Supercharged 3.4 issues

Hi everyone so I have inherited a 2003 dbl cab supercharged 3.4 that I’ve been chasing an issue for quite some time. The truck would run fine then after I shut it off it wouldn’t restart. I replaced O2 sensors, MAF sensor, coil, ignitor, and fuel pump. Got it running and starting again but now when it starts it almost wants to die and then revs up, when I go uphill from a stop and stomp on it it dies. Any info or help would be great.

 

Replaced sorry forgot that

 

I'd start with checking fuel pressure and volume. You can rent a fuel pressure tester from autozone.

 

Your STFT & LTFT is off. Possible leaking or dripping injector?

 

yeah man your fuel trims are rightly f**ked...wayy too lean. Long term fuel trims (LTFT) and short term ones (STFT) should be between -10 and 10. Your LTFT are at about 8 and your short term ones are at 20. High positive trim numbers means you're running lean, too low in the negatives would mean running rich.

Leaky/dripping injectors would result in lower negative numbers from excess fuel, since you're in the lean territory I would be looking for a big vacuum leak somewhere. That's the most common culprit. That or your MAF sensor or O2 sensors could be bad. When you replaced your sensors, did you go with OEM Denso ones? If you got aftermarket ones from another brand then you should return those for Denso branded ones...these trucks were built with Denso sensors and using anything else is likely to create problems. It's a common occurrence we see on the forum quite a bit.

Also beware of fake Denso sensors on eBay and Amazon...they are out there

Start looking closely for vacuum leaks too, do the smoke test if you have to in order to confirm

 

also do you have any check engine light codes? I would imagine you have a P0171 code at least for that lean condition. That scanner tool you used to get that info should also tell you if you have any codes.

I had a P0171 code for a lean condition when I got my truck a few years ago, had the supercharger installed by the previous owner. Turned out the EGR port on the back of the supercharger had lost it's cap and created a vacuum leak. It still ran OK though, didn't have the symptoms you describe. But that's something to check.

 

I had a p0171 code but have not since I started replacing parts. I replaced o2s with Delphi. But I want to say that cap on the back of my supercharger is missing as well. I’ll have to check

 

this picture is vacuum port on back of supercharger plugged engine idling

 

This picture is with vacuum port on back of supercharger plugged and engine at 2500rpm

 

Looks like the fuel trims are headed the right direction.

 

what’s next?

 

the brake booster is an often overlooked vacuum leak.

 

How does it run now with it plugged.
Still would check fuel pressure if it was me.

 

HELP!

Sensor MAF

https://www.tacomaworld.com/threads/long-term-fuel-trims-at-20——help.651601/

 

Fuel pressure can be tricky, it might test good
at idle but the real test is at WOT and you cant test that.
My fuel pump was tested at idle and showed perfect pressure. But at WOT the pump was not keeping up as my trims were very high.Only way I figured this out was replacing the fuel pump and my trims went from +20 to zero - + after the new fuel pump. You can’t test the fuel pump at WOT and that’s the spot where
it falls short especially for the superchargered motors, because they need 100 percent of the fuel pressure to keep the engine happy.

Replacing an old fuel pump because it’s not working 100 percent can actually fix
plenty of supercharger ping issues.
It took two hours to replace a friends fuel pump by pulling the bed off with an engine hoist.

 

Take the supercharger off and sell it to me.