Can i use a low/high-imp injector combination?

[Justen]

So after my rebuild, i put my stock injectors back in when installing the motor again. But I ordered a pair of bosch 1600cc low-imp monsters to replace my secondaries, haven't put them in yet though. I'd like to install them before i go in for a tune.

What I'm asking is for someone to confirm that i do have stock high-imp injectors in my 90' Turbo II. The stock ones are Denso 550cc reds.

...And is it possible to use high-imp primaries but low-imp secondaries in the same car?

If anyone knows where i can find a write up of how to solder in the resistors, that would be awesome. Thanks.

[Phoenix7]

1990 Turbo injectors are high impedance because the electrical system is high impedance.

Someone will correct me but as I understand, running low impedance injectors in a high impedance system will overheat and kill them.

http://www.rotaryresurrection.com/2ndgen/tech_injector_info.html
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. It 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.

[RETed]

Yes, all Kouki FC's run high impedence fuel injectors.

Throwing the low impedence fuel injectors into an originally high impedence set-up will fry the stock ECU.

Installing resistors is the standard thing to do.

What bothers me more is...
Are you trying to do this with the stock ECU???


-Ted

[RotaryProphet]

The problem is, even with resistors on the low impedance injectors, you'll have two high impedance injectors that open at the correct rate (about 1ms before the start of fuel flow @ 13v), and two high impedance injectors (thanks to the resistor) that open more slowly (about 1.4-1.8ms @ 13v, depending on the brand.) If both injectors acted like that, you could tune around it by increasing the injector open time in the ECU, but you'll probably have some trouble tuning the transition from your primary to secondary injectors; bringing them in earlier to compensate for the fact that a 1.5ms pulsewidth is giving you basically no fuel.

It's definitely doable in a mainly street driven car, but it wouldn't surprise me to see some hesitation in there at the boost threshold.

[djmtsu]

The stock ones are Denso 550cc reds.


I thought the stock high impedance 550's are purple?

Mine are.

[Justen]

My mistake, they are 550 purples.

I don't think i will put the low imp injectors in untill i get a standalone anyway, because i hear 1600s will most likely dump to much fuel into the motor when they actaully kick on, especially with the higher fuel press of a Walbro.

...But this lag in the injector cycle that you mentioned, wouldnt it be compensated for when i have the standalone tuned?

If worse comes to worse i could try to find low imp primaries and solder in resistors for all four injector leads.

Suggestions?

[Phoenix7]

yes, like RETed brought up....if you're on the stock TII ECU then stick with 550s otherwise the car will not run or run craptastically. You can't control 1600s with the stock ECU or piggy-back.

[RotaryProphet]

...But this lag in the injector cycle that you mentioned, wouldnt it be compensated for when i have the standalone tuned?

If worse comes to worse i could try to find low imp primaries and solder in resistors for all four injector leads.

Suggestions?

If you have a standalone that allows separate injector characteristics for different injector banks, then yes, that would solve the issue. Actually in that case, the ECU probably supports low impedance on one bank and high on another, so you wouldn't have any issue at all. Problem is, I'm unaware off the top of my head of any standalone ECU that does support that setup, save perhaps a Megasquirt, which has two totally separate injector driver circuits, and the software to tell it to use pulsewidth modulation and load clamping on the low impedance injectors, and full 12v on the high impedance side.

As for putting in low impedance injectors for primaries and using resistors all around, if you go standalone, just let them all be low impedance; just so long as you're not mixing, you'll be fine on almost any standalone. The only time you'd need to do that is if you're staying with the stock ECU.

[dudemaaan]

In the FD's the most popular ecu to run is the pfc which only supports high impedance injectors. The options we use around this are either resistors, or the FJO injector driver box, this converts the signal to use the injectors as they were designed as peak and hold. More fuel is available by using the injectors as peak and hold. The bosch 1680's are 5.1 ohm which just barely exceeds the pfc injector driver circuits, many people get away with no resistors, or as low as a 1 ohm resistor is considered within the driver's limits. I personally use 4 ohm resistors because that's what came with my injectors.

