Horribly degraded performance

I've read that the 4.0 doesn't like iridium.

But I've run iridium in multiple 4.0's without a problem.

My 05 came with factory iridiums. One side was ngk the other side was denso. I read somewhere that is because of how the factory is setup or something.

It seems that different years might have come with different plugs.

 

I removed my entire intake at 80k and it was nasty, gummed up from all the dirty breathing hoses that shoot dirty gases and oil into it, right into the clean side too.

I make it a habit to clean out the intake every year now.

 

Run an excessive amount of seafoam when you're tank gets low. Cross your fingers after doing so for a few days. It's not a miracle, but it might clean up those clogged lines and injectors.

This will foul up your spark plugs and sensors, but you can clean those off later.

 

ok Torpsd, here’s a puzzle for ya!

Stock injectors back in, and fuel trims hover around 0 with a variance of +-3ish.

lambda actual is about the same around 1.

All I changed was the fuel injectors and removed the rotrex from the belt system (back to original belt for stock physical load).

god forbid I swap to 650 injectors from FIC or Siemens injectors from URD and an ecu that has been flashed to a tune from THE debatably best tuner around for our trucks.

same MAF
same Af sensors
Same timing
Same fuel pump
Same spark plugs
Same same same except the injectors and ecu going back to stock state.

I do have to pull the fuel pressure (not that it matters much if it’s reaching a controlled proper state) for documentation purposes to help anyone ever following my path to worky worky.

any thoughts?

 

Sounds like your aftermarket injectors were giving more fuel per the same command voltage, as say another vehicle's with the same size/brand aftermarket injectors. ***Side note question*** How freely does the Rotrex spin, now that there is no belt on it? I think you would have mentioned it, but wanted to ask anyway.

 

One can assume that the fuel pressure regulator is working properly, since the fuel trims are where they are supposed to be now. Is is connected to a vacuum source, or nothing?

 

Will check on rotrex (making sure I spin it the right way).

and yeah, certainly does sound like more fuel per same voltage, but that just bothers the hell outta me if I know the pressure and have a certified characterization for each injector from FIC (which was the ONLY reason I got these, solely wanted to make damn freggin sure J and I had solid ground to stand on). I’ll talk with J about whether our Tacoma’s have injector temp scaling tables, which is what causes gm’s flashed with HPT to run rich (because they don’t have injector tip temp monitoring and typically GM folks don’t know about this and fail to update with proper assumptions or flatten table out) Highly surprised if this was it, because this isn’t anywhere close to his first rodeo, but grasping for straws here.

FPR is hooked up to ‘vacuum’ via air box. Seems silly to me when boost exists (which I don’t have in this case, but did not have an affect on trims at all when I ran same tests when disconnecting FPR vacuum line entirely — thought this was strange, but it as well is a newish OEM part with a line that has been verified to hold vacuum).

Will lyk about rotrex.. As always, thanks man! If you ever make it out to Maui, lmk and I’ll get you some beers!

 

Also had the rotrex air output out of the loop during last few tuned tests performed, simply using the stock air box to determine if that had a change on the negative fuel trims.

No change observed, so any boost to FPR shenanigans (if any) did not appear to have any affect on the fuel trims.

 

The vacuum line going to between the airbox to FPR sees very minimal vacuum. A little more when the sucking side of a F/I multiplier is after the intake. There is a certain name for that but it eludes me. Having that vacuum hose routed to a location post throttle body will give a true vacuum source. With F/I, then it would also give it a boost reference.

