To CTIS or not to CTIS

[pwrwagonfire]

In your situation and like ours, you are better off disconnecting it and removing it. It takes some work but is worth it.

If you are like our departments these trucks don't get driven everyday, everyweek or sometimes every month like they should. You likely to have flat tires when you get dispatched, not a good thing.

Oh, and purchase at least a couple of the large wheel o-rings that seal the rim. Any one od the military parts supplier on here should have them. If you have a tire repair or a leak, the tire guy should install a new o-ring. Chances are they won't have them on hand!

+100

With an emergency vehicle which may not be used everyday it isn't worth the hassle

 

[shovelheadmike]

I do more off road than on road (not counting parades), and I'd love for my system to work. However, since I'm very often deployed for extended periods, it just is not practical. I'd be coming home to flat tires with damaged sidewalls...

For the purpose of the vehicle that started this thread, and the required reliability, it should be left disconnected. Ask anyone who has/had it, and it seems that it fails when needed the most. Old Murphy...

 

[aztec]

My a3 ctis works great never any problems most if not all problems are poor maint the weak link is man failure allways has a reason

 

[Freight Dog]

I got my 5000 mile, A3 last year with a functioning CTIS. To date, I've put on an additional couple thousand miles, mostly road. The CTIS has worked flawlessly. I activate the system every time I drive the truck.
The middle tire on the right side leaks slightly if I don't drive the truck for about ten to fifteen days. That gives me an excuse to fire up the engine and go for a ride, under the pretext of exercising the system and airing it up. The lowest pressure I have ever operated the tires was around 25 psi.
Selecting, "Highway" brings them quickly up to 45psi. (less than 5 minutes)
We recently had between one and two feet of snow on my property. With the notion that if I was going to get stuck, I wanted it to be at home, I took the A3 out with 45 psi on the tires. It walked through that stuff like it wasn't even there.
Regarding the CTIS, every individual is going to have a different experience to tell you about. At this point mine has been a good one. The government spent vast sums of money for a system that would give you a traction advantage in time of need...at the push of a button.

As a CTIS proponent, I'd say, "Hook er' up".

Freight Dog

 

[Skycop]

Thanks so much for the input everyone! For those of you who have posted about us not driving the vehicle often, you are correct, although we do fire it up and let it run at least every other week and drive it around at least once a month (usually more). I have found that if you don't use it...plan on loosing it because it won't work!

As far as if we ever got ours up and running, we have no as of yet. The guys at our local Guard Armory are top notch and they just got back from deployment. I went over and have a pow-wow and have some plans to bring the truck over there this month (Janurary '11) to have a look-see. I will agree in the O-ring statement though, that regardless of my choice, the o-ring is a must have on hand item. The only problem is that I have had trouble finding them.

 

[2old2humps]

Ctis

I got my 5000 mile, A3 last year with a functioning CTIS. To date, I've put on an additional couple thousand miles, mostly road. The CTIS has worked flawlessly. I activate the system every time I drive the truck.
The middle tire on the right side leaks slightly if I don't drive the truck for about ten to fifteen days. That gives me an excuse to fire up the engine and go for a ride, under the pretext of exercising the system and airing it up. The lowest pressure I have ever operated the tires was around 25 psi.
Selecting, "Highway" brings them quickly up to 45psi. (less than 5 minutes)
We recently had between one and two feet of snow on my property. With the notion that if I was going to get stuck, I wanted it to be at home, I took the A3 out with 45 psi on the tires. It walked through that stuff like it wasn't even there.
Regarding the CTIS, every individual is going to have a different experience to tell you about. At this point mine has been a good one. The government spent vast sums of money for a system that would give you a traction advantage in time of need...at the push of a button.

As a CTIS proponent, I'd say, "Hook er' up".

Freight Dog

Hey Freight Dog, My A3 CTIS also is working with no problems since i got the truck a year ago (odo shows 25k). Your tire leak down is likely the o-ring on your two piece wheel rather than the ctis. I put my spare tire on and no more leak down. The o-ring was rusted to the rim. That tire-wheel assy is tough to take apart, needed a air hyd bead breaker.

 

[lonegunman]

My CTIS worked flawlessly for about a week, my truck has 6K when purchased and two brand new steer tires. I am betting at least one wheel sensor is bad and two tires tend to leak down after two weeks. My truck was an early 1999 built truck BTW.

