Coyote 4x died at traffic light

[TXeverydayDad]

So I took my roadster out for its first real run today. I’ve previously started the engine, brought it up to temperature and have the fan kick in (at 205), bringing the temp down so the fan shuts off (185 I think). Topped up all fluids, no leaks, everything seems good.

Today I drove around the neighborhood, working through the gears, and keeping rpms between 1500-3000. I did a short pull aiming for 4500 but it hesitated/stumbled at 4000. Figured it just needs a tune. After 4.5 miles I pulled over and stopped, shut down the engine and sorted out a seat belt issue. 2 minutes later, started right up, drove another 0.5 miles, was waiting at a traffic light and the engine just shut down. It wouldn’t restart. No crank, no fuel pump sound (that I could hear), nothing. We pushed the car to the nearest parking lot and no visible issues. Coolant hoses were harder than usual however. Temp was showing just over 200. I opened the hood, turned on/off the electrical system, ignition, fuel pump…nothing. I called my wife to come tow us home. 10minutes later, just as my wife was pulling up, the engine started just like normal and I drove the 1 mile home without issue. The temp was 180, when we got home it was at 205 and the fan kicked in as normal. However, coolant lines were softer now (?).I shut it down, waited a few minutes and the switched on the ignition and fuel pump without starting and I heard a buzzing sound coming from the Coyote fuse box. I cycled the ignition and didn’t hear the buzz again.It then started as normal and I pulled it into the garage.

Long story - any suggestions what could be the issue? I don’t have a code reader yet so dont know if it’s throwing any codes. My MIL is not lit .Could it have been an overheating issue and the engine shutting down to prevent damage? The temps I’m getting are higher than the temps normally mentioned for Coyotes, but the fan is PCM controlled and switches on/off. Or is it a bad relay?

I’m open to any and all suggestions/thoughts for next steps.

Thanks!
/Sam

[gbranham]

I don't know Coyotes, but 205 to kick the fan on is high for your average SBF. Mine kicks on at 195. Again, maybe Coyotes are different.

[gbranham]

Also wondering if heat is exacerbating a loose ground somewhere.

[TXeverydayDad]

Thanks! Yeah, I agree that 205 is high. I’ll reach out to Ford Racing on Monday to get their take on it. Might be something to change when I get a tune.

I’ve looked into the grounds as well and they seem good, but I’ll check again. I have redundant grounds, the engine is grounded to the frame and to the battery.

I just took it out for a short 5 min sprint and no issues. Temp was just about 200 when I parked. Then fan never kicked in. I measured the actual temps in the coolant lines with a FLIR and they were at 207 at the hottest point (the coolant line that goes ‘across’ the engine with a restrictor in it (according to the Coyote installation manual). The water temp gauge has risen to 205 when parked.

[gbranham]

I'm way out over my skis on this one, lol. I know our Coyote gurus will chime in.

[bishes]

I'm still learning coyote stuff, but isn't the fan circuit activated by the 'assumed' coolant temp from the CHT? So your gauge might show a temp different than what the computer is showing. I haven't even started my engine, much less driven on a tune-less engine but a proper tune would be my first shot.

[TXeverydayDad]

Yes, it’s an assumed temperature. It drives fine in low-throttle, low rpm but a tune is definitely a next step. But I want to break the engine in first before doing WOT pulls on a dyno.

[Jeff Kleiner]

You said when you were dead you couldn't hear the fuel pump run? If so check the plug at the fuel pump; the female barrels in the Ron Francis plug that mate to the male terminals are notorious for fitting poorly and leaving more than one car dead by the side of the road...sometimes intermittently, sometimes permanently. Just squeeze them so that they lock on tightly.

Jeff

[TXeverydayDad]

Thanks Jeff. I checked the terminals, although I’ve exchanged the Ron Francis connnector to spade connectors and they seem to be good. I did tighten them on the fuel level sender however.

[Nigel Allen]

If it won't crank and the fuel pump is not running either, then I doubt it is the fuel pump wiring. I would look closer to the start of the electrical circuit around the connections to the ignition switch and the ignition switch itself as plenty of those have been faulty the past.

A buzzing sound coming from the power distribution box is most likely a relay. This is definitely not a normal condition.

