NEW D-MAX /MUX /COLORADO FORUM

NEW D-MAX /MUX /COLORADO FORUM
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PostPosted: Fri May 01, 2020 1:40 pm 
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Joined: Tue May 10, 2016 2:46 pm
Posts: 6
Very interesting discussion on this topic. I will fit a switchable resistor into the circuit, giving me the option, relay switch, of having the EGR on or off depending on conditions and the type of driving I am doing, eg normal driving in town, driving open road or towing the caravan. I have an ultra gauge fitted so should be able to monitor parameters.
The question I ask, perhaps someone can answer is: EGR activates above 5 degC, is that a 100% operation or is it a linear operation as IAT increases? If it is linear then an adjustable resister/potentiometer would be nice, to be able to adjust the IAT that the ECU sees, obviously less than real temp, so as to reduce the EGR effect but not negate it altogether and maybe not totally compromise engine/exhaust temps as some are a feared.
Yep could all be done by some bright person electronically at $$$, but its a 2011 RC Colorado, going good, inlet manifold congestion???? Out of warranty.
The potentiometer could be mounted in the cabin and played with as required, used for extra grunt perhaps and then backed off using the ultra gauge IAT display readings.
Just another project to muck around with in isolation.
Cheers Muzz.


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PostPosted: Fri May 01, 2020 1:59 pm 
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Joined: Sat Apr 04, 2020 7:22 am
Posts: 9
Location: Burleigh Waters
I had one of those munji EGR cables, when i was using it i noticed engine coolant temp was always a couple of degrees hotter..Decided to remove it after I had the egr cleaned and catch can fitted..


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PostPosted: Fri May 01, 2020 3:26 pm 
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Joined: Sat Oct 12, 2013 5:36 pm
Posts: 1628
The Airflow sensor thermistor only tells the ECU what air temp it is so it can calculate the actual oxygen content of specific temp air entering the engine. Not sue, but if the ECU only wants to see if it is below or above 5 Degres then it will act according to its internal data map as soon as the change is detected. Altering the thermistor resistance value via a variable pot may not achieve much at all since the trigger point is reached. The thermistor is an NTC device so becomes less resistance as it is heated. Any mods have to comply with it's characteristics to do anything.

The Munji cable simply took the thermistor out of circuit and inserted a set resistance across the two wires going to the ECU for sensing.


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PostPosted: Tue May 12, 2020 8:21 pm 
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Joined: Sun Oct 13, 2013 6:51 pm
Posts: 789
Location: God's country
My cable has been fitted for 3 years now. The temperature according to my Ultra Gauge 2, is on 86 degrees or so - day in, day out.

Temp does go up higher of course, and the highest I saw it was 94 degrees when towing a heavy trailer on highway speeds into QLD late last year in Summer.

The cable makes no difference to the normal operating temperatures of your 4wd. They are a good thing.


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PostPosted: Sun May 24, 2020 2:43 pm 
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Joined: Tue May 10, 2016 2:46 pm
Posts: 6
Having purchased maf/iat cable connectors from JayDee auto cables and along with a 5k ohm potentiometer/variable resistance from Jaycar, I made up a cable to insert into the maf/iat connector.
The potentiometer is adjustable from 0 ohms to 5.4k ohms. Using the ultra gauge that I have fitted, showing Engine temp, inlet air temp, egr % open and erg % error, I ran a few trials with different inlet air temps dialed into the ECU. Trials were done on flat road with engine warmed up.
Normal connection of the system, ie using the thermocouple in the maf/iat sensor gave the following readings on the ulta gauge: Engine temp 86deg, iat showing the days ambient around 27 deg, egr 10-30% variable on acceleration for a very short time, then 80% on constant speed and deceleration going to 60% at idle.
With the iat dialed into 12 deg on the ultra gauge using the potentiometer the same readings as above occurred.
With 8 deg dialed in using the potentiometer: egr went to 0% on heavy acceleration then back to 10-15% on constant speed and to 60-80% on deceleration and 60% at idle.
With iat dialed at 4 deg: egr 0% on acceleration to 5-7% on constant speed, 60% on deceleration to 5-7% at idle.
The egr% error showed some momentary indication as the egr valve changed value but generally remained at 0% indicating the egr valve was doing as it was told by the ECU..
What to make of that?
egr was never constantly at 0%. Perhaps will dial the temp down further next time to 0 deg to see if that totally negates egr operation.
My thoughts are that at 8 deg iat setting some reducing in egr operation is achieved, more so at 4 deg setting, however running it constantly with a very small opening I suggest
could lead to premature blocking up of the valve. I think it needs to either be totally closed or sufficiently open to keep it clear, so perhaps the 8 deg setting will work.
No comments to make on power gain (subjective) or fuel usage as yet. There were no ECU errors brought up, everything as normal.


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