EGT stuck at 32 degrees.. Need a little help

[sean3073]

2007.5, 6.7L --- Have a mini max, DPF EGR Delete. Bought the entire kit back when it was sold with a factory plug in pyro, you just screwed it on in the block off plate next to number 6. Started getting erratic readings, 0 all the way to 9000. Did some reading, and every one said replace the probe. Well the factory "H&S" plug in probe is not sold any more. So a local shop whom I have trusted for years said, here is one, just cut the wires and splice it into the old connecter. Sounded good to me. Ran home and did that. Now my EGT says 32 via the Mini Max.

Here is what I have learned. All the after market probes work differently than the one I purchased way back when with the kit. The one I purchased years ago is a resistance style probe. I tested several OEM probes with a fluke and found the following; at 70 degree's they all read around 250K ohms. I would blow on it with my breath they would drop to like a 170K. So that answered that. I then checked the resistance to the probe he sold me and it has none. Indicating, and I might be wrong, but a "K" style. In short it generates it's own electricity. So then I checked the factory wiring harness to see if I had an issue there. It's putting out 4.9912 volts. With a factory probe plugged in or not, it's reading 32 volts.

Any ideas?

 

[sean3073]

Below is what I sent to another forum, hope this clears things up and helps some one. Still need help though.

Let me be a lesson to everyone in the community, there is up to 3 different types of "Pyro's". Some use dissimilar metals to generate an electrical current, others use the resistance. The resistance pyro's have to have voltage applied through one wire and a computer to see how much made it through the other wire. Our factory pyro's use 5 volts and resistance. It is an extremely fine and accurate piece of equipment from what I can tell in reading 12 hours on the subject now and going through factory service manuals. Let's talk Mini Maxx and other "Universal" pyro's. You can no longer get the factory style Mini Maxx plug in Pyro. That is the one that when you do the EGR delete you remove the cooler, install the block off plate next to the number six cylinder, and install the pyro in that block off plate. That pyro back then plugged into the factory wiring harness, next to the intake manifold, or where the EGR valve use to be, “prior to delete”. Basically it came with about a 5 foot braided wire, a factory style plug and it went along the fire wall and plugged right into your wire harness. So, on the Mini Maxx you would select “Factory Pyro”. What that does with the Mini Maxx is allow you to read what is coming across the CAN. It should be noted you can also see where it permanently assigned a temperature of 1820 or something like that to the pyro next to the DPF. Pyro 2 I think. So to come full circle, that plug in has been HAMMERED by the EPA and is no longer available due to the fact you have to delete your truck in order to even want to own one. Now,,,, all the aftermarket pyro’s with the PCM boards and extra wires use their own method of reading. Of which I have not looked into what it is, but I can tell you because I purchased and might have destroyed my ECM, yes that’s right, I might have ruined some circuitry in the section that reads voltage for a pyro, is that the aftermarket pyros that get hooked up to a PCM then to whatever displaying the information for you has ZERO resistance going across the leads. I mean ZERO resistance. That tells me they are using the type of pyro that generates its own electricity. To give you a comparison, factory and the old Mini Maxx pyro set up at 70 degrees F had around 250K ohms. I have on my shelf 3 brand new, OEM pyros from GM and I tested them all. In fact I can tell you that if you put one in your hand and blow air on it from your mouth to heat it up it goes down to 170K. All of them produced the same numbers. Anyway, to finish here, a local diesel shop said hey just use the old wire, and splice the new one into it. I thought to easy. Might not be a perfect match but seemed sound to me. Remember I had no idea that pyros came in different flavors and I really should have done my homework. So I did just that, effectively taking the very finely calculated 5 volts from the trucks ECM and directly putting it to the sensing wire back into the ECM. BAD BAD BAD!!! So all, please learn from my mistake, pass it along, DO NOT take an aftermarket pyro and just plug it in to your factory harness. Although I am not sure you can even buy one now.
I have spent HOURS now tracing wires and I am far from done, but I am hoping someone out there has had this problem and has a fix. I can tell you now it always reads 32 F unplugged from any sensor, and when I put a jumper wire in, effectively taking 5 volts and ramming it back to the ECM it reads 0 when I do that. It should read like 9,000 degrees.. When I remove the jumper it goes back to 32. I have also plugged in factory pyro’s, they all read 32. Anyone know a Cummin’s tech? 

