01 Fuel Injector Cleaning versus Replacement

Hello all,

For anyone thinking about paying for fuel injector cleaning I have had some experiences that may be helpful.

My 2001 with 230,000kms got a bad tank of gas in June (water contamination). This led to a number of complications but I finally got the car back on the road but with a rough idle when starting and an occasional misfire code P0301...P0304 This could be a number of things but eventually I was examining the fuel injectors.

I have the Repair Manual (I bought around 2002/03) and under the inspection procedure for P0300...P0304 page DI69 at step 4 it states: "Check resistance of injector of misfiring cyclinder (See page SF-9".

I measured my 4 injectors and at 20 degrees C their resistances are: 15.3, 15.0, 15.1, 15.0 (ohms).

The expected resistance for these injectors are in the range from 13.4 to 14.2 (ohms).

The manual says to replace the injectors. Easy for it to say...
But up here in Ottawa at the dealer the injectors are almost $200 each.

So instead I tried to see if a fuel injector cleaning would solve my problem ($100). I took the injectors off the car and brought them to an injector cleaning specialty shop. These guys do a flow test before cleaning and after the cleaning; all done in a test rack not on the car. They found one injector that was stuck open but the cleaning apparently fixed it.

But I still had the rough start.

I decided to pay a dealer for an hour's diagnosis because I just couldn't be sure that the injectors were the cause.

The mechanic looked at the spark plugs and said that the plug's appearance implied fuel injector blockages. The dealer recommended an on-car fuel injector cleaning ($200). I wasn't happy with this diagnosis and it appeared that the mechanic didn't follow Toyota procedure for this analysis.

But this prompted me to order the injectors myself from an online store in the U.S. (all 4 for $220 + shipping to the border). These were supposedly new injectors not re-conditioned.

Once I installed the injectors it was like I had my old Prius back pre-bad gas experience.

So if someone tempts you to clean the fuel injectors make sure you check the resistances of each injector first.

Happy motoring!

John

 

I believe the fact that one fuel injector was stuck open was a co-incidence to the fact that the injectors' resistance were above normal.

I think of an injector as consisting of two parts:electrical and plumbing. The plumbing is the part of the injector that the fuel flows through. The electrical has a solenoid that opens or closes a valve that lets the fuel flow through the plumbing part. If a 10 year old solenoid doesn't open exactly when the ECU tells it to then your idle may be a little rough.

So no matter how clean you get the plumbing part if the electrical part is delayed then your engine may run rough.

I recently had to replace a solenoid in a 5 year old gas dryer that was no longer holding the gas valve open longer than a couple minutes. So a 10 year old solenoid in 4 fuel injectors is not that bad.

But if you are following the procedure listed in the repair manual than you should catch this problem. The repair manual doesn't explicitly list "clean fuel injectors" as a potential solution. If you are thinking about cleaning them just make sure your electrical solenoid is working in the injector first.

John