Ok first of all, I'm using a VDO gauge and thermocouple. http://www.egauges.com/vdo_mult.asp?Type=Pyrometer&Series=Vision

It's installed on the bottom of runner #4 (drivers side) of the exhaust manifold. Using the weld-in bung, and the probe tip extends about 1/2" into the exhaust stream. The probe itself is 1.5", but the bung holds it out farther than tapping it would have. Nobody had the right tap for a VDO gauge.

Anyways, at idle (within 30 seconds or so of starting the car) I get about 750*F. Driving around normally gets around 850-950*F. Boosting for about 5 seconds doesn't really even register, but if I keep boosting off and on it maybe gets up to 1100*F.

These numbers seem really low, especially since I've heard people complaining they were hitting 1500 at low boost. I'm running rich enough to throw CELs sometimes (1.02v hehe) but most of the time I'm around 0.98v. Also the gauge seems to move very slowly, only a little faster than our stock coolant gauge. The needle movement is smooth, and the wiring's all correct. I did cut about 4 feet off the 12 foot wiring lead that came with the gauge.

What should I do to make sure my EGT is working right?

its probably fine, just your placement (I heard add 200 deg. if your at the bottom of the runner)
and the fact that your runnin soo rich

that seems extremely low.

1100* at wot while boosting?

a stock 420a will run hotter than that at wot

You said the probe was in the manifold, so there shouldnt be a 200* difference, and even if the probe was in the downpipe after the turbo and there was a 200* difference and you only saw 1100* @ WOT, thats STILL low.

maybe the vdo probe is just very slow reacting? :dunno:

You need to get the probe into the runner further, but make sure it does not touch the otherside of the manifold.

Idle temp 30 seconds after start is approx. 900F

Idle temp after easy vacuum driving. 1000-1050 after idling for 30 seconds before I shut it off.

This is probably the most accurate way to see if it is reading correctly. Boosted egt will vary greatly depending on amount of boost and fuel.

From initially reading your post it sounds like it is 150F lower than it should be, but your driving temps are WAY too low. My bet is that the probe is not reading accuately at all the the temps displayed are a certain percentage of actual temp. Basically it is farther off(cooler on the gauge) the higher the temp actually is.

150F to start with and maybe as much as 300F at higher levels.

This is just my opinion. Nobody will know for sure without actually checking out your car.

Suggestion. Redo the probe into the manifold to get it to set farther in the hole without bottoming out the probe itself.

If I remember correctly from my autometer EGT install, you are not supposed to cut the thermocouple wire that connects the EGT probe to the gauge as the gauge is calibrated to work with a specific length of wire. I will double check this in the installation manual but I am almost positive that this is the reason why your gauge is showing low temps and not working properly.

Yes, my information is correct. The thermocouple wire from the probe to the gauge is a special wire that can not be cut. The excess is supposed to be wrapped up and stored out of the way but never cut.

By the way, your probe is mounted in the exhaust runner which is correct. There is no need to add anything to your reading. If you mounted the probe in the downpipe after the exhaust gas has gone through the turbo you would see readings 200 - 300 degrees less than what they actually are at the exhaust runners.


Hope this helps,
Kurt

Kurt, I agree that cutting the wires may be the problem. I'm going to resolder the rest back on and see if that helps.

I did read the whole manual that came with the gauge kit and it didn't say anything about not cutting the wires shorter.

http://www.vdona.com/Tech%20Support/Automotive/instructionsheetspdffiles/0%20515%20012%20075%20--%20Pyrometer.pdf

I'm also confused since VDO supplies 3 different wiring kits for this gauge, maybe they're all ohm-balanced exactly the same or something?

o 6' lead wire (PN# 240-094) http://www.egauges.com/vdo_send.asp?Sender=VDO_Pyrometer_Lead
o 12' lead wire (PN# 310-153) http://www.nhspeedometer.com/vision.htm
o 30' EXTENSION wire (PN# 240-092) http://www.nhspeedometer.com/cockpit_page2.htm

Damn, makes me wonder if my EGT is actually accurate. I got the Westach probe with an AutoMeter gauge. When we installed them, my friend had to actually cut the small tip of the wire to make them fit on the Autometer black box for the EGT gauge. Here are my readings as best as I can remember them:

Idle during initial start after warmed up = a hair under 800 degrees

Idling at a light after barely hitting boost on and off = 800-900 degrees

Idling at a light after boosting a lot = 900-1000 degrees for a few seconds going to about 800-900 degrees

Cruising under vac. (10) around 50 mph= around 1100 degrees

Cruising under vac. (10) around 70 mph = a hair under 1300 degrees

Full boost = let's just say I'm running REALLY rich!!!!!!

I have an autometer egt with street probe. It has the box brain that both the probe wiring and gauge connects to. It is very accurate.

My guess is that you are approx. 100F low in all areas as comparing it to my car and after reading a hundred posts about egt. I left all the extra wiring and just wrapped up the extra. I completely forgot about cutting the wiring and it changing the resistance which the box is reading to tell the temp. That would indeed make a difference if any was cut off at all. More cut = more error

I just checked my egt yesterday and paid attention to it for this post. When I start my car it takes 30 seconds for it to reach 800F approx. After 1-2 minutes it goes to 900F and stays there until I drive the car. When I drive in vacuum, and then park the car to shut it off, it is approx. 1000F (+ or - 50F). When I drive at 10 vacuum at 65-70mph in 5th gear my egt reads 1350-1400(1380F yesterday) depending on if the road is completely flat or slightly up/down. This was at approx. 50F outside temp yesterday.

100F might not be a big deal, but it is massive when it comes to being 1600 or 1700 degrees. If you leave it as it is, you should consider not going over 1500F for your 7K 3rd/4th gear pulls.

If you only cleaned up the wire ends to install, then it should not be a big deal. It does seem like you are 100F lower than I am though. Hell, I could be wrong.

I have always noticed that if I hit 1650F that the car does not pull any harder and actually power drops/tapers off(knock causes spark advance to decrease). When my egt is at 1600F and does not climb any higher in 3rd/4th gear the car pulls hard all the way to 7200 rpm. My plugs are medium/dark gray in color.

We just cut the big tip off, so it'll fit in the black box probe terminal. I figure less than 1\4 of an inch.