Double check all your connections around the power distribution box, especially your grounds and main positive. Wiggle all your connections to make sure they're made fast

Very few issues with coyote engines have been faults from the factory. So I wouldn't get hung up on it being an ecu problem at this stage. Especially as the engine has run successfully.
Cheers,

Nige

[Jeff Kleiner]

If it won't crank and the fuel pump is not running either, then I doubt it is the fuel pump wiring. I would look closer to the start of the electrical circuit around the connections to the ignition switch and the ignition switch itself as plenty of those have been faulty the past.

A buzzing sound coming from the power distribution box is most likely a relay. This is definitely not a normal condition.

Double check all your connections around the power distribution box, especially your grounds and main positive. Wiggle all your connections to make sure they're made fast

Very few issues with coyote engines have been faults from the factory. So I wouldn't get hung up on it being an ecu problem at this stage. Especially as the engine has run successfully.
Cheers,

Nige

Well, looks like I get an "F" for comprehension on this one! I missed that no crank detail and thought it would turn over but not start :(

Jeff

[Nigel Allen]

If you have a battery isolator, check it is not faulty. Switch on your headlights, are they bright. Try cranking, do the headlights go dull?

Because the car was dead, then was able to be started again, makes me think it is a bad connection. Is the engine well grounded?

[rich grsc]

There is no 'break in' required on modern engines. Drive it like you stole it from day one

[TXeverydayDad]

If it won't crank and the fuel pump is not running either, then I doubt it is the fuel pump wiring. I would look closer to the start of the electrical circuit around the connections to the ignition switch and the ignition switch itself as plenty of those have been faulty the past.

A buzzing sound coming from the power distribution box is most likely a relay. This is definitely not a normal condition.

Double check all your connections around the power distribution box, especially your grounds and main positive. Wiggle all your connections to make sure they're made fast

Very few issues with coyote engines have been faults from the factory. So I wouldn't get hung up on it being an ecu problem at this stage. Especially as the engine has run successfully.
Cheers,

Nige


If you have a battery isolator, check it is not faulty. Switch on your headlights, are they bright. Try cranking, do the headlights go dull?

Because the car was dead, then was able to be started again, makes me think it is a bad connection. Is the engine well grounded?


Thanks Nige!

I'll re-confirm the grounds. I have a single main stud as a ground central by the battery, tapped into the frame, and the battery neg, Coyote, starter, engine ground (via a second frame connection) are all directly connected together and that stud/bolt doesn't wriggle. I haven't checked the cut-off switch so I'll do that. Any way to spot a bad one if it's intermittent apart from testing it when the car dies? I've also had a previous ignition switch 'fail' and have a new one that I've tested a few times already installed. My ignition is wired in parallel, so the SMR is triggered either by a button or turning the key. Neither worked when it was dead.

The buzzing relay is a concern. I didn't hear anything when it was dead but I heard it when I turned on the ignition when I was back home trouble-shooting, after it had been running again. I don't know which relay it was, but will definitely need more investigation.

[TXeverydayDad]

There is no 'break in' required on modern engines. Drive it like you stole it from day one

That's been my understanding and approach as well, but a good friend who works with engine development and testing at a large OEM recommends a short break-in period (40-50, up to 200 miles on break-in oil, gentle throttle, avoiding stable rpms, keeping it between 1500-4500) and an oil change before heavier applications, especially if you are planning to use the engine 'properly' in the future. For the average DD, there's no 'need' for a break-in because very few people will ever drive it like they stole it or run the engine at any level of real stress.

In my case, I'm getting to know the car and won't drive it like I stole it at this point anyway, cause I'll end up in a ditch... :p

[gbranham]

There is no 'break in' required on modern engines. Drive it like you stole it from day one

Wrong. Tell that to GM, who electronically limits RPM on new Corvettes until 500 miles have been driven. Ive been there, done that, twice. My GT350 owner's manual says to avoid high revs for the first 1000 miles, then change the oil. There is absolutely a break-in period.

[Cobradavid]

...10minutes later, just as my wife was pulling up, the engine started just like normal and I drove the 1 mile home without issue. The temp was 180, when we got home it was at 205 and the fan kicked in as normal....



