Hi all. My 2005 RX-8 is at the dealer getting the Cat replaced under warranty, and when they completed the work they told me about every issue they found with the car during their inspection and while they were doing the work. I was aware of most of the issues, nothing super major. One issue he mentioned was a lot of carbon buildup on the fuel injection/throttle body. The solution he said would be a fuel injection/throttle body cleaning for $149. So I have the following questions about that:

Is that a reasonable price for the work?
Is this common on RX-8's, or more so than other cars?
Is it really necessary work, and possibly hurting performance?
Could it hurt anything if it's not addressed very soon?
Would using a fuel injector cleaner work, or should they be avoided? (I imagine there will be varying opinions)

FYI The vehicle is out of warranty on almost everything at this point except the 3 major emissions components which are 8/80, and the extended warranty on the engine core/components which is 8/100. That might be relevant to the last question, since it could possibly invalidate the warranty.

Thanks!

 

That's a bunch of BS, it's just an upsell. carbon doesn't build up in the TB and the carbon in the intake tract won't get cleaned by their setup either. Just get a can of BG 44k and run it thru your tank.

 

Thanks for the reply. I can't say for sure that he said there was buildup in/on the throttle body, but he definitely said the fuel injector, and he did specifically say fuel injector/throttle body cleaning to resolve it when he quoted the price. Not familiar with BG 44k but I'll look it up. Appreciate the advice.

Anybody else have any input on this?

 

Pulling the injectors on an RX-8 is a bit of a task so I doubt they did that. Also, I have pulled apart a couple of engines with high miles on the injectors and I have never seen any carbon build up or any build up at all for that matter. It's an up-sell man, just a way to sucker you out of more money.

You know what the best injector cleaner on the market is? Techron.

 

once every couple of months advance auto parts has them for buy one get one free... i cant say it really works, im no expert.. but it wouldnt hurt and people claim that why its not like pulling them out and getting them cleaned and flow tested, it does a good job for what it is.

 

If used regularly on a consistent basis I am sure it helps. Not sure if it is worth it if you start using it after many years. A buddy of mine worked in the gas oil manufacturing industry and basically said it is as good as it gets in terms of cleaning agents for gas. Of course it's not a miracle in a bottle.

But either way clogged up fuel systems are not really an issue even in high mileage RX-8's. If you are really worried about it, pull the injectors, have them cleaned and flow tested, replace your fuel pump assembly, and be done with it.

 

Again, thanks for the replies. The car only has 45K on it, and I'm not really worried about the issue, I just relayed what the dealer told me and asked for input from other RX-8 owners that might be more familiar with the problem than I am on this particular car. It's the only RX-8 and only rotary engine vehicle that I've owned, which has a lot of quirks unique to and as a result of the engine type, so whenever there's a powertrain or emissions related issue I always check with the RX-8 community.

I just wanted to make sure it's not a major issue or something that could cause a major issue if not readily addressed, and so far it appears that isn't the case. I also wanted to get opinions on the use of over the counter fuel system cleaners, since I've heard varying opinions on them over the years and some people have said they just gum things up or move deposits from one location to another.

 

Buy 2 bottles of Techron Complete Fuel system cleaner.
Wait until you have a mostly empty tank of gas, and are at the gas pump.

Dump both bottles into the tank, and then fill the tank with fuel.
Go for a long highway drive to completely run the tank out in one shot.
Refill tank.
Done.

I always recommend running the fuel system cleaner through the car in one shot, because the best results I've seen with Techron is when the engine is hot, while its stripping carbon out.

Its not like its going to take you 600 miles to drain the tank.
Just 120 miles one way, and 120 miles back.

BC.

 

lmao, don't waste your money on such "service", it's almost pure profit for them.

The ONLY way to clean injector is to REMOVE it completely and have it clean at professional shop, and that usually cost about 25 bux each. and to access to the injectors you have to remove whatever sits on top of it, which cost MORE than 150 bux itself (to replace all the gasket and labor)

I ran thru 4 bottles of injector cleaners before I removed all 4 injectors from my FC, guess what, one of them are only 50% working. sent it off and cleaned all, now it works just like new(flow chart included)

IMO the injector cleaner stuff might work, just not as good as they want ya to believe.

and I think it's not a bad idea to clean all injectors every 100-150K miles, that's just me. YMMV

 

Thanks for the new replies. As I expected, there are a lot of different opinions on what to do about it, but so far everyone seems to agree that it's a waste of money to have the dealership perform the service that they're quoting. At least nobody has said that the fuel system cleaner will screw anything up, and that was one of my concerns, so I'll probably give one of those suggestions a try. I'm sure that having the injectors pulled and professionally cleaned individually is the optimal solution, but the car has 45K on it and I have no reason to believe there's any problem with the injectors other than the dealer saying there's a lot of carbon buildup, so there's no need imo for anything this costly.

 

Is premixing with lucas upper cylinder lubricant a bad idea? Claims to keep injectors running good too..

 

Lucas UCL is a "probably" on the premix, at least consistently. No real known benefit, and fuel filter clogs tend to appear when Lucas UCL is used as a premix. Why? It's not clear. But, it does tend to keep showing up. See the premix section in my modding thread in my sig for a run down of various premix types.

 

I always knew there were better premixes, i just happened to have a gallon of ucl, so i decided id use that for now. Im pretty much out so next bulk buy of premix will probably be the good stuff lol. Also been thinking about using the oil stabilizer... Ever since i was a kid i always got a kick out of playing with the lucas oil stabilizer displays they have at various auto parts stores. You know the one with two sets of like 3 or 4 gears and a little handle? For some reason i always loved those x)