Yader20

I have a 525 hp ls3 crate engine. I have an aftermarket classic instruments temp gauge with the sender in the back of the passenger side head. My problem is is that the aftermarket gauge reads 20 degrees or so cooler than what the ecu reads. I have tested the gauge and it checks out. I have swapped out the aftermarket sender and same result. I have added another engine ground. Same result. Any ideas what may be going on? The only thing left I can think of is to swap out the ecu temp sensor in the front of the driver head. This engine has only a couple hundred miles on it.

oange ss

iTrader: (50)

verify temp readings after the vehicle has sat for awhile. Engine off/key on, compare aftermarket gauge reading, ECU temp and ambient temp reading. Im betting your temp sensor for the ECU is reading high.

LilJayV10

iTrader: (39)

It is common for there to be a temp difference between the front and rear.

On a cold start in the morning, do both show the same temp?

Yader20

this is exactly the case but how do i get them to read close to each other? My after market gauge doest start reading temp till 175 and my after market dakota digital fan controller doesn't start to read until 140. and at 140 the engine is reading 160 from the ecu

LilJayV10

iTrader: (39)

So you want them to read all the same even though the temps are actually different?

aknovaman

iTrader: (7)

I have seen Gm factory sensors are generally within 2 degrees of nominal. If your dash reads wrong, warm the engine up fully then pull the needle and set it to what your obd2 scanner ready. Problem solved. Dash gages really suck for accuracy.

Yader20

no I want to know why they are so different