...I just took it out for a short 5 min sprint and no issues. Temp was just about 200 when I parked. ... The water temp gauge has risen to 205 when parked.

I've got a 4.6 SOHC in my roadster, so I'm not familiar with the Coyote engines. Is it normal for the Coyotes to heat up that quickly? From 180 to 205 in one mile drive? From (assumed) ambient to 200 after 5 minutes?
My 4.6 takes 5-10 minutes just to get to 150 on the gauge.

Could there be a cooling system issue causing or contributing to the problems you're having?

David

[TXeverydayDad]

I've got a 4.6 SOHC in my roadster, so I'm not familiar with the Coyote engines. Is it normal for the Coyotes to heat up that quickly? From 180 to 205 in one mile drive? From (assumed) ambient to 200 after 5 minutes?
My 4.6 takes 5-10 minutes just to get to 150 on the gauge.

Could there be a cooling system issue causing or contributing to the problems you're having?

David

It could be a cooling issue. It seems to take 5-10minutes to come up to 170-180 from cold. As soon as the fan kicks in the temp drops pretty fast.

I took it out today again, drove 8 miles and it barely reached 180. I was moving most of the time. When stopped and idling in the driveway the temp rose to about 200, but the fan never kicked in. No issues while driving/stopping at traffic lights etc today. Same route as yesterday and the only difference is that it’s a little cooler today and the engine never made it over 180 degrees. So it seems heat related.

[TXeverydayDad]

From Ford literature, it seems like the Coyote is entering a fail-safe cooling mode. Once the engine reaches a pre-set temperature, it first switches to alternate cylinder operation (which explains the hesitancy I experienced during acceleration) and if the temperature doesn’t drop, the engine shuts down completely. Once the engine has cooled down, it’ll start as normal, which is what happened.

So now I just need to figure out why it’s not cooling enough. Is it an airbubble/airpocket that just needs time to self-burp through the expansion tank? Or is the thermostat failing to open consistently? The upper coolant hose gets hot, the fan has kicked on, brought the temp down and turned off the fan again, so it seems to be working. However, the fan only kicks on at 205*. Could it be a wrong parameter?

[Blitzboy54]

Certainly could be. I have a couple questions.

1. Are you using the control pack to run the fan (orange wire from the Ford harness) or do you have the Ron Francis harness attached (Green and Blue)? I am assuming the control pack but want to be sure. But even if you were it wouldn't explain the over temp if the fan is running

2. Yes that is high, mine kicked on at like 178 and really never shut off again. I put a Constant Temp Controller in mine to keep it a steady 185. My experience with a Coyote is though it runs cool generally. At least int the NE I almost never get to 185 unless its sitting idle for a bit.

3. I see your using the Ford expansion tank. The beauty of the Ford expansion tank is it's self bleeding. Not sure were air would get in. There is a check valve on the hose that comes from the upper radiator, any chance that got put in backwards? That would block coolant and perhaps create a bubble?

What I would do if that's not it is fire up the engine and let it get to temp, you should feel very hot water coming through the return line. If you don't your thermostat isn't opening. Then drain and remove.

[danmas]

This may or may not be relevant but I thought I would share my experience. On my 351w with a bad tune the temp got to 205 really quick. When it was tuned the temp stays constant (when idling) at about 180. I also have my fan set to kick on at about 180. (That’s a tune setting in my terminator-x).

Maybe your tune is rough?

Dan

[TXeverydayDad]

Certainly could be. I have a couple questions.

1. Are you using the control pack to run the fan (orange wire from the Ford harness) or do you have the Ron Francis harness attached (Green and Blue)? I am assuming the control pack but want to be sure. But even if you were it wouldn't explain the over temp if the fan is running

2. Yes that is high, mine kicked on at like 178 and really never shut off again. I put a Constant Temp Controller in mine to keep it a steady 185. My experience with a Coyote is though it runs cool generally. At least int the NE I almost never get to 185 unless its sitting idle for a bit.

3. I see your using the Ford expansion tank. The beauty of the Ford expansion tank is it's self bleeding. Not sure were air would get in. There is a check valve on the hose that comes from the upper radiator, any chance that got put in backwards? That would block coolant and perhaps create a bubble?

