Weird EGT readings [Archive] - Diesel Place : Chevrolet and GMC Diesel Truck Forums

: Weird EGT readings


LeroyR
04-17-2007, 09:07 AM
I'll just state upfront I've already contacted Edge and they are up-to-date on this. I just wanted to run it by you guys and see what you think.

Yesterday morning with the Nor'Easter going on, I decided before leaving the house that I would reprogram the Evo down to level 1. Did the normal thing of turning the key to the on position, hit the menu button and selected power programming. Then, instead of selecting a program level, I changed my mind and backed out to the guage monitor screen. When I started the truck, the EGTs were reading 2200 F! Okay ... there's just no way, so I turned the truck off, waited a bit and started it up again. Again ... 2200F for EGTs. Now ... I know this can't be right, so I put it in reverse, backed out and the EGTs went down to what seemed normal. As I headed out though, the EGTs kept going down until they were displaying about 150F. Okay, that's about as normal as 2200F. For a while, the readings were all over the place - 150F up to 1000F over a period of 30s or so - just climbing and then going back down. I've never got a correct reading since then either. Now ... it just stays in the 150 - 200F range with the occasional foray to the 300-400F (or 600-800F) range then back down - then up - then down. I checked the cable going to the probe and everything appears fine. I did not pull the probe to inspect it, but outward appearance is fine. All other monitors are reading correctly - engine temp, tranny temp. I did try changing levels later in the day to see if that changed anything. EGTs are still weird. I also went back to stock (where I am now) and ... well ... at least the EGTs are consistently incorrect on each level. Edge thinks its the cable. Actually, they think it might be the chip in the EGT cable (the little box about a 1/3 of the way up from the probe) and are sending me a new one.

The guy I was talking to didn't think it was the probe because of how the EGTs readings were happening - since usually the resistance changes one way or the other and so do the readings but they don't fluctuate like mine was.

Anyone have experience here? I would rather it have been the probe rather than the frickin' cable! LOL For those of you who have had probes go bad, does this sound correct? I'm not doubting Edge, because from what I know about electronics, a resistor doesn't fluctuate like this. It may raise (or lower) as it heats up, but it doesn't raise AND lower like this. Anyone else had this problem?

There were no issues prior to yesterday. Readings had always been normal (about 800F @ 75mph or so). I find it very (as in TOO) coincidental that happening when I backed out of the power-programming. They didn't think it was related. I'm skeptical, but don't think it's the Evo since the other readings are correct and it will program to other levels. I'm hoping Monty and/or Rob might see this as well. LOL - that cable is a real PITA to run!

Twister773
04-17-2007, 12:52 PM
mine did the same thing but it was more drastic, i was in level 2 towing my trailer. i stop at the grocery store and turn the truck off and then turn the key back on cause the people with me wanted to listen to the radio. the boost was bouncing all over the place...max it hit was 18000 it recorded and 40000 for the egt. I started the truck and it still was going crazy with those two PID's....dont know what the problem was but i sold it and have the hot juice with attitude on its way:D

LeroyR
04-20-2007, 08:13 AM
[ update ]

I'm still waiting on the cable to get here so, in the meantime, I decided to go to level 3 and see what readings I would get at that level. They is still no rhyme nor reason to them, but the monitor displays a little higher set of "no rhyme or reason" numbers. When I rolled into a WOT, the EGT readings went to 2200F. I backed out of it to about 75 MPH and the readings went down to the 500F range for a while then made their way on down to 200-250F. The thing is ... the readings weren't as wildly varying as in stock, lvl 1 and lvl 2.

I'm not entirely convinced it's the cable, but will give it a try once it arrives.

tarmacblack
04-20-2007, 03:36 PM
It sounds to me like a cable issue. During our Alpha test the calibrations were off slightly on the converter boards, and it caused similiar EGT readings. If a part on that board has failed it could likely create a similiar problem to what we saw with the incorrect calibrations.

Keep us updated when you recieve the new "Tail" (EGT cable and converter board).

I do agree, that cable is a PITA to run, Too bad there isn't a more simple way to do it.

Best of luck.
Rob

LeroyR
04-20-2007, 03:56 PM
Thanks for the info, Rob. Having that history makes it more plausible. As to the cable run ... no pain, no gain. :D

LeroyR
04-25-2007, 05:08 PM
New cable run and everything is good. Thanks guys.

Twister773
04-25-2007, 07:02 PM
good to hear