Vroomaster

2 questions:
1. What size injectors are stock on an '86 N/A 7?
2. If you put a low impedence injector on an 87+ and it will blow the ecu, what would happen if you put a high impedence on a pre-87 rex?

Thanks

Ryde _Or_Die

Stock NA injectors are 460cc. Umm..I have always thought that NA injectors were low impedence since people simply put the 550cc TII injectors in sometimes. Not sure though.

Vroomaster

Thanks for the size.
They are interchangable as long as the TII was made before March(?) 87, after that they switched to high impedence.
I was wondering what would happen or what would be a good work-around for putting a high impedence on a low impedance system.

Ryde _Or_Die

People wire in resistors I believe.

Rotorific

iTrader: (1)

the only low impedance injectors in NA's are the ones from mid 87 and below...as far as the 550s good question i just know im putting them in my 88 how it works i dunno

HAILERS

If you were to put the high impedence injectors in the low impedence car, say just the secondaries, you'd have to go to the solenoid resistor pack. Cut the secondary wires that come out of the solenoid resistor pack a couple of inches from the pack, and then make two splices come from the power wire that feeds the solenoid resistor, and have those splices go to the secondary wires.

In other words jumper around the solenoid resistor pack for those injectors. Sorry, don't have the schematic in front of me so I can't give wire colors. If I remember the feed to the solenoid resistor is Black/yellow.

Oh, I have put 550's in my n/a secondaries before. I hit a bit of a boggggggggggg at 5100 rpm. It sorta cleared up a few hundred rpm later, but overall in my case I went back to the 460's. Just runs better.

DaleClark

iTrader: (55)

All RX-7s had low impedance injectors until sometime in '87, when they went to high impedance. This includes NA's and Turbos. All NA's have 460cc injectors, and all TurboII's have 550cc injectors

Now, here's where it gets interesting - all ECU's are designed to drive high impedance injectors. The earlier cars have a resistor block near the passenger side headlight to make the low impedance injectors look like high impedance to the ECU.

If you have an early car, you can bypass the resistor block, as stated above, to run high impedance injectors - the car will start, run, and drive just great. If you have a later car and wish to use low impedance injectors, you'll have to add a resistor to the circuit - Radio Shack sells 10 ohm 10 watt resistors dirt cheap.

And, I'm with the other guy - 550's in an NA ain't the best idea.

Dale

Vroomaster

cool, thanks for the replies

Roundabout

iTrader: (8)

I put 550 secondaries in my 87 Base and they work great, but I also have a mild streetport, stripped emitions, racepipe & custom high flow catback, K&N filter, no a/c p/s or air pump pulleys. It doesn't bog at all, it just keeps pulling harder and harder all the way up to 8krpm (thats what the tach is telling me)

HAILERS

ROUNDABOUT.....I've got the KandN and dual exaust from each exaust port, but no streetport. That might be the difference as to why I detect a bog at 51-5400 rpm or so.

Roundabout

iTrader: (8)

I was thinking the same thing myself (about the port job)