Wierd EGT Install Problems

[KTZed]

Ok so heres the deal...
Got my EGT/Boost/Oil press gauges installed.
Boost and oil press gauges work great. All gauges require a constant 12v and switched 12v supply which I have wired into spare spots in the fuse panel as shown.



I had already bought an Aircraft Spruce EGT probe prior to buying this 3 gauge kit and initially just ran a power wire to the gauge and tested the response of both the A/S probe and the probe that came with the gauge by heating with a propane torch, and as others have noted on here, the A/S probe responded much quicker (note that both probes worked at this time)
So...I buttoned all the wiring up and stuck the probe in the hole I drilled in the manifold when the engine was out, started the car and waited...and waited...no response. Went for a good drive, no response....ok...pulled the probe out and hit it with a torch again, works perfect.
The wierdest part about it is that the gauge seems to be somehow connected to the glow plug relay (note all of the gauges are wired to a terminal block running off the same 2 fuses and the others arent doing funny things). If you watch the vid, you can see the first sweep the egt and oil press gauges do, thats the normal "ricer start up sequence" or whatever you want to call it. But then the egt sweeps part way up and hangs there untill, "Click!" the glow plug relay shuts down and the gauge returns to zero, never to move again.  



So I dont know if somehow the egt probe is grounding on the exh manifold or something...even though this same probe is working for others? or....? Any ideas, however far out, are appreciated!

[Vincent Waldon]

That *is* strange...

Don't understand why your gauges need both a constant +12 and a switched +12... can't tell from the video what brand they are ??

For sure it's a type-K  EGT gauge ??  Any interesting sensor wire extensions ??

I'd be inclined to test your "grounding" theory... pull the EGT probe, wrap a wire around it, ground the other end... then hit it with the torch.

Given what you've described I'm betting the needle will not move... like you describe is happening with the engine running.

If it does go up then perhaps it's in a cold enough spot on the exhaust manifold that it doesn't heat up enough to register.. but that sounds like a long shot to me.

Did the gauge come with its own probe ??  Can you try that ??

[KTZed]

The gauges need both const and switched 12v because they have 7 different colors and need the const power to remember what color you last had it on. They are GlowShift lol

 

For sure it's a type-K EGT gauge ?? Any interesting sensor wire extensions ??

Well...heres the thing with that. It doesnt say anywhere what type the thermocouple is and the leads are pink(+) and blue(-)  :? which ive never seen on any thermocouple anywhere. I used the Aircraft spruce 7ft extension wire with the proper connectors...however, I did have to connect the extension lead to the gauge which I did originally with regular butt connectors, making sure that the wires were touching inside, but in that vid the wires were just twisted together with the same result...and yes I did try swicthing the polarity.
All that being said...it seems to work as long as the probe isnt in the manifold so that tells me its not the thermocouple leads.
I will try the probe that came with the gauge in the manifold next as I havnt tried that yet.
Still...that glow plug connection is creeping me out :shock:

[Vincent Waldon]

Yeah.... went to their web site and they don't say what kind of sensor they use... pink and blue doesn't sound like type K but ya never know.

The wire inside the pink and blue insulation... does it look silverish or copperish ??   Look similar to the wires on the EGT sensor you bought from Air Spruce ??

Propane torches can be way way way hotter than the average diesel... probably wise to try the sensor they gave you.

[KTZed]

Ok the wierdness continues. I tried your grounding trick Vince, and get this, no ground - works, ground to the turbo - works, ground to the manifold - works, ground to the -ve terminal on the battery - works, ground to the SS fitting in the manifold that the probe sits in - NO WORKY! Im seriously confused on this one. :x I dont even understand how thats possible.  :? ...I double and triple checked this cause I thought I was going crazy, but as soon as that probe touches the SS compression fitting, it links it to the glow plugs as in the vid. No other grounding scenario will make it jump up and down with the glow relay.

The wires look the same, as in they are all silvery, the pink and blue ones coming from the gauge are smaller gauge, like 22ga as opposed to 16ga  for the A/S ones.

The probe that came with the gauge seems to work regardless. Although I didnt get a chance to heat it up while in the manifold, it doesnt make the gauge jump with the glow plugs like the other probe does...the response really does suck compared to the aircarft spruce one though...

I'll sleep on it...thanks for the help Vince!

[burn_your_money]

Is the SS fitting grounded properly?

[Vincent Waldon]

but as soon as that probe touches the SS compression fitting, it links it to the glow plugs as in the vid. No other grounding scenario will make it jump up and down with the glow relay.
!

"Touches" or "is clamped into" ??  I ask because one remote possibility is that the pressure of the compression fitting is shorting the sensor internally ??

