Long term fuel trims at +20 - help

They are good but LTFTs are indicative of a deep lying issue which is forcing the PCM to make immediate changes of fueling strategy which is affecting fuel trims over time.

If the fuel pressure regulator is in doubt disconnect it and cap it and see if the fuel trims regulate downward in the lean scale, if it does, the fuel pressure regulator is doing its job and is raising fuel pressure when it is not vacuum regulated.

Injectors will be a more difficult diagnose and will require a fuel pressure gauge and a duty cycle device which will then require you having to pulse width cycle each injector and record the leakdown of each one after you cycle them.

Being modified has nothing to do with it as long as you are modified CORRECTLY. Even an NA vehicle will not run 0 LTFT quite honestly. I run 15 PSI on my junker and the long term fuel trims are so good that they are at about 5%. Granted, I have a 2nd gen, but you should not be that dirty regardless.

 

So cap the FPR first, if LTFT drops FPR is good, if it doesn’t, FPR is bad? Cap the back of the S/C as well right?

All 3 of my boost gauges are running off this FPR vacuum line, I wonder if that has something to do with it?

As far as the injectors, they have just 150,000 miles on them (as well as the rest of the stock truck parts) have Supra injectors that I was planning on installing after FIC tune,
As far as leaking injectors, I don’t really want to buy new stock ones because I already bought the Supra remans.

Thoughts?

 

um this might be a dumb question but...why do you have 3 boost gauges lol

 

My boost gauge is coming directly off the supercharger vacuum line,
Maybe reroute those vacuum lines away from the Fuel Regulator line so there is a dedicated line there.

 

Fic will have a built in boost guage.

 

Mmm, how does that work?
FIC has a boost port?

 

Fic has a on board Map sensor to read vacuum and pressure. You just click on the "guages" button, setup the scales, and then you have a boost guage on screen. Ofcourse this is only when you have the laptop open. Wide band can tie in too.

 

Methanol
Innovate
AEM FIC

 

3.4 FPR only gets clean air from breather. It does not see vacuum. Capping it will do nothing for LTFT.

My LTFTs are nearly 0 at idle. That's what you target when you tune. I have a spot in my map that the LTFT gets near -10 but I am not worried about it. That's the beauty of electronic controlled fuel injection.

A bad front bank 02 sensor will cause bad fuel trims. The most obvious choice will be a vacuum leak though.

 

So when you say lean out until open loop, what is the AFR your getting? I can be going uphill in 5th going 70 and at 1.5 to 2 PSI in closed loop with an AFR that drops to 14. No ping. If I floor it a lil more, it goes 13 AFR and if I floor it all the way 11.5. It seems to be adding gas as more and more PsI is added.

 

Yea, that’s perfect and what is needed with the supercharger, every truck is a little different.
A vacuum leak, a bad sensor Soo many little thinks can change that and game over you have bad trims

 

It’s critical to have 2500 RPMS or you’ll ping in boost. So we can manage that driving Manual. For automatics, it seems tricky to do that. How does your truck shift? When in open loop, you have the RPMs/air and gas. When in closed loop, Do you have the RPMs? Can you hit the throttle light to get to 2500 RPMs minimum?

 

Did a smoke test, had leaks in intake pipe but I fixed all those
New fuel pump
New Fuel Filter
New MAF (Dealership)

Getting frustrated

I get my boost and Vacuum readings of the line going into the FPR. Thinking about moving it elsewhere

 

Like I said fpr does not and should not see vacuum. If that's where you're getting aem fic vacuum from you wouldn't be seeing any, unless it's hooked up incorrectly.

 

I think his supercharger shows vacuum from the supercharger barb to the FUEL REGULATOR

 

Ok if that's the case then that port should be boost only. Somebody correct me if I'm wrong but that port still won't see vacuum.

 

It will see vacuum and boost on a SC setup.

 

Have you setup the Fic yet?

My source is in the same spot, you are good there. Maybe ditch 1 of your boost guages so there is less draw, probably not an issue tho.

 

No FIC set up

I actually unplugged it for now and ran the bypass

No change in LTFT as a result

Not programming FIC until I fix this

Thinking maybe removing the innovate one, since it’s not required for my mods as you suggested above.

 

Update

LTFT are down to +10 at ideal and +3 in boost

STFT stay between +2 and -2

Unplugged all my boost gauges

HOWEVER, now something new
I got some engine fluttering at 70 mph 3700 RPMs...weird

Only happened twice then stopped