 

For anyone else slightly confused about FPR shenanigans, here’s an article.

https://www.fuelab.com/blog/11-boost-reference-fuel-pressure-regulators/49

it all clicked to me when I thought about vacuum. When throttle body is wide open there is almost no vacuum, tons of air is flowing into the engine and it is assumed that tons of fuel will be needed. So FPR’s close up when vacuum decreases (which is basically saying when pressure increases).

now my brain wasn’t able to accept that a FPR from a naturally aspirated engine would works with boost too, but (after googling torpsd’s boost reference term to try learning — and still being slightly confused) when the pressure on the FPR’s reference line (the vacuum hose port) gets higher (less vacuum) it restricts fuel flow return, which increases fuel rail pressure. Well, what happens when the pressure on the reference goes beyond a atmosphere level (> 0psi).. the diaphragm in the FPR further constricts fuel exiting the fuel rail (via return line) to further increase fuel pressure to injectors to help them fight the now pressurized intake manifold to maintain the lambda (AFR/stoch) desired.

I’m guessing with a proper boost reference if nominal due pressure is 44 at idle, and I’m running at say 5psi boost, I would see 48 psi on my fuel pressure gauge.. instead of simply using the FPR up to atmospheric pressure levels (with a shitty vacuum source to begin — airbox itself isn’t under a lot of vacuum)

THIS ^^^ must be the actual reason behind the FPR mod that’s been eluding me even when trying to search for where it all started and why.

Damn, figured this out (after being pointed in the right direction by Torpsd) before coffee, today’s going to be good.

 

Hard to quantify, but I can turn it by hand with a slight amount of effort. It doesn’t spin freely, but it isn’t surprisingly difficult to turn.

definitey less force than opening a jar of pickles but definitely more than opening a fresh 20oz bottle of mtn dew.

 

Wait for it..

 

i've learned recently that pulling the efi fuses/disconnecting the battery doesn't actually reset all the learned values like I implied before. At least in the 3rd gens, you have to use Techstream or a bidirectional scan tool (I bought the Xtool/Anyscan A30M) to reset the throttle/transmission learned values. not sure if it's the same with 2nd gens

 

From my research, the people who had problems with iridium plugs likely had fake ones...

 

Lots of fakes on Amazon. Have to be very diligent.

 

The thought on the resistance of the S/C, was what if it was adding a ton of load to the engine, by not spinning freely. Seems that can be ruled out as well.

 

Sad on the fakes, seems like a TON of effort to make something seemingly real to sweep a few $$$.

Totally get where you were going with the SC spin test. Glad my creative quantification worked

Will update when I hear from J. REALLY looks like at this point the truck is unable to provide expected control for larger injectors. Why that is, TBD. Wish I could post my Scan logs here to supplement (attachment issues)

 

Screen capture or take a photo

 

If there’s something specific you’d like to see in a photo, lmk and I’ll PM one over. For now, J’s intrigued by the challenge and I’m curious to see where he wants to go from here to work through things.

Apparently my truck is ‘special’.. No clue why, but with stock injectors everything plays very nicely and fuel trims are seemingly perfect. Long terms are adjusting in tiny increments over time, and short terms are fluctuating with narrow variance as all described.

During a driveway data collection with the supercharger connected to driveline and within the air path of the system, my fuel trims even went slightly positive throughout most rpms.

fine fine fine fine until any other injectors get put in, when things go straight to mystery. Non stock reputable from trusted verified manufacturers cause my truck to spit -20.3 or -21.1 STFT ‘almost’ 100% of the time in ALL scenarios went for a light drive with values that should be safe to see if real world had any affect. Nope lol

only scenario where STFT change is seen is when I let off the gas entirely, causing the diverted valve and blowoff valve to do their things, and the STFT reliably dips to -3.1 on both banks for a snap moment before immediate return to -20.3 or -21.1 on BOTH banks.

the most interesting part to me (aside from the very unique repeatable numbers chosen — which seems like hitting the end of the system’s dynamic range to me, though I’d have to look at lambda values again to be certain — long day) is that the LTFTs stay at zero in all circumstances when using aftermarket injectors with proven and known tuning values.

Will update path forward and resolution with J. Guy’s been awesome to work with in spite of my truck being a special pain in the ass. If we wind up stumped, then I might actually pray for a TW council session

I’m hoping that whatever we wind up discovering will bring to light a new “oh shit that’s possible” aspect to look at when experiencing performance issues with this gen tacoma and not something lame.