Aftermarket injector flow rate too high?

Has anyone seen or heard of cheap aftermarket injectors flowing too much fuel, I suspect mine are moving more cc's than they should, but can't find any mention of others having this problem.

Got a new-to-me 4.7l and I'm buttoning up mistakes made by the previous owner. Found a vacuum leak yesterday and now I'm getting rich CEL codes and -20% fuel trims (long and short). If I reintroduce the vacuum leak, trims go back to +-5%.

PO swapped to some aftermarket injectors - likely a sub $100 set from Amazon. When I got the truck, these were leaking externally, and I had to clean up the plastic flashing around the o-rings to get them to seal, anyway they appear to be fairly low quality. I also cleaned the MAF and throttle body to no effect.

 

Did you unplug the battery to reset the ECU and the fuel trims? It thinks the vacuum leak is there and compensating for that, reset it and it'll calibrate itself to run without the vacuum leak.

 

I assume trims reset every time the DTCs are cleared, but it's easy and quick, I'll give it a try.

 

Battery reset had no effect. Exact same symptoms still present.

 

What's the story on the MAF? Original, OEM?

If the injectors are shit injectors, I'd probably start with fixing that issue, i.e. replacing them w/OEM or going with Dirty Deeds 12-hole.

Is it possible the previous owner sold the truck because they couldn't seem to fix a fuel/air ratio issue, and the injectors were their low-budget attempt to fix it?

 

Hitachi MAF, unknown age, looks good and no error codes related to it. Unplugging MAF and running engine yields very similar results in the trims.

The previous owner clearly liked upgrading the truck, but he wasn't very mechanically adept, so he ended up creating a bunch of little problems - the small mistakes really added up. Luckily the 2001 engine is pretty simple, and at this point, I've gone back over everything he did himself and corrected it plus performed routine maintenance - I had it running pretty good till I noticed the vacuum leak (loose banjo bolt on the manifold nipple to the brake booster). He also had some items done by actual mechanics, and that work looks okay.

 

Wanted to give an update, as I suspected it was the crappy aftermarket injectors flowing too much gas. I found the stock injectors in the box of spares, so I swapped over the the o-rings and seals and dropped them in last night - the aftermarket seals were in much better shape than the originals. STFT bounced back to between +0.5 to +10% indicating they probably need new filters and a good ultrasonic cleaning.

Now to decide on whether to leave the stock injectors as-is, clean and rebuild them, or upgrade to the 12-hole. I'm halfway considering buying an injector ultrasonic cleaner and flow testing machine just to unlock a new skill; it's only double the price of paying someone to do it for me.

 

Good news, and thanks for the update. So PO tinkering strikes again, eh?

I don't think you'll get any performance gains with the 12-hole. I have an ultrasonic cleaner for cleaning small stuff, it'll fit an entire small engine carb in it if I needed it, but typically use it on smaller stuff I'm too lazy to drill into. Not sure if it'd work for injectors.

But honestly ... If you've never used SeaFoam to clear out injectors, it's totally safe, just highly refined petroleum. I've used it in my crankcase and gas tanks of all my combustion engines. You can't overdo it in the fuel system. No fancy setup needed for injectors, just a power rig to make it pump, feed line, with a reservoir under to recirc the cleaner. Look no further than here:

https://www.youtube.com/watch?v=iqNqa7kaAtk

 

Yup, he got me again. I wonder how many more things are sitting in wait.

Because of the way the ECU meters fuel by-the-bank, I'm much more concerned with flow numbers matching for each bank of injectors. And setting up a test rig with a graduated cylinder plus fabricating a microcontroller to pulse the injector at a set rate (holding it open won't give accurate results and is said to be bad for them) is more work than just buying a $300 machine that pumps, measures, pulses, and ultrasonically cleans.

On the other hand, remanufactured sets come flow-matched, and the 12-hole are cheaper than the 4-hole.

 

Go for it! Dirty Deeds are, if I recall, a board vendor/supporter. They make a quality product a lot of guys here are using. Go for it.