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RAV4 carbon problem

Ok, I have a '97 RAV4 with 145,000 miles; well-maintained. A few months ago it developed a miss (cylinder #2) I replaced the spark plugs wire, etc. I could not get the miss to stop. Eventually I brought the car to my mechanic (he works at a local Toyota dealership and does work on the side). He checked everything I had checked, and found that new spark plug wire #2 was bad. Eventually he told me there’s excessive carbon build-up in cylinder #2, the rest look fine. The fuel injector is now partially plugged with carbon, miss is still there. He said the injector failed from the outside in, which he said is not normal. He gave me some chemicals; one to add to the gas (didn’t have any effect), the other two I was to mix and inject through the vacuum port on top of the throttle body. I asked if there was somwhere I could bring the car to have the carbon chemically removed; he said there was too much there for that to work, and eventaully the head would have to be pulled. He said between the cost of doing that and replacing the fuel injector, it wasn’t worth doing. Any thoughts??? I hate to scrap teh car,

3m injector cleaner kit!

That kit without the chemicals is $517. It’ll probably be 10 years before I’d use it again. What about the mechanic’s comments that there was too much carbon for chemicals to work and the injector fouled from the inside out?

@bz882 in your original post you said the injector fouled from the outside in.

Now you say it fouled from the inside out.

Which is it?

Injectors fouled from the inside out can sometimes be restored to working condition with an injector cleaning solution connected to the fuel rail.

Sorry, outside in.

@bzb882 here’s my suggestion.
Replace fuel injector #2
Replace all the plugs, wires, cap and rotor.
When it’s running on all cylinders again, have the mechanic decarbonize the intake.
Also consider hooking up the fuel injector cleaner to the fuel rail.

2.2 liter 5S-FE engine?

That car is worth saving, I believe. The 5S-FE is a pretty good engine, IMO.
Does the car look okay? Most everything is still working?

Just replace the injector, its not that hard or that expensive.,wpn_scat_name:Fuel+Injector+%26+Components,wpn_cat_name:Fuel+Systems+%26+Components)

Toyota Put Out A TSB Regarding Clogged Injectors In 1990 - 2006 Port Injected Models.
" Due to fuel quality concerns, some Toyota and Scion vehicles with Port Electronic Fuel
Injection may experience clogged or blocked fuel injectors. The following procedure has
been developed to clean the fuel injectors. "

I looked at the actual TSB # PG011-05 (and I believe there is at least one revision out there), but I can’t post it. Maybe somebody cn find one. Hers’s a link to some text from the bulletin.

Perhaps this is the same “kit” that Bzb882’s mechanic gave him/her (?).


Here it is. Unfortunately it’s not the revised TSB.

I believe the engine is a 3S-FE. I think I’m going to try to replace the fuel injector. Should I go with new or is remanufactured ok? I’m assuming I’ll have to replace the rubber o-rings (if that’s waht they are) on all 4 injectors so as not to risk having a leak when its all reassembled?

Are there any theories what is causing this unusual carbon build up? If it is just that you drive mostly short trips, maybe replace the one faulty injector, get a complete tune-up with new plugs and air cleaner and have the timing checked, then take the car on the freeway for long weekend drives with your spouse or significant other, to burn out some of that carbon. That may be all that is needed. At least for quite a while. And likely this will be good for both your car and your relationship. It’s a win-win!

I would swap injector 2 with one of the others to see if the miss moves too.
I would also do a compression test.

@bzb882 Yes, you do have the 3S-FE essentially the same as the 5S-FE,but 200cc smaller.

You’re right. Replace all the o-rings while you’re at it.
Remanufactured is okay, provided there is a decent warranty for the part.

No idea as to what caused the build-up only in cylinder #2, It just had a complete tune-up, and the timing appears to be fine. Once the car warms up (well warmed up, ot just to operating temp). it runs fine.

Compression test is always Step One for me and maybe these deposits are oil related.

@bzb882 … it could be that that particular injector is faulty, and sticking slightly open, at times when it should be completely closed. This could create a lot of unburned fuel just in that cylinder, and the associated carbon build-up. Maybe simply changing out the injector will get your car back on the road in good stead.

Fuel injection problems would be unusual for a Toyota though, as those Toyota fuel injection systems are said to be bullet proof, at least the FI systems on the early 90’s, they seem to be bullet proof. Maybe there’s been some changes in the design and it doesn’t apply any more. Or you just got unlucky and got a bad injector from the get go. Best of luck.

Once the car warms up (well warmed up, ot just to operating temp). it runs fine.<<<

You means it runs on 3 cylinders until warm, and then cylinder #2 just suddenly kicks in???

You means it runs on 3 cylinders until warm, and then cylinder #2 just suddenly kicks in???

Once it reallly warms up, the miss disappears. I checked the compression, and so did my mechanic, all cylinders were well withinh spec. From my notes:

Cylinder 1 180 psig
Cylinder 2 185 psig
Cylinder 3 190 psig
Cylinder 4 180 psig

I agree with George on this.

145,000 miles in 16 years suggests a lot of in-town driving. Even in a modern engine that’ll eventuallyy cause carbon deposits, as cold engines are intentionally run “rich”, and lots and lots of short drives mean the engine spends a goos deal of its time running that way. The long weekend drives suggested by geroge are what we used to call an “Italian Tuneup” they burn some of the carbon out.

The only thing I’d add is that if it were mine I’d change alll the injectors out. One may have been more prone to buildup for a plethora of reasons, but you probably have carbon deposits in all of them, and that’lll keep them all from spraying nice & fine. I doubt if any of your injectors are spraying cleanly at this age.

Has anyone here ever changed out the injectors on a '97 RAV4? Looking in my owner’s manual, the intake manifold stays put, but the valve cover, throttle body, egr valve and distributor need to be removed. Is that correct? I’ll try the Italian tune-up first, and then resort to changing the fuel injectors if that doesn’t work.