Miata down

[DWBOX2000]

01 Miata. Son took to autocross this morning. Car will not idle now, will run with foot on gas. Any thoughts on obvious things to check. I’m an hour and a half away. I can always AAA.

[Tobra]

First is search with "won't idle" in the title , second is with it in the post Good luck, sensor or vacuum deal is my guess without looking

https://forum.miata.net/vb/search.php?searchid=20215263

https://forum.miata.net/vb/search.php?searchid=20215253

[pavulon]

Fuel filter? Possible that debris in the fuel tank has been put into circulation.

[ben parrish]

Large vacuum leak....look at all hoses carefully. Or...clogged fuel filter.

[DWBOX2000]

Thanks all. I will relay the message. This is the 1st time his new throttle bodies are being tested.

[Zeke]

Originally Posted by DWBOX2000

Thanks all. I will relay the message. This is the 1st time his new throttle bodies are being tested.

That's your answer

[DWBOX2000]

Glad he paid a fortune to have them tuned. 😀 Thanks.

[Chocaholic]

Want to finish a race season with $1M in your pocket?

Start with $2M.

[speeder]

Originally Posted by ben parrish

Large vacuum leak....look at all hoses carefully. Or...clogged fuel filter.

Curious as to how a clogged fuel filter would only allow it to run at higher rpms and not at idle? That’s a strange one.

[LEAKYSEALS951]

I'll also throw in a $0.02 and say, if you can't find an obvious loose hose, make sure to go back and retighten the throttle bodies and everything intake related.

[DWBOX2000]

Got car home. Plugs were black so something not right. Runs fine but won’t idle. No abnormal smoke out of muffler. No change in sound. I told him to call the guys that tuned it and go from there.
Thanks everyone.

[unclebilly]

Timing belt jumped a tooth?

[speeder]

Timing belts do not jump one tooth. They either break or completely jump timing if the tensioner fails. The car would not run fine at higher rpms.

[unclebilly]

Originally Posted by speeder

Timing belts do not jump one tooth. They either break or completely jump timing if the tensioner fails. The car would not run fine at higher rpms.

How many teeth do they jump? How does one determine this? There is no reason they couldn’t jump just one tooth if blipping the throttle aggressively or engine braking.

How many Miata engines have you built?

Here is the first one I did for the endurance car I race in… it has had many podium wins since and we are racing it again this coming weekend in an 8 hour race.

[speeder]

Miata engines? Zero. Other engines? More than you. With chain/belt and gear driven cams. Air and liquid cooled, gas/diesel, motorcycle/car/truck, etc. If you want to use the argument of competence, I’m almost certainly a better skier as well.

[speeder]

Maybe there is something unique about Miata engines that allows them to jump one tooth of timing and exhibit symptoms of a bad airflow sensor, you might have me on that one.

[unclebilly]

We have had the not idle issue after a race before. Mass airflow sensors have been an issue.

A cam jumping is also possible. I think that car also has VVT and this could be the issue. Didn’t throw a code?

My race car is a 99 but that engine in the photo was a 1.6 for an 89 Miata. It is also SM legal (except for my endurance hubs).

[unclebilly]

Originally Posted by speeder

Miata engines? Zero. Other engines? More than you. With chain/belt and gear driven cams. Air and liquid cooled, gas/diesel, motorcycle/car/truck, etc. If you want to use the argument of competence, I’m almost certainly a better skier as well.

I’m not going to disagree with the skiing thing… but I did get 11 days in this spring after breaking a leg and blowing up my ankle in January… next season we can reevaluate my position on this matter.

I’ve got a similar engine building resume to you.

[speeder]

I'm just internet jostling with you, buddy. You might be better at everything than me.

[unclebilly]

Originally Posted by speeder

I'm just internet jostling with you, buddy. You might be better at everything than me.

me too.

A friend of mine is the local Miata Guru (hes had probably 40 and built MANY Spec Miatas). He has atleast 3 'in stock' right now.

He says check for vacuum leaks first.