Pyrometer issue

[eleblanc]

I have not had the time to read this whole thread.. Anyway, it happened with my autometer pyrometers too. Replaced the gauge and coupler per warranty. It did nothing. I was sharing a ground with some other things, my guess was a stereo ground. Anyway I dedicated a ground to the pyro specifically and it was fine. I had the exact same symptoms. It also started happening about 6 months after I installed it, but oddly the brand new gauge did the same thing almost immediately. If you have not, give it a dedicated ground (to battery, or a single ground to body or chassis), and it will be fine..

Will try that before i pull the gauge out to connect it directly on the thermocouple.

EL

 

[eleblanc]

i've been trying for the last 3 hours to solve this, even with the gauge directly on the battery and thermocouple, sometime it wouldn't work sometime it does..Then step by step i reinstalled the extension. I am now sure the issue is the ground when i have the negative wire of the gauge in hand and touch at different place to get a good ground, sometimes it work but usually not. Seems like i need really good ground. I've been for 3 hours looking at the same spot under the hood and never ever notice that huge flaw mostlikely causing my problems!

Can you see the problem in this picture?

Look closer.................
anyone know the size of the bolt that goes there?
In case you don't know it is the block to frame ground!

 

[SabreTooth]

Seems like i need really good ground. I've been for 3 hours looking at the same spot under the hood and never ever notice that huge flaw mostlikely causing my problems!

anyone know the size of the bolt that goes there?
In case you don't know it is the block to frame ground!

Er, yup. You can just see it on the original picture if you know what you are looking for but I didn't see it, just suggested you take a look though. The missing block ground is not good and fixing it will probably solve your issue. You've got an incidental ground from frame to block but who knows via what path.

Give both the block and the ground strap a good clean (remove oil & grease and wire wool or lightly sand) where they join to get a good ground. The use of a star washer between them will also help as this will "bite" between the cable ring and block.

If you cannot find an appropriate bolt by trial and error, I'll go pull mine and let you know. It'll be a standard Toyota metric bolt, probably [edit: M12 x ?.??. Looking at my vehicle M10 x 1.25 doesn't look beefy enough. If you don't have a thread gauge, buy one, they are indispensable. This bolt also holds an exhaust pipe clamp on my truck. I'll have to move a bunch of stuff from around the vehicle to get to it.]

Let us know how this worked out and whether it fixed the pyrometer issue.

 

[eleblanc]

Been looking for a bolt that fits there, found none. It is about 1/2" so about be M14. but i'm not sure, it is not M12 for sure. I'll check at toyota tomorrow but i doubt they will give me thread size, but just a part number to order..

Yeah i need a thread gauge..

I will temporarily install a other ground from block to frame until i find the bolt that goes there.

BTW mine doesn't hold a exhaust bracket at least not this specific bolt.

ANYHOW! that was my problem i used a vise grip to hold it in place and the pyro works numero 1 (number 1).

Sabretooth don't remove it yet unless toyota cannot give me thread size.

 

[SabreTooth]

Congrats

Congratulations on solving the puzzle. It's all about grounds when it comes to instrumentation.

I'm happy the fix is easy, despite the many hours you put in to solve the riddle. It just took time to understand how your set-up is, what had been tested with what results and what to look for.

 

[Zekester]

reading it all with interst...as I have the same problem...and still do.
the issue with me is it isn't intermittent, the neddle fluctuates to the beat of the music on my CD player...

here's how it goes:
12 v accessories off, 12 volt tach on, pyro needle reads steady
CD player on, volume low, pyro reads steady
CD on, hi volume, pyro deflects to beat of the music
heater on, pyro deflects to zero, but does bounce
hetaer and headlights, pyro stay on zero.
I'm adding another converter, to run the guages off one, and the acc off the other, then will track down what appears to be a ground issue when the lights come on

 

[Zekester]

Idle the needle is steady, has soon has i raise the rpm it start to freak out and when the rpm gets higher it goes vertical down and stays there.

check this video, speak for itself.
http://www.ericleblanc.com/files/ericleblanc/video/Pyrometer.wmv

I tough the ground was bad but the light in the gage use the same screw for the ground and the light is ok.

Interferance?

