Drives like crap when cold

TieNN89 · Postby **TieNN89** » Wed Jun 02, 2010 12:09 am

Does anyone know what is going on with my MX5

It drives like crap when its cold

When I pull up at a set of lights the revs just drop to 500rpm and kicks back up to 850rpm where it should be then when I take off the revs just drops and comes back to life again :S

It idles at 850rpm

project.r.racing · Postby **project.r.racing** » Wed Jun 02, 2010 10:03 am

the idle drop when braking sounds like the IAC valve.

How long do you allow it to warm up before driving?

Regie · Postby **Regie** » Wed Jun 02, 2010 7:18 pm

mine was doing this a few weeks ago.

I ran some injector cleaner though it and it fixed itself

TieNN89 · Postby **TieNN89** » Wed Jun 02, 2010 7:18 pm

not long

not even a minute

I try to let it run longer when I can though

Regie, what brand injector fluid did you use?

Regie · Postby **Regie** » Wed Jun 02, 2010 11:24 pm

TieNN89 wrote:not long

not even a minute

I try to let it run longer when I can though

Regie, what brand injector fluid did you use?

good question, but i remember it was red and treated 2 tanks....i just put the whole bottle in

manga_blue · Postby **manga_blue** » Wed Jun 02, 2010 11:47 pm

Engine coolant temp (ECT) sensor failure? ECU defaulting to engine hottish.

ECT test.jpg

Alex · Postby **Alex** » Thu Jun 03, 2010 11:41 am

Idle dip?
http://forum.miata.net/vb/showthread.php?t=127446
http://forum.miata.net/vb/showthread.php?t=127451

TieNN89 · Postby **TieNN89** » Thu Jun 03, 2010 7:05 pm

manga_blue wrote:Engine coolant temp (ECT) sensor failure? ECU defaulting to engine hottish.
ECT test.jpg

Would this be the same sensor that tells me how hot it is on the instruments?

If so it looks to be working fine

It also idles higher when cold as normal

93_Clubman · Postby **93_Clubman** » Sat Jun 05, 2010 6:23 pm

NA6 B6 engine used to have an extra sensor at the rear of the head, but from memory NA8 & NB8 BP engine just has the one sensor at the rear of the head.