 

[sean3073]

Ya, I am going to try something new. Call it throwing money at a truck, but I broke down and bought the kit, the H&S pyro kit with the PCM board. Any way, that is a K style Pyro, it produces a small amount of current based on temp. Not the way the factory ones work, resistance. Ok. I have to tell a bit of a story, then ask for some feed back. The other day I was riding with a buddy of mine whom has the same kit as I but he runs with the K style "PCM". I looked over and his temps where way low. His set up until my issue was the same. Example, 60 degrees, cold soaked truck, mine would idle around 350 to 400. Exactly what I expect. His truck, 200. Then driving down the road, 400, 500 or so if memory serves. WAY TO LOW. So here is the deal, 200 at an idle is not enough to boil water. Gentlemen we are running hi compression engines, hot enough to start a fire just cause of it. 350 400 at an idle is about right, but now that I have installed the H and S pyro kit with the PCM board, all my temps are way low, to the point of it being pointless to even have it installed. Or better put, mine are just like my friends that I noticed in his truck. I propose to all of you, What are your average idling temps. Please pass them to me. I want to compile some info. I have a distinct feeling that H and S has the temp arch curve programmed wrong. Let me add this, the pyro "PCM" style or K style is very accurate cold soaked. It matches my transmission, coolant on and so on. Start the truck and it's way off. Put my foot in it, and it's cold to the tune of 200 to 300 degrees. Remember the K style, "one currently sold by H and S" is a program run display. What i mean by this is that little computer board we all have shoved the yellow and red wires into then ran the USB cable to the little black box prior to the Mini Maxx is nothing more than a programming arch. Example, .0034 milli volts = 58 degrees, or on and so on. .0051 milli volts = 280 degrees. I am making these numbers up, but you all get the idea. I have started looking at how other units operate. The stand alone types that would connect into like isopro. "sp?" Any way, if you gents would be as so kind as to just leave your idle temps for me it would be great. It would immediately show the community that something is wrong with the HS "arch". Sean

 

[mfurrh55]

idle temp on mine is 350 deg.

 

[RustyJC]

With all respect, it appears to me that you went into this without understanding the difference between a thermocouple and an RTD (resistance temperature detector). Both are explained in the links in the previous sentence.

Rusty

 

[Bob4x4]

Why not just use a factory sensor??

 

[sean3073]

RustyJC, Very cool. I did not know the name of it. Thank you.. You said previous sentence?? Not seeing it, unless your referring to what I typed earlier. Thanx again. Sean

 

[sean3073]

Bob4x4, I have thought about that, but I am not sure the thing can take the beating it would receive two inches from the exhaust valve.

 

[sean3073]

With all respect, it appears to me that you went into this without understanding the difference between a thermocouple and an RTD (resistance temperature detector). Both are explained in the links in the previous sentence.

Rusty

Rusty, I just found the link's. Sorry. thanx again for the info.. You seem smart on the subject, what are you running for a sensor?

 

[HHhuntitall]

Sooo, you say they discontinued the thermocouple? I find that surprising, not saying you're wrong... They're still listed on the H & S's website as part number 709401.... Will it still not work with the older Mini Maxx's? http://hsperformance.com/store/acce...-mini-maxx-includes-thermocouple-and-pch.html

 

[RustyJC]

Rusty, I just found the link's. Sorry. thanx again for the info.. You seem smart on the subject, what are you running for a sensor?

Nothing on the 2011 - this truck's stock and in (extended) warranty. I ran a type K thermocouple on my 2002 with a pyrometer.

Rusty

 

[sean3073]

Nothing on the 2011 - this truck's stock and in (extended) warranty. I ran a type K thermocouple on my 2002 with a pyrometer.

Rusty

Rusty,
Thanx again for the info. I have done a ton of home work on all of the different subjects, "thanx to your help with RTD" and I am kind of amazed at what I have found. I am thinking of doing a video showing me testing factory RTD's Vs K style. Try to educate the community. I am starting to learn that Mini Maxx in the past two years has programmed down there "cockpit" readings. I have a feeling in an attempt to get guys to turn up there trucks and enjoy the horse power and pass the word on how well it works. But Have noticed about a 300 to 400 degree disparity around the 1000 degree mark. I have tested two different Mini Maxx systems in this subject area. Any suggestions on a gauge company with fast accurate readings? It seem's every one is running k style. I am thinking Isspro EV2..