Fuel Injector cleaning?

[Matthew Jeschke]

I need to know of a very good injector cleaning solution. I'd like to start with something I can add to my gas tank and see if it helps. I've got trims of 20% right now along with some annoying and somewhat random knock retard and think it maybe due to varnished and or gunked up injectors. I'd resolved originally by pulling LOTS of timing from my tune but I'm at a point I want to fix this and suspect I might have an injector issue.

Backstory: I've been chasing my tail tuning and with out of spec fuel system for years now. I thought I had it all sorted out but have a 20% anomaly in my trims when using good configuration (tune). It dawned on me, I've verified EVERYTHING in the fuel system, except Fuel Injector Flow. To adjust the tune we lowered the fuel injector flow by 20% which isn't ideal in my mind. There's an issue somewhere mechanically and I want to sort it out. I bought a set of used L59 flex injectors years ago... They don't leak but I never tested nor cleaned them beyond a leak test. I suspect there maybe some varnish buildup or gunk in them.

My bank 1 Sensor 2 O2 voltage seems to always lag bank 1 sensor 1. I fixed the EGR right after my build as it was leaking and that resolved a bank mismatch code but it still seems to lag. The O2 sensors were replaced in my build AND they are the same make / model. I do have an earlier P01 controller setup, where the grounding is chassis ground I believe for the O2 sensors. Not sure if that's causing some error (I'd think not). I've cleaned and inspected my grounds as well. The error doesn't show up in the trims which seem to be pretty close for both banks. However, if a few injectors lazy, maybe it could cause some issues that wouldn't quite get caught by the controller?

 

[Fless]

I've had pretty good success using BG44k and Techron, but you'd need to observe the treatment ratio (might need two bottles in a full tank).

Are you actually running the L59 injectors, or just waiting to use them? Based on your graphic the fuel trims are closer to 10%, so running a bit lean.

Done a fuel injector balance test to see any large variations?

If you can run E85 fuel or a mix of gas and E85, that will also help clean the system.

 

[15burban]

Redline si-1. One of the few that still have pea in it.

 

[Doubeleive]

meh, visit herko.com and just order a set of new ones, there "herko" brand are just oem that have had the numbers shaved off.
you can get a whole brand new set for a decent price.
Otherwise best method is to pull them all and have them professionally cleaned
2nd best is to use a cleaner kit attached directly to the fuel rail
anything else is going to be washed down results.

if you order some you can go with a 4 nozzle versus the 2 nozzle as well, presuming the originals are 2 nozzle

 

[Fless]

meh, visit herko.com and just order a set of new ones, there "herko" brand are just oem that have had the numbers shaved off.
you can get a whole brand new set for a decent price.
Otherwise best method is to pull them all and have them professionally cleaned
2nd best is to use a cleaner kit attached directly to the fuel rail
anything else is going to be washed down results.

if you order some you can go with a 4 nozzle versus the 2 nozzle as well, presuming the originals are 2 nozzle

The L59 FF injectors should be 4 nozzle, while the gas injectors have two.

 

[SilverSport]

Chevron Techron Complete Fuel System Cleaner...do you have a Napa store near you???...they often run a sale on their "Complete..." ...when I've had any issue I "double dose" for one time (1 oz per gallon doubled to about 2oz per gallon)...then I use it about once a year in my gas tank and I use Top Tier gasoline...

currently on sale at Napa

https://www.napaonline.com/en/p/CHV37802

Good luck,

Bill

 

[Matthew Jeschke]

Are you actually running the L59 injectors, or just waiting to use them? Based on your graphic the fuel trims are closer to 10%, so running a bit lean.

Done a fuel injector balance test to see any large variations?

If you can run E85 fuel or a mix of gas and E85, that will also help clean the system.

I'm running them. The graphic is from a older tune. We trimmed the fuel by lying to the PCM about injector flow rate. That was one of the intermediate tunes isolating the problem.

I'm assuming you need a test bench to do an injector balance test?

Redline s1. One of the few that still have pea in it.

So you're telling me I can just wiz in my tank?

meh, visit herko.com and just order a set of new ones, there "herko" brand are just oem that have had the numbers shaved off.
you can get a whole brand new set for a decent price.
Otherwise best method is to pull them all and have them professionally cleaned
2nd best is to use a cleaner kit attached directly to the fuel rail
anything else is going to be washed down results.

if you order some you can go with a 4 nozzle versus the 2 nozzle as well, presuming the originals are 2 nozzle

I found a set of the next generation ones there. Curious if the Gen IV engine ones have same fitment as the Gen III flex injectors?

