Na8 misfiring & engine shutting off

nelson92 · Postby **nelson92** » Thu Aug 30, 2012 4:26 pm

Hey guys, have had my na8 since early may and have replaced new coil packs, new Crank angle sensor, cleaned and service my injectors, replace fuel filter, changed oil to 5-30 full synthetic and I've always had this misfire until recently I cleaned out the throttle body, afm and it started to run perfect but today it started to misfire again and even shut down even though I'm doing the speed limit, no lights come up on the dash or anything.

I did wash my car recently and I'm thinking it may have something to do with that, but I don't know where to start looking.

Any help appreciated.

Tom

JBT · Postby **JBT** » Thu Aug 30, 2012 4:34 pm

You didn't mention plugs and plug leads ^^. Were they also replaced?

bruce · Postby **bruce** » Thu Aug 30, 2012 4:49 pm

Plug leads!

hks_kansei · Postby **hks_kansei** » Thu Aug 30, 2012 5:04 pm

GOOD plug leads are a must.

My car developed an annoying misfire and some good leads pretty much fixed it.

myredmx5 · Postby **myredmx5** » Thu Aug 30, 2012 6:11 pm

O2 Sensor?

nelson92 · Postby **nelson92** » Thu Aug 30, 2012 7:31 pm

Oh damn yeah I have replaced the recommended plugs and new top gun leads too.

nelson92 · Postby **nelson92** » Thu Aug 30, 2012 8:15 pm

My mate reckons its the afm, looked up on eBay and there going for $250 brand new, anyone got hook ups?

manga_blue · Postby **manga_blue** » Thu Aug 30, 2012 8:48 pm

You said you washed it. Check for water or corrosion in the high tension tops of the coilpacks.

nelson92 · Postby **nelson92** » Thu Aug 30, 2012 9:33 pm

manga_blue wrote:You said you washed it. Check for water or corrosion in the high tension tops of the coilpacks.

will do asap tomorrow morning.

oh when i was driving home from work, going at 80kms, car shuts down again so i pulled over, restarted the car and revved it for a few seconds and then drove home fine.

its diggin my head in!

Postby **Okibi** » Fri Aug 31, 2012 1:30 am

Where are you located Tom? Perhaps a forum member is local to you and could help you diagnose the issue.

nelson92 · Postby **nelson92** » Fri Aug 31, 2012 9:03 am

Okibi wrote:Where are you located Tom? Perhaps a forum member is local to you and could help you diagnose the issue.

I'm located in Sydney Liverpool area okibi.

hks_kansei · Postby **hks_kansei** » Fri Aug 31, 2012 9:49 am

Just out of curiousity..... how did you clean the AFM?

IIRC they're pretty sensitive, so it doesn't take much to ruin one.

93_Clubman · Postby **93_Clubman** » Fri Aug 31, 2012 12:58 pm

If it's not water as MB suggests then check your ECU & the engine earthing point. Not a common problem so far on the NA6 & NA8, there have been a few ECU issues. In particular Conti's NA8: search.php?keywords=ecu&terms=all&author=conti&sc=1&sf=all&sk=t&sd=d&sr=posts&st=0&ch=300&t=0&submit=Search

nelson92 · Postby **nelson92** » Fri Aug 31, 2012 1:49 pm

hks_kansei wrote:Just out of curiousity..... how did you clean the AFM?

IIRC they're pretty sensitive, so it doesn't take much to ruin one.

sprayed brake cleaner in it and let it dry.

93_Clubman wrote:If it's not water as MB suggests then check your ECU & the engine earthing point. Not a common problem so far on the NA6 & NA8, there have been a few ECU issues. In particular Conti's NA8: search.php?keywords=ecu&terms=all&author=conti&sc=1&sf=all&sk=t&sd=d&sr=posts&st=0&ch=300&t=0&submit=Search

i took the car to the gym today, havent had any issues so far.

ive checked for water, nothing seems to be the problem, im taking it to work again today to see if it'll happen again.

but thanks for the link.

hks_kansei · Postby **hks_kansei** » Fri Aug 31, 2012 1:53 pm

nelson92 wrote:sprayed brake cleaner in it and let it dry.

That may not have done it too much good.

I'm not sure what's in brake cleaner, but I do know that generally a specific AFM cleaner, or electrical contact cleaner, are recommended (double check this is right with an MX5 AFM)
Brake cleaner is pretty harsh.

Personally, I wouldn't bother cleaning the AFM. IF you've got a half decent air filter it shouldn't get dust etc on it, and any engine PCV vents are all downstream of the AFM so it shouldn't get oily.