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Pyro needle flutters?

2K views 16 replies 13 participants last post by  Bigs 
#1 ·
This problem initially happened randomly when the HID spotties were switched on. Thinking it was caused by EMF, i separated the sender wire away from other wiring and it seemed to fix it until yesterday (months after the last time) when the lights were off and it happened again.

I'm going check that the sender wire isn't near any powered wires again, apart from that maybe a fault with the gauge?

It's an AutoMeter sportscomp gauge so it's no cheap and nasty but doesn't rule out being fault.
 
#2 ·
I have occasionally had this happen with mine too. Mine is a VDO.

I suspected that it may have been due to the wires touching the firewall or the engine exhaust as that is the only place they are loose enough to possibly touch anything intermittently.

Interestingly it only seems to occur on the winding, relatively rough road I take through the hills to get into Adelaide. I have never seen it happen while driving in a straight line.

Good luck.
 
#5 ·
I had a simular problem with my mcnally gauge. It turned out to be caused from where I had run the earth to a bolt in the engine bay.

I had also run the earth from my intercooler fan to the same spot, and when the fan came on it would make the needle on my boost gauge go crazy and my egts to freeze. Earthed fan somewhere else problem solved.
 
#6 ·
I recently had the same problem with my pyro (same brand and series as yours), it turned out to be the Earth cable from the battery to the block/chasis.

I replaced these with heavy duty cables that the guys as battery world made up for me (about $30) and has completely fixed the problem, and also the car starts that little bit better (thanks to the info from Jet-6)

My problem was when the air-con was working.
 
#7 ·
I too had the same problem with the same autometer gauge, i checked my earth and recleaned it and havent had a problem since. while i was poking around the back of the gauge i noticed the main power feed had been quite tropical, almost half melted looking yet even though its fused it has never blown a fuse and from what i can see has no shorts anywhere, ive had a good look too.

Jlowe
 
#8 ·
Sorry for digging up a old thread.
I have a autometer pyro also and has been installed for 8 months or so with no problems. Then about a month ago the needle started to flicker when any power use was turned on "blinker - lights etc" then this week every time you drive it it flickers.
So I googled and found could be bad earth. So I run a new earth from gauge direct to battery, Still the same. Then I run power as well straight to battery, Still flickering. I notced that when you turn the engine off the pyro needle is steady at the right temp???
I take out the probe when engine running and needle is steady, put back into dump pipe and needle flickers. So then I run the earth from the gauge to the probe on the dump pipe and all is solved.
I have checked the earth strap from battery to engine, all looks good.
Any Ideas??
 
#13 ·
My Autometer will do the occasional bounce but it only occurs when idling in traffic and the EGT drops below 180C, but that is not your issue. With regard to earth, many GU's had problems with the main earth, many of us have fitted a secondary earth strap as described in the GU Bible (top of page). This is a worthwhile (cheap) mod in its own rite anyway so you lose nothing if it doesn't work on this occasion.
 
#11 ·
Trial and error mate, you will get there eventually. Sounds like your on the right track though.
Hope you find it soon, it can be very frustrating.

Regards
Nigel.
 
#12 ·
My problem with the autometer pyro gauge was in the pyro itself. The two wires had a break right under the protective covering which was enough to hold them in place but as soon as any vibration was sent thru the wires it would make the gauge needle go crazy and bounce all over the gauge.
If the earth is not the problem check for any breaks in the wiring.
 
#16 ·
Some more info for you, direct from Autometer.



Hello Shayne,

I have a few simple tests for the pyrometer. The first would be to ground the pyrometer directly to the engine. The pyrometer is very particular about the ground, and grounding to the engine will be the best available ground on the vehicle. This will be better than any chassis ground or even the negative terminal on the battery.

Next, check with a voltmeter that you have at least 12 volts between the red power wire and the black ground wire while the vehicle is running. It is very important you are getting over 12 volts for normal operation.

The last thing is to check the calibration of the gauge itself. To do this, remove the two probe leads from the back of the gauge. Power the gauge on. You should see the pointer sit between 0-100F.

Let me know what you find and I can assist you further.


Thank you,
Kevin
Tech/Service

Auto Meter Products
413 W Elm St.
Sycamore IL 60178
1-866-248-6357
 
#17 ·
Some more info for you, direct from Autometer.



Hello Shayne,

I have a few simple tests for the pyrometer. The first would be to ground the pyrometer directly to the engine. The pyrometer is very particular about the ground, and grounding to the engine will be the best available ground on the vehicle. This will be better than any chassis ground or even the negative terminal on the battery.

Next, check with a voltmeter that you have at least 12 volts between the red power wire and the black ground wire while the vehicle is running. It is very important you are getting over 12 volts for normal operation.

The last thing is to check the calibration of the gauge itself. To do this, remove the two probe leads from the back of the gauge. Power the gauge on. You should see the pointer sit between 0-100F.

Let me know what you find and I can assist you further.


Thank you,
Kevin
Tech/Service

Auto Meter Products
413 W Elm St.
Sycamore IL 60178
1-866-248-6357
Interesting. I have moved the earth from the sender to the engine and is still working. I must have some resistance from battery earth to engine earth or its picking up some interference from the alternator, because it only happens when the enging was running.

Cheers for the info.
 
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