Herko Fuel Injector 12613412 For Silverado Sierra Yukon XL Express 2500 3500 6.0L-V8 2010-2013

Buy 12613412 Fuel Injector Herko Automotive. Fit Chevrolet,GMC,Express 2500,Express 3500,Express 4500,Silverado 2500 HD,Silverado 3500 HD,Suburban 2500,Tahoe,Sa

store.herko.com

Chevron Techron Complete Fuel System Cleaner...do you have a Napa store near you???...they often run a sale on their "Complete..." ...when I've had any issue I "double dose" for one time (1 oz per gallon doubled to about 2oz per gallon)...then I use it about once a year in my gas tank and I use Top Tier gasoline...

currently on sale at Napa

https://www.napaonline.com/en/p/CHV37802

Good luck,

Bill

Cool thanks. I don't think we have Napa here where I live. I'll take a look though.

 

[strutaeng]

@Matthew Jeschke most of the more advanced tools can perform an injector balance test, and there's even a gadget that Amazon sells for like $30 that pulses injector a certain amount of time. You do not have to remove anything.

You hook up a pressure guage, prime the fuel system, then go around one by one pulsing the injectors. You record the primed pressure, and the pressure after the pulsing. They should have very close values, within 1 psi ideally.

 

[Doubeleive]

I'm running them. The graphic is from a older tune. We trimmed the fuel by lying to the PCM about injector flow rate. That was one of the intermediate tunes isolating the problem.

I'm assuming you need a test bench to do an injector balance test?


So you're telling me I can just wiz in my tank?


I found a set of the next generation ones there. Curious if the Gen IV engine ones have same fitment as the Gen III flex injectors?

Herko Fuel Injector 12613412 For Silverado Sierra Yukon XL Express 2500 3500 6.0L-V8 2010-2013

Buy 12613412 Fuel Injector Herko Automotive. Fit Chevrolet,GMC,Express 2500,Express 3500,Express 4500,Silverado 2500 HD,Silverado 3500 HD,Suburban 2500,Tahoe,Sa

store.herko.com

Cool thanks. I don't think we have Napa here where I live. I'll take a look though.

good question, I do not know. I would try to maybe call herko on Monday and ask if they know they have been selling injectors for a really long time, otherwise a engine builder or maybe a tuner shop.

 

[Fless]

@Matthew Jeschke most of the more advanced tools can perform an injector balance test, and there's even a gadget that Amazon sells for like $30 that pulses injector a certain amount of time. You do not have to remove anything.

You hook up a pressure guage, prime the fuel system, then go around one by one pulsing the injectors. You record the primed pressure, and the pressure after the pulsing. They should have very close values, within 1 psi ideally.

^^ This. Just a bidirectional scanner that will do the individual triggers and a fuel pressure gauge.

 

[Matthew Jeschke]

@Matthew Jeschke most of the more advanced tools can perform an injector balance test, and there's even a gadget that Amazon sells for like $30 that pulses injector a certain amount of time. You do not have to remove anything.

You hook up a pressure guage, prime the fuel system, then go around one by one pulsing the injectors. You record the primed pressure, and the pressure after the pulsing. They should have very close values, within 1 psi ideally.

Oh cool that's ingenious. I do have the pulsing tool / injector tester. I could pressure test the injectors RIGHT on the motor. I really like that idea!

good question, I do not know. I would try to maybe call herko on Monday and ask if they know they have been selling injectors for a really long time, otherwise a engine builder or maybe a tuner shop.

Okay cool. Thanks.

 

[hagar]

Are you just assuming the fuel trim problem is the injectors, or have other tests brought you to that being the only thing left? If i were trouble shooting a left and right blanketed large fuel trim issue, I wouldn't even consider injectors as a potential issue. You aren't going to have consistent left and right bank positive trims because of dirty injectors, they would all need to have the same or similar problems at once which isn't really likely.
I would start by making sure the fuel pressure is in spec, and if it is, unplug the maf and log the fuel trims again while running on the speed density side of the tune. As long as the stock tune is in place, and the vehicle is all stock, you should see the fuel trims get close with the maf unhooked if it's a faulty maf.
The fact you are getting knock shows the thing is more likely having immediate commanded fuel starvation from something like the maf or low fuel pressure. If you just had a consistent injector flow issue across all injectors, the positive fuel trims should be enough to keep the engine fueled properly and not knock. If the engine is running lean because of the maf, fuel trims wont be able to compensate for the transient lean fuel issues quickly enough to prevent knock.

