Mx5 mk1 Low Power. Airflow Meter?

Technical Area Engine, Transmission, Exhaust etc
2

Hi

 

I have a 1990 Eunos mk1 which has a low power issue. On motorways with a steepish gradient the power drops to an extent where it will only do approximately 30mph. I have connected an LED to the diagnostic box and am getting error code 10 which I believe is ‘Intake air thermistor in airflow meter’.  The wiring loom connected to the airflow meter has some insulation tape wrapped around it suggesting that someone has previously tried some form of repair.  

 

Any advice on what to try next would be appreciated. Are there any further tests / ideas I can try?

 

Thanks

Paul

3

Is the repair to the wiring OK?

4

I would be very surprised if there has been any repair to the airflow meter wiring. If there is black insulation tape wrapped around the wire and rubber shroud just beyond the connector plug, that is totally standard. It does look a bit Heath Robinson but standard Mazda.

Takes about 5 minutes to replace the airflow meter. If the diagnostic says airflow meter, definitely worth trying a replacement.   

5

Correct me if I’m wrong but - I’m under the impression the airflow sensor can be cleaned with MAF cleaner to remove the build up of crap ? 

 

Just found this - 

https://www.youtube.com/watch?v=gRfaPfTcfOM

6

A 1990 MX-5 doesn’t have a hot wire mass airflow meter like that.  It has a flapper type sensor where the incoming airflow physically swings a flap valve open against a light spring.

A MAF like that one was first used in the 1.8 engine which didn’t enter production until 1993.

7

Thanks for replies

 

I have replaced the airflow meter with a second hand one but still have the same low power issue.  

I agree that the insulation tape around the wiring is standard mazda as all looked ok underneath. 

I’m also not sure that the diagnostics is telling me that it is airflow meter. When I turn the key I get one long flash only - it does not repeat. Does the single flash indicate that the diagnostics is on and any errors would follow the first flash?

The low power issue seems to occur around the time that a colling fan comes on.

 

Any ideas on what I can try next?

Thanks

8

Have you checked the cam timing?

9

Hi Plodski

I can confirm that your car diagnostics are not showing an error. The single long flash and then out indicates happy crude diagnostics which I’m sorry to say is no help with your low power issue.

Is the cooling fan coming on at the appropriate time ie. when the car is starting to get too hot after left idling for 20 mins or so or a hard thrash in hot weather? The 1.6 MK1 has a sensor on top of the thermostat that turns the fan on when the coolant is at the correct temperature. I’m just wondering if the thermostat is stuck open or something.     

 

 

10

1990 has a short nose crank…have you checked the crank pulley hasn’t moved, or is wobbling?