sikkFD93

After test driving and accidentally drift-racing sideways up a speedway on-ramp, and subsequent boosting rocket launches down the freeway, at which point I was sold on the RX-7 and decided the three day drive was worth it, with shaking hands and adrenaline withdrawal I recently imported a 1993 FD from British Columbia, Canada. Sea-level. I drove it to the mile high city, Denver Colorado. After familiarizing myself with the vehicle as much as possible during the three-day drive, I realized the aeromotive fuel pressure regulator gauge was reading 20 PSI. I don't know if it was like that at sea level or whether it changed with the elevation. So I raised it (the adjustment stud and lock nut were not by any means loose) to 40psi, which seemed to help lower knock. Seemed to help the air fuel ratio which was at like 16 under boost, now it's under 13 or 12 A/F while boosting; seemed to lower the boost level which was immediately skyrocketing above 15 psi just above 4,000 rpm/red light flashing and now it's under 13psi boost all the way to 8300rpm, and seemed to lower the average operating water temperature from 220 to 210°F. It actually read 235°F at one point (before adjusting fuel pressure to 40) in the midst of a hill climb of the Great American Desert. Needless to say I immediately pulled aside and idled down, while changing my undertrousers!!!

1) can your fuel pressure regulator change psi output as you move to thinner air?
2) would anybody who's adept at tuning rotaries have had any reason to tune this TwinTurbo masterpiece at a mere 20 PSI fuel pressure?
3) is it a logical expectation that adjusting the fpr as I did, change these things I mentioned?
4) is boosting with a/f at 16 considered an extremely lean condition?
5) is boosting a/f ratio of 12 within spec?
6) is 210°F coolant temp still about 20°F to high?
7) is it feasible that a Walbro 255 lph fuel pump is running on stock wires? Or was the seller full of s**t?
8) could this setup with K&N filters, stock but non-sequential turbos, Greddy elbow and blowoff valve, HKS exhaust and intercooler, Fluidyne radiator, APEXi boost controller, apexi power fc commander...be running on stock fuel pump and injectors?
9) should I replace my coolant hoses, Mazda thermostat, radiator pressure cap, and coolant?
10) how do I know if my water pump is still good? Is it like an H22A4 honda prelude water pump which spews water on the ground as soon as you add it when it's bad, or is it like the Honda oil pump which seems to go on forever?
10.5) Aargh! ...do I need to tear my engine apart just to see what injectors, pump, etc...are assembled on this rig and whether it is or is not street ported as I was told, whether rotors are dented and seals intact?
11) do I need a tune ASAP before I ruin my engine?
12) have I already ruined my engine?
13) Does anyone know of an adept and trustworthy turbo rotary tuner in Colorado? Or any rotary guy at all? I think I may have the only running FD in the god forsaken state!!!

I am more than willing to hear any and all comments, advice, and feedback that a knowledgeable rotary person might have to offer.
Thanks in advance,

Steampunk Motor

armans

iTrader: (2)

You mean ~20PSI drop just because of the higher altitude? Sounds to me very unreal

I'm not a tuner, but 20PSI sounds like very low. Think it is 38PSI at 0 manifold pressure for stock FDs.

Not sure about the boost level drop, but the temperature drop is normal. Part of the reason rotary engines want to run richer is that extra extra fuel have cooling effect on the engine.

Yes.

Around 10 PSI you may want to be in 11s

It may be normal if the car was under stress a lot in a very hot weather.

Yes.

Yes, depends on how much boost the turbo makes, also how rich/lean the car is running. You can read injector duty cycle information from your power fc.


at least re-flush the coolant. sometimes people go for a low temp thermostat, just search in the forum - lots of info on it.


not sure about the water pump, but I think that oil pump is "forever"

fuel pump is in the fuel tank To reach the injectors you should remove the upper intake manifold, and make your way through the rat's nest to the injects. Technically exhaust port could be determined by removing the turbo manifold and see if the ports are enlarged, but for intake ports and dents/weared housings etc engine should be teared off.

Probably yes, make sure you tune is fine, because your car was running very lean

If it runs, it is not too bad. But you may want to do a compression check.


Have you explored the regional sub forums here?

sikkFD93

Thanks for your response. In my defense, I have always known the fuel pump is in the fuel tank...that's how I know it has stock fuel pump wires ; ). Reading it again, yes I see you believed I thought it's in the engine itself LOL

question 7, you responded 'yes'; was that yes you can run a walbro 255 off stock wires?
or was that yes the seller was full of it

question 10.5, venting frustration. Meant to say tear the car apart : )

*Found an FD tuner well versed in apexi power fc near me, finally!! And, he's an engineer to boot...Eureka!! going to meet up tomorrow; I'm stoked!!!

armans

iTrader: (2)

question 7 - i meant the wires. You can reuse stock wires or do the "direct 12v" mod

Evil Aviator

The fuel pressure regulator is supposed to operate using differential pressure. If the fuel pressure changes with altitude, then something is wrong.

Yes, the previous owner could have used cheap low-pressure carb fuel hose rather than the proper high-pressure EFI hose which is very expensive.

sikkFD93

So, since I raised it to 40 psi and got a tune I could rupture fuel lines if they're not quality?

sikkFD93

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Evil Aviator

Yes, check the brand and SAE rating marked on the fuel hose. Some of the cheapie fuel hose is only rated for 35 psi.