Pyro going weird

Lantec · 07-13-08, 12:57 PM

I have a ISSPRO Pyro in my 3B and it's been fine for almost 2 years now but I was driving it last week, the pyro readings were all over the scale. It would just drop down to 300, as soon I as I pressed the accelerator, it was fly all the way up to 700 but then flutter from 500 to 900 and back down to 300.

Mind you, the entire time, I'm on the highway doing light acceleration, I'm sure I'm not overfueling or anything.

is it a connection problem or has the pyro bit the dust?

eleblanc · 07-13-08, 02:11 PM

Check the engine ground.

Dougal · 07-13-08, 06:18 PM

Check all the connections. These things run on millivolts so it takes nothing to upset them.

Big Blue 84BJ60 · 07-13-08, 06:36 PM

make sure the wire sheathing hasnt worn off and is shorting somewere on a metal part

UpsideDown · 07-13-08, 10:25 PM

note that the thermocouple/sensor do require replacement from time to time.

Lantec · 07-13-08, 10:48 PM

thanks, I'll check the wires underneath and see what happens

lowenbrau · 07-14-08, 04:46 PM

24 volt truck? Solar converter feeding the gauge?

Tapage · 07-14-08, 05:35 PM

did you use the head shield wire .?

Lantec · 07-14-08, 11:16 PM

Quote:

Originally Posted by Tapage

did you use the head shield wire .?

nope. it has a turbo so it's attached to the manifold pre-turbo

83bj60 · 07-15-08, 01:27 AM

don't forget these meters usually have electronic components (zener diode, reference thermistor and an amplifier/comparator circuit). It's usually not just a simple millivoltmeter.

But agreed, first check the simple things. Make some tests with a simple k type thermocouple with a propane soldering gun. If it goes all over the place again, it's the meter itself, otherwise it's the sender.

MichaelP · 07-23-08, 05:10 PM

Are you still having the problem? Were the conditions such that you would not have been over 900° normally? If so, then I suspect either bad connections to the amplifier box, or internal failure of the amp box.

Regards,
Michael Pliska
ISSPRO Engineering Manager

Tapage · 07-23-08, 05:40 PM

Wou Michael .. nice to have a ISSPRO pro here .. !

I have a complete set off ISSPRO gauges in my Cruiser .. ( oil press / boost / pyro / trans temp ) and have a question about the oil press gauge .. but there comes in another thread.

seapotato · 07-23-08, 07:42 PM

I had an autometer pyro do this. thing just went crazy needle bouncing around all over the place. was the ground wire on the back of the pyro.

vibrated loose. was fine after.

cheers,
ryan

MichaelP · 07-24-08, 07:01 PM

A simple thing to remember when diagnosing pyrometer problems is that the gauge is basically a really sensitive voltmeter, and the sensor (thermocouple) generates a very small voltage in proportion to the temperature difference between the "hot end" in the exhaust and the "cool end" at the gauge. Bad connections between the thermocouple, leadwire, and the gauge can lead to readings which are intermittently below the expected reading. However, you typically won't see a value ABOVE the expected reading (even intermittently) unless your gauge or amplifier box is bad.

Regards,
Michael Pliska
ISSPRO Engineering Manager

07-13-08, 12:57 PM	#1
Lantec IH8MUD Regular Join Date: Aug 2006 Location: Coquitlam, BC Posts: 292	Pyro going weird I have a ISSPRO Pyro in my 3B and it's been fine for almost 2 years now but I was driving it last week, the pyro readings were all over the scale. It would just drop down to 300, as soon I as I pressed the accelerator, it was fly all the way up to 700 but then flutter from 500 to 900 and back down to 300. Mind you, the entire time, I'm on the highway doing light acceleration, I'm sure I'm not overfueling or anything. is it a connection problem or has the pyro bit the dust?

