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LMTV CTIS $10 upgrade to ~75psi for Highway

Ronmar

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Well if my math is any good, 75PSI is 136% of 55PSI. So the 20PSI sand setting X 1.36 should net you something under 27PSI? Interesting mod.

Is that new sensor the same physical size as the one you took out? On my PCU the sensor is installed on the front side screwed up into the valve block with the connector pointing down. I had to remove the bottom cover where the solenoid valves and coils are located in order to get a wrench on it to unscrew it... There isnt any room for anything larger with that configuration...
 
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Third From Texas

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Yes, same size (the OEM on mine would have uses a larger wrench to remove, but it had a small copper extension). Body of the transducer and length were the same, though.

One of the guys on FB pointed out that there are some that mount from the bottom so I'm sure there were several adaptations used over the years.
 

coachgeo

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Nice higher for highway.... but offroad sounds too high..... wonder if you could put a Tee there and mount both the send units..... then with a dig thru the schematics to figure out a way to wire them both into things along with a two way switch that selects which sender is to be in operation. With this you would end up having 6 settings available to you.
 
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Third From Texas

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Nice higher for highway.... but offroad sounds too high..... wonder if you could put a T there and mount both the send units..... then with dig thru the schematics to figure out a way to wire them both into things with a two way switch that selects which sender is to be in operation.
Well, for a $10 mod I'm quite pleased. It should save some tread and possibly a bit of fuel on the road. As for off-road, I think 27 psi in the sand should be enough and can always air down further as needed (I do a LOT of sand driving). The 45 psi might be a hair high for xcountry, but again it all boils down to terrain (IMO, the ideal would be to have total control of the presets as well as a manual override...like in the current Arduino mod being worked on).

But for now I just need to troubleshoot why my sand setting is whacky (it was pre-existing). When I press the sand setting, it starts to cycle properly but the does a vent at the tanks then flattens the front left under the driver, and doesn't air down the other three any further. The "Run Flat" button starts to flash and nothing happens until I switch out of sand mode. I haven't looked thru the TM troubleshooting guide yet, but I suspecting a valve or solenoid...
 

wandering neurons

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Nice to know that we can push the CTIS to increase tire pressure, and it's an easy and cheap mod.
BUT WHAT IS THE PART NUMBER AND WHERE DID YOU GET IT???
 

Third From Texas

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Ah, sorry. I had added them to the "What did you do today" thread but forgot it here.

Fixed....

Thanks

eBay search: Pressure Transducer Sender Sensor 0-4.5V Stainless Steel for Oil Fuel Air Water
Amazon search: AUTEX Pressure Transducer/Sender/Sensor 150/200 Psi Stainless Steel Compatible With Oil, Fuel, Air, Water (150 Psi)


*Be sure to get the 150# version
 

wandering neurons

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Fantastic, thanks so much! I missed it in the other thread!
;-)

Ah, sorry. I had added them to the "What did you do today" thread but forgot it here.

Fixed....

Thanks

eBay search: Pressure Transducer Sender Sensor 0-4.5V Stainless Steel for Oil Fuel Air Water
Amazon search: AUTEX Pressure Transducer/Sender/Sensor 150/200 Psi Stainless Steel Compatible With Oil, Fuel, Air, Water (150 Psi)


*Be sure to get the 150# version
 

coachgeo

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North of Cincy OH
Nice higher for highway.... but offroad sounds too high..... wonder if you could put a Tee there and mount both the send units..... then with a dig thru the schematics to figure out a way to wire them both into things along with a two way switch that selects which sender is to be in operation. With this you would end up having 6 settings available to you.
Tom, whom suggested this mod orginally spoke up about the idea of putting both transducers on a Tee.

(after install on tee).... plumb both of them in parallel and have a 3 pole double throw switch to choose between them. New transducer comes with plug, get another plug for the other one and a male plug for the harness and wire it up. No cut wires.
 

mkcoen

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Before I replaced the CTIS controller I simply aired all the tires up to 75psi. Since I wasn't doing any offroading I left them there and it rode great on the highway. Of course after I replaced the controller it automatically aired them down and I didn't bother coming up with a fix.
 

wandering neurons

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I’ll post results in a few days. I’ve got the higher pressure transducer in my M1081. Am leaving Colorado Springs tomorrow morning headed to Reno Nevada driving the truck, pulling my 5500lb zombie emergency response vehicle (HMMWV kit on suburban chassis)
 

Keith Knight

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Thanks for the info. I just ordered the pressure sensor and I ordered a 3 circuit / 3 pole toggle switch from McMaster Carr part# 7343K861 and a 1/8" Tee so I can hook both sensors up and switch between the high and low sensors.

