I have noticed that the hand held Temp gauge is always off by 30 to 40 degrees compared to the On Board Unit.

I tested on different engines and the results were the same. Like eveybody knows the Hand Held Temp gun has to be as close as possible to the glow plug center by pointing it from the top of the heatsink. In all the tests the On Board device, to put down a number, would be 270 while on the Gun the readings were 220.

I dont think the OFNA T Gun is damaged or not calibrated, its just reads about one to two inches away because the crown does not let you read any closer. So, everytime you tune with the gun always add about 30 to 40 degrees specially during break-in.

I know the unit is not damaged because I have a cooking probe inserted on the automobile's A/C vent. In the digital display the reading was 62, on the cooking probe about the same and in the OFNA temp gun just a 2 to 3 degrees off be it a little lower or higher.

It makes sense the MIp or VENOM device installed on the buggy or stadium truck reads more accurate because is as close as it can be for making accurate readings. So far following the 30+ rule for temp gun readings has worked well for me.

IMO the In-car-temp gage is junk.. Stick with the Hand held...

Yours might be off but my Duratrax guage is always within five degrees of the test temp. It's also a whole lot more versitile than any engine mounted guage. Maybe you got a bad guage.

One of my buddies tested his Duratrak temp gun against his friends onboard temp unit and the on-board unit was way off. Like 30-50 degrees. He also suggested to stick with the temp guns and not bother with the on board units. They seem to be inacurate!

~ Simply Unreal

try changing emissivity settings on the temp gauge
seems that when people have problems with the gun they dont change the emissivity on it, to the proper setting

How do I do that...? Emississippi deal

I love my little duratrax temp gun.

It's all goto do with were you put the onboard temp lead
I tested my handheld with two others so I know it is correct. Then I moved the onboard temp wire up to the next fin on my head untill it was the same as the handheld

I dont know which temp gun you have but here is A manual
http://www.ofna.com/pdf/pcr-ir-Manual.doc
if this is not the one you have check your manual
I use the duratrax temp gun and it has the same instructions

I have stayed away from the On board temp gauges and just use the handheld gun. Mine is OFNA and does not have any adjustment knob or button. I did test the OFNA with the vehicles A/C digital display and a Temp cooking probe.


Thanks for the reply

The guy who said his on-board was way off the gun...it's the GUN that's wrong, not the on-board, unless it has a problem.

On-boards are 'generally' more accurate than the guns, by simple virtue of the fact that you wrap them round the bottom fin of the head, it's closer to the actual engine temperature, guns will normally read lower, as they are being pointed at the glow plug.

Fact is, all these cheap temp readers are pretty inaccurate (or should I say total pants, they're a vague indication at best, unless you get very lucky). You have to spend $200 plus to get a good one and it needs recalibrating by the manufacturer regularly (every 18 months or so). Go to a track and ask a bunch of different people to tell you your engine temp. Bet you get a slightly different reading each time.

Make sure to clean the sensor on your handheld unit. Dust will make it read low by about 20-40F.
Been there done that.

My El'Cheapo Duratrax is accurate to with in a few degrees. I've tested it by heating a cooling head in the oven and measure it with a contact thermometer and the Duratrax.