advice

[fcrotory]

So I did a s4/s5 long block swap on a 91'. All s5 parts on sp s4 block. Now car won't start. I'm not using 5/6 port sleeves,emission rack, and alot of vacuum deleted. Any ideas. I got spark and fuel. Maybe timing??

[sickofpistons]

Did you use the original harness with the new s4 injectors?
I got this information from rotary resurrection..

Mazda RX-7(Gen 1 and 2) Fuel injector identification guide
(Note that some injectors carry the same part number as others but plug styles and resistances can vary. Low impedance refers to 2-3 ohms, high impedance refers to 12-13 ohms.)

Year type impedance plug style plug notch position flow rating color part number

•• 84-85 13B NT low square center 680cc orange 195500-0900
•• 86-87 13B NT low square center 460cc red 195500-1350
•• 86-87 13BT low square center 550cc tan 195500-1370
•• 88 13B NT high square offset 460cc purple 195500-1350
•• 88 13BT high square offset 550cc purple 195500-1370
•• 89-91 13B NT high oval center 460cc red 195500-2010
•• 89-91 13BT high oval center 550cc purple 195500-2020


As a side note, replacement fuel injector clips (for wiring harness) can be obtained from auto parts stores to replace broken stock clips. I got the parts from autozone:
GP Sorenson part 800-9416 Fuel Injector Connector.

I have not found an aftermarket source for oval injector clips.

More about injector impedances on 2nd generations:

1986 and 1987 model cars used low impedance(2-3 ohm) injectors. Low impedance injectors have a center notch on the plug. The wiring harness used with LI injectors integrates an injector resistor pack, wired inline between the ECU and injectors(under stock air box) to bump overall load seen at the ECU to 12-13 ohms.

1988 and later models used high impedance injectors. 1988 HI injectors have an offset notch on the plug, and all post 1988 injectors are HI with an oval plug(until 3rd generation side feed injectors which are totally different). The wiring harness on these models deleted the injector resistor pacl, carrying the 12-13 ohm load from the injectors directly to the computer.

When performing engine/wiring/injector swaps, the type of setup must be noted and kept together. This is easy as LI injectors will only plug into a harness meant for them(due to the position of the plug notch) and vice versa for HI injectors and harnesses. 88 and post 89 HI injectors and harnesses are not interchangeable.

A car that previously ran one type of setup can be changed to the other…keep the injectors and wiring harness together. The ECU will not know the difference.

It is also possible, but not necessarily recommended, to use HI injectors on a LI harness and vice versa:


•• TO do so you must modify the injectors to fit the opposing wiring harness by taking off the notch on the plug.

•• IF using LI injectors on a HI harness, you must splice into the harness, at each injector lead (for a total of 4) 10 ohm/10watt resistors available at radio shack for a couple of bucks. Doesn't matter which wire of the 2 per injector you splice to, polarity isn't an issue here. This bumps the LI resistance up to acceptable load for the ECU to see.

•• IF using HI injectors on a LI harness, you must unplug the resistor pack. Next, locate the supply wire in the center of 5 terminals. Bridge jumper wires from this terminal to each of the 4 outlying terminals, which basically completes the circuit without resistors, carrying the HI injectors' 12-13 ohm load directly to the ECU just as a HI harness would.


Hope this helps.

[sickofpistons]

Or it could be timing, im new at this too.

[vex]

Really depends on a lot of factors here. When you swapped everything over did you keep the S5 injectors or did you go to the S4? They changed impedance if I remember correctly. If you kept the S5 (which it sounds like you did) you need to ensure you're not passing the injector harness through the resistor blocks. If that's not the case, and you've confirmed good compression on the engine, you may have just flooded it to hell. Pull the spark plug, pull the inj fuse from the engine bay fuse box, crank over with the gas pedal depressed for a few seconds. Ensure all excess fuel is out of the engine, maybe even leave it over night with the plugs out. Reinstall plugs, fuse, and crank over. If it kicks but doesn't stay idling there may be another issue.

[My5ABaby]

Describe what you mean when you say it won't start. It won't turn? Won't catch? Runs for a couple seconds and dies? Etc.

[diabolical1]

i'm with My5ABaby. can you better describe what the car does when you crank it? also, you said you confirmed fuel and spark, let me first ask where you confirmed your fuel? at the injectors?

Originally Posted by sickofpistons

I have not found an aftermarket source for oval injector clips.

KG Parts

[fcrotory]

Update:

Car starts everytime now. Idles kinda high. Now, when u slowly open Tb it will rev to redline. But, if u try to stab it, it Jus cuts out and backfires. I'm thinking it could be in limp mode. I'm using everything s5. Lim,uim,fuel injectors,front cover,mop,afm,tps,etc. NOTHING is s4. But the harness was butchered to crap. So I fixed everything with butt connectors that needed it. The car itself is a 91'. The block is a 87'. That's where I'm at now. Thanks for it guys help. Hopefully someone knows what's going on.

[vex]

I dare say you might have your primaries and secondary injector clips reversed.

[fcrotory]

I know the secondarys are not backwards. Primary, egh, it's kinda hard considering there length.

[NoDOHC]

I would look into the grounds on the harness. Make sure that the TPS is connected correctly and reading. Does the CEL flash at all?

[fcrotory]

I can check grounds. What about afm. If it was bad, could it cause the fuel cut? Cel is on, but not flashing. I should Prolly manually check codes but not to sure how to do it.

[sickofpistons]

Originally Posted by fcrotory

Update:

Car starts everytime now. Idles kinda high. Now, when u slowly open Tb it will rev to redline. But, if u try to stab it, it Jus cuts out and backfires. I'm thinking it could be in limp mode. I'm using everything s5. Lim,uim,fuel injectors,front cover,mop,afm,tps,etc. NOTHING is s4. But the harness was butchered to crap. So I fixed everything with butt connectors that needed it. The car itself is a 91'. The block is a 87'. That's where I'm at now. Thanks for it guys help. Hopefully someone knows what's going on.

What did you do to finally do to get it to start?
It could be in your harness or CPS timing, pull it back out and make sure your lined up.

I had the same problem with the cps, it was fine under 3200 but anything after that it stumbled and poped.

[vex]

Originally Posted by fcrotory

I know the secondarys are not backwards. Primary, egh, it's kinda hard considering there length.

I do not mean that you have the injector clips for the individual location reversed but may, point-in-fact, have the secondary injector clips hooked up to the primaries and the primaries hooked up to the secondaries. (Don't ask me how I know that could be a cause of those symptoms)

[sickofpistons]

Originally Posted by vex

I do not mean that you have the injector clips for the individual location reversed but may, point-in-fact, have the secondary injector clips hooked up to the primaries and the primaries hooked up to the secondaries. (Don't ask me how I know that could be a cause of those symptoms)

Dont the secondaries activate after i think 3200? If that was the case then the car shouldnt even start?

[vex]

Originally Posted by sickofpistons

Dont the secondaries activate after i think 3200? If that was the case then the car shouldnt even start?

But the 'primaries' (in the secondary location) are firing.

The issue comes to the fuel injection blending going on. When you floor gas the 'primaries' in the secondary location are unable to keep up with the air flow thus stalling out the engine. However you can creep up the RPM range if you don't floor it as the injection doesn't get 'out-flown'.