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Does injector cleaning really improve fuel economy?


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33 replies to this topic

#1 MR_Loyale

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Posted 17 February 2013 - 09:22 PM

I remember about 6 months after I bought my Loyale in 1994, the dealer service guy tried to sell me on an injector cleaning service. Now I am no mechanical genius, but even I could tell that ws not needed at least at that new of a car.

 

I have seen videos suggesting that cleaning fuel injectors will improve fuel economy and make it run smoother. Has anyone else had experience doing this? I know there are a variety of things out there from service shop machines to simply a can of seafoam. 

 

 

I have never had an injector cleaning service done. I just throw in a can of techron every few years.  My fear is that an "injector service" would cause more problems than it would solve and injectors aren't cheap. My soob runs ok to me right now so maybe best to leave well enough alone.

 

Please post your experiences on this topic.


Edited by MR_Loyale, 17 February 2013 - 09:22 PM.


#2 Subruise

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Posted 17 February 2013 - 09:33 PM

i use seafoam through the gas tank every so often, this usually coincides with a treatment of the oil as well. I have noticed a difference but I will say that a 6 month old car should never need cleaned that early.



#3 MilesFox

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Posted 17 February 2013 - 11:27 PM

My dude used techron to try and solve a misfire issue. He ultimately replaced what was a bad injector, but the techron did help it run smoother until he got the part. If you are already treating with techron, you may as well not need the professional service.

 

you onlyhave one injector anyway assuming you have spfi. supposedly the injector cross references with nissan if you think you should replace it. but i think the nissan has a higher flow rate.

 

are you trying to improve economy, or just administering preventive maintenance? The alcohol blend fuel these days hurts the fuel economy compared to straght gas



#4 MR_Loyale

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Posted 18 February 2013 - 01:55 AM

My dude used techron to try and solve a misfire issue. He ultimately replaced what was a bad injector, but the techron did help it run smoother until he got the part. If you are already treating with techron, you may as well not need the professional service.

 

you onlyhave one injector anyway assuming you have spfi. supposedly the injector cross references with nissan if you think you should replace it. but i think the nissan has a higher flow rate.

 

are you trying to improve economy, or just administering preventive maintenance? The alcohol blend fuel these days hurts the fuel economy compared to straght gas

 

 

I am trying to do a little bit of both. Over time small changes in performance make it almost imperceptable until it gets really bad. How long should a fuel injector be expected to last? I got 20 years on mine so far. Aren't there rubber bits in there too?  They can't last forever I suspect. I do have SPFI so it is only one injector. If I thought I would gain 20% or more  would spend the money to replace it. Right now I do more short grocery gettting trips than long hauls so I expect the mileage to not be the best.

 

Is it worhwhile preventative maintenance to replace them on a schedule or just wait until they throw a code? I recall when the O2 sensor went bad, it bucked and hopped like a trip on a wagon trail in a horse drawn carriage. It did that for a week unti the CEL came on and gave me the code to replace it. 



#5 grossgary

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Posted 18 February 2013 - 06:46 AM

considering how easily Subaru's make 200,000 miles without replacing or really doing much of anything but oil changes with whatever brand oil you want....it's hard to imagine it makes much difference to me.  that being said i do MMO and Seafoam from time to time...but I wonder what that little bit of fluid can really do in the lines...

 

it's helpful to keep track of your gas mileage so that if it drops then you know something needs addressed.  i wouldn't expect any gains just strictly due to age or mileage.

 

i've had injectors rebuilt before and noticed no difference in performance or mileage...i just did it due to age or the engine already being apart, etc.

 

there are companies like RC Engineering and Witchhunter  http://witchhunter.com/  (the later being the cheaper of the two - only $22) that will clean and rebuild your injectors.  they do a pre and post rebuild flow chart comparison of your injector. if you plan on another 100,000 miles to me it's often a good value to do something like this if you're so inclined.


Edited by grossgary, 18 February 2013 - 06:47 AM.


#6 davebugs

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Posted 18 February 2013 - 10:10 AM

I run Lucas and soemtimes Seafoam through every gas vehicel I have or take care of atleast every oil change.  I buy Lucas by the gallon and refill those little bottles.