What I would do if that's not it is fire up the engine and let it get to temp, you should feel very hot water coming through the return line. If you don't your thermostat isn't opening. Then drain and remove.

1. yes, I’m using the orange wire from the Coyote
2. My expectation is that it should sit at about 185
3. The hose is correctly installed. Maybe need to check the valve to see that it’s oriented correctly in the hose. It’s the Mishimoto hose. The strange thing is that the fan has kicked on, and resulted in engine temp dropping to the point that the fan turns off again. It’s just that the temps are 20* higher than expected before the fan kicks in. The gauge measures correctly as I’ve checked the temp of the hoses compared to the gauge and they are within 1* of each other.

I'll bring the engine up to temp again this weekend and see how the system heats up and if/when the thermostat opens.

To Dan’s point, it might be a wrong parameter in the tune. It’s still the standard crate engine tune at this point. Or a combination of the above.

I appreciate the input

[Nigel Allen]

From the thermal imager photos, I can see you have the self bleed hose from top of engine to header tank. It also looks like you have installed a heater bypass hose, but a bit hard to tell from pic
Do you have a restrictor in that hose? I don't recall the size, but the factory hose has one and it is a requirement apparently.

[TXeverydayDad]

From the thermal imager photos, I can see you have the self bleed hose from top of engine to header tank. It also looks like you have installed a heater bypass hose, but a bit hard to tell from pic
Do you have a restrictor in that hose? I don't recall the size, but the factory hose has one and it is a requirement apparently.

Hi Nige,

yes, I have the restrictor in the heater bypass hose. I plan to do some further thermal imaging this weekend to see if there are any apparent issues. The previous thermal images (from a video) seem to show that everything is working as it should. All hoses that should be hot are hot and fluid seems to flow. It’s just that everything is 20* hotter than it ‘should’ be…

[edwardb]

My Coyote experience is Gen 2 and Gen 3. So FWIW. I've not seen routine temps as high as you're describing. Fan turns on at 188 - 190 and turns back off not much higher. For regular driving, it hovers around those temps. The only time I've seen temps at 200 or so is on hot summer days in stop and go driving. But the fan pulls it right back down again. Keep in mind (unless you're doing something different than I'm expecting) you're referencing temps you're seeing on your instrument panel gauge which is getting its reading with a sensor in the LH side of the block intended for a block heater. Normal setup and what's shown in the FF instructions. But this is NOT the temp the computer is using and may/may not correlate with the temp the computer is actually using. You can scan the ODB2 port and see the ECT that the computer is using. Would be interesting to see how they compare. I just looked at some tune files for my Coyotes and the temps were always in the 189 range, plus or minus a little.

[TXeverydayDad]

My Coyote experience is Gen 2 and Gen 3. So FWIW. I've not seen routine temps as high as you're describing. Fan turns on at 188 - 190 and turns back off not much higher. For regular driving, it hovers around those temps. The only time I've seen temps at 200 or so is on hot summer days in stop and go driving. But the fan pulls it right back down again. Keep in mind (unless you're doing something different than I'm expecting) you're referencing temps you're seeing on your instrument panel gauge which is getting its reading with a sensor in the LH side of the block intended for a block heater. Normal setup and what's shown in the FF instructions. But this is NOT the temp the computer is using and may/may not correlate with the temp the computer is actually using. You can scan the ODB2 port and see the ECT that the computer is using. Would be interesting to see how they compare. I just looked at some tune files for my Coyotes and the temps were always in the 189 range, plus or minus a little.

Thanks Paul. Yes, the values are from the gauge from the sensor in the LH lower block and they correspond to the temperatures I’m getting with a FLIR camera on the cooling hoses. I’ll see what values the computer uses through the OBD2 reader this weekend. What I’m perplexed about is that since the fan is controlled by the Coyote and seems to work (switches on/off automatically depending on temp), I expect the fan would switch on at a temperature (whatever the absolute number) that is lower than the fail-safe temperature. In this case, the engine switched off without the fan being on.

Maybe it’s as simple as an intermittently faulty relay?

