posting for a friend. we hooked up a stewart warner egt gauge on his 07 DMax that he got from summit racing. have it wired into the 10 amp acc. on the side of the dash and the prob is in the downpipe. i know its not the best place but hes worried about drilling his manifold. anyways we wired it in and it was at about 200 then it shot up the over 1600 degrees and never came down. called stewart warner they said the gauge was bad. exchanged it for a new gauge with summit. put the new one back in and it started at 200 again then jumped around up to 1000 then back down then to 1400 then back down to 200. so unhooked it. looked over all connections hooked it back up sat a 200 for a few min started across the parking lot and jumped over 1600 again and wont move from there. any ideas??

posting for a friend. we hooked up a stewart warner egt gauge on his 07 DMax that he got from summit racing. have it wired into the 10 amp acc. on the side of the dash and the prob is in the downpipe. i know its not the best place but hes worried about drilling his manifold. anyways we wired it in and it was at about 200 then it shot up the over 1600 degrees and never came down. called stewart warner they said the gauge was bad. exchanged it for a new gauge with summit. put the new one back in and it started at 200 again then jumped around up to 1000 then back down then to 1400 then back down to 200. so unhooked it. looked over all connections hooked it back up sat a 200 for a few min started across the parking lot and jumped over 1600 again and wont move from there. any ideas??


im not sure but I think the issue is with it installed in the downpipe. mine and a few people i know are all in the manifold. maybe someone else has installed it there.

I know if you have a bad ground, it will cause the gauge to go berzerk.

posting for a friend. .............. the prob is in the downpipe. i know its not the best place but hes worried about drilling his manifold. ..........




I like my EGT gage thru the OBII port plug and play Edge insight. Prob is in the manifold - tell your buddy to GROW A SET and drill his manifold. :D

I worried about it too, but was really easy to do. I used a vacuum while drilling and tapping with the engine off - than a magnet to probe inside just incase. But seriously - even the dudes that drill it with the engine running have no fears - cast iron is very SOFT.

;)

I don't think the location of where it is located has anything to do if it reads correctly or not. Yes, it should be in the manifold for accurate reading but it should still work any where there is exhaust gases. I think your ground is bad or a junk gauge or probe. 1400* and then a quick jump down to 200* and back up is definetly a sign of it not reading correctly, especailly just driving around in a parking lot. I don't know much about the quality of Stewart gauges today but a good gauge is not cheap. Your buddy might consider another brand if if turns out is the gauge again. Mine idles around 300 +- and increase up to around 700-800 at normal acceleration. Its always going up or down like a darn tach but no instant jumps like you describe.

One point to make, you want the egt readings from the hottest location which is in the manifold.
My last truck I monitored pre turbo and post turbo, when towing pulling a long grade I had as much as 400-600 degrees difference, post being cooler.

I would do it the way "Duramax-LMM" said.
I did drill the pilot hole with the engine running but shut it down to tap.
To much of the tap filings flying around blowing in the face it was bad even with goggles.
I used grease on the tap, I tap in 3 steps I went only about 1/3 of the way used a shop vacuum and a magnet then started the engine for 10 seconds.
Then used the same steps another 1/3 of the way vac/mag started the engine for 10 seconds.
Finnished up the last 1/3 of the way with the same procedure.

Agree with the others regarding accuracy where you have the sensor located, but that's not causing what you're seeing. Sounds to me like an electrical problem, another bad gauge or possibly the sensor.

It also could be not having a good ground in the downpipe v.s. being in the manifold.