 

Figuring it's easier to keep them clean while they have flow than to wait until they are restricted and hope the cleaner can get in there AND remove whatever the problem is.



#7 ivantruckman

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Posted 18 February 2013 - 10:27 AM

a lot of times the o ring on the  injector hardens and causes fuel to leak around the injector  , from my experience the worst enemy of the fuel injection system is water  ,  and the worst thing for o rings is alcohol based fuel treatments ,  i think  dri gas, followed with a treatment of sea foam is a good idea.



#8 NorthWet

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Posted 18 February 2013 - 12:27 PM

Having a single injector, I would expect that improper function would show up first as drivability issues (e.g. - poor idle, poor midrange response, poor full-throttle running).  Beyond that, I like GG's response.



#9 maozebong

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Posted 18 February 2013 - 02:43 PM

injector cleaning solutions are typically pointless unless you have a tank that is contaminated. think about it. gasoline is a natural solvent.

 

any injector cleanliness issues are going to be bits of dirt and other non-solubles like rust and dirt. removing the injector and using compressed air while actuating the injector works better than any snake oil solution. 

 

but to really answer the question, cleaning a clogged injector that has less than prime flow will worsen mileage because the car can use more fuel. cleaning a leaky injector will improve mileage because its not dripping fuel. 



#10 NorthWet

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Posted 18 February 2013 - 03:18 PM

injector cleaning solutions are typically pointless unless you have a tank that is contaminated. think about it. gasoline is a natural solvent.

 

any injector cleanliness issues are going to be bits of dirt and other non-solubles like rust and dirt. removing the injector and using compressed air while actuating the injector works better than any snake oil solution. 

 

but to really answer the question, cleaning a clogged injector that has less than prime flow will worsen mileage because the car can use more fuel. cleaning a leaky injector will improve mileage because its not dripping fuel. 

I disagree with pretty much everything said on the included post, except for the value of cleaning a leaky injector.  I am not wanting to start an argument, I just don't want others to get the impression that this is inarguable fact.



#11 The FNG

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Posted 18 February 2013 - 10:13 PM

I had a Ford Ranger once that had the fuel filter get plugged up with dirt. When I got it replaced, I must have had a lot of dirt and debris get flushed through the fuel system because it threw an engine code. I used a bottle of techron and within a few miles, it was cleared up and it ran great. Now, I like to use seafoam at every oil change, but I don't think it is that necessary unless it is an extreme situation. I like to think of it as a preventative item that doesn't hurt anything if it is not really needed.



#12 nipper

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Posted 19 February 2013 - 12:04 AM

An injector cleaning only should be needed over 100K miles once, or if there is running issue where everything else has been ruled out. It is something you can do yourself and no need to pay a shops prices for it. 

 

When you have only one injector, any injector problems would be easy to find :)



#13 presslab

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Posted 20 February 2013 - 01:36 AM

Don't use Witchhunter, they royally screwed me over.

With MPFI, if you have a lopey idle, cleaning the injectors will likely help, and get better mileage. With SPFI it's not as critical.

I now clean my injectors using a special pressurized bottle. To use this you remove the fuel line and unplug the pump. It's not as good as a professional service, but once you have the fittings, the cleaner itself is cheap.

#14 NorthWet

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Posted 20 February 2013 - 02:15 AM

I now clean my injectors using a special pressurized bottle. To use this you remove the fuel line and unplug the pump. It's not as good as a professional service, but once you have the fittings, the cleaner itself is cheap.

Do you just crank the engine?  Does this mixture combust, or do you have the concern of cylinder washing?



#15 Legacy RallyGuy

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Posted 20 February 2013 - 06:03 AM

Don't use Witchhunter, they royally screwed me over.

With MPFI, if you have a lopey idle, cleaning the injectors will likely help, and get better mileage. With SPFI it's not as critical.

I now clean my injectors using a special pressurized bottle. To use this you remove the fuel line and unplug the pump. It's not as good as a professional service, but once you have the fittings, the cleaner itself is cheap.


