Sticky throttle at lights and long stops

Purecaboos · Postby **Purecaboos** » Tue Dec 04, 2018 10:31 am

Hey All,

I have a recent development with my NA6 that I have to look at on the weekend when I get time, in a nut shell when I stop at lights or a stop sigh the throttle is 'stuck' closed and needs a good kick to get it to open again. Does not happen all the time, just every now and again. Enough to be annoying and sometimes downright dangerous.

I have had a quick look and can't find any issues in the workshop as it works perfectly each and every time I have looked at when I get home in the garage.

Symptoms are, when they occur:
1) drive normally all day
2) stop at stop sign
3) go to start, throttle wont go down
4) mash to floor, feel it go 'click' and throttle works
5) slide through right hand turn looking like a stole the car :-P
6) wonder what is wrong now...
7) look in garage at home and it all works fine

Before I pull the while think apart, any hints? Is this a common thing?

Cheers

Greg

Purecaboos · Postby **Purecaboos** » Tue Dec 04, 2018 10:34 am

Oh, and it only happens when it is hot. Never at the start of a drive only once it is really warm and happy....

I don't notice it when getting on and off throttle when driving, only when I stop for a few seconds at closed throttle.

hks_kansei · Postby **hks_kansei** » Tue Dec 04, 2018 10:51 am

Thankfully the throttle is a simple setup with only 2 pivot points.

One is at the pedal, where there's a pivot, and then at the end a hook that holds the cable and pulls it through the firewall.

On the NA especially there is a moderately common issue where the steel bracket holding the accelerator pedal will bend or break, which shifts the pedal slightly and can make the throttle cable start to rub against the firewall and feel stiff.
So poke your head under there and have a look.

The second pivot is at the throttle body, where the throttle blade opens and shuts.
Usually this is pretty reliable, but have a look anyway, and check by hand to make sure it all moves freely, and that the spring snaps the trhottle shut.
If you remove the crosspipe from the throttle body you'll be able to visually inspect the throttle blade to make sure it's not been damaged (really unlikely)

So yeah, if both of those are ok, last possibility is the throttle cable, which may have frayed or got too much sh*t built up inside it's sleeve and need replacement.

Purecaboos · Postby **Purecaboos** » Tue Dec 04, 2018 11:05 am

Thanks HKS-KANSEI,

I will have a look underneath the dash anyway this weekend as a whole bunch of cables fell down on the way to TAFE this morning. One quick cable tie and things are back up underneath instead of blocking the brake pedal :-P.

I love my little MX5, it keep me interested by always have something to puzzle about.

Cheers

Greg

hks_kansei · Postby **hks_kansei** » Tue Dec 04, 2018 12:30 pm

If your pedal box is bent/broken and you're replacing it, try and get an NB one.

Fits straight in, but Mazda from memory slightly changed the size/location of the strengthening folds/ribs, and they dont seem to have as much issues with breaking as the NA units.

It's still an arse of a job to change them though.