Power loss as truck warms up

[nlc56]

2004 Ranger XLT 3.0 (not flex) 5 speed 2wd
Truck runs great when cold but as it warms up, it becomes sluggish and loses all low end power once up to temp. Taking off it bogs down heavily but hasn't stalled. It will rev up but still seems to be way down on power. It will throw a misfire code when under load, codes vary from random to misfire upon startup to cyl 6/2/3/5 (not all at once)
Parts that I've changed; plugs, wires, coil, sensors (crank, cam, maf, ect, iac, tps, o2), cam synchro, two injectors, fuel pump and filter, both heads (reman) and thermostat.
I've changed plugs twice, from NGK to Motorcraft both gapped to .44.
Thermostat I've changed twice, first one was factory temp current one is 180deg.
Cam Sync I've triple checked position multiple times using TDC.
All three cats are gutted.
I'm not sure where to go from here....

 

[ericbphoto]

Wow. What a mess. Wait for the heavy hitters to chime in here. But one thing that could contribute to the problem is gutting the cats. The ecu wants to see a difference between the O2 sensors before the cats and the ones after the cats. That tells it that the cats are working.

I would verify that the plug wires are hooked up in the right order and maybe put the original thermostat in.

 

[nlc56]

Wow. What a mess. Wait for the heavy hitters to chime in here. But one thing that could contribute to the problem is gutting the cats. The ecu wants to see a difference between the O2 sensors before the cats and the ones after the cats. That tells it that the cats are working.

I would verify that the plug wires are hooked up in the right order and maybe put the original thermostat in.

Yea, truck has me questioning my life choices lmao.
I have actually been thinking that the lack of cats might be a problem, they were gutted when I bought the truck :/
And the plug wires are 100% hooked up right and I will be swapping back to factory temp t-stat

 

[Guanfy]

Phew, lots to unpack here. Running fine cold then bad once warm plus all the parts you've thrown at it makes me think you might have a bad ECU. As long as everything you replaced was done right and not done with el-cheapo replacement parts.

Since your truck has an OBD2 port I would get one of the nice OBD2 scan tools that lets you look at live data and see if that can help figure out what is going on here.

 

[Roert42]

If there is an issue with the rear cats getting wrong readings you can bypass them. I have seen little dongles that plug into the connector.
I assume there is just a resistor in there to trick the computer into thinking it is a good reading.

 

[nlc56]

Phew, lots to unpack here. Running fine cold then bad once warm plus all the parts you've thrown at it makes me think you might have a bad ECU. As long as everything you replaced was done right and not done with el-cheapo replacement parts.

Since your truck has an OBD2 port I would get one of the nice OBD2 scan tools that lets you look at live data and see if that can help figure out what is going on here.

I haven't really looked into ECU yet, I assume that a bad ECU would cause this problem? And I do have a scan tool that I can see live data, just not sure what I should be looking for.

If there is an issue with the rear cats getting wrong readings you can bypass them. I have seen little dongles that plug into the connector.
I assume there is just a resistor in there to trick the computer into thinking it is a good reading.

The rear o2 sensors have spacers currently and haven't thrown any codes. I plan to remove the spacers and see if it runs any better/throws a code.

 

[Guanfy]

I haven't really looked into ECU yet, I assume that a bad ECU would cause this problem? And I do have a scan tool that I can see live data, just not sure what I should be looking for.


The rear o2 sensors have spacers currently and haven't thrown any codes. I plan to remove the spacers and see if it runs any better/throws a code.

If the Engine computer is starting to die, it can do lots of very weird things. They don't die that often but when they do it can be very hard to troubleshoot. Based on the fact you've swapped in so many parts with what I assume are new ones and you are still seeing the exact same issues it makes me think ECU.

 

[nlc56]

You mentioned your ranger is a 2004 3.0..ford had serious issues with valves on this engine, from 2003 to 2005. You should do a compression test on the engine, and prepare yourself that there may be a heads removal job for a possible valve job. Many 3.0 owners from those years of the ranger had alot of issues. Even throwing some of the same codes.

Already replaced both heads with set of remans

 

[nlc56]

Update

Had a mechanic check the truck out, after an hour and a half he didn’t have an answer as to what was causing it. He agreed that a pcm might be at fault.
Reman pcm installed today and programmed; still didn’t fix the problem.....

 

[pjtoledo]

back in the good 'ol days someone would chime in and say you had the valve lash too tight. you did say something about swapping heads didn't you?
did it do it before the head swap?
how long does it take to get sluggish?
how long does it have to cool down to run right?

take the t-stat out so it won't warm up, what happens?

what all did the mechanic check?

 

[nlc56]

back in the good 'ol days someone would chime in and say you had the valve lash too tight. you did say something about swapping heads didn't you?
did it do it before the head swap?
how long does it take to get sluggish?
how long does it have to cool down to run right?

take the t-stat out so it won't warm up, what happens?

what all did the mechanic check?

Yes it did it before the head swap
As it comes up to temp it gets more and more sluggish, so I would say around 140° is when it starts to become noticeable.
I haven’t checked to see how long it has to cool down yet. The trucks an extra vehicle so I don’t drive it, I usually work on it then get pissed at it and leave it for a few days lol
I haven’t tried running it with no t-stat, but I have tried the factory temp 192° and a 180° (currently in truck) and neither changed it.
The mechanic checked all of the sensor operations as well as swapping a few parts with the ones I had replaced. This included tps, iac, cam sensor, maf, plugs, wires, coil. He determined the engine was running rich and the pcm was not compensating for it. When he was testing the maf, he took the air filter out and the computer did not sense a change.

 

[nlc56]

*FIXED*
Crank bolt had backed off enough to allow balancer to slide off keyway. Previous owner had replaced the balancer and apparently didn’t torque the bolt as well as lost the washer.

 

[pjtoledo]

that's certainly a unique fix for a warm up issue.