idle speed

[Davidbolam]

Does anyone know what speed the mx5 engine should idle at. Mine was running quite high until I blocked off the hole for the brake vaccum. Now it seems to be running high again. About 1200 rpm

Has anyone got any ideas??

David

p.s im hoping to go for my first drive tonight (on my private road - of course)

[skov]

Does anyone know what speed the mx5 engine should idle at. Mine was running quite high until I blocked off the hole for the brake vaccum. Now it seems to be running high again. About 1200 rpm

Has anyone got any ideas??

David

p.s im hoping to go for my first drive tonight (on my private road - of course)

Hi David,

It should be between 800 and 900 rpm when it's warmed up, and higher than that when cold.
Not sure how much higher, but 1200 might be about right for a very cold engine.
If it doesn't settle down as it warms up check for air leaks and check your coolant temp sensor (the one that the ECU uses, not the one the clocks use!).

[Davidbolam]

Hi David,

It should be between 800 and 900 rpm when it's warmed up, and higher than that when cold.
Not sure how much higher, but 1200 might be about right for a very cold engine.
If it doesn't settle down as it warms up check for air leaks and check your coolant temp sensor (the one that the ECU uses, not the one the clocks use!).

Thanks skov.

I will check this tonight.

David

[Davidbolam]

I notice last night that when the engine had warmed the rev's dropped to around 900.

My next question is about the temperature senders....

Am I right in thinking that the sender on top of the thermostat controls the fan and the sender at the rea of the engine is linked to the ECU. Is there a third sender for the dash temperature guage.

Thanks

David

[skov]

I notice last night that when the engine had warmed the rev's dropped to around 900.

My next question is about the temperature senders....

Am I right in thinking that the sender on top of the thermostat controls the fan and the sender at the rea of the engine is linked to the ECU. Is there a third sender for the dash temperature guage.

Thanks

David

900 sounds good to me!
Might be worth adjusting the idle screw at somepoint.

That's right on the temp sensors.
The one on the thermostat is just a switch and turns the fan relay on and off.
At the rear the 2-pin one goes to the ECU, and the one with a spade connection goes to the instrument cluster.

[Davidbolam]

900 sounds good to me!
Might be worth adjusting the idle screw at somepoint.

That's right on the temp sensors.
The one on the thermostat is just a switch and turns the fan relay on and off.
At the rear the 2-pin one goes to the ECU, and the one with a spade connection goes to the instrument cluster.

Thanks John.... Once you've passed your IVA please don't stop using my forum. you seem to know the wiring etc inside out!

[skov]

Thanks John.... Once you've passed your IVA please don't stop using my forum. you seem to know the wiring etc inside out!

Don't worry, I still plan to drop in and check on you regularly when I'm done :D

[Davidbolam]

Another question....

Should the fuel pump prime itself once the ignition key is turned on? Mine only seems to run when the flap in the air inlet is moved.

This means that if it hasn't ran for a while I need to manually push open the flap to get it going or let it turn over for quite a bit.

David

[skov]

Another question....

Should the fuel pump prime itself once the ignition key is turned on? Mine only seems to run when the flap in the air inlet is moved.

This means that if it hasn't ran for a while I need to manually push open the flap to get it going or let it turn over for quite a bit.

David

No, it only runs via the flap, or during cranking.
If you want to prime it I think you can short one of the pins in the diagnostics box to gnd.

[Davidbolam]

Thanks again!

I can't find a relay for the headlights but they seem to work. Any ideas what it looks like or if there is one?

David

[flyerncle]

Most fi systems prime the fuel system with ignition to avoid the long cranking to make the flap move to tell the ecu the engine is running,Mazda have used a set up like the older Bosch system with the air flow being sensed by the box at the end of the pipe.

It is also normal to have higher revs when cold to compensate for the rich mixture at cold idle.

You solved the vac problem that also makes them run high when inlet air is not regulated,Had a car in the other day had started idling high after he topped up his oil,he had pulled the breather pipe of the inlet manifold.

[skov]

Thanks again!

I can't find a relay for the headlights but they seem to work. Any ideas what it looks like or if there is one?

David

There is one, but I can't quite remember what it looks like or where to find it :confused:
I've got a feeling it's somewhere in the engine bay on the MX5.

[Johno]

Hi David,
On mine there wasn't one only the retracta relay which has nothing to do with it. Spent ages looking for it to no avail.....

[Davidbolam]

Hi David,
On mine there wasn't one only the retracta relay which has nothing to do with it. Spent ages looking for it to no avail.....

That's what I thought.

Cheers

David

[skov]

I could be wrong then!
There seems to be one on the wiring diagram I've got though... :confused:

[Johno]

Hi John,
It was on the wiring diagram I had also which confused the hell out of me...:eek:
The only relays I had left after I stripped out all the crap were the,
"Open circuit relay"
"Flasher relay"
"Horn relay"
All the heavy loaded stuff seems to go through the main fuse block...:confused: