Modifying EGR for improved fuel economy

[editor at autospeed]

Backlground to EGR - http://www.autospeed.com.au/cms/A_110577/article.html

Modifying the Honda Insight’s EGR -

Part 1 - http://www.autospeed.com.au/cms/A_110555/article.html
Part 2 - http://www.autospeed.com.au/cms/A_110581/article.html

[b1shmu63]

Hi Editor, welcome to the forum.

It's nice to see you chose to drive an Insight. I really enjoyed reading your article on the formerly mysterious EGR valve. In my mind your explanation helps me to understand why a sticking EGR or an EGR with a defective potentiometer (variable resistor) would cause the bucking that has been reported by some owners. It is also nice to see you making mileage mods and documenting them thoroughly.

[tubesguy]

Hi Julian -

Nice to see that you've found a way to post again on the forum. Love the site, and love the frequent focus on the Insight, even if I've gone down the evil turbo-diesel road. - Pat

[Dgate]

I'm confused...in tweaking the EGR part two of the article it states...
All this sounds really good, but if the amount of EGR is too high, combustion can become unstable and so fuel economy (and emissions of hydrocarbons) rise. In practical terms, this can be felt by the car bucking or jerking.

If this is so then why have several owners found clogged up manifold passage ways cause bucking or jerking as well?
This would be the opposite to full flow EGR which he says is causing the problem.

DGate

[editor at autospeed]

I assume that the valve is sticking open rather than closed, or that the valve is slower to close. Opening is caused by the magnetic field of the solenoid, closing I assume by a spring.

[Dgate]

???????

DGate

[editor at autospeed]

1. I have experience the bucking problem that has been previously described

2. Cleaningthe EGR valve fixed it

3. I have found that bucking can be replicated by electronically increasing the amount of EGR that occurs through the clean valve

4. To make sure that in fact the modification of the EGR was occurring in the intended direction, I monitored average EGR valve coil current and also the feedback sensor voltage to ensure increasing feedback sensor voltage did in fact relate to increasing valve current and increasing valve opening.

5. If the EGR valve, when being pulsed in standard form, is slower to close through being carboned up (eg material on the seat, asymmetric open/close behaviour), then the behaviour makes sense.

6. As mentioned in the series, decreased EGR results in quicker throttle response but a slight flat spot when slowly feeding-in throttle. Excessive EGR results in bucking at part throttle. Optimally increased EGR results in improved part load urban fuel economy. Note that I run advanced ignition timing as well; it may well be the combination of advanced timing and EGR which is proving the success.

7. I am a little surpised that people aren't immediately trialling this mod, as it cost less than a few dollars, gives infinite adjustment to the increase, and is very easily implemented in the engine bay.

8. The three very cheap and simple mods - filter on TPS, increased ignition timing and EGR increase have revolutionised bottom-end response and made achieving better fuel economy significantly easier. All for under about $10 total.

[JakkedUp]

I'm confused here. So the procedure is:
1. Use the "increased EGR" configuration. What was your "best" ohm setting out of the 10kohm pot?
2. There is no capacitor used in the setup correct?
3. From the diagram shown http://us1.webpublications.com.au/stati ... 55_6lo.jpg the wht/blk wire is cut a few inches away from plastic connector that plugs into EGR Valve. Wh/blk end from plastic connector soldered to one end of pot. The other wht/blk end is soldered to the variable output of the pot.
4. Grn/blk wire is stripped of insulation 1/4" and the other fixed end of pot connected.
End of EGR mod?

PS, where can we find your "increased ignition timing" mod?