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CTS 2, EGT probe?

5K views 10 replies 8 participants last post by  D_R_C 
#1 ·
Do I need to install EGT probe in my 2015.5 to monitor exhaust gas temperature?
I plugged my cts2 in and there is a post turbo EGT temperature reading and it works.
Why do guys install probe in manifold?
I try to search and couldn't find answer.
Thanks.
 
#2 ·
It depends on how you use or drive your truck. If you tow or like to show people what your truck has under the hood.....then yes i would say you should have an EGT in the manifold. If you use it like an everyday commuter car then you dont really need to have one IMO.

In regards to your second question. The reason to put one in the manifold is to get a temperature as close to combustion temperature as possible. Believe it or not, the post turbo EGT that you can view currently can be up to 400 degrees different from what you are actually seeing in the manifold for temperature. I have both and that is what i have seen through the years of driving my 15 LML. What this means is if you are towing or getting on it hard and you are seeing 900 degrees after the turbo, you are probably seeing 1200-1300 degrees at the manifold. Not keeping EGTs in check can do some not so good things to a motor.
 
#3 ·
the goal of the manifold mounted probe is to capture as close to cylinder temperature as possible. The goal of that sensor is not to protect the exhaust components but to tell you when to back off so you dont melt a piston. As stated above, if you are not pushing the truck to the point where your likely to hit high EGT's then its still advised, but optional. If you are using the truck in a way where you regularly hit high EGT's then 1, you should probably change some things either via tuning or adding air to bring temperatures down, but you should absolutely be watching the manifold temp. By the time the exhaust makes it to the factory sensor it will be much cooler than it is at the cylinder port due to expansion.

The worst thing you can do is have a high HP tune, with a factory turbo, big injectors and start towing heavy up a hill. That for example would be an excellent recipe for a melted piston and, while this situation should not exist to start with, if it had to for some reason, an EGT monitor in the manifold would be the only thing possibly able to keeping you on the the road considering you could almost forge steel at the temperatures your likely to hit inside the engine.

on the other hand, if you have a stock truck with a light tune, your likely safe unless you really push the truck to its limits.
 
#4 ·
OP hasn't specified if he's tuned or not. I drag a 15,000lb 5iver thru the mountains with a stock truck & don't have a manifold probe, and have no issues, truck looks after itself. If you're tuned ya, you probably wanna install a probe.
 
#6 ·
Even on my stock truck I wanted the probe in the manifold for shut down purposes. I like to know my EGT's are below 375deg before shutting it down. You could go by post turbo but I've found there is a significant delay between pre turbo and post turbo readings.
 
#7 ·
There ya go! How often do you see people pull off highway to fuel and shut down less than 1 minute from offramp. Gotta cool down that turbo man whether its a little turbo-4banger BMW or a semi truck. I'm looking for a cheap monitor now just so I can see shut down temps, it is driving me a bit nuts idling off highway for 5-10 min "just in case", or when I'm fueling with truck idling and some snowflake tells me I'm gonna blow the whole station when the non-combustible diesel vapors spontaneously combust. The drive-thru's get you too! You exit highway and pull into a what-a-burger, they can't hear you over engine noise...… so you shut the motor off or let the turbo cool first? Show me the damn temps. This should be a standard gauge in all factory turbo'd vehicles, especially with all the turbos going into small motors nowadays
 
#11 ·
Install a aftermarket flowing airfilter then watch those EGT's drop twice as fast after pulling a long grade when your waiting for the EGT temps to drop before you shut'er down.
Another plus with a aftermarket flowing airfilter your EGTs will run a little cooler compared to having a stock paper airfilter.
Cooler EGT's = being able to push it a little harder to get up that steep grade.
 
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