Just for clarity, the days I tested/recorded the temperatures, the ambient temperature was in the high 90’s.

[Nigel Allen]

Paul brings up a good point about the temp sensing point. As he says, an OBD2 reader will confirm readings as sensed by engine computer. If you have the reader plugged in and note the fan engage / disengage temperatures, then you will know the programmed numbers are. It will be interesting to see if the fan cuts in consistently (see my note about buzzing power distribution box) with a possibility of a bad relay.


To prove the cooling system is working, you could temporarily wire the fan to run constantly. Then check to see it is able to hold the temperature within range. The reason I suggest this is that my Gen 1 Coyote fan (FFR supplied) engages at 185 and drops out at 175. On a hot day, say 95+ with the car stationary, the fan will cut in, but tends to stay running. IE it holds and slightly drops the temperature, but does not seem to get down to the drop out, until I get some vehicle movement. I have a fan shroud and have a factory cooling set up. Have never experienced overheating, even on 105 day.
I have oil temperature gauge on my Gen1. It seems to pretty much track the coolant temperature. As does the CHT.

Sensible questions:
- With the engine running, there should be a steady stream from the small hose on top of the engine back to the header tank. Can you confirm?
- Did you find what the buzzing noise was coming from the Power distribution box? This is not normal and needs to be tracked down. If it is the fan relay, it could be the problem.

Dumb question:
- is your fan running backwards?


Good luck,

Nige

[michael everson]

Just an FYI I had a coyote over heat and pass by the cap. My fault, the fan was unplugged. Engine temp was about 220 on the gauge. Shut if off, pugged in the fan and started it right back up. Cooled off on its own once the fan came on. I doubt yours is coolant related.
Mike

[Erik W. Treves]

Doesn't sound cooling related to me either. Higher temps could be related to air in the system - but honestly 205 on a coyote isn't warm.

[TXeverydayDad]

Thanks for the input Mike and Erik. If it’s not cooling related I’ll need to do some deeper troubleshooting. I’ll check for any codes this weekend hopefully.

[TXeverydayDad]

Just a quick feedback. The only code logged in the system is P061B which seems to be a ‘normal’ code for an out-of-the-box, non-tuned Coyote. That’s consistent with why the engine cuts out at about 4000rpm. I’ll take it for a ride later this weekend and log the trip and troubleshoot some more.

[danmas]

Just a quick feedback. The only code logged in the system is P061B which seems to be a ‘normal’ code for an out-of-the-box, non-tuned Coyote. That’s consistent with why the engine cuts out at about 4000rpm. I’ll take it for a ride later this weekend and log the trip and troubleshoot some more.

That is pretty consistent with what I experienced although my engine is very different obviously. I bet a tune on this will help a lot. But I know nothing really. Just a hypothesis.

From my reading:

The P061B code indicates an issue with the internal control module's torque calculation, which can lead to the engine running hot, especially if there are modifications like a new intake or throttle body. It's advisable to check for any air leaks, ensure the MAF sensor is clean, and monitor the cooling system for any issues.

[TXeverydayDad]

As I was reading the codes last night I noticed a line through the speedometer digital display. It’s not constant, disappears at restart and sometimes shows up, sometimes not. Related electrical gremlin? Or a faulty display?

220919

[F500guy]

I see that on occasion, disappears at next power cycle.

[TXeverydayDad]

Update: Drove the car to a weigh station this weekend. 6miles each direction. While moving, the temp stayed at 180*. When stopped, it creeped up to just over 200*, but dropped to 180* quickly as soon as we started moving. The fan never kicked in. I didn’t push it over 4000rpm as I still have the P061B code. The gauge temp and OBD values are very similar, although the gauge lags the OBD value by about 30secs..

So my conclusion is that the cooling system works as plumbed, as it cools the engine efficiently when moving. Something seems to be off with the fan, potentially a faulty relay or wrong parameters, will be checked further. The initial stall can probably be attributed to the engine’s overheat protection, and I’ve not managed to re-create the issue since. The engine needs a tune to be put under real load and will also confirm fan threshold temperatures.

Thanks for all the inputs and ideas in helping me work through this!