My opinion would be to leave it off, air the tires up using a compressor or the glad handles, just like an A2 and never look back.

Why? My question exactly, why bother with it. If you local guard guys can get it handled for zero dollars, fix it. It would be pointless to spend money and wasting hours of time fixing something that will break shortly after repair anyway. Especially since it is not required for what you intend to use the truck for anyway.

 

[AceHigh]

The manifold has like 2 or 3 solenoids, so I first thought why not just rig up a few switches to power the "up" solenoid when needed and the "sown" solenoid when needed. Once I got a manifold in my hands I realized that is not possible.

 

[oldMan99]

The manifold has like 2 or 3 solenoids, so I first thought why not just rig up a few switches to power the "up" solenoid when needed and the "sown" solenoid when needed. Once I got a manifold in my hands I realized that is not possible.

I know next to nothing about the system but I was wondering pretty much the same ting myself; Why not just make it a manual system? However, from reading the various threads, it seems that the problems are far more than just the computer part of the system and from what you just said the "Manual option" is not feasible anyway.

To bad really because the concept of being able to change the tire pressure as needed on the fly and keep the tires at designated pressure at all times is really great. I guess it is just a case of either a system that needs more engineering, less complexity, better quality parts a combination of all 3 or maybe it is just better left off and tended to the old fashioned way. After all, since nobody is (usually) shooting at us we should be able to take the few minutes to get out of the seat and walk around the truck and do it. Still in all, a cool concept though....

I wonder what it would take to use one of the several commercially available after market type TPMS (Tire pressure monitoring system) units on these trucks? Do they use the same valve stems as "Normal" vehicles? the TPMS will obviously not adjust your pressures for you but at least at a glance you can see what they are. Note: Some TPMS will give you actual pressure, some only give you a warning that your out of a pre-set range. Of course the actual pressure is much more useful on a vehicle that you will be using different pressure for different driving conditions/loads.

 

[mktopside]

I know next to nothing about the system but I was wondering pretty much the same ting myself; Why not just make it a manual system? However, from reading the various threads, it seems that the problems are far more than just the computer part of the system and from what you just said the "Manual option" is not feasible anyway.

To bad really because the concept of being able to change the tire pressure as needed on the fly and keep the tires at designated pressure at all times is really great. I guess it is just a case of either a system that needs more engineering, less complexity, better quality parts a combination of all 3 or maybe it is just better left off and tended to the old fashioned way. After all, since nobody is (usually) shooting at us we should be able to take the few minutes to get out of the seat and walk around the truck and do it. Still in all, a cool concept though....

I wonder what it would take to use one of the several commercially available after market type TPMS (Tire pressure monitoring system) units on these trucks? Do they use the same valve stems as "Normal" vehicles? the TPMS will obviously not adjust your pressures for you but at least at a glance you can see what they are. Note: Some TPMS will give you actual pressure, some only give you a warning that your out of a pre-set range. Of course the actual pressure is much more useful on a vehicle that you will be using different pressure for different driving conditions/loads.

Most of the after market TPMS systems bolt to the rim through the valve stem. With the current setup, that might make filling the tires difficult. However, I don't think that they "need" to be attached that way to work. I'm sure they could be glued inside the rim in their entirety, they would work just fine. There are a number of different designs out there, and some of them attach to the inside of the rim with a 10mm bolt, those would be easy to attach somewhere.

I wonder if there is a "diagnostic" mode for the control unit? Or if there is a manufacturer specific interface for the computer that allows it to be reprogrammed/reflashed or simply just changed to not be as annoying.


ETA:

http://www.cmautomotive.com/products.htm

Go to the download section on the right and download the .pdf for their products. I'm just reading through it now, at the very least it's an interesting read. Looks like I was right, and they do offer a "programable" option......... if they'll let you buy it.

 

[AceHigh]

The task seemed easy enough when I started. Here are 2 pics of the manifold. Just 2 solenoids and I think a motor. The motor I think directs air to various axles, but I didn't get that far. I tried activating each solenoid but I still could not get air to pass thru.

On the bottom are 4 outlets marked "Tire" (on the A3 only 3 are used, 1 per axle) and the large red outlet. Also is a port marked "Air In" and another marked "PPS"

I still think one could use the existing plumbing and add solenoids.

