Ever had your throttle body cleaned? No? Do it!

[tk421]

Howdy,

As most of you have probably noticed by now I am having a coldside supercharger kit fitted shortly. In the meantime I had Top Tune in north sydney do my 100k service to get it out of the way (I was at 95k). At the same time my idle dip I had got a little worse and we thought it was a good idea to get things stabilised and clean on the efi side prior to the fitment, even if not that much of it is going to get used. Easier to work it out if things go wrong that way. Therefore it was time to get a clean of the intake path.

Firstly the throttle body was BLACK and I mean BLACK. I have only done around 27k since I have owned it (3.4 years) so I guess lots of short trips will do that. However I had a mania intake fitted shortly after I got it and with this service Its has become apparent that it was dirty at 68k when I got the car.

Jason and his team have always done a great job but even on just driving up the driveway out of the garage I could tell instantly something has changed, throttle responsiveness seemed a little different.

The BIG surprise was when I stomped on it and PHWOAR the noise was 500% better. Before I had just this deep intake roar, this hasn't changed in the whole time I have had it and I always thought it sounded great. But now this is accompanied by this hard edged rasp past 4k that is just fantastic. . Hard to say if hp has improved, the butt Dyno says so. Things were so gummed up in there I wouldn't be surprised. The idle is of course a lot nicer now too and things just sound crisper in general

So yes this is all coming off in a couple of weeks and its a case of enjoy it while it lasts (yes i'm sure the super will sound even better ). The purpose of this post though is to highlight that If you have done a few ks like I have and never had the TB cleaned, maybe it might be worth getting done - Particularly if you have a CAI

Another vote for Top Tune

Cheers

Steve

[SuperMazdaKart]

keep in mind, the throttle body butterfly valve has some plastic seal on it that is easily taken off by carby/throttle body cleaner so get a good one thats dedicated to just throttle bodies (don't know which myself since this info comes from miata net where they tend to use a lot of products not available in ausland...).

even if the seal is taken off, not to hard to adjust the thing so it's all proper again.

anyone know which cleaner available here won't ruin the coating?

[brenno]

Aah, so that was your car at Top Tune yesterday. While I was waiting to pick up my car there I had a quick gander at your car. It looks pretty nice and clean!

Jason cleaned out the throttle body on my car a few weeks back, but I didn't really notice a big difference like you did.

Another good rap for Top Tune for me too. My car was in there yesterday just to get the belts tightened, and I still got the full car wash!

[marcusus]

Hmmm... I wonder how clean mine is. I just did my 100k service (incidentally, my mechanic is quite good/trustworthy, and he reckoned the timing chain didn't need changing... does this sound right to people?) and my mechanic didn't mention it. I wonder if it's worth going back and getting it done.

How can you check how dirty it is?

[NMX516]

Hmmm... I wonder how clean mine is. I just did my 100k service (incidentally, my mechanic is quite good/trustworthy, and he reckoned the timing chain didn't need changing... does this sound right to people?) and my mechanic didn't mention it. I wonder if it's worth going back and getting it done.

How can you check how dirty it is?

These cars use a timing belt - not chain - but anyway, it is meant to be done at 100k. Worst case it breaks, and you're stranded - it won't send pistons into valves or anything nasty like that, but yes I would have it done. Not changing it is a false economy. It's not a case of if it will break, but when. Unless your mechanic went to a lot of trouble to pull all the front of the engine off to inspect the timing belt, he wouldn't know what condition it is in... And if he had gone that far, slipping on a new belt would have been very easy. Sounds to me like he just didn't want to do it

[marcusus]

mmm... he reckoned it was a chain, not a belt. I thought it was a belt too, but he's the expert. He said he had a look at it as well and it looked fine. He's definitely not into screwing people, but it wouldn't surprise me if he was a \"if it ain't broke don't fix it\" kinda guy (in this case the belt ain't broke, therefore don't fix it).

It's an NB8A if that makes a difference.

Maybe I should pay top tune a visit and get them to give it all a looking over, considering all these recommendations for them.

[tk421]

Yeah I agree. You should definitely do a change of the belt. The belt and the idler bearings needed changing on mine.

After a drive up the old road this afternoon I think mine was probably just dirtier than most really as whilst its reving out more cleanly and nicer at high RPM it still feels the same squirt wise (though sounds a LOT different as I noted). You can easily see when its dirty. Just pull off the pipe that hooks up to it and look in there . You could see mine was black. When Jason does a service he takes photos of everything. Thats the only reason I know what mine looked like .

