tps filter mod=more lean burn?

[budomove]

someone posted this link on Red's ongoing ecomodder thread yesterday:

http://autospeed.com/cms/A_110187/article.html

doesn't sound like the results are really conclusive.

[kapps]

Interesting. It's nice to see some actual A/F data as to how lean these little engines get. This mod may help new drivers that are used to more abrupt throttle movements but experienced Insight drivers are probably already used to the correct throttle movements. I have no problem edging the throttle right down to the verge of going out of lean burn by simply watching the mpg readout. I've been using this same technique to get good mileage in my MINI Cooper S using a boost/vac gauge.

I do have a couple concerns regarding this modification though. If this mod delays the signal to the ECU, what happens when you quickly hit the accelerator? The throttle body is going to let in a lot of air but the ECU still thinks your cruising. This could be dangerous if things get too lean. Also, if you're accelerating hard and let off, things could get way rich (not very dangerous but not good for mileage). I'd still prefer a more instant reaction at the pedal and let me worry about how I actuate the throttle.

[editor at autospeed]

Works very well. Have monitored real time AF ratios there are no problems. ECU uses MAP sensor as major determiner of load and that reacts as standard.

[JimIsbell]

The desensitizing is not so aggressive that it will cause harm. Unless you make it so. The filter, as I have it is a 5.1K resistor and a 100 uf capacitor and the filtering is just enough to take out the little bumps that EVEN an experienced driver, cannot take out of the road you are driving on. One of the roads I drive on is somewhat rough and you cannot always anticipate EVERY bump, especially on a strange road. If the tires are hard, as they should be, the bumps can knock you out of lean burn. But this mod smooths the response, doesnt delay it, just smooths it so that you don't drop out when you hit a rough road or get a gust of wind. There is a website in OZ that shows the scope pictures of the filtering, I cant find the link right now. Any delay is microscopic. What is important is the removal of jitter and spikes.

[JimIsbell]

Here's the link. The previous poster is the editor there? http://autospeed.com/cms/A_110187/article.html

[Insightful Trekker]

From an electronics perspective there's no issue.

As far as MPG improvment, I've not expereinced such roads that "knock" me out of lean burn so I have no experience there.

From an automotive engineers perspective its not so clear cut. And given _all_ the many different driving conditions expereinced by the Insight fleet adding this slop to the TPS _can_ and is (under some driving conditions) a _step_ in the wrong direction.

In and of itself enough to do damage? Unlikely. But have other sensor(s) pushing a/their limits due to aging or pending failure and the sum of the whole _can_ do bad things to the combustion process.

I only post this to help balance the the tone of this thread. No modification is the best thing since sliced bread.

I could post many parallel examples from first hand expereince. Sure it can be fun, and is definitely a learning expereince. Just do it with your eyes wide open. And don't pay ($$$) more than the fun is worth, or the value of the lesson learned.

Sincerely,

[uhtrinity]

Here is the thread that mentioned the TPS mods back in April.
viewtopic.php?f=4&t=7484
I still have the mod installed, set at 5k ohm / 100uF, and it still does what was intended, mainly helping the driver stay in lean burn. As I stated in that thread, it also allows me to lock assist / regen with mima, which I could rarely do before do to bumping the throttle.

[JimIsbell]

Another thing that may be being missed here is that the mod does not JUST smooth the operators "footprint", but any potentiometer, such as the one in the TPS is prone to "noise" that is generated by the contact sliding over the resistance. This "noise" could be a big factor in keeping in "lean burn" especially as the cars age. This filter will take out much if not all of the noise.

I know that since I added the filter I find myself in lean burn almost 60% of the time in town while before I could only manage 20% of the time. I have yet to try it on the highway on a trip but if its as good as I think it is I should be able to manage 80% or better on level ground. That will be a big improvement.

I am leaving on a 2800 mile trip this Friday and will report back on the mileage as time permits

I will be using the TPS filter, Cold air induction, and experiment with AC shut down when climbing hills. The car will be fully loaded with my wife's perceived needs for such a trip, my wife, and the AC will be running for the whole trip (not sure if that last comma has to be there or not...# My last long trip average was 75 MPG. I hope to get better that that on at least part of this trip from Corpus Christi TX to Austin TX to Corsicana TX to Tyler TX to Fayetteville AR to Columbia MO, to Algona IA, then return.

[Insightful Trekker]

Originally Posted by JimIsbell

I will be using the TPS filter, Cold air induction, and experiment with AC shut down when climbing hills.

"Cold" air induction has been shown to _reduce MPG_ and narrow the lean burn window. Presumably due to poorer fuel vaporization and is more significant in cooler weather.

A/C on is an MPG killer +10%. You will be able to "recover" some of the losses by reducing the engines load on the uphills. Same technique as "rollercoastering" the hills for hyper MPG.

HTH!

[JimIsbell]

When I say "cold" air induction. I am referring to the relative state. Here in S.Texas, cold air is 90F, under the hood air is 160F or more.. "cold" air induction has shown to increase MPG on my car in my climate. I havent had it in the winter yet, but the low use of the AC will help then.

In the winter....60F ....I will switch back. We dont have a real winter down here.