07-13-08, 02:11 PM	#2
eleblanc BJ addict Join Date: Jul 2006 Location: Montreal TLCA# 16338 Posts: 1,398	Check the engine ground. __________________ 1983 BJ42LV 3B turbo diesel, 5 speed, power steering 24V Viair 450C, ARB locker front/rear, OME Heavy 4.56 R&P, BF Mud 255/85 (34") Warn M12000 24Volt http://www.ericleblanc.com/gallery/m...p?g2_itemId=20

07-13-08, 06:18 PM	#3
Dougal IH8MUD Lifer Join Date: Jun 2007 Location: Being stalked by 2 hillbillies Posts: 1,481	Check all the connections. These things run on millivolts so it takes nothing to upset them. __________________ VOODOO Engineering: Doing it first time with one clay doll, not four times with two.

07-13-08, 10:25 PM	#5
UpsideDown IH8MUD Addict Join Date: Sep 2006 Location: Koksilah, Vancouver Island, BC Posts: 575	note that the thermocouple/sensor do require replacement from time to time. __________________ 1978 FJ40 - parts vehicle - PM me 1987 HJ61 VX 5spd - loaded - daily driver 1981 BJ42 - ARBs, Warns, oba, ps, h55f, hws, soa

07-14-08, 04:46 PM	#7
lowenbrau IH8MUD Lifer Join Date: Jan 2003 Location: Calgary AB TLCA# 5513 Posts: 2,495	24 volt truck? Solar converter feeding the gauge? __________________ Rocky Mountain Land Cruiser Association TLCA # 5513 '87BJ74, '86BJ70, '78FJ45, '53M100, '90M101cdn I support our Troopies

07-13-08, 06:36 PM	#4
Big Blue 84BJ60 IH8MUD Regular Join Date: Aug 2007 Location: brampton ont Posts: 252	make sure the wire sheathing hasnt worn off and is shorting somewere on a metal part

07-13-08, 10:48 PM	#6
Lantec IH8MUD Regular Join Date: Aug 2006 Location: Coquitlam, BC Posts: 292	thanks, I'll check the wires underneath and see what happens

07-15-08, 01:27 AM	#10
83bj60 IH8MUD Lifer Join Date: Apr 2006 Location: Laurentians North of Montreal, QC Posts: 1,402	don't forget these meters usually have electronic components (zener diode, reference thermistor and an amplifier/comparator circuit). It's usually not just a simple millivoltmeter. But agreed, first check the simple things. Make some tests with a simple k type thermocouple with a propane soldering gun. If it goes all over the place again, it's the meter itself, otherwise it's the sender. __________________ 91HDJ81VX (The Beast), 4B JDM, since Nov 06 83BJ60 (The Old Faithful), Still Running, Gone to a New Home 83BJ60 (Rusty but Trusty), Dec 90 - July 98, Parted Out 76FJ40 (Big Red), April 87 - July 93

07-23-08, 05:10 PM	#11
MichaelP IH8MUD Rookie Join Date: Jul 2008 Posts: 2	Are you still having the problem? Were the conditions such that you would not have been over 900° normally? If so, then I suspect either bad connections to the amplifier box, or internal failure of the amp box. Regards, Michael Pliska ISSPRO Engineering Manager

07-23-08, 07:42 PM	#13
seapotato IH8MUD Addict Join Date: Jan 2005 Location: Aimlessly Poking Morons with Sticks. TLCA# Reset to Zero.... Posts: 751	I had an autometer pyro do this. thing just went crazy needle bouncing around all over the place. was the ground wire on the back of the pyro. vibrated loose. was fine after. cheers, ryan __________________ I disagree. 87BJ70 BJ109/55. Bluefish & Grover.

07-24-08, 07:01 PM	#14
MichaelP IH8MUD Rookie Join Date: Jul 2008 Posts: 2	A simple thing to remember when diagnosing pyrometer problems is that the gauge is basically a really sensitive voltmeter, and the sensor (thermocouple) generates a very small voltage in proportion to the temperature difference between the "hot end" in the exhaust and the "cool end" at the gauge. Bad connections between the thermocouple, leadwire, and the gauge can lead to readings which are intermittently below the expected reading. However, you typically won't see a value ABOVE the expected reading (even intermittently) unless your gauge or amplifier box is bad. Regards, Michael Pliska ISSPRO Engineering Manager

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