That's all assuming you dont have smaller than stock injectors installed for some reason.

 

[Matthew Jeschke]

I should be more specific. I'm going through my system with a microscope so to speak. There's a knock anomaly I cannot isolate and the only thing I've not mechanically verified is the injector spray pattern and flow. The PCM is generating low trims, banks are mostly the same. However, I'm not convinced the 0411 P01 nor P59 PCMs we have are capable of isolating more nuanced injector issues; specifically injector spray pattern and injector to injector balancing (only bank to bank).

I've taken apart the entire fuel system, replaced new & verified all specs per FSM. I bought used Flex Injectors years ago for my build. I verified the injectors don't leak but never verified spray pattern nor injector balance (flow per injector). I'm thinking the injectors were well used and I should have had them cleaned in the least... They were good enough to run the truck but I've never been able to address what appears to be a random knock issue in my tune (the knock is real not false).

I've never been able to advance the timing beyond the base timing table (low octane spark advance table). This is basically the factory's known safe timing table. I finally hired a professional tuner to help me figure this out after many years of never being able to clean up this knock issue.

- The knock is experienced under throttle changes that are gradual to rapid. VERY VERY VERY light throttle changes under load do not provoke the knock.

- I cannot isolate the knock to any given airmass and or RPM. If I could I could just pull timing in that area... Basically it's not correlated with airmass.

- I can see random knock when TCC is locked or unlocked. However, it's more pronounced and can appear consistent under lockup. Yet I can be locked and have the condition appear one time but not the next the engine is under that given load.

- AFR is good and verified by WB. Power enrichment / non stoic AFR tracks accurately and quickly adjusts as expected.

- I have no misfires... I'd assume a misfire if I had one wouldn't create knock though (possibly a rich condition?).

- Engine runs PERFECTLY smooth at idle and light cruise (around town part throttle) say under 45 mph.

- The trim between banks is no more than 3% different and that's only at idle (under 1200 RPM where I have no knock issues). That said bank 2 is biased lean under idle... possibly a effect of distance from bank one rail where fuel is fed in? Either way likely a non issue.

- I'm running Shell premium octane fuel. I'm at 2500+FT MSL here so that's 91 octane. NOTE: I only ever run name brand fuel typically Shell.

I'd had scaled my VE table to 150% in my tune (I always found this odd as engine is naturally aspirated)... The tuner however, helped me better isolate the fueling error. We used a known good VE table scaled for my cam then adjusted the flow rate in the calibration from what should be ~36#/hr down to 30#/hr. This leads to me to believe there maybe some issue with the injectors. I'm starting to think I'm not getting a consistently (1) metered fuel mass and or (2) even mixture in the cylinders.

I could buy brand new injectors but I'd still want to verify pattern and flow. So I'm leaning toward getting a couple used sets; reconditioning them (clean), then measure their flow and pick the ones that are most evenly flow.

Side note I'm looking for a fuel rail, & crossover tube... and or a shop in Tucson AZ area that does injector flow testing. I keep searching google for one but it's just shops that run cleaner through the fuel system.

I can however, build a test bench. I have the stuff and function generator to create the required pulse. I might do this by raising the fuel rail, pulsing a single injector at a time then measuring the weight of the fuel metered.... But would be much easier to rig up a second fuel rail on my workbench if I had one.

OR God willing run several adult doses of fuel injector cleaner through my system and have the problem clear itself up.

 

[DoubleDingo]

The best fuel injector cleaner I have ever used is Motor Purr. Hard to find, but it cleans the fuel system very well. The mom and pop store I bought it from closed their doors and I bought every bottle they had. When I bought the Tahoe I brought a bottle to add before driving it back. Poured in, topped off, and ran it hard going home. Did it need it? Don't know, but it didn't hurt. Also used the Motor Purr Tune-Up in the crankcase on the oil change and the clean oil came out black. If you can get your hands on Motor Purr, get it, and use it.

 

[Marky Dissod]

The knock is experienced under throttle changes that are gradual to rapid. VERY VERY VERY light throttle changes under load do not provoke the knock.

This, more than anything else, makes the injectors suspect; they should be able to keep up with your foot.

 

[hagar]

Have you changed all of the injector data from the original stock tune over to the data that flex fuel injectors run?
If all of the data is correct, why are you using the fuel injector flow rate to dial in the air to fuel ratio, rather than adjusting the maf and ve until the air to fuel ratio is correct?

