Fuel injector

Quick question, With a leaking fuel injector into the intake manifold, this would cause normal fuel trims to crash into negative numbers as - 19 to -25?

Just want a confirmation this is possible before I pull the fuel rail as for the factory service specs.

As always, thank you for your time and input

I would have to say yes.

Have you performed a leak down test on the fuel rail? Does it hold pressure?

I would also look at voltage and current wave forms for each injector to determine which one is doing this. SD has several videos on this, especially in his premium channel.

Did the fuel system leak down, it passed with norm spec and pressures. The book calls for the rail pull. I was thinking of putting a vacuum gauge and vacuum on the rail, didn’t know if that was “ kosha “... would be a lot easier than pulling the rail.. is that what they do now?

You could push a cheap USB endoscope down the inlet to look for signs of wettness. Also what happens to the o2 signal when you introduce a vacuum leak

Funny you mention that, I pippyback a vacuum leak into the intake manifold and returned my fuel trim to factory specs. So adding o2 actually corrected problem, not fixed obviously... that’s what points me to fuel injectors.

Again thank you

Retired wrote: Did the fuel system leak down, it passed with norm spec and pressures. The book calls for the rail pull. I was thinking of putting a vacuum gauge and vacuum on the rail, didn’t know if that was “ kosha “... would be a lot easier than pulling the rail.. is that what they do now?

You mean like A/C system leak testing with vacuum? :blink: I've never heard of it, but I dunno why it wouldn't be OK? Though, I don't know how any residual fuel in the rail will do with being under vacuum (vaporize, I'd imagine), and I don't know if the injectors will stay closed with vacuum on the supply side.

If you end up doing this, let us know how it goes!

First pull out the spark plugs and see what they look like. That's always an easy way to see what is happening in each cylinder and to check whether they are all even or one cylinder has "something going on" that's different to the others.

Thanks for helping.
I will test fuel inj by factory man first, pulled and on rail and charged. Once I identify the dirty inj I’ll try the pressure method to see if it has any diagostic quality.. keep you informed.

Thanks for helping, everything is new. The car is running fine, I just wanted to keep my fuel trims in-line with specs. The long term FT is adjusting for short term richness. Meaning the computer is compensating for an underlying problem. Hope this helps