[lasse2]

Before I had my Gen III Coyote tuned, the fan would not kick on until I reached 205 degrees and then kicked off at 195. That being said, the fan wouldn't run while the car is moving, even on summer days (in Seattle). On a "hot" day at a stop light after driving, the fan would kick on for less than a minute to bring the temps down to the 195 range. In cooler weather, the temps would stay below where the fan would kick on. My engine tuner moved the set point for the fan to kick on at 195 and off at 185 and now I hear the fan more often but rarely when the car is moving. To be honest, I preferred the higher set points when the fan ran less often but it isn't really an issue. The thing I've found odd is that when driving on cooler mornings the engine doesn't get above 180. Sometimes as low as 165. I would think that the thermostat would try to maintain a warmer operating temperature.

[TXeverydayDad]

Before I had my Gen III Coyote tuned, the fan would not kick on until I reached 205 degrees and then kicked off at 195. That being said, the fan wouldn't run while the car is moving, even on summer days (in Seattle). On a "hot" day at a stop light after driving, the fan would kick on for less than a minute to bring the temps down to the 195 range. In cooler weather, the temps would stay below where the fan would kick on. My engine tuner moved the set point for the fan to kick on at 195 and off at 185 and now I hear the fan more often but rarely when the car is moving. To be honest, I preferred the higher set points when the fan ran less often but it isn't really an issue. The thing I've found odd is that when driving on cooler mornings the engine doesn't get above 180. Sometimes as low as 165. I would think that the thermostat would try to maintain a warmer operating temperature.

Thanks Lars. Good to know my numbers are not completely crazy. Still strange that the engine shut off, as the gauge didn’t seem to be too high. But I’ve not managed to re-create the situation. We’ll see as I take it out on longer runs.

[TXeverydayDad]

Update:

The engine died again today. I was out on a mild neighborhood run. Drove 12 miles, temp stayed around 170-180 while driving. Total now is 92 miles. Pulled back into my driveway, turned the engine off. I was looking at logs from my OBD reader and suddenly lost connection with the device. Ignition was still on. I tried to start the engine, no dice. No crank, nothing (like when the master disconnect is turned off). Turned everything off and on a few times, made no difference. 30 seconds later, it started as normal. I ran it 30 seconds, but a neighbor came up and wanted to chat so I turned it off.

5 minutes later I tried to restart it and it started to crank, then stopped after 1 sec. 30 seconds later I tried again, and it started. Ran for about 1 minute as I was looking/listening and then it just died on its own again. After it died, I noticed the tach is doing weird stuff, jumping around all over the dial. The temp was 208 on the gauge/obd. After a few minutes the tach settled down and when it was still, the car restarted as normal and I drove it into the garage and turned it off.

Why would the engine send tach pulses when it’s shut down? I’m hearing something faint from the Coyote fuse box as wel, so could be an issue there. The obd only shows P061B. Since the OBD disconnects when the engine dies, it would seem like the Coyote CPU turns off completely/dies.

I’ll probably need to spend some time with Ford on the phone on Monday.

[Nigel Allen]

1. OBD should not disconnect unless you turn the ignition off. Indicates a bad electrical connection.

2. If you are running speed hut gauges and you interrupt the power briefly, they will do weird things. This is because on power up they do the whole full sweep and return to zero. Indicates a bad electrical connection.

3. In previous post you mentioned a buzzing sound coming from the power distribution box. Another symptom of a bad electrical connection.

[TXeverydayDad]

1. OBD should not disconnect unless you turn the ignition off. Indicates a bad electrical connection.

2. If you are running speed hut gauges and you interrupt the power briefly, they will do weird things. This is because on power up they do the whole full sweep and return to zero. Indicates a bad electrical connection.

3. In previous post you mentioned a buzzing sound coming from the power distribution box. Another symptom of a bad electrical connection.

I agree Nigel but any idea where? The Coyote harness is completely self-contained apart from ignition and starter sense wires and the fuel pump connection. The OBD is untouched, the fuse/power distribution box is untouched. The tach only has 1 connection wire spliced into the coil on a cylinder. It sweeps as it should but then goes on to do weird stuff. I’ll try to attach a video soon.

So is this leaning towards a Coyote harness/CPU issue? I know Blitzboy had a harness issue preventing him from start. Could this be something similar, albeit an intermittent issue?

