EOT sensor and sluggish trucks. - Ford Powerstroke Diesel Forum
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Old 01-28-2012, 02:57 PM
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EOT sensor and sluggish trucks.

Been noticing the EBV cycling on the highway, and the more it does it, the more I get ornery. I went over to use my friend's MODIS today, and ran through some of the diagnostic tests, and was unable to do a cylinder contribution test due to the engine oil temp voltage being right around 2V (aka 140F to the ECM). I drove the truck around in a very spirited manner, held it at 2K RPM for 30 sec, etc... EOT voltage stayed constant, moving maybe a tenth of a volt one way or the other right around 140F in the data stream. Exhaust back pressure data looked good, desired fuel volume was good, desired fuel mass was a hair high but not enough to make me think it's way out of limits.

[edit] I also let my truck cool down for 45 minutes with the hood open, and the EOT reading was the same before startup. [/edit]

I didn't have a 2.2K ohm resistor to stuff across the EOT connector, so for now I am left with the assumption that not only is the EBP valve staying partially closed a good deal of the time (and screwing my fuel economy/performance), but the computer is adversely adjusting my injector pulse width to compensate for the "cold" oil.

EOT sensor is nothing that is listed in my store, nor at my buddy's store... so who can/should I source it from? Ford or International? Where exactly is this thing located anyway? I'm assuming it's somewhere on the HPOP reservoir but it's raining and snowing right now so I'm not in the mood to look.
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Old 01-28-2012, 05:17 PM
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Unplug it. Simple
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Old 01-28-2012, 08:09 PM
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^^^^^ Then the PCM will always think the engine is stone cold. Don't think that's a good idea.
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Old 01-28-2012, 08:11 PM
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Huh no it won't mine is unplugged and gutted it won't effect anything just don't start it up ice cold and beat the bag out of it I diss connect them and hook them up for customers on toggle for exhauste brake
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Old 01-28-2012, 09:20 PM
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Uhhhmm, that's the EBPV. The OP is posting about the EOT sensor.
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Old 01-29-2012, 04:23 AM
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I infer stand he is saying the Ebpv is staying quarter open and etc
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Old 01-29-2012, 07:51 AM
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The Engine Oil Temperature (EOT) sensor is located on the backside of the High Pressure Oil Pump (HPOP) Reservoir. Here's some basic info on it:

Quote:
The engine oil temperature (EOT) sensor is a thermistor type sensor that has a variable resistance that changes when exposed to different temperatures. When interfaced with the powertrain control module (PCM), it produces a 0 to 5 volt analog signal that will deduce temperature.

Cranking Fuel Quantity/Timing Control -- The EOT sensor signal is used to determine the timing and quantity of fuel required to optimize starting over all temperature conditions.

Idle Speed -- At oil temperatures below 70C (158F) low idle is incrementally increased to a maximum of 950 rpm.

Temperature Compensation -- Fuel quantity and timing is controlled throughout the total operating range to ensure adequate torque and power is available.

Glow Plug Control -- The glow plug relay and lamp ON time are controlled by engine oil temperature.

Detection/Management

An EOT sensor signal that is detected out of range (high or low) by the PCM will cause the PCM to ignore the EOT sensor signal and assume an engine oil temperature of -34C (-29F) for starting and a temperature of 100C (212F) for engine-running conditions. The CHECK ENGINE light will also be illuminated as long as the condition exists.
I would get it from Ford or International (I actually don't have the part number handy for it). Cheers!
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Old 01-29-2012, 08:08 AM
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The EBPV is evidently doing exactly what it's supposed to be doing. But it's doing it based on bad information from the EOT. Yeah, there is a purpose to disconnecting or gutting the EBPV, but the EOT will still be wrong, and as the OP said, will still be adversely affecting how the engine runs.

As for the EOT, it's on the back of the HPO reservoir; two wires, green/red and gray/red.

Edit (post leap-frogged with the previous): This is interesting:
Quote:
Cranking Fuel Quantity/Timing Control -- The EOT sensor signal is used to determine the timing and quantity of fuel required to optimize starting over all temperature conditions.
There've been a lot of posts on the various forums lately about hard cold starting, even after confirming a good glow plug system, etc. Gotta wonder if this isn't a factor.

Last edited by madpogue; 01-29-2012 at 08:16 AM.
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Old 01-29-2012, 11:50 AM
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An update:

I found a few aftermarket sensors and found them all to have ~30k ohm values at room temp, dropping as the bic lighter flame was held near the tip. I pulled mine, and it unfortunately is doing exactly what the new sensors are doing... so it would appear my EOT is good. The Ford PN on my sensor is F5AF-12A648-AA 7H26C.

What I'm confused on is why the resistance drops as temp increases, and the ECM reported voltage drops as temp increases. I would think the two would have an inverse relationship. Now I have to figure out why mine is stuck at 2v and 140F.
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Old 03-16-2012, 09:19 AM
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If it is in default how does long does it stay it cold start before it switches to engine running?
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