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Engine temp/MAT sensor



I own an 89 L98. I have that digital dash, which I love and have had NO PROBLEMS with... I heard...."heard" that the read out on the temp gauge is WAY off from the actual engine temp. Has anyone had trouble or experience with it? I'm very technical with things like temps, PSI, etc.... so yes...5degrees F would erk me.

I'm also messing around with the MAT or IAT(same thing) sensor. I cut the factory harness and extended it to the bottom/side of the airbox and plugged the Plenum with brass fittings. I used the factory sensor...but tonight i've been playing around with it..and noticed that in a normal temp...or 75-80F IE A/C house... its reading about 2.72K ohms. i then put it in hot water...and took a cigar lighter to it briefly....and its taking...almost an hr for it to come back to normal readings....(its fairly new). I personally think that this thing has to much metal which heat soaks...and is a bad design. I've read that using that 92+ (SU176 Autozone part #) works better....and i agree....b/c it has less metal and lets the actual element inside see the air......so it will react quicker.... All this makes me wonder abouth the ECT (engien coolant temp) b/c its the same as the MAT in my 89....SU109......so the engine could cool off and not actually have the ECM know it til way later....so the A/F mix is off. i'll let you all know what comes of my experiments and brain storming....


Motor head!!!!
Feb 13, 2001
Valencia, CA,USA
88 Convert ( SOLD ) /1973 coupe 4 speed/1964 Vert!
Reguarding the Gauge accuracy

There are ALOT of factors which control the temp gauge accuracy..

For example the sensor GROUNDS.
As resistance goes UP so does the gauge.

2nd Internal CRUD on the sensor will increase the error both on the electrical side & mechanical.

3rd If you think the sensor retains heat by itself.. what about when it's bolted into the TBI plenum..... Talk about hanging on to heat!

4th The VOLTMETER itself in the gauge set ( on the TEST BENCH) is accurate within .25 of a volt... in the car.. all bets are off! but it's been within 3% AVG.

So put a heat sink on the sender itself and mount it in an area where it gets LOTS of airflow!

But the O2 sensor has final say so in the mix department ( when that's working correctly!)


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