 

[mktopside]

Looking at the download from CM's site, it looks like they went to great lengths to make sure the bearing area that the air passes through was only under pressure when inflation/deflation was occurring.

..........another thing to worry/obsess about I guess. LOL

 

[Disciple]

If you're not using the system all the time (you wouldn't unless transitioning between some pretty serious off-roading and pavement at least once a week) check these out. I'm sure many of you already know about it, but just mount one of these tanks on your truck. They run on CO2 and are much better than compressed air or even most compressors.

[URL]http://www.offroadair.net/OAbrochure.pdf
[/URL]

 

[mudguppy]

... I still think one could use the existing plumbing and add solenoids.

i'm with you - if the axle lines are already plumbed, why couldn't you add 3 (or two if you tie the rears together) 3-position valves to either fill, block, or dump air from the tires...?

... the bearing area that the air passes through was only under pressure when inflation/deflation was occurring. ...

could you explain more? i don't understand how this is possible unless there is a valve on the outside of the hub.


<popcorn>

 

[mktopside]

i'm with you - if the axle lines are already plumbed, why couldn't you add 3 (or two if you tie the rears together) 3-position valves to either fill, block, or dump air from the tires...?




could you explain more? i don't understand how this is possible unless there is a valve on the outside of the hub.


<popcorn>

:::: I dunno.

Download the zip file I linked to at the end of page three. It's from CM's site and it talks about how their system minimizes pressure in the bearing area by depressurizing the lines from the manifold to the wheel valve, so that the bearing seals last longer.

 

[AceHigh]

Looking at the download from CM's site, it looks like they went to great lengths to make sure the bearing area that the air passes through was only under pressure when inflation/deflation was occurring.

..........another thing to worry/obsess about I guess. LOL

That surprised me. When I replaced the manifold, with all the tires in the 40 psi range, I simply disconnected the air lines- no pressure anywhere and none of the tires deflated.

 

[oldMan99]

There was discussion of after market CTIS.

Gentlemen, I give you:

YouTube - TirebossVideoPage's Channel

Their homepage: Tire Pressure, Tire Pressure Monitors, Tire Pressure Table, Tire Pressure Gauge, Tire Pressure Sensors - Tire Boss

It looks flimsy as all **** but they say it is designed for oil field, forestry/logging, construction the do show some interesting pictures and a ton of videos.

I thought it was interesting if nothing else.

 

[MATT]

The TireBoss system is a great idea but those air lines sticking out will get torn off! It's amazing what a little, or lack of, air pressure can do.

I think the wheel seal/o-ring design of the A3 is a huge improvement though. I don't see a way gear oil could ever contaminate the brake shoes unless the inner bearing o-ring fails. Yah?

 

[rwoods]

Having owned two A3 my are as follows: 1) A functioning CTIS will inflate a tire much faster than you can manually. 2) Not all flat tires common to A3s are CTIS related. 3) The A3 was clearly modified for a desert environment. Bushwacking will likely take out some CTIS air line which will limit or eliminate it's use. (Off topic but related to the A3's intended use, a w/w A3 can easily lose its oil tank in rough hard pack terrain and can easily lose an air line or fitting in the brush; either of which can render the winch useless.) 4) Functioning wheel valves are critical to proper inflation- ( I have one that always deflates the tire to 35 psi once it hits 45 psi so the CTIS just recycles. And I have one that doesn't deflate so it will continue inflating pass 45 psi.)

My conclusion is if your use includes bushwacking, I would lean towards disabling the system. In other situations, if your tires hold air and the system works then keep it; if it doesn't work and the fix is simple then fix it. If the fix is complicated, I would forget it. If your tires don't hold air, then as your's is an emergency vehicle find and fix the leaks and if it is CTIS related fix the CTIS if simple and if not then disable it.

Ron

 

[AceHigh]

Functioning wheel valves are critical to proper inflation- ( I have one that always deflates the tire to 35 psi once it hits 45 psi so the CTIS just recycles.

That is interesting! I noticed that sometimes my pressure gets to 45 then drops pretty quickly. I just thought it was the CTIS system. Now when I activate the system I run it up to about 43 then shut it off and it holds. Strange!