 
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Keith Knight

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I was going to do what ronmar did, I even bought all the parts to do it but my dilemma is that my CTIS is working properly and the CTIS controller does a great job at always checking the pressure and adjusting when necessary. My only reason was so I could get higher pressures but this way I don’t loose any benefits of the controller and get higher highway pressures.
 

wandering neurons

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OK, survived the road trip from Colorado to Nevada, 1000+ miles, across I-70 and US Hwy 50 - a.k.a. America's Loneliest Highway. No failures!!! Some fantastic scenery not normally observed.
Of notes on the drive: Fuel gauge sticks at times, drops 1/8 of a tank after jumping for 15 minutes (suspect the tank sender). Oil pressure gauge had a few fluctuations part of the second day, but otherwise held at 40-42 psi when at running speed. And a strange whistling noise near the charge air cooler when boost is on when climbing hills. and it fluctuates when the cooling fan kicks in. I'm very glad that I had my drive shafts rebuilt, fuel and oil filters changed, and general maintenance. 20,000 lbs of truck, 300 lbs of tools and parts, 300 lbs of lumber in the bed, 200 lbs of me and luggage, and pulling the 5,500 lb Zombie Truck (flat tow).
Found most of my fuel charges and present these results:
High of 8.6 mph, low of 3.6 mph. Low was climbing from the Utah/Nevada border into Ely, NV - lots of headwinds. But there was lots of hills through the whole drive, including 10,250' outside Vail, CO.
Speeds were held to 45 mph except downhill (50 mph) and uphill (30 at times).
Nothing pre-pressure transducer to compare with though. But still impressed with the mileage.
Of note: The steering seems a little heavier with the higher pressure transducer, and I noticed that later in the day, after driving a while, the CTIS would insist on topping off pressure in the tires while driving, rather than just test and go.
As it is said, your mileage may vary...
 

wandering neurons

Active member
249
113
43
Location
Fallon, NV
OK, survived the road trip from Colorado to Nevada, 1000+ miles, across I-70 and US Hwy 50 - a.k.a. America's Loneliest Highway. No failures!!! Some fantastic scenery not normally observed.
Of notes on the drive: Fuel gauge sticks at times, drops 1/8 of a tank after jumping for 15 minutes (suspect the tank sender). Oil pressure gauge had a few fluctuations part of the second day, but otherwise held at 40-42 psi when at running speed. And a strange whistling noise near the charge air cooler when boost is on when climbing hills. and it fluctuates when the cooling fan kicks in. I'm very glad that I had my drive shafts rebuilt, fuel and oil filters changed, and general maintenance. 20,000 lbs of truck, 300 lbs of tools and parts, 300 lbs of lumber in the bed, 200 lbs of me and luggage, and pulling the 5,500 lb Zombie Truck (flat tow).
Found most of my fuel charges and present these results:
High of 8.6 mph, low of 3.6 mph. Low was climbing from the Utah/Nevada border into Ely, NV - lots of headwinds. But there was lots of hills through the whole drive, including 10,250' outside Vail, CO.
Speeds were held to 45 mph except downhill (50 mph) and uphill (30 at times).
Nothing pre-pressure transducer to compare with though. But still impressed with the mileage.
Of note: The steering seems a little heavier with the higher pressure transducer, and I noticed that later in the day, after driving a while, the CTIS would insist on topping off pressure in the tires while driving, rather than just test and go.
As it is said, your mileage may vary...
And as teasers, pictures (no particular order):

Fruita, CO (first overnight)
IMG_2987.JPG

Somewhere, western CO
IMG_4750.jpg


Somewhere, central CO
IMG_4752.jpg

Somewhere, central CO
IMG_4753.jpg

Last day, Cold Springs, NV - SNOW!
IMG_4765.jpg

Family photo, Colorado Springs, CO
Buddy's M-35, an M-35 he is restoring, and Goliath
IMG_4741.jpg

Your intrepid road warrior outside Colorado Springs, CO, start of trip.
IMG_4744.jpg
 
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