1990 mx5, 550 injectors, T28
 

hi, ive just finnished buildin my 1990 1.6 mx5 , ive got 550 injectors, adj fuel pressure reg, t28 off an s14, LC1 wide band and removed the AFM and just fitted a MSPNP9093, sorry if this has been covered in the past but i need base map or a suitablemap for this, also what should i set the fuel pressure to? could some one please help ive not had any experience with this side of things

remove the afpr.

+1

the 550's will flow more than enough at stock pressure. It would be silly to tune with rising fuel pressure.

i no longer have the standard fuel pressure reg, what is the standard pressure, or will i be better buying a new standard pressure reg?

35psi at idle. 48-50psi at atmosphere.

Q : How well will a 1.6 idle with the 550 injectors and the Megasquirt PnP and a Walbro 190 ? ?

I have the 550s on order for extra head room and I was told that my idle may suffer...

Can I get them altered to a better atomizing pintle when I rebuild them ?

Cheers.

Poobs :)

You'll be able to idle them fine, especially if you have sequential injection. Don't worry about altering the injectors. Plenty of people on here run 20 year old rx-7 550s with no problem, myself included. Just make sure they're clean and flowed before throwing them in. Deatschwerks is where I send my injectors.

Thanks man !

Maybe I should have give more info ...

This is going to be ( at least at the start ) a relatively low boost set-up - maybe 5 to 6 lbs.

Put it this way. I ran 12PSI and 190whp on 460cc injectors with a stock fpr. around 85% duty. You'll be just fine running a stock FPR.

My suggestion, find an OEM FPR and run that for now. Once you hit the dyno for a real tune, throw the AFPR on and set it to 35-38PSI. A AFPR provided it is a legit quality brand (like aeromotive) will hold fuel pressure much steadier than the OEM one. Less fluctuation in pressure. I noticed it big time when I went from my stock one to the Aeromotive.

Sorry, I neglected to include all the information - I am running a Megasquirt stand alone ECU and don't have a AFPR.

I run RX7 550's (which ended up flowtesting at 600cc...) they'll idle fine at stoich with sequential injection, however getting them to consistently idle at that AFR is becoming the bane of my life.

It's the final 5% of the tune which is super hard to nail.

Thanks for posting. I already ordered the 550's but I'm counting on the injector rebuilding place trading me for a set of 400 plus flow injectors if need be.... ( ? )

Keep your 550s. They should be the last injectors you need until/if you go above 250whp.

You don't need an AFPR, but a Walbro 190HP might not be a bad idea. You'll find out if you need a new fuel pump when you start pushing a little more boost. I ended up getting one because my old setup was an e-manage+afpr and the stock pump couldn't hold more than 60psi to redline.

Thanks guys

So far, opinion seems to be evenly divided between 550s or smaller :)

falcon. I tried to PM you but your message box is full...

Well, during our tuning session both AFR and injector duty cycle seemed to be ok for high kpa at 6psi boost. So, I may be selling the 550s