[Nigel Allen]

I agree Nigel but any idea where? The Coyote harness is completely self-contained apart from ignition and starter sense wires and the fuel pump connection. The OBD is untouched, the fuse/power distribution box is untouched. The tach only has 1 connection wire spliced into the coil on a cylinder. It sweeps as it should but then goes on to do weird stuff. I’ll try to attach a video soon.

So is this leaning towards a Coyote harness/CPU issue? I know Blitzboy had a harness issue preventing him from start. Could this be something similar, albeit an intermittent issue?


As the engine will run OK for reasonable periods of time, it makes me think that the ECM is OK. However, it could be something heating up within the PCM or a relay in the Power Distribution Box??

To try and track down whether it is a fault with the car or with the Coyote, make up a pilot lamp and hook it to the ignition positive on feed to the Coyote. If possible, run the negative wire from the pilot lamp to the ground that you created for the Coyote ECM. If the lamp stays on when the engine shuts down, then it your wiring is good and the Ford factory wiring, power distribution module or ECM have issue.

Best of luck fault finding. At least your fault hangs around for a bit, which may help in finding the culprit.

Cheers,

Nige

[TXeverydayDad]

For my ignition, I have the RF harness connected to the ignition switch and the IGN to the Coyote connected to a protected toggle switch in series with the ignition key. That way I have continuous ignition to the harness/rest of the car and can isolate the ignition to the Coyote. In the first video below, I turn the main ignition key off and then turn it on again. In the second video, you can see how the tach stops moving when I disconnect the Coyote ignition while the gauges continue to be on, which to me indicates an issue with the Coyote harness/ECM. This behavior only shows up when the engine is hot (over 200*).


https://youtu.be/LGQueb1JolY?si=aeIsckhGotV5YMzx

[TXeverydayDad]

https://youtu.be/DWUmUqFsXpY?si=l4wVF_nLcUhZR5aR

[Nigel Allen]

For my ignition, I have the RF harness connected to the ignition switch and the IGN to the Coyote connected to a protected toggle switch in series with the ignition key. That way I have continuous ignition to the harness/rest of the car and can isolate the ignition to the Coyote. In the first video below, I turn the main ignition key off and then turn it on again. In the second video, you can see how the tach stops moving when I disconnect the Coyote ignition while the gauges continue to be on, which to me indicates an issue with the Coyote harness/ECM. This behavior only shows up when the engine is hot (over 200*).


https://youtu.be/LGQueb1JolY?si=aeIsckhGotV5YMzx

That IS bizarre. I certainly agree with you that this could be a harness / ECM issue. Are you still getting the buzzing sound from the PDM?

Only taking a guess, is it possible that the supply to the ECM is being interrupted by a bad connection / relay (I am not familiar with the gen4 Power distribution) If you have a buzzing relay in the PDM, it could cause wierd issues, including dodgy signal to the tach.

Carry out a test by powering the ECM directly from the battery. This will take the ECM isolator and key switch out of the way.

As this is temperature rated, could the fan circuit be causing a problem? Fan likely draws too much current for the ECM isolation switch you have installed. I did the same thing and had issues with the starter motor solenoid drawing high current and destroying the ECM isolator switch.

Hastily typed, but I hope this makes some sense.

Cheers,

Nige

[TXeverydayDad]

That IS bizarre. I certainly agree with you that this could be a harness / ECM issue. Are you still getting the buzzing sound from the PDM?

Only taking a guess, is it possible that the supply to the ECM is being interrupted by a bad connection / relay (I am not familiar with the gen4 Power distribution) If you have a buzzing relay in the PDM, it could cause wierd issues, including dodgy signal to the tach.

Carry out a test by powering the ECM directly from the battery. This will take the ECM isolator and key switch out of the way.

As this is temperature rated, could the fan circuit be causing a problem? Fan likely draws too much current for the ECM isolation switch you have installed. I did the same thing and had issues with the starter motor solenoid drawing high current and destroying the ECM isolator switch.

Hastily typed, but I hope this makes some sense.

Cheers,

Nige

Thanks Nige! I appreciate your input and suggestions!