The pfc can also be used on 2nd gen rx7s by using an adapter harness. You can't run larger injectors on the stock computer without it running like crap, and you can't change the impedance of the injectors or it will run like crap and you risk burning up the injector drivers. You need a standalone computer and then you can mix and match and tune it out.

[RETed]

The problem is, even with resistors on the low impedance injectors, you'll have two high impedance injectors that open at the correct rate (about 1ms before the start of fuel flow @ 13v), and two high impedance injectors (thanks to the resistor) that open more slowly (about 1.4-1.8ms @ 13v, depending on the brand.) If both injectors acted like that, you could tune around it by increasing the injector open time in the ECU, but you'll probably have some trouble tuning the transition from your primary to secondary injectors; bringing them in earlier to compensate for the fact that a 1.5ms pulsewidth is giving you basically no fuel.

This point is moot.
The stock fuel delivery with the stock ECU always runs on the rich side.
Running slightly lean due to the increased dead time of the fuel injectors is not going to noticably change the way the engine is running.


-Ted

[RETed]

I thought the stock high impedance 550's are purple?

Mine are.

Something is wrong.
Purple tops are low impedence.
Purple tops should also be rectangular plug.

Red tops are high impedence.

These color combinations are for stock FC injectors only.

The only purple top, high impedence fuel injectors I know of are 850, side-feed injectors that FD's run as secondaries.


-Ted

[RETed]

My mistake, they are 550 purples.
If they are 550's purple, then they are low impedence.
Do you have the fuel injectors resistor "box" located in the engine bar right behind the passenger side headlight?


...But this lag in the injector cycle that you mentioned, wouldnt it be compensated for when i have the standalone tuned?
Ignore all of that.
It really doesn't apply to you.


If worse comes to worse i could try to find low imp primaries and solder in resistors for all four injector leads.

Suggestions?
As you have already said, dropping 1600's without proper control is going to lead to a badly running engine.
Basically, once you go into boost, the engine will flood with no much fuel that the engine will conk out on you.
Don't bother worrying about such things until you get everything sorted out properly.


-Ted

[RETed]

Problem is, I'm unaware off the top of my head of any standalone ECU that does support that setup, save perhaps a Megasquirt, which has two totally separate injector driver circuits, and the software to tell it to use pulsewidth modulation and load clamping on the low impedance injectors, and full 12v on the high impedance side.

Haltech's could do this from day one.
Previous models can handle up to a 1A current draw through each fuel injector channel.
If you wanted, you could mix and match high and low impedence to your hearts content, but I would not recomment doing that with each "bank" on a staged set-up.

Current Haltech models can control up to a 2A current draw, as some "high performance, motorsports" fuel injectors now ohm out down to 0.5-ohms.

Haltech's could always run low impedence fuel injectors on one bank and high impedence fuel injectors on the other without fuss.
No need for resistors...
No need for outboard impedence circuits or driver boxes...


-Ted

[RotaryProphet]

Haltech's could always run low impedence fuel injectors on one bank and high impedence fuel injectors on the other without fuss.
No need for resistors...
No need for outboard impedence circuits or driver boxes...


-Ted

Well, there you go, Haltech can do it, too. I've never tuned one, but it's still nice to know.

[djmtsu]

Something is wrong.
Purple tops are low impedence.
Purple tops should also be rectangular plug.

Red tops are high impedence.

These color combinations are for stock FC injectors only.

The only purple top, high impedence fuel injectors I know of are 850, side-feed injectors that FD's run as secondaries.


-Ted

O RLY?

89-91 13B Turbo, high oval center, 550cc, purple, Denso# 195500-2020

[FerociousP]

my s5 TII Ovals are purple... both sets...

[Justen]

I think a pfc is what i'm going for. From what i understand, Banzai Racing carries the adapter harness and map sensor that will let me use the FD pfc in an S5... and they'll install resistors into the harness for low-imp injectors for a little extra.



