Hi All,

Having problems with my Engine Coolant Sensor. Here is what I have done/observed to date:

1. Noticed temp gauge bouncing all over the place.
2. Looked under hood and noticed some coolant leaking around the ECS.
3. Ordered OEM Coolant Temperature Sensor 99-03, SKU F65Z10884AA
4. Pulled old ECS and plug broke from sensor body during removal so obviously needed replacement.
5. Installed OEM ECS., During installation, used Mass Air Flow Sensor cleaner on plug. Blew plug with compressed air afterword and allowed to dry.
6. On startup, gauge initially pegged and after driving for a little while, gauged dropped to 0 and did not move.
7. Worried that "OEM" ECS was not OEM, went to Ford and purchased same SKU sensor, installed, with same result - pegs initially then drops to zero when warm.
8. Tested voltage across terminals on female plug - ~5 volts.
9. Test OHMs from red/white wire to ground - ~20-40 OHMs

Probably unrelated ??? but truck had been running kind of rough, I think . Also, in the last month when the fuel light came on at ~20 miles distance to empty, if I didn't get to the gas station within a couple miles, truck started running really rough and would die even though computer said 7-10 miles DTE. Had a similar problem about a year ago although the same symptoms (run rough then die) would show up at about 1/8 tank. I dropped my fuel tank and the pickup had broken off. Installed new pickup and the problem went away. Anyways, after replacing the ECS, drove ~5 miles and seemed to be running a little rougher. Next day, started driving to work, was running even rougher, turned around and while parked in the driveway, started shuddering and died and couldn't be restarted. We are down a vehicle so had to get it fixed pronto. Towed to mechanic who replaced one injector. Mechanic said codes showed one bad glowplug in the other bank which he did not replace. Anyways, after the injector replacement, still seems like it might be running just a little rough.

I am thinking I have a short somewhere causing the ECS problem. Maybe also causing my perception of the truck running a little rough? Any help troubleshooting the ECS is much appreciated.

 

Bumping it hoping for a little help. I have Forscan and ran ECT related PIDs and I am getting the following values:

ECT.OBDII, degree C - -40
ECT_V - 0.00
ECT_F - No Fault
ECT, degree C - -40

 

The computer doesn't see coolant temp so you won't see it on anything pulling info from the computer. The coolant temp sensor is only for the gauge. The coolant temp can't be causing the rough running, but there could be an electrical issue causing the goofy reading and your rough running, that I can't help with.

Repeatedly letting it run low on fuel and sucking air isn't good for it so you should stop waiting for it to tell you that you're 7-10 miles from empty.

 

Our 7.3 reads EOT(engine oil temp) that sensor is on the back of the HPOP resevoir. Could be a bad connection or the sensor itself. As for the bouncing needle could bee the temp gauge cluster taking a dump or you have an air pocket in the cooling system.

 

I would say check the harness where it crosses over the valve cover at the 42 pin connector. Make sure none of the wires have chafed against the valve cover.

 

I would click around my signature, there's some good stuff in there. If you can't see my signature line, you'll want to get on the full site.

I'm almost certain there was no problem with that injector... but I emphasize almost. Manual transmission trucks have 2 ECTs, and they don't match location or style - watch out for mixing these up. Intermittent missing cylinders is commonly caused by a bad UVCH, but that should have popped a code for your mechanic.

This is what I do when electrical stuff starts acting stupid: I take things apart and start cleaning connections. In the case of the 7.3L getting stupid signals from the engine, I would lift that wire bundle to the 42-pin connector on the engine side, and look for chafed wires underneath.