As designed by Ford, the Coyote ECM is already directly powered by the battery. The fan is controlled by the ECU and does not go through any of my switches. The ECU ignition toggle switch is just a sense wire to the ECU, no real power flows through it.

I’ve started discussions with Ford and I’ll run through their trouble shooting steps. They didn’t like that the tach was spliced into the coil wire but instead said it should be on pin 1 in the C146 connector. In the end, they think it sounds like either loose connection (pin or wire) in the Coyote harness or something with the power module (relays/fuses), so pretty much our thoughts here on the forum. I’ll be doing some shake testing and we’ll see where we end up.

[Nigel Allen]

Thanks Nige! I appreciate your input and suggestions!

As designed by Ford, the Coyote ECM is already directly powered by the battery. The fan is controlled by the ECU and does not go through any of my switches. The ECU ignition toggle switch is just a sense wire to the ECU, no real power flows through it.

I’ve started discussions with Ford and I’ll run through their trouble shooting steps. They didn’t like that the tach was spliced into the coil wire but instead said it should be on pin 1 in the C146 connector. In the end, they think it sounds like either loose connection (pin or wire) in the Coyote harness or something with the power module (relays/fuses), so pretty much our thoughts here on the forum. I’ll be doing some shake testing and we’ll see where we end up.

I think i had a brain fade moment, like the gen 1 Coyote, the ignition wire is only a sense wire and carries little current, sorry to send you in the wrong direction. On my build i initially used a 50amp toggle switch to isolate Batt+ supply to the PDB. It was a dumb idea. 1. the switch manufacturer was optimistic (China), the switch could definitely not handle 50 amps. 2. When cranking, the starter solenoid pulled ~20amps on its own. This quickly turned the switch into a molten mess .

The original plan for the PDM supply toggle switch was to act as an isolator for the HAAT circuit. After the switch burnt up, I got rid of it and instead just used my main battery isolator to do the job.


My last suggestions are:
- to monitor the ignition sense feed to the ECM, to ensure it is rock solid. Do you have a multi-meter with min/max record feature? However, if that were an issue, I would expect more than a misbehaving tachometer.
- Apply heat to the ECM with a heat gun to see if you can replicate the issue. However the heat related issue might be elsewhere...

Best of luck going forward,

Nige

[TXeverydayDad]

Making some progress - doing a harness shake test with the engine running narrowed down the problem area to/in/around the PDB (Coyote fuse box).

Before I started the car the first time I could hear a relay buzzing, but it stopped and the car started as normal. With the engine running, I shook the wire harness all around and when I pulled on the harness around the PDB, the engine shut off.


https://youtu.be/srs82YhuMDY?si=hkMzGyoJSdaN1hrK

I dug around the PDB and found a loose-ish nut for the power to the box from the 250A fuse. I tightened it hard and the car started as normal. Hopefully this was the issue. It makes sense since it felt like I just lost all electrical power to the engine, and this would explain it. A little strange that it would be affected by heat, but at least it’s one nut that needed to be tightened either way. I’ll continue around and check everything else again as well.

[Nigel Allen]

Maybe not directly affected by heat. Possibly the extra current drawn by the radiator fan caused enough volt drop across the loose connection to cause engine shutdown. Let's hope you have found the smoking gun.

Cheers,

Nige

[TTimmy]

I dug around the PDB and found a loose-ish nut for the power to the box from the 250A fuse. I tightened it hard and the car started as normal. Hopefully this was the issue. It makes sense since it felt like I just lost all electrical power to the engine, and this would explain it. A little strange that it would be affected by heat, but at least it’s one nut that needed to be tightened either way. I’ll continue around and check everything else again as well.

Well, you’re not the first to miss that. I had the same problem; though my symptoms were not intermittent. Thus a less frustrating troubleshooting exercise.

Not sure if it entirely explains the bizarre tach behavior. Regardless, I hope all this is behind you!

[TXeverydayDad]

Well, you’re not the first to miss that. I had the same problem; though my symptoms were not intermittent. Thus a less frustrating troubleshooting exercise.

Not sure if it entirely explains the bizarre tach behavior. Regardless, I hope all this is behind you!

Thanks! Let’s hope so!