 

[Matthew Jeschke]

The best fuel injector cleaner I have ever used is Motor Purr. Hard to find, but it cleans the fuel system very well. The mom and pop store I bought it from closed their doors and I bought every bottle they had. When I bought the Tahoe I brought a bottle to add before driving it back. Poured in, topped off, and ran it hard going home. Did it need it? Don't know, but it didn't hurt. Also used the Motor Purr Tune-Up in the crankcase on the oil change and the clean oil came out black. If you can get your hands on Motor Purr, get it, and use it.

This is good to know. I'll keep an eye out for it. I've got a couple gallons of the Lucas injector cleaner. I use it quite regular but I suspect it's a "mild formula" for "mild symptoms". Separate topic, I add it once in a while as I've heard it can improve mileage. I've yet to arrive at any conclusion on that.

This, more than anything else, makes the injectors suspect; they should be able to keep up with your foot.

I'm thinking so. It's not surfacing in the WB data but then again, maybe too little resolution in that data to catch it.

Have you changed all of the injector data from the original stock tune over to the data that flex fuel injectors run?
If all of the data is correct, why are you using the fuel injector flow rate to dial in the air to fuel ratio, rather than adjusting the maf and ve until the air to fuel ratio is correct?

The injector characterization is correct. There were two choices for the same part number; choice one is return style characterization w/ ~3 bar, choice b is return-less style at ~4 bar. I tried both... The 3bar return style was correct. We originally scaled the flow as I'm using a 4 bar regulator so it went from 33# to 35.4# (simply use the figures from the 4 bar return style config). Long story short, the tuner's config resulted consistent trims for LTFT and STFT at low and high loads which leads to me to believe the characterization is accurate.

I'd formerly done as you suggested and tuned fuel mass empirically scaling the VE table and MAF calibration. The tuner I hired used a stock 85mm MAF curve and known good VE table for my specific cam. How he built the VE table I have no clue. But it was SPOT on for my engine. Trims were consistent across the board. What was off was a 20% offset for LTFT nearly across the board.

With the 35.4#/hr I got 20% LTFT. As we'd verified the VE and MAF correct the finger pointed at the injectors. Given it was consistently around 20% LTFT leads one to believe it's an issue with fuel flow so adjusting injector flow rate seemed appropriate and brought the LTFT within a few percent. It was brought down to 30#/hr in the PCM which is even lower than the spec for those at 3bar which is 33#/hr. This seems to point to the injectors having some issue. Maybe varnishing on the pintle and or behind the cap, possibly more, restricting flow and spray pattern?

That's when I suspected an injector issue. Either atomization and or metering is possibly off. Am I splitting hairs. Likely you'd never notice this on a stock engine with stock tune. Unfortunately my custom build requires I get nuanced to sort these things out. Something is certainly off mechanically as I can only run the base timing map reliably. Advancing it even with premium fuel results in random knock only correlated with anything but the slightest increase in throttle position.

Even adding more fuel; 12.6:1 AFR doesn't mitigate the knock. I've tried even richer (somewhat pointless) and the knock when throttle is increased the knock response is somewhat consistent... under what load and RPM never seems to be though so I cannot address it with the tables in the PCM.

 

[hagar]

The injector flow rates are a constant that is relied upon for many of the engines running functions. Changing the injector flow rate until the afr is close is not the proper way, even though it gets the afr to where it needs to be in general.
You are supposed to set your injector values as per the gm data, then you correct your error via the maf/map.

If you don't do it this way and hack the injector flow rate tables, you end up with problems like this. The injector flow is a constant, what is not a constant, are the maf and ve values. If you are changing the injector flow rate to trick the engine into running richer, the computer is not seeing the proper air flow it should, and that messes up every table in the computer.

There are transient functions on ecms Who's sole purpose is to keep things like your problem from happening, they smooth out fuel shots and also timing transitions.

It makes absolutely zero sense to tune an engine via the injector flow rates beyond entering the proper base data. 20 percent fuel trim after building a new engine with a new air intake with a new cam, isnt even a lot, it is perfectly normal and always requires you build a new maf curve to correct it.

 

[Marky Dissod]

Either atomization and or metering is possibly off. Am I splitting hairs? Likely you'd never notice this on a stock engine with stock tune.
Unfortunately my custom build requires I get nuanced to sort these things out. Something is certainly off mechanically as I can only run the base timing map reliably.
Advancing it even with premium fuel results in random knock only correlated with anything but the slightest increase in throttle position.

My fear is that your injectors are not splitting hairs properly. If they can only handle the gentlest transitions without knocking,
it's either an injector issue, or an injector wiring issue ...

 

[Matthew Jeschke]

I think so. I need to make or preferably find somebody with an injector test bench.