Miatacrazy716

iTrader: (2)

I am in the beginning stages of finally installing my microsquirt. I am going to be running NA till I get everything figured out and running good on its own before boost is added. I have a few questions?

First I added a ford tps and noticed while I had the throttle body off there are 2 coolant lines and a air intake line going into the lower portion of the throttle body. I did a rather lengthy search and found nothing about this but are they necessary to keep or can I plug them off since I am going megasquirt??

Second question I searched a found a few threads on is should I add the larger injectors now or wait till I add FI? I already added a walbro 190 hp fuel pump. The injectors are redtop rx7 injectors. If I did miss a topic while I searched sorry but all I have is my phone please bare with me. Thanks again

Joe Perez

iTrader: (8)

The coolant lines on the underside of the throttle body are there to prevent icing. If you drive in areas where carb icing is possible (high humidity and temperatures slightly above freezing) them it should be kept.

Ideally, ALL changes to the fuel system should be performed prior to adding forced induction, so that you have time to learn how the engine reacts to them and tune it in a "safe" environment.

Miatacrazy716

iTrader: (2)

Thanks for the reply. The car will only be driven in the summer and my common altitude is under 1200 ft above sea level. What about the air intake tube the feeds into the lower section as well any thoughts on that?

I will for sure add the injectors now but will have to add a fuel pressure regulator. What's the common psi used to feed the injectors?

Thanks again, Bill

Miatacrazy716

iTrader: (2)

Thanks for the reply. The car will only be driven in the summer and my common altitude is under 1200 ft above sea level. What about the air intake tube the feeds into the lower section as well any thoughts on that?

I will for sure add the injectors now but will have to add a fuel pressure regulator. What's the common psi used to feed the injectors?

Thanks again, Bill

WestfieldMX5

Why on earth would you want to add a fuel pressure regulator???
Yes, you can install the injectors now, but I suggest using yellow RX8 injectors over those old RX7 injectors.
Unless you're going for high boost, even the stock fuel pump is more then adequate.

Miatacrazy716

iTrader: (2)

This is on my 91 1.6. I read alot of threads on running larger injectors for boost. I seen the majority use the 190hp fuel pump. I already have the 190hp fuel pump installed but running the stock fuel rail setup with stock injectors. I read that when you trust just the stock fuel pump you can run lean. I didn't want that. I will be around 12lbs of boost hopefully when done. I have a new aftermarket fuel rail and those rx7 redtops for my boost application.

Unless I read the wrong threads this was a common application. I just never found any anything that talked about a fuel pressure regulator. Can I just reuse the stock pressure regulator then with my rx7 injectors.

thenuge26

iTrader: (2)

Sell your aftermarket fuel rail and RX7 injectors, buy RX8 injectors

Joe Perez

iTrader: (8)

That is the air supply to the idle control solenoid. It must be kept.

(Why are you so anxious to rip parts out from under the hood?)


While it was once common to install rising-rate pressure regulators, modern ECUs such as Megasquirt are perfectly happy driving large injectors at stock pressure (which is about 45 PSI above MAP in the 90-97 cars.)

Unless your stock FPR is malfunctioning, you don't need anything else. The stock fuel rail and FPR will be perfectly adequate into the low to mid 2xx HP range with injectors in the 450-550cc neighborhood. The only thing you might need is a 190ish fuel pump

Miatacrazy716

iTrader: (2)

Thanks Joe. I have removed everything that is possible and non functional to me and my use for the car. I want to wire tuck everything as well so it looks clean and uncluttered.

Is there a serious issue of using the rx7 redtops vs the rx8 injectors besides modern technology and maybe a better spray pattern? I have read alot of build threads using the redtops with no major ill effects.

Joe Perez

iTrader: (8)

Ah, you're one of those people.



No problem at all. They work fine, they're just not the best solution available today, and other injectors are currently considered to be more en vogue.

Miatacrazy716

iTrader: (2)

I appreciate your time and not grilling me for asking some questions I couldn't find the answers too!!