BRealistic

Ok, I understand the benfits of pre-mixing, and removing the oil metering pump. But one thing I do not understand: If most n/a rotary Mazdas die due to general lack of maintenance that leads to: loss of coolant or failure of cooling system, low oil level, and failure of the OMP= then why didn't Mazda make an OMP sensor that would alert if the OMP wasn't performing properly? You have an oil pressure sensor, but from erading posts it seems OMPs go before the oil pump goes bad? right? Am I missing something, or is this one of those 'designed in failure' things? Maybe Mazda knew if the OMP had a failure idiot light, that people would never blow their engines?

purple82

The OMP didn't get a monitor until 89.

bliffle

Same question occured to me, but I lost interest when I went to MMO premix.

B

BRealistic

Huh, the S5 has an OMP sensor? I didn't know that. I guess Mazda realised their error.

BRealistic

I thought you were supposed to pre mix with 2stroke oil? You guyz are so confusing.

peejay

Yes the S5 has an electronically adjusted OMP instead of a mechanical linkage (throttle body linkage) controlled one.

Technically it doesn't monitor OMP output, it only monitors the position of the output adjuster. (The eqquivalent of making sure the throttle linkage rod isn't hung up full open or full closed)

This is why the '89-up OMP costs more than many FC's are worth. ($1500 or thereabouts)

racermike

I have yet to see a bad omp. Bad lines or leaky omp yes, but no actual failure. Have I just been lucky?

racermike

damn computer

peejay

The one in my '80 was dead, dead, dead. Never bothered finding out why. I just started premixing and kept on truckin'.

j9fd3s

iTrader: (3)

ive only seen one that didnt pump oil, lots of leakers though

mike

racermike

I have also never seen an oil pump go bad. Except for TWO from Racing Beat, and that was 20 years ago (bad batch)....

BRealistic

Ok, now I am confused. The purpose of pre-mix is to protect the engine because the metering oil pump will eventually go bad, but nobody has ever seen actually one go bad???!!??? What?

racermike

I'm only speaking for myself.
Racers go pre-mix so that the engine always sees the same mix and it is completely controlable. The omp system has some lag time and the mix can vary.

peejay

It's not because "it will eventually go bad". It's so you can yank the OMP off and throw it far, far away, so that you no longer inject dirty, cruddy oil that was not designed to burn cleanly.

MIKE-P-28

iTrader: (1)

yeah 89 up is totally electric , and will trip a check engine code

Fatty_FC3S

So then if you go to a standalone engine management, the 89-91 OMP no longer works? Then you HAVE to go premix? Just curious....

MIKE-P-28

iTrader: (1)

only aftermarket ecu I know if that will work the facotory 89+ OMP is a Haltech e11

hornbm

yes yes, I have the s5 electric OMP on my car. It seems like a nice idea, but from what most of the FC guys told me, the electric OMP is not as good as the mechanical ones.

The S4 rx-7's seem to last a lot longer before having seal problems than the s5's do.

The only thing the electric OMP really does differently than the mechanical one, is if its messed up or not plugged in, it throws the ECU into "limp mode"

purple82

You can use a mechanical pump from the S4 or earlier.

Pele

iTrader: (28)

There is an adapter that fits between the OMP and the engine. It basically plocks off access to the engine oil and allows the OMP to pump from a seperate resivour.

This'll allow you to run Synthetic if you prefer, but it'll also allow you to use deticated burnable oil for the engine.