newguyinnc
OBS Enthusiast
- Joined
- Jun 1, 2014
- Messages
- 51
- Reaction score
- 14
I have thought about doing this to see if the sending unit for the ECU was what was giving me a bad reading and in turn causing the ECU to give a bad timing and fuel curve leading to a lean condition. Only reason I haven't so far is that with a scanner hooked up with live data, I've confirmed ECU temp readings with a good heat gun at the intake manifold below the thermostat housing. The sending unit for the gauge is much harder to verify with a heat gun because of it's proximity to the exhaust manifold, which is why I verified it's accuracy with an auto meter mechanical gauge. (making the same test run under the same conditions with the truck and getting same results). My mechanic already hotwired the aux fan to be "key on" hot. It dropped the temps by about 10°, but the getting hot after putting a load on it still persists. Without the fan running it would run 220° down the highway, then creep up to 235° after pulling off the highway. After hot wiring fan it runs down the highway at 212-215° and creeps to just over 220° after pulling off highway. This is all with an empty truck. I used the truck to pull my dump trailer home from my shop for some yard cleanup and even with the aux fan hotwired, the truck ran 220° and when pulling up to a stoplight crept up to 235° again. I almost definitely have a flow problem or a restriction somewhere.Put the Autometer capillary bulb/sending unit in a "tee" fitting with the computer's temp sensor then compare the temps.
Putting an electric fan switch in the cylinder head is a great way to make the fan come on earlier.
Autometer gauges are +/- 3% over the entire range of the gauge so they are pretty accurate.