The options we use around this are either resistors, or the FJO injector driver box, this converts the signal to use the injectors as they were designed as peak and hold. More fuel is available by using the injectors as peak and hold.

If I understand this correctly, an injector driver box/module will work better than individual resistors? Only the box will convert the injectors to peak and hold? Or will the individual resistors also convert them?

[Justen]

and the stock injectors are most definately high-impedence.
...550cc Denso 195500-2020 Purple, oval connect.

[dudemaaan]

I think a pfc is what i'm going for. From what i understand, Banzai Racing carries the adapter harness and map sensor that will let me use the FD pfc in an S5... and they'll install resistors into the harness for low-imp injectors for a little extra.

The pfc is a good choice, you should get the datalogit also. I can't imagine using a pfc without the datalogit. You will also be able to use the fast reacting air temp sensor. See the thread in my signature.(Here) (http://rotarycarclub.com/rotary_forum/showthread.php?t=8381) The open element IATs allows much more precise tuning and a more accurate air temp table. If you do decide to go with the improved IATs you might see if Banzai will install a bosch connector on the IAT harness. The sensor uses the same connector as aftermarket bosch injectors so it shouldn't be a big deal for them to do. Or you could install it yourself, it's simple enough.


If I understand this correctly, an injector driver box/module will work better than individual resistors? Only the box will convert the injectors to peak and hold? Or will the individual resistors also convert them?

The injector driver works better then the resistors. The resistors only protect the driver circuit. It doesn't convert the signal, they also make the reaction time of the injector slower, which is why you should use the smallest resistor you can get away with. 1 ohm for bosch 1680's is probably ideal.

The injector driver minimizes injector "on time" and allows for faster response. This gives more control over the injector and allows for lower duty cycles and easier transition tuning.

In reality most hesitations caused by large secondaries with resistors can be tuned out. If you don't mind spending extra money on the driver box, and want the extra response then by all means go with the driver box. It's not worth the extra money for me though.

[Justen]

Ok great. Thanks for all the info and opinions, i appreciate it.

That IAT sensor is definately something i'll have to invest in.

So i looked up the Datalogit. Is this software easier to use / commonly used in tune shops? It seems like theres no need to pay extra for the hand held pfc commander if i have the datalogit software, and its not like i'll be tuning the car myself anyway... I know this is probaly a question for the Engine Management Sect but i figured i'd ask you (dudemaaan), since you know what youre talking about.

Anyone else run this setup?

[djmtsu]

Kevin Landers (Rotary Resurrection) is running a PFC with the Banzai adapter and a GT35.


Oh, and he is making over 400hp, with A/C and PS.

[Justen]

Oh, and he is making over 400hp, with A/C and PS.

Well thats very good to hear, haha

[dudemaaan]

Yeah that setup is probably the most popular standalone setup for rx7s. Most rotary tuners would prefer to tune using the datalogit over the commander since you can hook a laptop to it. It also allows you to log a wideband o2 and several other inputs which makes tuning on the street possible. If you ever had a desire to tune yourself this is the way to go. Pretty much all i use the commander for is a gauge. So yeah the datalogit is way easier to tune with.

[Justen]

ok great. thanks for everything guys. Got a lot of great info. I appreciate it

[RETed]

O RLY?

89-91 13B Turbo, high oval center, 550cc, purple, Denso# 195500-2020

my s5 TII Ovals are purple... both sets...

and the stock injectors are most definately high-impedence.
...550cc Denso 195500-2020 Purple, oval connect.


*sigh*

I've had this beef with Kevin Landers before, and he still hasn't changed his chart.
I assume you guys are talking about this?
•• 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

Taken from: http://www.rotaryresurrection.com/2ndgen/tech_injector_info.html

Welp, if you're going to blindly follow what he said, you're all wrong.

What he calls: "•• 86-87 13BT low square center 550cc tan 195500-1370" is actually supposed to be PURPLE.
Brand new fuel injectors are PURPLE and turn to tan due to heat and age.

What he calls: "•• 88 13BT high square offset 550cc purple 195500-1370" is actually supposed to be RED.
Brand new fuel injectors are RED and turn pink due to heat and age.