Sorry, missed the end of the thread when I last posted...so you solved it? bad ground? I'm lost, my ground is good between block and frame, the pyro shres the same ground as the other 12 volt items. I will try to run my converter direct from the battery, with it's ground coming off the battery, with a relay. Does it matter which battery? I thought this was a no-no due to unbalanced loading? Should I run the pyro ground back to the battery?

I wish I knew about the 24 v pyro, but never found it in any threads : (

Driving me nuts!

 

[eleblanc]

reading it all with interst...as I have the same problem...and still do.
the issue with me is it isn't intermittent, the neddle fluctuates to the beat of the music on my CD player...

here's how it goes:
12 v accessories off, 12 volt tach on, pyro needle reads steady
CD player on, volume low, pyro reads steady
CD on, hi volume, pyro deflects to beat of the music
heater on, pyro deflects to zero, but does bounce
hetaer and headlights, pyro stay on zero.
I'm adding another converter, to run the guages off one, and the acc off the other, then will track down what appears to be a ground issue when the lights come on

Take two long wires, plug both the the positive and negative of the battery that has the negative to the frame. Then feed the gauge with power from those wire from the battery, if the needle doesn't move with the beat of the music leave the negative on the battery and replug the power (red wire of the gauge) to were you had it installed, and test again.

EL

 

[eleblanc]

Sorry, missed the end of the thread when I last posted...so you solved it? bad ground? I'm lost, my ground is good between block and frame, the pyro shres the same ground as the other 12 volt items. I will try to run my converter direct from the battery, with it's ground coming off the battery, with a relay. Does it matter which battery? I thought this was a no-no due to unbalanced loading? Should I run the pyro ground back to the battery?

I wish I knew about the 24 v pyro, but never found it in any threads : (

Driving me nuts!

Hook your gauge directly to the battery just for testing purpose. The battery with the negative to the frame, should be right side.

Then hook up the red or 12V+ of the gauge to the converter or the same way you currently are, except the ground.

 

[dieselcruiserhead]

congrats! That is great.. Who would have thought the probe required a ground as well. Anyway! Best, Andre

 

[eleblanc]

Went for a test run, at idle temp is about 400 deg F
And at 60mph in fourth, high rev and throttle floored, but flat road, i got it to 1250 deg F, that is max i was able to get it

 

[SabreTooth]

Who would have thought the probe required a ground as well.

Just for clarification in case others read this thread with a similar problem, the thermocouple (probe) does not require a ground per se (it has two wires and that's all that is really needed), it just needs to have the exhaust manifold and the gauge ground to be about the same and not fluctuating. (It's has to do with the input circuitry for the gauge. All input circuits require a reference of some sort or another or are usually voltage limited and if the frame of reference (offset) keeps fluctuating, that is just bad for measuring sensitive instruments).

The missing block ground strap in eleblanc's case meant that the manifold ground and gauge ground were not referenced to each other. When the vehicle is revved the relative ground shift between the two points will likely vary and this effectively masks the very small thermocouple signal and renders the reading rubbish.

 

[Zekester]

I will be testing my system this evening, but barring anything as enlightening as finding the ground starp off, I'm thinking in the end I should just run a wire from the neg on the battery that is grounded to the frame to both the 24v and 12v ground on the converter, and go from there.

 

[Zekester]

Solved

The floating ground theory wins! I ran a 10Ga wire from the converter to the same negative post that the block is grounded too....and Voila, all problems disappeared, I can now run my heat full bore, lights on, tunes cranked,...no deflection on the pyrometer!!

Thanks to all that contributed to solving this....

 

[SabreTooth]

Mszekely,

Congratulations. Glad your problem is solved.

Regards,

 

[eleblanc]

The floating ground theory wins! I ran a 10Ga wire from the converter to the same negative post that the block is grounded too....and Voila, all problems disappeared, I can now run my heat full bore, lights on, tunes cranked,...no deflection on the pyrometer!!

Thanks to all that contributed to solving this....

So it wasn't the converter?

On mine the ground off the converter is on the body, i probably have a good ground to the frame.

Congrats!

 

[Tapage]

The floating ground theory wins! I ran a 10Ga wire from the converter to the same negative post that the block is grounded too....and Voila, all problems disappeared, I can now run my heat full bore, lights on, tunes cranked,...no deflection on the pyrometer!!

Thanks to all that contributed to solving this....

Thanks for saharing with us your solution .. to keep in our DB !