Cleaning fuel injectors

[cj847]

Not sure where to post this. Moderators please move if needed.
One thing I have been reluctant to try is having fuel injectors cleaned. I finally tried it the other day and wanted to post the why and the results.
First, I think in general fuel injectors don’t need to be cleaned. Gasoline at the pump has enough detergents to keep them in good shape. The first pic is a shot of one of my LS swaps. The LTFT and STFT are near zero, indicating no problem.
On my other LS swap, I had very high long term fuel trims. They were +25 which is when the CEL is supposed to come on. Along with that, the short term fuel trims were +15 to 20.
There are multiple things that can cause fuel trim to be out. First, I checked for vacuum leaks and found none. Then, I checked the MAP readings they were OK. The MAF was giving believable readings as well. Fortunately, I have another LS swap, so I pulled the MAF from it. It showed immediate drop in LTFT into the low 20’s. So, I replaced the MAF. Still, LTFT should be <10 generally. I decided the only thing left was clogged injectors.
I pulled the injectors and sent them to Advanced Injector. Turnaround time was just a few days. The injectors came back with a full before and after report. As you can see, even though my junk yard LS probably has close to 300k miles on it, the original injectors only varied about 5% from original specs.
After re-assembly, the LTFT’s have been slowly dropping. It takes a while for it to update. As you can see from my live data, LTFT are down to around 8 and the short terms are still mostly negative. So, I’m calling it a successful venture.
In conclusion, I think that your fuel injectors probably don’t need to be cleaned unless you have some issue that points to a leaking or clogged injector. Or, you are building a high HP motor and need the injectors to be balanced.

[LS short box]

On my LS swaps with a used LS I always send the injectors out to be cleaned and flow checked. Just one thing less to worry about upon first start up.

[sfont66]

I agree, our family tends to keep vehicles a long time. And I commute to work driving on average 175-200 miles a day 3or 4 days a week. It’s not uncommon for me to run a vehicle 250-300,000 miles, (up here the road salt and winters claim the vehicle before the miles usually) never had a problem with injectors though on my personal vehicles…..

However if the vehicle has sat a long time, or the injector history is not known as in the case of an engine from the salvage yard then I would definitely have them cleaned professionally or buy new.
In my case I tried to use injectors that came with a ls6 intake I bought used.
I tried to clean them myself with a kit bought off of Amazon. The kit worked well for what it was, but the problem was that one or two of the injectors would unknowingly stick at random. This resulted in 1 cylinder filling with fuel and locking the engine up when initially trying to start. I was very fortunate that I didn’t damage a piston or rings.
Lesson learned, in the future I will send them out to be cleaned professionally if I question their history, or buy new.

[cj847]

Just noticed I didn't attach my report.

[Willie Makeit]

If you have the ability to clear out or "reset" the STFT and LTFT you will see the change in the LTFT numbers to be more accurate, as it has "wiped out" the old STFT data that causes the LTFT numbers to be so skewed.

Not sure that's doable with a hand-held tuner, but that feature is available on software such as HP Tuners.

[jrblanke]

I purchased my donor vehicle in 2014. I didn’t attempt to start my LS swap until 2021. At some point in that time I did pull the intake and drained the rail, but it was too late. I figured my injectors needed to be cleaned, but I thought I would attempt to start the truck. It started but only ran on 4 or 5 cylinders. I finally pulled my injectors and shipped them off earlier this month to a guy who rebuilt them. He flow tested them and found that 3 were clogged and 1 functioned at 50%. Once rebuilt the flowed great and were functioning to spec. So in my case, having my injectors cleaned and flow tested was something that was needed.

[mattfranklin]

Yes, the detergents in modern fuels should be able to deal with keeping things clean. The "Top Tier" labeled fuels should be fine tuned to deal with the most challenging injectors, GM's SCPI: https://ww2.arb.ca.gov/news/arb-requ...rucks-and-vans

So they should be more than ok for regular PFI injectors. If you're concerned, toss in a bottle of Techron Concentrate Plus at the recommended rate. One ounce of bottle per gallon of fuel tank. Several jobs ago I tested that stuff. It does an excellent job on injectors, intake valves, and combustion chambers.

Originally Posted by cj847

Not sure where to post this. Moderators please move if needed.

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In conclusion, I think that your fuel injectors probably don’t need to be cleaned unless you have some issue that points to a leaking or clogged injector. Or, you are building a high HP motor and need the injectors to be balanced.

[LS short box]

I never had an injector plug just from sitting over the winter. I run non-ox premium gas in all my hot rods and lawn equipment.
But when you buy an LS from a salvage yard you never know what fuel has been used and how long it has sat.