And finally...
What he calls: "•• 89-91 13BT high oval center 550cc purple 195500-2020" is actually supposed to be RED.
Brand new fuel injectors are REd and turn pink due to heat and age.

...or are you guys color blind?

Show me some pics of these PURPLE high-impedance 550's with the oval connectors?
I've never seen such a beast in my life after working on five Kouki FC turbos...


-Ted

[dudemaaan]

Theres an easy way to find out if the injectors are low or high impedance. Just hook a multimeter up and check the resistance. (ohms) High impedance is usually around 12 ohms and low impedance is usually under 5 ohms.

This won't tell you the size though. But generally high impedance is 550cc and under the exception being FD secondaries which are 850, or bored out secondaries which can be 1200 and 1300cc.

I did find this chart. Not sure how accurate it is but Here (http://www.robietherobot.com/storm/fuelinjectorguide.htm)

I removed all the other car types and put only the information for RX-7's.
http://i10.photobucket.com/albums/a145/dudemaaan/untitled-1.jpg

Based on the post above mine I made another chart. So basically just look at the color and take a guess on what you want it to be haha.
http://i10.photobucket.com/albums/a145/dudemaaan/untitled1-1.jpg

[djmtsu]

Its OK, you can never convince Ted he is wrong. He is happy in his own little rotary world.

I took the info I posted above straight from the 2nd Gen FAQ on the 7club.

Examples, pics under the UIM (which I JUST took) of my S5 TII in the garage:

My flash makes it look hot pink, but I assure its purple.

http://lh5.ggpht.com/_OFjbTkyhkOs/Ss0P-bQGEnI/AAAAAAAABjE/AnNcYC1b5Ok/s400/DSC01234.JPG

And another that was removed from an S5 TII parts engine.

http://lh3.ggpht.com/_OFjbTkyhkOs/Ss0P_D0xiJI/AAAAAAAABjI/8FEbajPJaTc/s400/DSC01237.JPG

[dudemaaan]

So are those 550 cc injectors then? 195500-2020?

[djmtsu]

Correct.

At work, I can:

1) get up
2) walk out door into warehouse
3) walk 45 feet to a rack
4) pull box out of bin
5) open box and remove a PURPLE Denso 195500-2020
6) go back to desk and correct REted

:D

Also, companies like Standard Motor Products, GB Manufacturing, and Beck/Arnley all sell Mazda part# N370-13-250 remanufactured. They are all purple.

[RETed]

Your "hot pink" looks like "red" to me.
I can only dig up one 1988 "red" injector so far - too lazy to take a pic, but I will get to it.

Here's the pic I took years ago when I was up in CZ.
Pic from hIGGItrix:

Far right - 1988 FC turbo, "red", high-impedence, rectangle plug, offset key
Second from right - 1987 FC turbo, early, "purple", low-impedance, rectangle plug, center key
(If you're wondering what the two left injectors are, they are non-turbo, 460's with slightly different colored "orange" tops.)
http://rx7cz.net/photos/workshop47/IMG_2382.JPG

The purple is light, but it's definitely purple.
It does turn "tan" with heat and age.
All the (Zenki) FC turbos I've worked on had these types of injectors.
The half dozen of Kouki FC turbo's I've worked on only had "red" injectors (with the oval plugs).
I've never seen purple ones on Kouki FC turbo's.
So call me liar all you want - I stand by my statements as I've seen through my eyes and experience.

You're right about the pic you posted - that one is obviously purple.


-Ted

[atsronnyats]

any one know of a good source to buy new connector for these injectors?

or good vehicles to pull from?...i heard dsm carried these same style at one point....there again they are denso.

only ask because my connectors are broken,brittle not reliable. have found a good write up on the subject thought id ask

will any of these work---- http://www.bmotorsports.com/shop/index.php/cPath/109_175

[Trout2]

Another option I didn't see mentioned and the best approach in my opinion is Injector Dynamic, high impedence 725, 1000 and 2200 cc injectors.

Jack