Cleaning intake manifold/injectors

[dazza]

Hi everyone,

Has anyone actually taken the intake manifold off and had a look at their injectors for carbon buildup? I'm very interested to give this a go as there's plenty of guides on the mazdaspeed forums. I'm getting poor fuel economy lately and guess it can't hurt to see how bad they are. Would it be worth running some Subaru upper engine cleaner through before I take the manifold off or bother taking it off at all if I do this? If I do do this I'll be sure to put some photos up!

Thanks!

[mpsgarage]

The injectors are in the head & inject straight into the combustion chamber.

[Scaredycrow]

Think you're more likely to see the carbon build-up on the valves. From my understanding anyway. Might be worth checking your spark plugs are in decent nick and also gapped correctly while you're in there.

[Reedy]

My fuel economy has started to suck lately so next service I was gonna ask for an intake decarb, you should do it about every 10 000 and my car is sitting at 28000 atm.

[Doug_MPS6]

I guess it depends on how many kms your car has done and and what % change in fuel burn are you worried about.

On a low kms car any degradation in fuel consumption is likely to be one or more items from a bunch of other factors I'd be investigating first. If you are running a self-tuned program, check your fuel settings and timing. Even check for binding brakes, including handbrake, and tyre pressures. You might clean your MAF and look at your air-filter and check your plugs, although the plugs in these cars last for eons. Even ask yourself if your driving habits have changed significantly.

The last thing I'd be stressing over is taking off the manifold or pulling injectors (which are in the head, not the manifold) until all other avenues have been exhausted (pun slightly intended).

My fuel burn hasn't changed in 65,000km and remains good; it's never been "decarbed" by any process, physical or chemical, and I don't drive like a granny, even though (regrettably) the car spends too much time in the city.

Look for the simplest solutions first, not the most complex that involve time, effort and money and which, unless you have a lot of experience, are likely to cock up and incur even more costs.

As an aside, and this isn't directed at anyone in particular but from what I read here a lot of the time, I reckon the biggest problem half these cars suffer from is meddling owners long on enthusiasm but short on experience.

[Scaredycrow]

As an aside, and this isn't directed at anyone in particular but from what I read here a lot of the time, I reckon the biggest problem half these cars suffer from is meddling owners long on enthusiasm but short on experience.

Bahahahaha its true. But hey, its something to spend time and money on

[dazza]

yes i meant the valves. was just curious reading the us forums seems to be a common problem. maybe ill leave it thanks

[Scaredycrow]

yes i meant the valves. was just curious reading the us forums seems to be a common problem. maybe ill leave it thanks

fwiw I run the upper engine cleaner through periodically. I notice a difference in smoothness, particularly at idle. You don't have to dismantle the engine to put it through though. Just make sure you change oil afterwards!

[Doug_MPS6]

I still think the best thing for most of these cars is a decent drive. Squirting around town for 80% of their lives involves lots of cold starts, short bouts of high loading, often at less than optimal temperature, lots of rich mixture being fed in one moment, then a sudden shut off again at the next set of lights, and so on. I find that my car smooths out a lot after a good run way better than messing around with it and dumping reagents in, and I get to go somewhere interesting too, it keeps the car mobile rather than a garage queen and is probably cheaper. One look at the exhaust tips after a good run tells you a lot too.

Unless something is seriously amiss (and I''m sure that would probably be owner-inflicted), most of these cars could be driven around Australia now with nothing more than an oil change beforehand, and the cars would probably finish up running better than when they started off.

[OzCJ]

Been having issues around 45000 km where the car would crank longer than usual only after engine was warm. Baffled me and the service team for ages and finally found that EGR valve had a ot of buildup. Give it a good clean and now the power delivery is so much smoother and the engine is lively.