Jason also highlighted that my engine has been reconditioned at some stage, certainly something that noone else has ever picked up. He said there was nothing sinister about it though (for example the reconditioners stamp was on it). Good to know this has happened though.

[marcusus]

Oh well. Since half the service has been done, it'll only cost me half as much to get the belt/chain changed (in theory). Maybe when I get a free moment (or perhaps a morning off work) I can swing through and just get the train to work and back to pick up the car.

[Garry]

When I clean mine I notice a big improvement in idle quality but not much else.

What SuperMazdaKart said about the black sealant stuff Mazda uses to seal the throttle plate. TB cleaner does a great job of disolving it. I accidentally cleaned mine off and I couldn't get the idle speed low enough with the air bypass screw.

[SuperMazdaKart]

Which tb cleaner you use?

I can only find two easily available to buy, Nulon's & CRC's. Did you actually spray it onto the butterfly valve directly? Am trying to work out if it's worth doing an engine decarb myself using the aerosol cleaner & squirting into the Purge Control line while the engine is running. Mazda uses this method but with their own Top Engine Cleaner liquid (probably same sorta stuff as the famed Seafoam which we can't buy here).

Problem is the purge control line is almost directly on top the butterfly valve & spraying it in there might get cleaner on the damned thing. Though when the valve is open the back bottom end of the valve plate (which doesn't have the seal) is pulled up towards the line, so any cleaner can only get on the back & with the airflow be sucked off so the seal on the front should be fine with this method?

Spose I could just use the PCV line, but then the mixture won't be as even between all cyclinders..

Did you end up fixing the idle? what's it idling at now & with A/C on?

[Garry]

SuperMazdaKart,

I used the Nulon stuff, safe for throttle bodies according to the can.

The idle bleed screw air passage is on the top of the throttle body on NB's so I thought I'd be clever and stick a rag in the throttle body to absorb the excess TB cleaner that I sprayed into the idle system but the rag got soaked in TB cleaner and totally disolved the seal stuff. In the past I'd sprayed the TB cleaner onto a rag and carefully wiped the TB and managed to leave the seal stuff intact. Actually, probably the seal stuff would have been OK if it didn't have the rag there to expose it to the TB cleaner longer.

It was idling at 1200rpm even with the idle air bleed screw adjusted up tight. Everything I've read said not to adjust the throttle stop because it stuffs up the Throttle Position Sensor adjustment so I didn't touch that. I used a very thin smear of silastic around the TB where the throttle plate seals. It works but the silastic is slowly breaking down from the fuel vapour so one day I'll get around to doing something a bit better. The idle speed is back in spec now though the idle dip has started to come back after about 12 months since I cleaned it last so I guess it's time to clean it all again.

For what it's worth, I asked Flying Miata if they knew what the black sealant stuff was and they said they have no idea but they use a few coats of paint to seal it back up again.

[SuperMazdaKart]

bummer, i bought nulon's yesterday.. spose thats a 2nd can of a degreaser now heh.

might end up just having a decarb done at a well reputed mechanic or even mazda dealer.

[marcusus]

he might be a nice guy & you think he's doing the right thing by you but it's quite obvious he isn't an expert.
you're MX5 has a timing belt, not a chain & i'm willing to bet he didn't check anything, he just assumed it's a chain & as chains have a much longer service life than belts it wouldn't need changing yet.
your timing belt will break at the most inconvenient time if you don't change it soon.

Yeah, no doubt. He's definitely a good bloke. Just perhaps a bit lazy
Might have to give them a ring up and let them know that I want the belt changed etc.

[dab]

hey,
I use motortech brand carbie cleaner and a tooth brush to clean my throttle body. I havent had any trouble with idle speed. If you are worried about eating away gaskets ect.. use petrol to clean it.
Another way to clean your engine internally is with water. poor smallish anound of water in the breather hose in the intake and hold the revs up for a bit. This will clean your pistons.

[SuperMazdaKart]

yeh? Motortech? is that a MotorMates own brand?

well I've found a cleaner which should do the job very well, Subaru's Upper Engine Cleaner. sold in a 150g spray can is designed to decarbon an engine, Subaru Boxers are more prone to engine carboning than a typical straight 4. the spare parts dept assured me it'd be good on TBs & word of mouth is it does a great job of cleaning out an old engine. will see soon enough.