Idle dip......Gearbox problems?

[Blugg]

What does a fuel regulator look like? What does it do?

I read on miata.net forums of people having the same issues. Lumpy idle when cold, perfect idle when warmed up and some speculate that it's caused by the car running too rich on cold.

[Fra66L]

Normal NB8A problem.

Try taking off theintae crossover tube and caefully cleaning the throttle body and butterfly plate with a VERY SOFT, CLEAN rag and some (oxygen sensor safe) carby/throttle body cleaner (pressure pack can). I do this every oil change and it pretty much eliminates the problem.
The throttle clearances at idle are marginal and once you have a nice coating of Ick (technical term) thanks to EGR and PCV, the clearance is worse so a regular clean keeps things happy...

Cheers,
T

[Woo]

It connects into the front end of the fuel rail and regulates pressure Blugg. The NB8A base pressure is 36 psi, and as the engine vacuum decreases the regulator increases the pressure in the rail by holding fuel in the rail. As the pressure increases more fuel is injected at each injection pulse.

On a force fed motor (or even a Naturally Aspirated motor) by increasing the fuel pressure increases the delivery by upto 40%. This is good for making power and avoiding detonation.

The regulator that I replaced the stock unit with is a Malpassi with a 1:1.7 rising rate (called a RRFPR -Rising Rate Fuel Pressure Regulator). What this does is for every kPa of boost the fuel rail pressure increases 1.7 kPa. They are also available in 1:1 (which is what the stock units are).

Usually good for about 10-15 kW at the wheels

They have an adjustable base pressure of between 10 and 100 psi, so really allow for oversized injectors to be mechanically controlled rater than adjusting the pulse duration.

Hope that helps

Wòó


This is the Malpassi that I fitted