My '87 TII has purple top injectors, they are supposedly the stock injectors and are new within the last year probably, with only a few thousand miles on them. Trouble is, the FAQ shows tan top injectors for the '87, as well as being low impedance versus high impedance for the purple tops. Now, the ones on there work fine, so I guess the ones I swap in need to show up as high impedance to the ecu one way or another. I bought a pair of 720cc injectors, I think they're Denso, and they have a light tan or you could say off white color. I measured the resistance of a couple purple tops and tan tops and the purples both gave 2.3 Ohms and tans both gave 2.6 Ohms, is that sufficient enough to know that they're both high or low impedance or does the resistance change significantly under load?

btw I'll be installing an Rtek 1.7 to compensate for these bigger secondaries, and while I realize I would need an upgraded fuel pump in order to hit higher boost, I should be fine on the stocker while running stock boost, or even up to 8 psi, shouldn't I?

 

quick searchy searchy

Year Engine Plug Size Colour Part #
84-85 13B NA, low square center, 680cc, orange, 195500-0900
86-87 13B NA, low square center, 460cc, red, 195500-1350
86-87 13B Turbo, low square center, 550cc, tan, 195500-1370
88 13B NA, high square offset, 460cc, purple, 195500-1350
88 13B Turbo, high square offset, 550cc, purple, 195500-1370
89-91 13B NA, high oval center, 460cc, red, 195500-2010
89-91 13B Turbo, high oval center, 550cc, purple, 195500-2020



Square corner plugs = low imp.
Round corner plugs = high imp

Off-center plugs = High impedance
On-center plugs = Low impedance.

But really:

Use an ohmmeter to measure accross the two terminals. 1-3 ohms = low impedance, around 10 or higher = high.


and at least rewire the stock fuel pump if your gonna keep it for a while.

 

i just reread your post and now I don't know if what i posted even helps. You already read the FAQ and this is what is causing the confusuin in your case. Okay. i see your dilema now.

I can say that my '87 TII had the purple tops injectors in it when I bought it but I am pretty sure we went with low impedance for some reason... I'm getting really confused now, let me look through some of my old threads real quick.

For some reason I'm thinking that some of the later TII from '87 got the purple plugs. I'll be back.

but both the injectors you have, that measure 2.3 Ohms and 2.6 Ohms, they are both low impedance injectors. If the low impedance were working for you before the new should work as well.

Do you have the resistors on your fuel injectors harness?

 

they are both low impedance...the high impedance would measure around 12 ohms i believe. they should work (with supporting mods)

 

right, they're both low impedance but why are we finding purple injectors in the '87's? Did they use both for a while?

Trying to answer than one, I stumbled across this thread a while ago which i think makes it even less clear.

I am confused why my TII from Feb. '87 has low impedance injectors but i can't notice the resistor pack.

 

Did someone wire in resistors into your engine harness, near the ECU?

 

I don't see any resistors wired in, but that doesn't mean they aren't there. However, I went ahead and tried the 720s and they work fine with the Rtek 1.7 (except for a terrible 3800 RPM stumble that only shows up sometimes, I'll have to try a couple more things for that). At the same time I swapped injectors I was cleaning up all the old major grounds and applying dielectric grease, and that hasn't solved my slow turning speed, the stumble is now worse, and I still can't pass 6500 RPM under load... This really blows... dirty ignition switch??? I also read that adding a ground to the boost sensor might help the stumble.

Anyway, about the injectors, what's even more confusing is that a few different injectors listed in the FAQ have the same part numbers. Different color, but same part number. Hm... I've brought it up before and I think somehow it works out, but it does serve to confuse those of us who don't know the intimate details of our vehicle's past. I have figured though, in my case, that the PO wanted it left in the stock configuration and the people before that just treated it as a machine to get them from point A to point B, very carelessly, so I haven't found any prior modifications thus far.

 

I take part of that back, it has been turning over faster, but not real consistently...

 

You do realize that they now have an Rtek 1.7 with a 3800 stumble fix right? check out their website

 

yeah I heard about that last week. I've been busy with other stuff, but I will probably send it in soon if it can be done under $30.

 

The FAQ about injectors is .....lacking. It ain't right. Mid 1987 the injectors changed from low to high impedence. There's a chassis number involved with the change in mid 1987.

The lows should have a solenod resistor package attached to the harness below the AFM/AIRBOX area. Bolted to the chassis.

The correct resistance in the harness for the low injectors is 6ohms, as stated on the side of the stock resistors in the package.

Colors???? Believe what you will. That might apply to Nippon Denso stock injectors, but NOT aftermarket replacement injectors. If the numbers like 195500-1370 are embossed on the side of the injector, then that's Nippon Denso. No number embosssed....could be an aftermarket injector whos color has no meaning.

 

In the following thread, RETED has a post that lists the 1986-1987.5 impedence and then the 1987.5- and on impedence. https://www.rx7club.com/forum/showth...=highimpedence

 

someone ought to throw those into the FAQ then. thanks, Hailers

 

I had to do a lot of research when I bought my 87 GXL T II swap, with the s4 it had tan top injectors that where low impedance there should be resistor pack that is bolted to the frame by the air flow meter probably hidden by your air filter box. its kind of a 4" long by 1/2" wide thing covered in an aluminum heat shield it should have 4 or 6 wires coming from it I don't remember for sure how many though but if you look at your injector clip is the little aligning pin in the center bottom? if it is then they are low impedance and require a resistor pack now if you cant find the resistor pack then unplug the engine harness at the ecu and read the resistance from the ecu plug if it is in the high impedance range then you're good I believe all the second gen 7's ecu's only work with high impedance.

starting on page 32 is an ecu pin-out page 34 has the actual ecu connector pic.
http://www.rotaryheads.com/PDF/2nd_g...tems_turbo.pdf

 

Ok so this makes sense now.

My TII, made in February of 1987, had these injectors in it when I acquired it:




They are low impedance:


I replaced them with 4 of these Venom 720cc:


Is this the resistor? It's been temporarily relocated in this pic:

 

Yes. That's it. The solenoid resistor package with the aluminium cover.

The injectors (purple ones) look like aftermarket injectors similar to ones I've bought in the past. They're Purple and flow around 140-145 cc a minute....turbo figures. I *THINK* they're Beck-Arnley if memory serves. An example of why I said earlier that color isn't the key because they might be aftermarket injectors and not Nip Denso.

Those Beck-Arnley ones cost about fifty bucks apiece.

The solenoid resistor package has five wires going in it. One is a power wire (black/yellow on the harness side of the plug) and one each of the other four go to a fuel injector to power the injector. Take the aluminium cover off and you'll see the resistors with *2X6ohms* written on the side of each of the resistors.

 

Wow, those purple tops are so virgin, I've never seen such vibrant purple color like that before!


-Ted

 

140 cc's per 15 seconds, not per minute. Slight mistake. Purple 550's.

Purple LOW resistance injectors with the keyway in the MIDDLE, not offset. Scew going by colors.

 

Makes good sense. The injectors were supposed to be newer, as in not from '87, 550's but I wanted to go with the 720's and the Rtek 2.0. I'm gonna post for sale thread in the parts section if anyone needs some nice 550's.

Thanks for all of the great info guys. I like being "in the know" when it comes to my RX7 and this has cleared up some confusion. I knew enough to buy low impedance replacements but didn't quite understand why as it was an 87.

So much potential on RX7Club. I Love this place. Thanks again.