ECO Mod: Howto reduce level of enrichment when cold

[Cobrajet]

And that's great. A flash or component replacement by the manufacturer is fine.

It's a re-flash. I had it done on mine. Glad to hear the cold-start enrichment can be corrected with some ingenuity and without a trip to the dealer, though.

[Eggman]

R1 x (R2 + 2500 Ohms)
----------------------------------- = resistance of the modified circuit at a given temperature.
R1 + ( R2 + 2500 Ohms)

For some reason that equation doesn't look right to me. I thought calculating parallel circuits dealt with the reciprocal of the sum of reciprocals.

I forget the formula - it's been a while since I've done this. But I think I see what you are saying.

[flatbroke]

It's a re-flash. I had it done on mine. Glad to hear the cold-start enrichment can be corrected with some ingenuity and without a trip to the dealer, though.

I can't sugar coat this, that's a hack job repair. You go to the dealer, you sit in the lounge and have a cup of coffee and a doughnut while watching ESPN or checking facebook, while a qualified tech does an update on your ECM. Costs you nothing other than a little time and a little gas.Sounds much better than trying to booger an extra coolant sensor into a factory engine harness.

[foama]

For some reason that equation doesn't look right to me. I thought calculating parallel circuits dealt with the reciprocal of the sum of reciprocals.

I forget the formula - it's been a while since I've done this. But I think I see what you are saying.

The formula is definitely correct for the total circuit at whatever given temperature.
You could compare that value with the value of the unmodified circuit, and look it up in the graph what that value means in terms of reported temperature. That is the difference this mod makes.
You can try it or leave it, I have it working in the Mirage and also in a completely different other car.


The point is, this mod reduces the enrichment below whatever the ECU would otherwise do.

Its fine if they reflash your ECU because enrichment is way too much, but thats a different issue.

[cyclopathic]

Forgive my ignorance but does Mirage have one sensor or two?

DSM had 2 sensors. ECU was going nuts until we replaced the 2nd one. There was no errors on OBD2 reported to indicate that this was an issue.

[Teasmade]

Forgive my ignorance but does Mirage have one sensor or two?

DSM had 2 sensors. ECU was going nuts until we replaced the 2nd one. There was no errors on OBD2 reported to indicate that this was an issue.

Having looked at the service manual and circuit diagram, it appears there's just one sensor. That'd make sense to my mind; in the past I've owned a couple of Mitsubishis with the twin coolant temperature sensor setup - One fed the ECU and the other was there solely to give a readout to the temperature gauge in the instrument cluster. Seeing as we don't have a temperature gauge, there's no need for the second sensor.

[Cobrajet]

I can't sugar coat this, that's a hack job repair. You go to the dealer, you sit in the lounge and have a cup of coffee and a doughnut while watching ESPN or checking facebook, while a qualified tech does an update on your ECM. Costs you nothing other than a little time and a little gas.Sounds much better than trying to booger an extra coolant sensor into a factory engine harness.

The reflash may not be an option for people outside the US, and it sounds like the OP is in Europe.

[Eggman]

I can't sugar coat this, that's a hack job repair.

There is no need for sugarcoating - it's not a repair. And I don't recall anyone asking you to do it to your car. However, I am glad for your insights on the pitfalls on these types of modifications. And I must agree - it's one heck of a hack job.

---

The formula is definitely correct for the total circuit at whatever given temperature.
You could compare that value with the value of the unmodified circuit, and look it up in the graph what that value means in terms of reported temperature. That is the difference this mod makes.
You can try it or leave it, I have it working in the Mirage and also in a completely different other car.


The point is, this mod reduces the enrichment below whatever the ECU would otherwise do.

Its fine if they reflash your ECU because enrichment is way too much, but thats a different issue.

foama, here is what I figure the change will do.

Temp	R1	R2	R3	R2+R3	Total	≅℃
-40℃	50㏀	50㏀	2.5㏀	52.5㏀	25.65㏀	-30℃
-30℃	28㏀	28㏀	2.5㏀	30.5㏀	14.6㏀	-20℃
-20℃	15㏀	15㏀	2.5㏀	17.5㏀	8077Ω	-10℃
-10℃	9㏀	9㏀	2.5㏀	11.5㏀	5048Ω	5℃
0℃	6㏀	6㏀	2.5㏀	8.5㏀	3517Ω	10℃
20℃	2.2㏀	2.2㏀	2.5㏀	4.7㏀	1499Ω	35℃
40℃	1.1㏀	1.1㏀	2.5㏀	3.6㏀	843Ω	50℃
60℃	600Ω	600Ω	2.5㏀	3.1㏀	503Ω	65℃
80℃	300Ω	300Ω	2.5㏀	2.8㏀	271Ω	82℃
100℃	170Ω	170Ω	2.5㏀	2670Ω	160Ω	100℃
120℃	100Ω	100Ω	2.5㏀	2600Ω	96Ω	120℃

Notes:

• Since I don't have the actual sensors on hand for testing, all figures are approximate based on interpreting the sample performance chart provided.
• The calculations took a bit of time (for me) but not too much. I hadn't done such calculating for a while, so it was good to brush up. There were only eleven data points. If anyone cares, I would appreciate someone checking my math!

If you like, it could be included in the first post rather than be buried at the bottom of the thread.

Thanks for sharing this clever modification.

[cyclopathic]

Looking at calculations above IMHO it is just easier to block radiator.

[Eggman]

Looking at calculations above IMHO it is just easier to block radiator.

That, a engine heater, and this sensor circuit mod. Who will be the first?

Keep in mind that the value of R3 can be adjusted for different results. I think foama selected a value that produces mild changes without throwing off the operating temperature readings too much. I think his set up is rather clever. He could have gone with a more aggressive value.

I developed the chart to start that question off - what if we changed R3? Also, what exactly are the real world results of testing the entire setup, rather than guess at it? Put the sensors in a pot of boiling water and measure away.

P.S.: Don't forget a warm air intake. 3Dplane - what do you think?