I bought this truck a few months back to be a weekend warrior, I knew it needed some tlc but I’m now stumped. Engine ran fairly smooth, auto transmission shifted smoothly in 2WD and 4WD, had only what I thought was mainly cosmetic front damage. As I was replacing headlights grille and other cosmetic stuff I found the signs of what was possible an engine swap, I’ve deducted that it may be a 4.0l out of a Sport Trac. I reclamped any loose hose and tighten any bolts I found. Any minor leak I took care of and seem to be fine holding fluids. I knew when I bought it was gonna need a new exhaust from including cats all the way back. I was holding off until I was ready to commit to the project. I was able to drive for around for about 800+ miles when one day it just went “pop” and bogged down and drove like it was in a limp mode. I figured the cat finally gave out completely. I bought all new cats and muffler and pipes. Cut out the old and bolted on the the new but it just won’t run properly. It still has rough idle, loss of power, I figured that fuel systems will need a really good cleaning so wasn’t expecting it to be perfect but it seems to be more than that. Had a mechanic look at it, he found the fuel pump and relay already replaced and suggested the ECU. I got a replacement one that had been reflashed and ready to go. Starting replacing things like pcv, and worn tubes, egr and sensors (egr, camshaft position) cleaned maf sensor. Truck started to run better but not correctly. Found the O2 sensors I bought were probably shitty and replacing 1 of 3 with Bosch OE. That sensor is registering but now I’m not confident the other two are good. Found the belt tensioner broke, replaced it (that confirmed the engine swap since the one I pulled out was the OE for theSport Trac not the Ranger). Engine now just won’t start properly, long crank and seems just not getting proper fuel intake. I plan to replace the throttle body and intake manifold but fear after that and 2 more Bosch O2 sensors (could that be it? Do they make that much trouble?)it won’t be enough. I now hear a ticking and am afraid the timing chain tensioners I’ve read about may have failed too. Also afraid the wiring harness may have a short, the camshaft sensor is still an issue code P0340 and I done 2 sensors and ECU as stated before. Any advice or knowledge about these issues or engine swap troubleshoot would be great. Thanks in advance.

 

I've had the ThrottlePositionSensor\TPS go out & cause loss of power & limp mode.
DifferentialPressureFlowElement\DPFE on the exhaust riser tube to the EGR Valve is also a NotoriousFailureItem;
look for the DPFE or the connecting hoses melted\burned; clean those riser tubes out with CarbSprayCleaner.
Give entire AirIntakeSystem=MAFSensor\ThrottleBody\EGRValve\IA CValve\Manifold\PCVValve a good cleaning & resealing.
Do you have any rattle during first few seconds after starting?

 

I’m definitely going to add the throttle sensor to the list, the DPFE is done(I called it the egr sensor) but I’ll go back and spray cleaner in those tubes that’s a good idea. I’ve got the intake gaskets and will do a deep clean.
Unfortunately I have started to hear a rattle at startup…

 

How long since OilPressurized TimingTensioners have been renewed?
Should do this every 75kMiles, before their internal 1WayValve+Seal+Spring wears out.
Hopefully you don't have TimingGuide damage yet?

 

It was a timing chain issue, new re-man engine with warranty installed. labor for timing chains is the same to install new engine. Now I know all is good internally and have comfort of little chance of another failure with another part. thanks for advice