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5.0 Engine Swap Electrical Problems


1992SuperRanger4x4

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Hello, this is my first post so don't yell at me.
I need help diagnosing a problem that happens when it gets really hot outside. I live in SC so it gets pretty warm here from time to time. On the hottest days, the engine will run perfectly if you are cruising down the road, but if you go and stop for a drink and go back outside to start it up sometimes it will do this.

https://instagram.com/p/BMXdRfTAy4O/

The truck is a 92 Ranger XLT and we swapped a 5.0 HO out of a 92 Ford Thunderbird Sport (same engine as 94-95 Mustang GT). All we did to the engine was a new distributor, tune-up kit, tri-y long tube headers with 2.5" straight pipes, new fuel pump (for 4.0 V6), new water pump, timing chain, no 02 sensors, new ignition control module, new coil, no smog pump and EGR delete, new rear and front main seals, no AC, no Thermostat to help with cooling, oil filter relocation, and new fuel filter. Normal things for a 5.0 conversion. Something is obviously getting too hot underneath the hood but have no idea what. Pls help ASAP because there is a show coming up and I don't want this to happen there. The truck will always start up but when the computer takes over the timing it seems to want to only run on two or three cylinders and then die.

Here's a bad picture of the engine bay

https://instagram.com/p/BWNUpATgxQk/


Here's a piping video for yall :icon_thumby:

https://instagram.com/p/BMSDK26APuY/
 


Rock Auto 5% Discount Code: F9A1A579ACFAD1: October 1st, 2021

RonD

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Welcome to TRS :)

1992 T-bird 5.0l used TFI ignition system, is that what you used?

The TFI module should be mounted on Rad support where it gets a little cooler air circulation, distributor mounted tend to get heat soaked after engine is turned off and sits.
This can cause no start or stumbling start if TFI module doesn't cool off enough

Remote mount info here: http://www.therangerstation.com/tech_library/remote_tfi.shtml

Where did you end up putting the computer?
It needs a cooler area as well or when engine is off it can get heat soaked

You need to put in a thermostat, 190degF would be best, no thermostat can actually cause hot spots in your engine which won't show up on your temp gauge.
The opening in thermostat valve slows flow to radiator allowing better cooling as coolant flows slower thru radiator and water pump circulation is better thru the rear of the engine because of limited outflow to radiator.

If you don't want the thermostat then cut valve out of old thermostat and put open plate into thermostat housing to try and balance flow, it will still be a bit larger than it should be but better than no restriction.

A working thermostat can never cause overheating, it purpose is to maintain 190-210degF engine temp for longer engine life and cleaner oil, oil burns off contaminants(moisture, blow-by) when coolant is above 160degs, even better if above 190degF, thats from the SAE research
 
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1992SuperRanger4x4

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Yes, I did know about the TFI getting hot and it is mounted on the side of the engine bay. The reason why I do not think it is that is because we bought a new one to swap it out if this does ever happen and it did not help at all. Would this still happen with a brand new cold one or is it another component causing this? BTW the computer is located where the stock computer was located in the Ranger under the passenger side kick panel. When we had the thermostat in we had overheating issues so that is why we took it out in the first place.
 
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RonD

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OK, but it only does the stumbling on restart when engine bay is hotter, i.e. in warmer temps?

Open the hood all the way after parking, to let out heat and see if it restarts better, just trying to see if it is a component in the engine bay that is over heating or not related to engine bay heat at all.

A fellow here had a similar issue, he drove around to get engine bay warmed up then went home, got the stumbling restart and then put a bag of ice on the coil, waited a couple of minutes, then removed bag, and tried to start, did the same with TFI module.
Turned out to be TFI module.
Just thought it was a "unique" method, lol.

Not sure you can get a vapor lock at 35psi fuel pressure, but..........if you lose fuel pressure when engine is off then fuel in the lines would be at 0psi so could turn to vapor near exhaust in engine bay, and that could cause stumble at restart


Not sure why a working thermostat would cause overheating??
It sets minimum temp, has nothing to do with maximum temp, odd, but you are there so taking it out is better than running hot.
 
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1992SuperRanger4x4

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It doesn't happen every time only under extreme hot weather circumstances and sometimes it will do it when it's idling for a very long time. I think it has something to do with the electronic timing because a few minutes before it does the juddering it starts really galloping and having a real rough idle like the computer keeps slowly advancing the timing. If you do let it cool down for like 10-15 minutes then it will start up and run no problem. It can't be the TFI because we bought a new one that was room temperature and bolted it up when it was doing the juddering and it still did the exact same thing.
 

RonD

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Try cooling Coil down when it does it

Or do the opposite, use a Heat Gun CAREFULLY to heat up components to see if you can duplicate the stumbling
 
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1992SuperRanger4x4

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UPDATE:

We have tried to change out every part of the electrical spark system to no avail. It just keeps doing it. A helpful Mustang owner from the parts store pointed out that this may not be an electrical spark issue but instead it might be an air fuel one. His reasoning behind this was because it sounded like it was stalling out like it was running out of air or fuel. This would make sense of why you can just rev it up and it drives like normal until it comes to an idle again. What do you guys think? He also said the reason why it might only do it in hot weather was that the air would be thinner and thus it would need more of it to compensate. We were playing around with it the other day and noticed right before it's about to die it starts to suck a ton of air and howl relative to the engine speed that it was at. if you tried to rev it up when it was starting to die it would backfire into the intake. Could this happen with not enough air or too much fuel? well anyway, we are thinking of putting on wideband O2 sensors with a quarterhorse chip or something equivalent that way we can read the data coming from every sensor and it would be a lot easier to diagnose problems. Just let me know what you guys think.

Thanks
 

Bruce2

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Is your fuel filter in the frame rail up by the exhaust? Our 1988 would do this cause it was vapor locking be cause of fuel filter was right next to the exhaust and headers.
 

1992SuperRanger4x4

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We put the fuel filter across from the exhaust so I don't think it could be that. it's pretty far away from any hot points. IDK if this matters or not but we put a fuel filter on the return side of the line. We did this because the old 4.0 filter had one end that was bigger and then another end that was smaller so we used it like an adaptor because we were too lazy to go get an adaptor XD. The strange thing is though when we were playing with it when it was dying ALL of the electronics were room temperature because it was a "cold" start. The only thing that was warm was the air around the engine. When it was doing it the engine would idle fine and then all of a sudden it was like someone flipped a switch and it started to idle rough and proceed to die. That would be the only case that I have for it being electrical though. someone told me that it could be the MAF sensor causing a false reading and making it fail. Could this be? I tested it by unplugging it when it was running and it still did the dying thing but then I plugged it in and it ran much better but after a couple of seconds, it went back to dying.
 


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