Question regarding modern fuel injection

[zerfetzen]

Hi,
I have a buddy who just took his '07 Impala SS in for a few things at 15,000 miles.  While he was there, they hit him up for a fuel injector cleaning.  He agreed.  While the car was getting worked on, we talked about the fuel injector flush, and thought it sounded fishy, but want to see what you think.

Upon picking up the car, my buddy asked the service guy about the injector cleaning, and he said it needs to be done every 15,000 miles.  I asked him if that means that the fuel filter isn't doing its job, and why would the injectors need cleaning?  He replied that the injectors carbon up, that the carbon comes out the valve and onto the injector.  Does carbon really get on the injectors?  I'm thinking about an old school carbureted engine, where it would have to travel out the valve, through the head, through the intake, and into the carb.  Is the setup for a modern fuel injected car that different?

PS
When we read the bill, it said: "flush and service fuel injectors, injectors clog with fuel deposits".  So is it about cleaning fuel or carbon deposits?

I was curious what you think.  Thanks.

[Rolling_Thunder]

on modern cars, the fuel injector is usually situated at the end of the intake runner, usually having its spray hit the back side of the valve. So it is extremely closer to the combustion chamber...       however remember when the valve opens it immediately sucks air in - with modern cams with little over-lap there is less of a chance of carbon exiting the intake valve but still plausible i guess....        I don't know for sure...       ever 15,000 miles seems a bit excessive to me - I know people going 150,000+ miles without cleaning their injectors....     but who knows...      those were also Toyotas....        not american cars that break and require constant maintinance -       

Other than that I can't really help you - I would guess cleaning them periodically would help efficiency but as far as time intervals, i am not sure as to what is correct.

[Kevin68N71]

Bullsh!t.  We have had several BMWs, and if there is ever an excuse for maintenance (brakes are a good example) we hear about it!  Never had those injectors cleaned.  Never on any of my Ford or GM company cars.  Had new Chevy van for years, never had it done, each of those cars had over 60,000 miles.  On the older systems, have a 190,000 Mustang GT and never had the injectors cleaned, in fact, only have replaced one.

Unless there is something different on this engine I have not heard of, not sure.  There are additives that will clean injectors too.

To me, this sounds phony.  And by the way, exactly WHICH new American cars need constant maintenance???

[no318]

There are 2 different services.  1) flushing the injectors.  2)cleaning the induction system.  I have seen many driveability problems fixed by this as well as gains in mpg, idle quality, and performance ... IF the system needs it.  My opinion is more like 40-60k intervals.  Sure there are lots of FI cars out there that run "fine", but not up to potential. 

BUT it is an easy sell to some and just a way to make money.  NOT all cleaners are the same.  I have seen many chemical make ups and the cheap stuff over the counter and at Wal Mart are just that....cheap. 

Several reasons carb. stuff (or Throttle body injection) aren't as affected are...1) 1 injector per cylinder = SMALL orfices.  2) Located IN the intake is hotter than above.  3) it is constantly exposed to PCV and EGR in the intake which can bake on the pintles.

[Badbob]

I have improved the drivability of many fuel injected engines by cleaning injectors and induction systems, I even had a ford pickup come in that wouldnt even idle. A simple injector cleaning (Motorvac) made it idle fine. I can tell by looking at an ignition system scope waveform if a cylinder is running leaner than it should be. Dirty mass airflow sensors are also a common cause of reduced power (especially when using an oil soaked K&N air filter) and should be cleaned periodically as well.  15k miles is a little excessive, I would go about 30k. Too bad it all costs money as does other maintenance, for you maintenance naysayers if you want to run your spark plugs 100k and never change out that Dexcool go ahead and run it into the ground, I believe in preventative maintenance. ASE Master 20 years, now in gov't fleet maintenance. You can clean your own injectors by running a cleaner dumped into the gas tank once in a while, though less effective.