I've not had any trouble in my several dealings with witchhunter, but that was almost six years ago...  Either way they provided me with a pre cleaned and post cleaned flow rate/leak test results...  I went from having a slight sputter at idle and a random hiccup under full throttle to smoothness...  Petrol injectors aren't really rebuilt at all, just cleaning the needle valve of varnish/gum and then cleaning the basket/filter and replacing o-rings.  

Injectors can fail in a non-repairable way, especially the SPI injector, if the actuator isn't available.

Dirty injectors can be cleaned, snake-oil doesn't do a good job, but just short of taking out the injectors, seafoam and techron cleaners performed the best from my experience :P

Cleaning duration... I'd send a little seafoam through every 3,000 mile oil change on my STi and every 15,000 miles on my Legacy.
Unless you're using gross fuel/old fuel, spending $3-$7+ every 3,000 miles isn't really worth it...  I had a friend that ran Techron through his rx8 EVERY tank, changed his oil every 1,000 miles with royal purple and worried that it wasn't enough...   With the oil, fuel treatment and ulcer medication, he could afford to use Pennzoil from 1972 and change his engine when worn out each time.. hehe



#16 presslab

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Posted 20 February 2013 - 09:16 AM

Do you just crank the engine? Does this mixture combust, or do you have the concern of cylinder washing?

Yep, you run it for about a half hour on the stuff. It combusts but just well enough to idle.

I've not had any trouble in my several dealings with witchhunter, but that was almost six years ago...

Basically they engraved numbers right where the lower o-ring is, which caused it to leak and flood the cylinders when turned off. I was very polite about it but I just got the run-around and flat denial that it could cause any problems. Eventually he wouldn't return phone calls and emails. My car was down so I had to buy a full set of replacement injectors.

Edited by presslab, 20 February 2013 - 09:17 AM.


#17 skishop69

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Posted 20 February 2013 - 06:01 PM

Cleaning injectors will NOT increase your gas mileage unless the deposits are holding the pintle open and even then, only very little. Possible but very unlikely. Restricted injectors have little to no effect on mileage. The ECU uses MAF or MAP inputs and throttle position to determine injector pulse width(PW) thus controlling the fuel flow out of the nozzle. This fuel ratio is crossed checked by comparing the O2 readings against a predetermined table stored in the ECU. If they do not match, the ECU either increases or decreases the PW so they match. This is called fuel trim (FT). An increase in PW to a restricted injector only allows the proper amount of fuel to flow to maintain the optimal 14.7:1 AFR. Now, dirty injectors will affect power, acceleration and idle if the spray pattern is poor because this results in improper atomization under low vacuum which causes fuel puddling in the intake. Or if the injector tip is so restricted that increasing PW still won't allow the correct amount of fuel to flow causing a lean condition. Cleaning injectors will help these problems as long as the underlying cause does NOT lie with the o-ring. As for cleaners. The top 2 for immediate (1 tank or less) results are Seafoam & BG44K. Next is Techron and then Lucas or STP for general 'maintenance'. From what I've personally witnessed of these cleaners, BG44K is hands down the best whole fuel system and combustion chamber cleaner. It will clean lines, filters, injectors, valves, runners and piston tops. I know this for a fact as I've had a few engines apart before and after running it through the system. Down side is it's expensive as hell. Seafoam is a great cleaner and my first recommendation because of what you're getting for the price you're paying. I use it myself unless the problem is severe and there is over 100k on a questionably service engine then it gets the 44K. 



#18 NorthWet

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Posted 20 February 2013 - 06:51 PM

... Now, dirty injectors will affect power, acceleration and idle if the spray pattern is poor because this results in improper atomization under low vacuum which causes fuel puddling in the intake. ...

Spray pattern affects effective mixture, through puddling, poor atomization, poor mixing.  The effective mixture is what produces the quality of idle, acceleration and power.  The O2-sensor reads the results of this effective mixture and trims the mixture richer.  (The O2 sensor senses oxygen concentration, not A/F ratio or unburned fuel.)

 

Point is, spray pattern affects the quality of the air/fuel mixture, and the system is likely to react by increasing fuel flow to compensate.



#19 presslab

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Posted 20 February 2013 - 09:22 PM

Above I noted the distinction of SPFI vs MPFI.  With multiple injectors, it's quite possible that one cylinder is running leaner than the rest, and as there is only one O2 sensor the computer can't fix it.  On a turbo motor it's not just mileage at stake, you can melt your motor.  So in this case a dirty injector can be a big problem.

