will be off, making your fuel mileage calculations off. 

Do you guys get winter blend gas in WA? It is common to get worse mileage in the winter.

 

[eaglescout526]

There’s actually a different adjustment procedure for the 2.5L than the 4.0L in cruisers tips. I really need to go and find the tips to tell 2.5Ls to advise against that tip. The TPS output voltage at WOT should be about 4.63v. 

[TeKdo]

20 minutes ago, 89 MJ said:

In my opinion, 16.8-17.5 isn't terrible mileage for being in town.

 

Were your previous mileage calculations with the AX-15 as well? Being that the AX-15 is a heavier duty transmission than the AX-5, it would make sense that the new transmission would take more power and reduce fuel economy. 

Is your speedometer still accurate since the trans swap? If you got a different tooth speedo gear in the transfer case, both your speedo and odometer will be off, making your fuel mileage calculations off. 

Do you guys get winter blend gas in WA? It is common to get worse mileage in the winter.

 

 

The old calculations were with the AX15.

 

The speedo and Odo are also accurate to both GPS and gear calculator specs.

 

We do have winter blend gas here in WA and I knew that it would get less mpg than normal summer gas but I didn't think it'd be 4 to 5 mpg

[TeKdo]

33 minutes ago, eaglescout526 said:

There’s actually a different adjustment procedure for the 2.5L than the 4.0L in cruisers tips. I really need to go and find the tips to tell 2.5Ls to advise against that tip. The TPS output voltage at WOT should be about 4.63v. 

 

A process like that is kinda what I was suspecting. I remember nickintime talking about that in one of his 2.5 videos, but he never went into the process of how to do it with a voltmeter...he just used his REM system to find when the TPS read as fully closed.


Is that 4.63V regardless of input voltage btw? I know that the input voltage for my sensor reads a 5.13 or 5.15V.

[89 MJ]

34 minutes ago, TeKdo said:

 

The old calculations were with the AX15.

 

The speedo and Odo are also accurate to both GPS and gear calculator specs.

 

We do have winter blend gas here in WA and I knew that it would get less mpg than normal summer gas but I didn't think it'd be 4 to 5 mpg

Ok, just figured I’d check

[eaglescout526]

17 minutes ago, TeKdo said:

Is that 4.63V regardless of input voltage btw

No it’s output voltage to the ECU. The acceptable range is 4.62v-4.65v for proper adjustment. I always set mine to 4.63 or 4.64. Nice middle ground. 

[TeKdo]

3 minutes ago, eaglescout526 said:

No it’s output voltage to the ECU. The acceptable range is 4.62v-4.65v for proper adjustment. I always set mine to 4.63 or 4.64. Nice middle ground. 

Cool, I will be trying that adjustment when I get off of work tonight.

[eaglescout526]

It’s at wide open throttle. So you’ll have to have something hold the throttle open while you do the adjustments. 

[TeKdo]

1 minute ago, eaglescout526 said:

It’s at wide open throttle. So you’ll have to have something hold the throttle open while you do the adjustments. 

That's what I have my brother for lol