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Old 04-21-2007, 05:28 PM   #1
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Default EGT Probe

Anyone recommend a particular probe for MS. Looking to mount it in the manifold and don't want a big real deep one. The one i had seen before is now gone off their website.
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Old 04-21-2007, 06:20 PM   #2
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Uh chad i wouldn't run pre turbo with the probe just in case it breacks. and then Bye bye turbo. just thought i would throw that out there.
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Old 04-22-2007, 03:18 PM   #3
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Anyone?
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Old 04-23-2007, 10:54 PM   #4
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I had a pre-turbo EGT on my STI (the probe is still there cuz I haven't gotten a plug for the bung yet >.>), and the tip burned/broke off the probe, and AFAIK my turbo is still fine. I haven't actually pulled it and looked at the turbine wheel, but the car still runs fine. I'm not sure I'd be too worried about going pre-turbo. And it's my understanding that EGT is really only meaningful pre-turbo, as close to the exhaust port as possible.

My probe came with my Zeitronix ZT2. I haven't replaced it yet, because they won't sell it without the extension cable that I don't need another one of. Last time I looked, there's a fair number of probes available on ebay, and you could probably find a probe from any gauge manufacturer that makes an EGT Gauge (like Autometer).

What does the MS do with EGT? Just log it?

-Mike
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Old 04-23-2007, 11:38 PM   #5
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Yeah it just logs the EGT. It will allow me to tune timing for lower EGTs. It would work in tandem with the knock sensor. I don't like the idea of tuning timing till you hear detonation or see specs on the plugs.
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Old 04-24-2007, 12:49 AM   #6
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Old 04-24-2007, 12:52 AM   #7
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I've seen those. Thanks for the link again.
I like these.
http://www.egauges.com/vdo_send.asp?...PRO_Thermo_1_5
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Old 04-24-2007, 03:06 PM   #8
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Yeah, I was looking at the inconel 2000deg one at the bottom for extra lifespan. But I think some plug modification would be required for it to work with the Zeitronix cable, and I'm not sure if you can just bust out a soldering iron, because I think it's sensitive to the metal used in the connections. Or maybe the connection isn't that important, and it's just the cable that matters.

-Mike
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Old 04-24-2007, 03:18 PM   #9
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I know that the connection itself matters. When attaching the EGT probe to megasquirt you have to use EGT appropriate connectors for it to be accurate.
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Old 04-24-2007, 03:26 PM   #10
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I think the length of the cable connecting the probe to the gauge/ecu is a calibrated length for the probe. Autometer warns that the cable should not be shortened or extended.

I'm using the long style probe in the collector of my greddy manifold. Pointed directly into the inlet, hopfully it doesn't let go! Reaction time is nice and fast.
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Old 04-24-2007, 03:50 PM   #11
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I've been running an autometer egt in my manifold pre-turbo for 23k+.... works fine and no breaking off...

Pre-turbo, a few inches from the head is the best place to measure anyways.
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Old 04-24-2007, 08:08 PM   #12
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Do the Miatas have some golden rule in regard to which cylinder runs the hottest? I seem to recall the Honda guys always putting their EGT probes after a particular cylinder on the header because it would be consistently hotter.

Cheers
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Old 04-24-2007, 08:25 PM   #13
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Why not just use a thermistor? then you dont have to worry about burning the probe up.
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Old 04-24-2007, 08:28 PM   #14
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Quote:
Originally Posted by saboteur View Post
Do the Miatas have some golden rule in regard to which cylinder runs the hottest? I seem to recall the Honda guys always putting their EGT probes after a particular cylinder on the header because it would be consistently hotter.

Cheers
Cylinder 4 runs the hottest.
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Old 04-24-2007, 09:13 PM   #15
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EGTs respond much slower than A/F gauges or knock sensors ... I use an autometer gauge/probe and use it to monitor EGTs on a daily basis but not to tune timing. The knock sensor is your answer for that. BPs can take quite a bit of timing.
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Old 04-24-2007, 09:17 PM   #16
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What is a knock sensor going to tell you about dangerously high EGT from having timing too retarded? In fact the knock sensor and how the ECU is tuned to deal with it can cause EGT to rise. The EGT will help alert you to the problem.

You could have a perfect A/F, or even be rich and still run EGT that are dangerously high.

All of these things are tools for tuning. The knock sensor in my mind is less a tuning device and more a safety device.
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Old 04-24-2007, 09:19 PM   #17
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Quote:
Originally Posted by cjernigan View Post
Cylinder 4 runs the hottest.
Didn't reverant (I think that's his name) show that #4 was not the hottest using four EGT probes? I know someone posted about this.

The problem with #4 running how has to do with the coolant routing and not the EGT.
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Old 04-24-2007, 09:33 PM   #18
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EGTs don't react as fast to timing that is too advanced, this is what I meant ... an EGT gauge is great and I have it, but for pushing timing to the knocking point they are not the best tool to use.
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Old 04-24-2007, 09:46 PM   #19
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But you can get knock with out having any issues with timing. IAT and fuel can do it. The EGT is probably the most effective at telling you that your timing is too retarded.

My point is that nothing will tell the entire story.
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Old 04-24-2007, 09:53 PM   #20
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Yeah I understand that. I would put it in #4 anyway just because it is closest to the firewall, thus the shortest amount of wire running through the engine bay.
I don't want EGT to tell me when I'm to advanced, that is what the knock sensor will be for.
I also still need to get a GM IAT and install it in my IC piping.
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