2.9 loses power when warmed up

[Bondo]

It could be the coolant temp sensor.

The air is cooler at night (when you arent having problems), therefore your coolant is running a tad bit cooler and the engine is happy.

Do you have a 180 degree thermostat?

 

[86 4x4]

to be honest i have no idea if its a 180 or 190 i need to look int that bu the temp gauge has been stayin where it usually does so i dont know if that would be it or not but worth lookin into thanks for the advise

 

[Bondo]

Worth a shot, sure.

 

[NMB2]

i actually took the thermostat out completely due to how hot its been and trying to troubleshoot this issue. Is the CTS the one that sits (looking at the front of the motor) top left of the intake/waterpump area?

 

[IMenriched]

i actually took the thermostat out completely due to how hot its been and trying to troubleshoot this issue. Is the CTS the one that sits (looking at the front of the motor) top left of the intake/waterpump area?

yes that is the one.

with T stat out....what temp are you running?
Do you have factory gages? or mechincal gages?
mechincal gages will give you better feed back than the factory sending units

 

[NMB2]

i replaced that sensor.. no change. with the t-stat out it still runs alot hotter than i think it should. up on the N and O usually. sometimes higher. I've pretty much given up on this... ive spent about $250 in the last few days and all for nothing. ive replaced everything that supposedly can cause it AFAIK. maybe its just how it is?

 

[Jspafford]

N O R M A L mean nothing.. Get a mechanical guage and KNOW what the temp is.

 

[Area 52]

Not sure if this would account for the symptom, but if the air filter box baffle door (which functions via vacuum) is stuck in the cold start position, wouldn't the intake air be constantly super heated as it draws the air across the passenger exhaust manifold? Ambient air temp versus air pulled across a 450 degree manifold???
I would do a quick check by pulling off the flex hose from the manifold to the air duct to the filter box and plug the opening with a warm/hot engine running. If it dies out...bingo...the baffle door is stuck closed to outside air...intake air only from the manifold position.

 

[wildbill23c]

Old thread but the 1987 Ford Ranger I picked up a couple weeks back is doing this exact same thing. Waiting on a fuel pressure tester but I'm pretty certain its not a fuel problem as I just installed a new pump and filter and the issue starts after its warmed up. Would a malfunctioning TFI cause this problem? I thought when the TFI was failing or fails the vehicle just dies immediately. I get a rough idle, hesitation, lack of power, down to feeling like its missing on all cylinders, sometimes flooring the accelerator will clear it up then it takes off again and is fine for a bit then starts doing it again during heavy throttle it doesn't do it, but it does this under light load like during cruising speed then when trying to accelerate it will do this, as well as after taking off from a stop it'll lack power, have the sluggish not running on all cylinders type problem. Coil, TFI? I'd think a temp sensor not working right would have problems showing engine temp on the gauge too? Gauge itself is towards the bottom 1/4 of the "normal" band and actual temperature is running 197-200 degrees at its highest then the thermostat is fully open and cools back down to the high 180's low 190's almost immediately.

I'm at wit's end here with this thing LOL. Love the truck but its not returning it LOL.

Read on some other forum about cracked heads or blown head gaskets, but I don't have any signs of coolant in the oil, no missing coolant, and engine oil level remaining the same and clean...luckily when I picked it up they hadn't changed the oil so I was able to see that there wasn't any oil/coolant contamination and no residue on the oil cap. But that don't explain why its fine sometimes and sometimes it acts up.

At first I thought it was fuel related due to the fuel reservoir in the frame rail being cracked, but that has been replaced as well as the fuel pump in the frame rail, and a new fuel filter just to be safe. Also replaced the fuel pressure regulator as well.