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As some members may know who have been on runs with me, my car runs quite rich.
Most tanks running 98 Octane I see 350 to a tank

About 18 months ago I replaced the O2 sensor which didnt do much to alleviate the problem.

Recently I replaced Plugs which helped a little and not long after that Air Flow Meter.

After doing all that it made very little difference, so after some reading on Miata.net and other pages I decided to replace the ECU Water Temp Sensor on the back of the engine.
I disconnected the ECU night before and then replaced the sensor.
The next day I drove the car however it ran worse... Flooding between 1-2k RPM and stuttering and hesitation from 4 -6k rpm.
Then thanks to Gobsmax I followed this http://www.miata.net/garage/Engine_Diagnostics.html
and found the ECU to have error code 9. Pulled the car apart today and found one of the pins in the ECU temp sensor not making connection.
Fixed that and car runs better however still rich.

The car when it came from Japan had a lot of 1.8L parts on it so a friend suggested that it may have 1.8L injectors, however I am not sure how to tell.

Does anyone have any ideas?

corners wrote:The car when it came from Japan had a lot of 1.8L parts on it so a friend suggested that it may have 1.8L injectors, however I am not sure how to tell.

Does anyone have any ideas?

If the JDM NA6 injectors are the same as the Aust delivered ones, & I expect they are, then they should have blue tops. Aust delivered NA8 injectors have tan tops.

The injectors are blue tops

I fitted new leads today, still the same problem

As you know NA6s are notorious for running rich - maxwolfie's JDM NA6 only used to get about 325-350kms from a tank around town & 400ish kms h'way, but of course approx kms per tank isn't the best way to estimate it, & the right foot has a big impact too.

Btw, I saw this:
viewtopic.php?f=29&t=27734
& thought there might be some info in the following that's useful:
viewtopic.php?f=29&t=40436&start=15

93_Clubman wrote:As you know NA6s are notorious for running rich - maxwolfie's JDM NA6 only used to get about 325-350kms from a tank around town & 400ish kms h'way, but of course approx kms per tank isn't the best way to estimate it, & the right foot has a big impact too.

Btw, I saw this:
viewtopic.php?f=29&t=27734
& thought there might be some info in the following that's useful:
viewtopic.php?f=29&t=40436&start=15

I know have an O2 sensor and high flow cat and have for sometime now..

I checked the PCV valve and cleaned it but alas no different.
Also checked the valve on the side of the plenum. Its passing plenty of water so should be fine.
Checked for any intake leaks, couldn't hear nor find any. The intake is aftermarket.
Looks similar to this:
http://www.revlimiter.net/miata/images/engine2.jpg

Not sure what else to change or diagnose

corners wrote:The intake is aftermarket. Looks similar to this:
http://www.revlimiter.net/miata/images/engine2.jpg

Not sure what else to change or diagnose

Looks similar to the Monster Flow intake - might be time to book the car in with MX5 Plus in Bris.

Hmm....just a suggestion, but perhaps it just needs a proper tune? If all the narrowing down you've done so far isn't really helping then a tune is probably called for.

is your car getting up to temperature? it should sit about 1/2 way on the guage and get there fairly quick (within 5 mins). If knot check uot the thermostat

corners wrote:I know have an O2 sensor and high flow cat and have for sometime now..

The reduced backpressure of the hiflow cat + exhaust will have negative effects on most engines (so will extractors). With the NA6 you can adjust the flapper spring tension on the AFM and it will lean/richen the mixture. Cut open the seal (black lid) on top and adjust the spring tension.
It should be done in small steps and preferrably with an O2 sensor logger (borrow a wideband) so you don't lean it out too much (2-3 clicks should be more than enough).

PS: It has worked for me, but it's not my fault if you blow yours up