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Q: Is it really worth performing a fuel system cleaning? on 2007 Honda Accord

I took my car into Firestone. One of the recommendations that they came back with for my car is a fuel system cleaning. Its about an $89 service. Honestly I'm not exactly sure what they do for this service. Its something about "chemically cleaning the fuel injection system." They claimed that the throttling was a little sluggish in my car. I haven't noticed any difference although I don't really pay that much attention and can't really tell that my car was sluggish. Is this cleaning worth it? I guess a cleaning is a cleaning and it won't hurt. Its just one of those things that you really wonder if its a complete rip off or not because you'll probably never notice a difference.
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First of all the answer is yes, it is worth performing a fuel system cleaning, if it is done completely and correctly, however there are different types of cleaning services.

Most of the time they are not performing a complete cleaning service, and in fact they are not cleaning the fuel system they are cleaning the intake system - they probably don't even know the difference.

I do not like the sales tactics used by many Franchise type repair shops to sell an otherwise legitimate service, making it sound like you have a problem and making it sound like they are doing more than they are. A truly complete and thorough service is time consuming and much more costly than $89, done right it is worth every penny!

All internal combustion engines build up carbon deposits in the intake manifold, throttle plates, backs of the intake valves, top of the pistons and the fuel injectors.

The most common cleaning service is a chemical drip, that is the bottle of chemical is attached via a hose to the intake and with the engine running the chemical is drawn into the engine trough the intake, past the valves and into the combustion chamber.

That is what you will get for $89, and if the tech physically cleans the throttle plates with chemical and a brush prior to doing the drip then it is a good service and good value, however, this does NOT clean the fuel system (nothing is going through the injectors, unless they add a can to the gas tank)and one can of chemical isn't enough in most cases to do the job thoroughly.

The only way the fuel system can be cleaned is by running chemical through the fuel injectors, either by adding it to the tank or running the engine from special equipment that is hooked into the fuel lines on your car and runs the chemical into the injectors.

A "complete fuel system cleaning" consists of two parts, a top engine clean and a fuel injection clean.

At best a drip service is a minor top engine cleaning, if they physically clean the throttle plates at the same time, it is a good value and will help, not hurt your car or pocket book.

The next best service is a thorough top engine/throttle body cleaning: the throttle plates are physically cleaned with chemical and a brush, then while the engine is running the chemical is flooded into the intake a little at a time until the engine stalls (this wets the carbon on the valves and pistons) and after letting the chemical soak for 15-20 minutes the engine is started back up and run with the chemical drip, burning off the loosened carbon and excess chemical. The whole process take about an hour and uses two-three cans of chemical, and no way will you get this for $89, the chemical alone is nearly that much.

A can of chemical can be added to the tank for cleaning the injectors, this is the best value and will clean the injectors over a period, of time but if they are really dirty (you would notice symptoms like hesitation, stalling, misfire) it is not as effective as cleaning the injectors with special equipment by running chemical thru the injectors while the car is running.

The most complete (and costly) is combining the top engine clean i described above and hooking up special equipment the run chemical thru the injectors, the high concentration of chemical thru the injectors cleans the fastest and best (on the car).

A minor Throttle body and drip cleaning is a good service about every 60k mile on any car, a more thorough top engine clean around 150k or if the car is run short distances and lots of stop and go traffic.

Ad a can of 100% Techron to your tank every so often should keep the injectors clean. i only recommend injector clean with special equipment when i have identified driveability problems related to the fuel delivery.

That's a lot of info, sorry if it makes your head spin!

Bottom line: not all mechanics and services are created equal

Best wishes,

Robert Grove, ASE Certified World Class Technician, Automotive Hall of Fame, 1996

<a href="">Mobile Orange County Mechanic Service Irvine, Tustin, Huntington Beach, Santa Ana, Orange, Anaheim, Mobile RV Repair</a>

<a href="">Mobile Mechanics in Orange County</a>
Hey Robert - this is a great explanation - I'm sitting in the dealership Service area staring at a $189 bill for "System Decarbonization and Throttle Body Service, then Add Fuel Treatment" for a 2008 Highlander -- do you think I"m getting the $89 treatment mentioned here, or perhaps something a little better (if not the full treatment you describe as best case)? THanks!--anthro
Try yourself- really simple. Pick up bottle of seafoam from your local autoparts store ($10) and follow directions on bottle.
If your car is performing as it should with no noticeable loss of mpg, dont mess with it. That's my poinion and may be wrong!
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The service mentioned is preventative in nature when done prior to a problem and can help reduce/prevent longer term issues, why wait until the MPG drops or symptoms like hesitation and cold start/stall symptoms show up, better to be preventative don't you think?

It isn't required, but it really is a good service - if done properly! Just a can of cleaner dripping into the intake is like change changing your oil filter and leaving the old filter oil in the pan!

Robert Grove
Mr. Grove's answer and replies are terrific. I just had fuel system clean from a national franchise for my 2001 Honda Accord Coupe with 180,000 for 99.99. The process took a half hour. Can I assume that I had just a cleaning of the intake system vice fuel system? Can a franchise actually perform the fuel system cleaning if asked?
I assume that a Honda dealership with attendant service center would be well poised to provide the entire file system cleaning. But I am wondering if I need such a service.
Car seems to run well.

Different subject: are there symptoms or type of feel or noises that would suggest that it is time for a new timing belt?
Would there be certain driving characteristics after the change that would be noticeable? is this important enough and complicated enough that only a Honda service center would be certified or capable of this kind of work? Thank you for your time in all your responses. I just found the site after I returned from my service. I will be sure to check in from time to time to see what's going on. Again, thank you.
Hello! I have a 1994 Nissan Sentra, which has 205,000 km. on it. A friend gave me the car a few months ago. In Canada, to change ownership, the car must go through a certification process. Some work was done on the vehicle and it drives like a dream. In the freezing cold weather we have been having in Canada this winter, the car does not even hesitate to start. That is until two days ago. I took it in for an oil change and the garage also looked for an oil leak, since I had seen a wet spot under the car. I left the car at the garage for 5 hours. When I went to drive away, the car would not start. It kept trying to turn over, and sounded at times that it was 'catching' a bit. It eventually starts with the help of some pumping on the gas pedal when I hear it trying to 'catch'. Now, when the car sits overnight or for a few hours, I go through the same process to start the car. I believe that there must be an issue with the fuel delivery system. It seems to me that it is very coincidental that this problem started right after the garage had done some work on the car. Can anyone please tell me if an oil change would have any bearing on the gas delivery system? Do you have any suggestions?
no............If you've been doing proper maint. it is not necessary. if done correctly as robertgrove suggests , it can't hurt , but if done carelessly , it can do damage to catalyst later on. Your car , your call.....Maybe a tankful of premium every so often would help.
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Certainly use caution! The top engine cleaning procedure I mentioned should be done by a professional.

Good gas (I like Chevron), regular oil changes, and occasional fuel additives (Sea Foam or Techron) is important to follow and will minimize but NOT eliminate carbon build up.

Even with good maintenance there is ALWAYS carbon build up, especially at the throttle plates, valves and piston tops. Buying good gas like Chevron and using Techron or Sea Foam every so often could reduce or eliminate the need to do the intrusive injector cleaning with special equipment, but it just won't take care of the throttle plates, valves and intake build up.

Even with proper maintenance, a top engine clean is valuable preventative service, waiting until there is a problem is like waiting to change your oil until it goes bad, you can do it, but I don't recommend it!

Premium gas is not "better" than regular, it has the same additives, the only difference is the burn rate - regular burns quicker and premium burns slower require different ignition timing.

Just my two cents.... coming from 35 years of professional hands on experience

Robert Grove, ASE Certified World Class Technician
Automotive Hall of Fame 1996
State of California BAR Certified Smog/Emissions Instructor
check my credentials:
I agree , but it is VERY hard to find techs willing to take the time(all trying to 'beat' the flat-rate) to perform the service properly as you stated.
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