Running lean and rich at the same time.

Muddinfun is on the right track... I have actually had 4 reversed O2 sensors* on a non Toyota product with your exact symptoms. I would disconnect all 02 sensors from the PCM and drive her around for 5 minutes then see if the issue(s) are better or worse. By taking the O2 sensors out of the input stream you are forcing the PCM to use fixed values for the engine to run. This will point you in the direction of is it mechanical or electrical.
reconnect the O2 sensors, clear the codes, warm the engine and monitor your front o2 sensors and the MAF. slowly raise the rpm from idle to 2500 ish and watch the fuel trims if they go from what ever they are + and/or - and slowly creep close to zero you have a vacuum leak. If they do not change monitor the MAF and see if there is steady increase in g/sec of air intake.

The last one is kind of a bizzare one but it still happens. If the grounds from the cab to the frame to the battery are flaky there is feedback into the PCM and strange things happen. With a digital multimeter set the range to less than 3 volts DC. Put one lead on the motor and one on the battery negative post. Any reading above .3 volts DC and you have bad ground(s). Switch the meter over to mAmps and do the same thing, anything above 30ma is considered too high. The PCM is dealing with mili-amps on most of its circuits and with bad grounds this excess has to go somewhere. The non Toyota product that had all of the "issues" had almost 1.5 volts DC and a fluctuating 750 miliamp reading, as soon as I added new additional grounds, motor to body, body to battery, body to frame, she ran normal, the smog monitors would run and clear and she passed smog. This probably took me 3 weeks of on and off thinking, tinkering and research before the answer popped into my head at 4 in the morning. A quick check of wire colors from harness to o2 sensor leads proved my theory correct.

I hope yours is as simple as this was AFTER I figured it out.

*why this manufacturer decided to use non-polarized plugs of the o2 sensors is beyond me... passenger side front o2 sensor pluged into d/s front o2 sensor lead and vice-versa sure made her run like crap.

 

OK a fuel pressure check should have been done first before any blame was placed, it is the major player. The pump is capable of something close to 70 PSI dead headed so about half of the fuel is returned to the tank during normal operation. So if it's showing 35 PSI at the rail there is nothing wrong there. It basically is the only thing in the entire system that remains constant (except WOT then it jumps up maybe 10 PSI) everything else is variable. The amount of time the injector stays open is totally controlled by the electronics this is what sets the fuel mix so if the fuel pressure is correct the blame lays elsewhere. Because the injectors are fired in pairs it could be related to an electronic issue if one of the injector drivers in the ECU is bad (not allowing the injector to open) it's going to be lean on two cylinders. Or if they have been tinkered (miss wired) it would produce the same effect.

 

Pressure isn't balanced along a rail with injectors sapping it as it passes. By your logic the return line pressure should be the same as the feed pressure.

Also, flow rate can be disrupting to the injectors, thats harder to measure.

 

I have swapped ECU’s and that didn’t work. I have not tried a fuel pressure test yet and I am about to test for vacuum leaks with propane.

Edit: Also, I am having 20% lean on one bank and 20% rich on another.

 

Is the engine running smooth? If you are running rich and lean at the same time and sensors have been ruled out, I would actually be more inclined to tell you that the new/ remanufactured engine had its timing chain installed incorrectly. Especially if the engine is running like garbage alongside with those poor readings. Just for shits and giggles after all things have been ruled out sensor wise you may want to pull both valve covers and check TDC.

 

Engine isn’t smooth. Rough idle and occasional white smoke.

 

Yep, that sounds like a timing chain. Those engine remanufacturers don't know how to rebuild engines to save their lives. Part of me doesn't blame them because there are so many factors to rebuilding the engine internally that it is easy to forget to tighten or install something on the engine incorrectly. There is just simply too many factors, however, that does not excuse them from doing things wrong because their job is to rebuild engines CORRECTLY and reliably.

I am HIGHLY reluctant to go with one whenever I am shopping for engine replacements for vehicles at work. We have had endless issues with those guys, so now we go low mileage used or we go local reliable engine rebuilder who has a long track record of putting out good stuff and has an excellent warranty.

 

As stated by @Glamisman and @Muddinfun try disconnecting the 02 sensors and see if it runs better. Forcing it into a predetermined /backup fuel strategy will rule out a fuel control issue.

If it still runs poorly then i would begin to suspect a mechanical issue.. like the chains mentioned above. Put a vacuum gauge on it and see what you have, needle should be steady around 18-21 in/hg

 

No, return line pressure is no greater than return line friction loss, maybe 5-6 PSI tops it is strictly a dump back into the tank. I had an incident once on a BMW with a smashed return line the fuel pressure rail was close to 60 PSI it was too great for the engine to actually run. Again liquids don't compress well, the pressure you are measuring is the pressure on the fuel rail it is line pressure otherwise there would be more than one test point. I would agree there is a tiny drop for a millisecond as the injector opens but no one has a instrument accurate to measure it. The flow rate through an injector is miniscule immagine how many times it opens and closes in only one mile.

 

What about the regulator malfunctioning and not allowing enough pressure in the rail? I assume it is just mechanical and can fail as well. If pressure in the rail isn’t around 30psi, I wouldn’t just assume the pump is bad no?

 

Ok how did you determine 20%? I think someone else mentioned O2 sensor disconnect that will definitely put it into limp mode and it will go into basic operation. Fuel pressure check is operation number once that is determined then you can eliminate the rest one by one all the variables relay on fuel pressure it is the only constant. Connect a vac gauge to the intake if it's low you have a leak. If it wakes up with a shot of cab cleaner in the throttle body it's lean that is unregulated fuel.

 

Yes the regulator is located in the fuel rail is is a mechanical device it has a vac hose that is connected to the intake when the intake pressure is low (WOT) it kicks up the pressure some thing around 10 psi it does this by restricting the return flow. It is the controlling factor in overall fuel pressure. Yes a pump can go bad but usually it doesn't just lose pressure they just quit. The pressure regulator is pretty simple there is no magic basically a spring and a valve seat and seldom go bad. A failing pump usually ends in the truck stopping.

 

The truck still runs, it has a rough idle, smokes and has a knock... I will not drive it due to the condition. I am worried about washing pistons like previously stated on the previous engine..

 

So, who do you use for remanufactured engines?

 

I am reading 20% from hp tuners.

 

I've always had excellent luck with Jaspers, but we don't use them much because they are more on the expensive side and customers are cheap but hey, buy once, cry once right? (Thats not the way they see it)

20% is quite a bit and it could be enough to trigger a tooth or two on each cam being off from TDC on the crank.

 

What is the 20%? 20% of what? It's been close to 20 years since I had to deal with this stuff I'm sure things have changed a lot but there is a basic under laying operation that is common to this day and all electronic fuel injection systems follow the same basics. VW was the first to street a electronic fuel injected car that was 1968 (I was 22 and fascinated) that same basic system is what's on modern vehicles to this day. So help me out here the day I stop asking questions is the day I quit learning.

 

I am on my second Jasper engine.

 

The 20% I’m referring to are fuel trims being read via hp tuners scan tool on a laptop. It connects to the obd2 port and gives live data read outs.

 

You've went through two on this truck?

Should be no more than 5.5%+-