 

I know the OP has SPFI, so in this case the atomization can be a problem, as mentioned by NorthWet.

 

 

This is the stuff I use to clean injectors.  It requires a special tool/regulator to connect it to the engine.

http://www.oreillyau...CSF56/N0043.oap

csf56.jpg



#20 skishop69

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Posted 20 February 2013 - 10:39 PM

Spray pattern affects effective mixture, through puddling, poor atomization, poor mixing.  The effective mixture is what produces the quality of idle, acceleration and power.  The O2-sensor reads the results of this effective mixture and trims the mixture richer.  (The O2 sensor senses oxygen concentration, not A/F ratio or unburned fuel.)

 

Point is, spray pattern affects the quality of the air/fuel mixture, and the system is likely to react by increasing fuel flow to compensate.

The key to my quote is 'under low vacuum'. As in vacuum (airflow) inside the intake in response to throttle opening. At cruising speeds' ie: 2k and up, the puddling effect then does one of two things depending on the intake design. It either atomizes poorly, or turns into a micro-stream and enters the combustion chamber. This, in fact, causes the O2 sensor to see it as rich since the fuel does not completely combust and leaves very little O2 behind and the ECU will trim the mixture leaner. And the O2 DOES measure AFR but based on the O2 concentration left after combustion. In perfect combustion of s 14.7:1 mixture, there is a specific amount of O2 left based on the volume of the engine, the volume of the air in the combustion chamber and the amount of fuel injected. The ECU has a predetermined 'map' that knows what this amount is under many different operating conditions. If the O2 goes over or falls blow the map value, which is an AFR of 14.7:1, then the ECU adjusts accordingly.  Standard 3&4 wire O2 sensors are no where near as accurate or sensitive as Lambda O2 sensors, but that is what they do in a round about way. Not trying to start a pissing contest, but I've been a licensed emissions tech for 10 years, built custom intakes, and have done fuel mapping for custom injection systems, so I do have some insight here. The point being, cleaning injectors has little to no effect on mileage in the majority of vehicles on the road. There are of course, always exceptions.



#21 NorthWet

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Posted 21 February 2013 - 01:51 AM

OMG, there is so much not right that I am going to just leave it... almost.  Anyone who does not understand the perils of measuring something by indirect means should expect invalid conclusions.

 

Peace and love.



#22 skishop69

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Posted 21 February 2013 - 09:24 AM

http://www.autotap.c...gen_sensors.asp

 

Pay particular attention to the How It Works section, paragraph 3.

 

http://www.autoshop1...m/forms/h37.pdf

 

Pages 3&4 (the whole article is good)

 

http://www.ztechz.net/id12.html

 

This one has a great graph

 

http://www.12v.org/e...ection=hw&sm=o2

 

Very good all around info

 

I could have been more clear in stating the Lambda (or wideband) O2 sensor measures actual AFR. As for intake design information, if you're really that interested, the info is out there. Other than that, I apparently need to tell all my instructors and my friend with a Masters in internal engine combustion design who works for Rausch racing that they have been giving me bad information.



#23 skishop69

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Posted 21 February 2013 - 09:38 AM

Oh, and I apologize for the unintentional hijacking of the thread and subsequent left turn it's taken.



#24 presslab

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Posted 21 February 2013 - 12:02 PM

Anyone who does not understand the perils of measuring something by indirect means should expect invalid conclusions.

 

Not taking sides, but this is an insightful statement.   :)   It's a chicken and egg thing though; if they don't understand the perils they likely won't expect anything invalid about their conclusions.  :P

 

To further detail this thread (I'm bad, I know) this is an interesting read:

http://www.amazon.co...n/dp/111804312X



#25 skishop69

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Posted 21 February 2013 - 02:05 PM

When all you have is an 'indirect' means of measuring as you call it, that is what you are stuck using. Measuring O2 in the exhaust stream to correlate AFR is not indirect. Inaccurate to a degree, yes. At the time, it's all the engineers had to work with. Unless they're wrong too.... Hence the development of wide band O2.






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