Decelleration Issue - NB8B

[speed freak]

Have used Red Line SI-1 Complet Fuel System Cleaner in the past:
"Cleans injectors and carbs; to like-new efficiency;
Prevents fuel system rust;
Cleans intake valve deposits;
Lubricates upper cylinder and valves;
Reduces pre-ignition and run-on;
Cleans emission control systems;
Stabilizes gasoline and prevents carburetor icing; &
Safe for all gasoline vehicles."
http://www.redlineoil.com.au/Uploads/Do ... 002_03.pdf

Got a can of Subaru Upper Engine Cleaner, but haven't used it yet. Will get around to using as mine has relatively low kms compared to Marty's & many have used it successfully.

Re NB8 IAC:
"If it is the IAC, you can unbolt it from the bottom of the TB, clean it out with TB cleaner. There is a small bellows inside, the actuator rod can gunk up and not let it meter air properly. You can't disassemble the IAC, and it isn't repairable. A new one costs north of $200".
http://forum.miata.net/vb/showthread.php?t=468262

Was also this post with a link to a write-up with pics, but it might be for the NA: http://forum.miata.net/vb/showthread.php?t=404313

Thanks mate, thats a huge help. Ill give that fuel system cleaner a go, cant hurt.

Do you need to remove the throttle body then remove the IAC? Im not too keen on playing with the throttle cable thats all, I know I can do the rest but if I stuff something up with the throttle or cable that would be bad.

Any ideas about the oil in the TB and IM? I looked again before when taking pics of the IAC and it had a pool of oil in the TB again. Intake manifold still looked clean though but Im a bit worried about the pool of oil. Im thinking it could be excessive blow by but not sure why or where from.

[93_Clubman]

Do you need to remove the throttle body then remove the IAC?

Any ideas about the oil in the TB and IM? I looked again before when taking pics of the IAC and it had a pool of oil in the TB again. Intake manifold still looked clean though but Im a bit worried about the pool of oil. Im thinking it could be excessive blow by but not sure why or where from.

You should just be able to undo the screws to drop the IAC.

Is there any chance that what you're seeing after cleaning is the brown coloured coating that acts to seal the TB butterfly?

If not, then check PCV valve on the top coldside of the cam cover. Also check that the breather pipe from the top hotside of the cam cover is also not blocked. Some of the earlier models at least had a small white plastic valve in them.

The part with the 9BK written on it is the PCV (positive crankcase ventilation) valve.

The first thing to do is to fix the valve's hose fitting by opening its hose clamp up by squeezing the lugs on the clamp with a good sized pair of pliers, then pushing the hose fully onto it and slipping the clamp properly over the hose.

If the leak is more from the base of the PCV valve instead then the valve could be blocked or the rubber grommet it sits in could be cracked. It's a routine replacement part with a life anywhere between 20,000kms and 200,000kms, depending on what sort of trips the car does. If it's blocked then it can do some serious damage but it's dead easy to fix or replace.

Google "testing PCV valve" or "testing PCV valve site:miata.net" and you'll get the idea. It comes out of the engine cover with a firm straight pull. Basically it should rattle inside if you shake it and it should allow a small amount of air flow from the engine to the intake manifold and it should not allow a large flow from the engine to the inlet manifold and it should not allow any flow from the inlet manifold to the engine.

You can get a replacement valve and grommet from Mazda for about $30 or for much less from a Repco or Supercheap or similar.

[speed freak]

cheers mate, ill have a look at that tomorrow.

nah before cleaning the whole inside of the IM and TB had a decent thickness of a oil colour film/sludge on the inside, after the clean both were pretty well spotless. After 2 days the TB now has a small pool of engine oil sitting in the bottom at the front of the butterfly valve as it did before I gave it a clean. could very well be that pcv valve, might just get a new one I couldnt imgaine they would cost too much.

cheers
Rhys

[de Bounce]

How I cleaned mine.
Need 2 bolts to put into the coolant hoses.

Start by removing the electrical connections
Remove the coolant hoses and plug with bolts
Remove throttle body (2 x bolts, 2 x nuts from memory)
Remove IAC from below throttle body (2 x screws)
Liberally spray with carby cleaner, etc.

Refit in reverse and check for leaks (coolant and air)

Cleaning the IAC didn't work for me!

Cost of replacement from Mazda Aust is north of a grand last time I checked.
I purchased a 2nd hand one from a NB8A from a fellow forum member.

[speed freak]

How I cleaned mine.
Need 2 bolts to put into the coolant hoses.

Start by removing the electrical connections
Remove the coolant hoses and plug with bolts
Remove throttle body (2 x bolts, 2 x nuts from memory)
Remove IAC from below throttle body (2 x screws)
Liberally spray with carby cleaner, etc.

Refit in reverse and check for leaks (coolant and air)

Cleaning the IAC didn't work for me!

Cost of replacement from Mazda Aust is north of a grand last time I checked.
I purchased a 2nd hand one from a NB8A from a fellow forum member.

Thanks mate, Ill give that a try on my weekend, fingers crossed it works as its quit annoying.

north of a grand for a new one from mazda I shouldnt be too surprised though plus I seen a new replacement EGR valve which cost $500 + from an online store. Parts arent cheap...

cheers

[speed freak]

looks like the IAC will become a mechanics problem or someone other then me with more tools and experience.

took off the throttle body etc but the screws must be welded in place. almost half a can of wd40 was used with no luck. screws have deteriorated too tops are really weak and they arent liking the extra force thats needed to get them out. gave up, cleaned throtlle body butterfly even more and the inside of the housing. sprayed TB cleaner down the hole that goes into the IAC valve though, done this a few times and drained it out.

I dont want to jynx myself but the small drive I just went on when running erins showed no signs of a problem anymore, I could take it right down to almost idle before I put the clutch pedal in. Hopefully its not just a temporary fix, fingers crossed it will stay this way otherwise its another thing the mechanics can deal with haha.

[93_Clubman]

link doesnt work.

viewtopic.php?f=29&t=36182&p=652192#p652192

[tescoking]

I know it's not the question you asked but why ate you using the gears to slow down? Brake pad changes are way cheaper than a clutch and possible worn synchros...

You shouldn't brake with your gear in neutral, it is very dangerous, didn't your driver instructor tell you this? Specially in high speed and going down hill. Always brake first then clutch.

[tescoking]

looks like the IAC will become a mechanics problem or someone other then me with more tools and experience.

took off the throttle body etc but the screws must be welded in place. almost half a can of wd40 was used with no luck. screws have deteriorated too tops are really weak and they arent liking the extra force thats needed to get them out. gave up, cleaned throtlle body butterfly even more and the inside of the housing. sprayed TB cleaner down the hole that goes into the IAC valve though, done this a few times and drained it out.

I dont want to jynx myself but the small drive I just went on when running erins showed no signs of a problem anymore, I could take it right down to almost idle before I put the clutch pedal in. Hopefully its not just a temporary fix, fingers crossed it will stay this way otherwise its another thing the mechanics can deal with haha.

Trust me, it can be remove, it is not welded. It just too tight because Mazda used machine to screw on the IAC, you only need your screw driver and strenght, some WD40 might help

[tescoking]

It is reasonable to be that tight, no one ever remove the IAC from the year it built till now.

[tescoking]

viewtopic.php?f=29&t=61437