Just for more data... and if you have a multimeter... what's different about the battery ground vs. the intake manifold ground vs the exhaust manifold ground vs the actually fitting as a ground  ??

Or.... put your multimeter on a very low (millivolt) setting and see if perhaps the dissimilar metals between the compression fitting and the exhaust manifold itself is generating an offset voltage that for some reason is confusing the EGT.  The linkage to the glow plugs (which pumps a lot of current into the head and therefore could expose some kind of weird voltage differential) is a clue for sure.

Really really grasping at straws here, but when we find the answer it's gonna be a strange one.

[KTZed]

KTZed wrote:
but as soon as that probe touches the SS compression fitting, it links it to the glow plugs as in the vid. No other grounding scenario will make it jump up and down with the glow relay.
!



"Touches" or "is clamped into" ?? I ask because one remote possibility is that the pressure of the compression fitting is shorting the sensor internally ??

Heh ya I though about that too and it just has to touch it in any way and it makes the gauge jump.
Unfortunately I dont have a DMM, its on my list of things to get, so that sort of testing couldnt be done.

I ended up just hooking up the probe that came with the gauge and now everything works (imagine that  :roll: ). The response isnt *amazing* but it is plenty adequate as far as im concerned.

My theory on the whole thing is that maybe this particular gauge needs a specific TC junction type (grounded or ungrounded, not sure which) and the aircraft spruce one was the opposite. It could also be possible that the gauge has a signal amplifier built into it and that was somehow getting messed with by the glow plugs...like you say, theres a lot of current going through the head.
Overall im pretty happy with the setup as it sits now so i'll probly just leave it rather than giving myself a headace I dont need.
So I guess for future reference, anyone running the GlowShift EGT gauge should use the supplied probe.

Just out of curiosity, for those of you running a totally stock 1.6TD, what are your max egt's like?

Thanks all for your input!

[jimfoo]

I'd bet either the engine has a bad ground, or the probe is bad. That's the type of gauge I have, and I've never had any problems at all with it.

[KTZed]

Hey Jimfoo are you you using the aircraft spruce probe with that glowshift gauge, or the probe that came with the gauge? I dunno, maybe the probe is bad but that seems unlikely...i'll probably just leave it as is as it seems to work fine now although the egt's seem a little high for a stock motor. Im able to hit 1400F on a hard pull. Any ideas on what they should be?

[jimfoo]

I'm using the probe that came with it. Hmm, mine had high egt's too. Wonder if it was the gauge/probe, or if they were that high, although the water temps got hot whenever the egt's were over 1200. I wouldn't go past 1400, or hold it there myself for long. That's assuming it is pre-turbo. If those temps are post, then they are too high.

[KTZed]

Ya I was only having problems with the Spruce probe and the GlowShift gauge combo. Using the supplied probe works fine.
Thats interesting that you had high egt's as well...maybe these gauges/probes arent that accurate?
On my drive home tonight (essentially over a mountain) the gauge showed a steady 1500F and my foot wasnt all the way to the floor, it was just enough to hold 100km/h. That would worry me but its a 100% stock engine moving a light 2 door golf and ive been driving it back and forth over said mountain twice weekly, and generally beating on it daily for the last few weeks with no ill affects.
I will test this probe/gauge accuracy later this week as we have all sorts of expensive digital thermocouples and temperature controllers at work (high tech composites manufacturing). I will hit each with a torch and compare the readings as something still seems fishy...

BTW probe is mounted in manifold right in the middle just behind that downpipe brace bolt.

[KTZed]

Update:
I did some testing with a digital thermocouple and the glowshift probe and got fairly similar readings although the digi TC was almost too sensitive and it was hard to get a steady reading from it. So maybe ive been running really hot the whole time
Anyone have input yet on what a stock 1.6TD runs for EGT's?

On the plus side, I just finished a 2.5" mandrel bent exhaust with just a resonator and installed my home made boost controller and am running 15psi. I now have a hard time getting the EGT's to reach 1400F and the boost response is way better with that exhaust

[jimfoo]

Good to know they're accurate.   As long as you weren't at 1400 for long periods of time, you should be ok. I seem to remember people running around 1100 with a hard pull, but they'll probably chime in.

[KTZed]

1100 on a hard pull?!...mine will do 1100 during normal easy acceleration...1400 max is an improvement for me and I have only got it that low since the 2.5" exhaust and upping the boost...dammit now im second guessing the accuracy of the gauge again.

What could cause high EGT's in a stock motor...retarded timing? Timing is the one thing I havnt checked yet.