Recently, I have noticed that my EGT's are running higher than usual. In the past, EGT's at idle tended to be around 300 or so. Recently, temp at idle is 400-500, and my economy is down 1-2mpg. When the truck was at the dealer, they checked fuel flow, return, injector flow, balance rates, etc and said they where all fine. The ambient temp is around 95*. Can a 30 or so degree increase in ambient temp cause 100-200 degree increase in EGT?

Once the truck has gone back to the dealer again this week to replace another hose associated with the P/S and brake system, I will be putting on my MBRP pipe. Is it possible my cat is becoming restricted (I have about 32,600 on the truck)? I know my grandfathers plugged within two years while pulling his trailer from AK to NY, and I don't want that happening to me, hence the MBRP pipe.

No a 30 degree rise does not equate to another 100F increase.

Check your air filter for restriction.
My first thoughts lean towards injectors.

Check your air filter for restriction.
My first thoughts lean towards injectors.

I just replaced the air filter, so we'll see about that...

Injectors was my first thought, since idle is a touch rough (not real bad), economy has gone down, and the increased EGTs, but they said everything checked out ok... When the truck goes back for the accumulator and hose replacement, I'll ask for a printed report of the fuel ystem tests...

Could also be a probe on it's way out.

I would check it against a different EGT probe.

O crap, Almost forgot check your MAF for any contaminants especially if you have an aftermarket air cleaner!

The EGT Gauge/probe is only about 7 months old... If it was going bad causing the high reading, wouldn't it be off all over? I turned the ignition on this AM after the truck had sat all night, ambient temp was about 80*, and the needle on the gauge sat just a touch above the 75* mark.

When I replaced the air filter last night, I looked in the intake tube and it's clean. I have the stock airbox, and have always used paper air filters.

Cougar, I have had faulty probes right from the box before. Can you source another one and test them out?

Cougar, I have had faulty probes right from the box before. Can you source another one and test them out?
Errr... not really, unless someone nearby here in MO or BIGBLOCKBILL has an Autometer Pyro that the pyro could be temporarily borrowed...

When I first start the truck, it sits around 200-300*. Once I've been driving it, it typically won't drop below 400* when sitting.

Well, Maybe you can 'borrow' one from another member who is close.

I have 2 on hand at all times (all good ones as tested, but for how long: 3 months 3 years or any other WAG)

Just trying to eliminate any variables (cheap stuff first)

Well, Maybe you can 'borrow' one from another member who is close.

I have 2 on hand at all times (all good ones as tested, but for how long: 3 months 3 years or any other WAG)

Just trying to eliminate any variables (cheap stuff first)

True... After I drop my truck off at the dealer for the Accumulator replacement, one of the Power Steering/brake booster related hoses replaced, hopefully my RR tire (reason (True...%20After%20I%20drop%20my%20truck%20off%20a t%20the%20dealer%20for%20the%20Accumulator%20repla cement,%20one%20of%20the%20Power%20Steering/brake%20booster%20related%20hoses%20replaced,%20ho pefully%20my%20RR%20tire)), and maybe the steering grind while turning left, once I get it back, the MBRP pipe is going on ASAP, so we'll see if that makes a difference... Is there any good way to test the probe?

True... After I drop my truck off at the dealer for the Accumulator replacement, one of the Power Steering/brake booster related hoses replaced, hopefully my RR tire (reason (http://True...%20After%20I%20drop%20my%20truck%20off%20at %20the%20dealer%20for%20the%20Accumulator%20replac ement,%20one%20of%20the%20Power%20Steering/brake%20booster%20related%20hoses%20replaced,%20ho pefully%20my%20RR%20tire)), and maybe the steering grind while turning left, once I get it back, the MBRP pipe is going on ASAP, so we'll see if that makes a difference... Is there any good way to test the probe?

Yes. Test them using an ohmeter VDC and electrical resistance at room temperature

3-5% good.... more than that no. IIRC McRat has the values for what the temp readings are corresponding to temps.

I just had a bad probe, took about 4 months for it to go bad, read 2187 at idle and pretty normal under boost, I called Edge Product techs and they said the probe should ohm out at 1.5 to 3 ohms, since mine was a complete open when it was cold I knew it was bad, they sent another free of charge.