Coolant Crossover Questions

[tonewyork89]

Alright so I'm looking at my crossover and there's 2 temp sensors? it's a 97 and i was thinking about doing MMR's crossover delete. Will the lack of a sensor affect the car? I know i sound like a noob but i'm just unfamiliar with sensors and that shit :shrug: thanks

 

[Mustang Matt]

Alright so I'm looking at my crossover and there's 2 temp sensors? it's a 97 and i was thinking about doing MMR's crossover delete. Will the lack of a sensor affect the car? I know i sound like a noob but i'm just unfamiliar with sensors and that shit :shrug: thanks

One goes to the gauge and one goes to the computer. Normally the sender for the ECU is the one on the driver side, but there have been reports that the factory sometimes shipped them on different sides. (with the wiring flipped as well!)

If you delete the gauge one, your gauge won't work.
If you delete the ECU one, your tune won't work. (Don't do that!)

Fun fact: 99+ the gauge gets it's signal from the computer so there's only one sender.

 

[stangbanger856]

Ther is an easy way to find out wich one is witch, un plug one of them. If the fans turn on that's the ECM one. If not its the gauge.

 

[mwolson]

I've seen them on either side with factory wiring, so you can also check that. The gauge wire is red with a white stripe if I remember correctly.

In 96's, the gauge sender is a single stud style sensor. It depends on the nuts holding the crossover to the engine for the sensor ground. Sometime after that (maybe late 96, Ford switched to the same two pin connector for both sensors (brilliant). It got rid of issues with bad sensor grounds, but led to sensors getting swapped which confuses both the gauge and the PCM.

 

[newossab]

I thought that the MMR crossover delete had provisions for the temp sensors.

 

[USMC53CHIEF]

I thought that the MMR crossover delete had provisions for the temp sensors.

so did I, I know I saw it on their post, but to be honest Im kind of tired and lazy and dont feel like looking for it. If someone doesnt post it up by tomm Ill look for it. lol sorry . But anyway, the MMR kit has to have it in there somewhere.

 

[encasedmetal]

OP- talk to modularspeed on this forum. He has a kit he sells that actually provides locations for both sensors.

 

[na svt]

OP- talk to modularspeed on this forum. He has a kit he sells that actually provides locations for both sensors.

...and it's cheaper.

 

[Mustang Matt]

I've seen them on either side with factory wiring, so you can also check that. The gauge wire is red with a white stripe if I remember correctly.

In 96's, the gauge sender is a single stud style sensor. It depends on the nuts holding the crossover to the engine for the sensor ground. Sometime after that (maybe late 96, Ford switched to the same two pin connector for both sensors (brilliant). It got rid of issues with bad sensor grounds, but led to sensors getting swapped which confuses both the gauge and the PCM.

Hey Mark,

In hindsight, why wouldn't Ford have used the same sensor for both the gauge and PCM or at least the same sensor on both sides? Seems like that would have been easier/cheaper.

 

[na svt]

Hey Mark,

In hindsight, why wouldn't Ford have used the same sensor for both the gauge and PCM or at least the same sensor on both sides? Seems like that would have been easier/cheaper.

I'm sure the bean counters would have made them do so if it were possible.

 

[USMC53CHIEF]

I'm sure the bean counters would have made them do so if it were possible.

actually in my opinion, somewhere out there is a room full of ford engineers and designers laughing at our frustrations lol

 

[encasedmetal]

actually in my opinion, somewhere out there is a room full of ford engineers and designers laughing at our frustrations lol

now you know full well they've long forgotten about our cars...

 

[USMC53CHIEF]

now you know full well they've long forgotten about our cars...

lol thats right, Im sorry I meant while they still cared in the first 5 minutes after the first one rolled of the line

 

[mwolson]

Hey Mark,

In hindsight, why wouldn't Ford have used the same sensor for both the gauge and PCM or at least the same sensor on both sides? Seems like that would have been easier/cheaper.

I can only speculate, but I am pretty sure that the senders for the gauges were in use for a long time before the EFI systems were developed. My bet is that there is something about the gauge sender that makes it sub-optimal for the PCM. It probably has something to do with the resolution of the temperature input ADC around the normal operating temperatures and above.

I bet Ford decided it was cheaper to keep using the old gauge technology and add a sender for the PCM than it would be to change the gauge technology to match what was needed by the PCMs.

That is only a guess, but it is based on putting myself in the shoes of the engineers as they were making the transition from carbs to EFI.

 

[tonewyork89]

What would happen if i just used 2 of the ECU senders? I mean i can't see it being bad if one just goes to the gauge, it seems that i can only find one sensor anyway, can't hurt right? (one of mine broke)

 

[mwolson]

The ECT sensor that the PCM uses has a resistance of 1,180 Ohms when the coolant is at 248*F, and the resistance of that sender goes up to 58,750 Ohms when the coolant is at 50*F. The ECT sensor that drives the gauge has a resistance of 9.7 Ohms at Hot, and 74 Ohms at Cold.

So If you try to use a PCM sender as a gauge sender, the gauge will never move from below the Cold mark. Conversely, if you try to use a gauge sender as a PCM sender, the PCM will think the ECT is probably somewhere between 500 and 1000*F.

 

[tonewyork89]

so, any links or anything to get the right pieces? jw

 

[mwolson]

I'd call Tousley Ford...

 

[tonewyork89]

apparently you can find them on Rockauto.com but it's confusing which is which, i'll stop by my local ford dealer's parts department tomorrow then if need be we'll call Tousley, stupid bs of course

 

[na svt]

I have some sensors