My bad, my bad. You are right about what I said. There is no way these two plugs can be switched.

I checked continuity between the ECU and the plugs, when unplugged from the injectors. Warm engine.
Front - 3X; rang out - settled around 1.1ohm
Rear - 3Z; rang out - settled around 0.9ohm

 

Continuity has nothing to do w/the engine temp as you are measuring the segment of a wire to see if it is at least partially intact. W/that being said, w/o going through this maze of posts did you state one of the secondary plugs was loose? In addition did you try driving the car w/the TPS unplugged?

 

Sorry about that too. Just haven't had much time to actually try and diagnose the problem. I'm usually pretty busy. I think I have it figured out now, and I appreciate your patience, satch.

Yes, the rear plug's clasp is broken, so it doesn't snap into place, it just slides on. However I do not believe that to be related with my confirmed front secondary code, 71. The front plug is intact.

I have not tried to drive the car without the TPS.

 

So, how do you have it figured out?

 

I meant I thought I had figured out the test. I will try my best to report back tonight with results from driving without the TPS plugged in.

I'm guessing that if there is no change in the driveability of the car after unplugging the TPS, that is most likely the culprit. As I said before I got one for free from a friend of mine that I can try out and see if it works.

 

it should rev fine if the tps is the issue but i doubt it is since it is RPM dependent but the TPS can cause all sort of strange issues.

basically 6500-ish is where the primary injectors simply run out of steam on their own, so i suspect it is solely a secondary injector problem.

 

Regardless of the codes you are getting you need to repair the damaged secondary plug and go from there instead of trying to solve possible multiple problems at the same time.

 

I messed with it today some when I did the tests, and I had no problem on a 30 minute brisk drive to the city. I unplugged the TPS and drove like that the first 5 miles and there was only a slight increase in responsiveness and it didn't backfire as much.

Do you guys know if other Mazdas use the same injector plugs as the 7? I don't ever see RX7s of any generation in my Pick n Pull. Like I said though, I have a spare tps I can test out but not inj plugs.

Tomorrow I'm going to try and find some plugs and see about swapping the primary wires for secondaries and running her.

 

Do a search and there are new injector plugs you can easily find.

 

Also, I want to correct myself based on Ben's comment. I did initially say this hesitation was 6500+, which it is, and I do still hit a wall there, but now, it's much more random. I get it before secondary transition sometimes. I'm gonna find some plugs on here.

 

A new plug is cheap. Just find where to source them from posts made by other members on this board. It's been mentioned time after time. Just use the advanced search feature.

And at what rpm are you having the problem at besides 6500?

 

Well, it's not exactly specific. Sometimes it bucks when I blip the throttle to put it in gear from a stop which is like 2k-3k. Sometimes it does it around the secondary transition, sometimes ~4500. If it is in the mood to hesitate, range of the hesitation is random, but it always hits the wall at 6500.

These past couple times I've driven it, knock on wood, it hasn't done it. I can tell if it will or not because sometimes, it will idle lower and a little rough. That's when it hesitates. When it doesn't hesitate, it idles smoothly and around 850. That is when it will pull to redline all night like last night. It even pulled nicely when I drove it with the TPS disconnected.

 

KGParts.com - KGParts Fuel Systems

5th from the bottom.

a few cars from the late 80's and early 90's use the same clips such as the MKIII supra and the FD3S.

 

Thanks, Karack. I really appreciate it. Hell I even looked on ebay. I'll have some of those en route soon and I'll let you guys know how it goes together.

In the meantime, on wednesday I am going to run the car on just the secondaries and report results for that too.

 

Also, might I ask, my trailing coil might be suspect as well. Is it possible that the trailing coil is the problem if it arcs sometimes? Every now and then on a cold start, I won't get tach for 15 minutes or so and it'll pop on. I feel like it won't make a difference since it doesn't drive any different, but I still wonder and want to touch all bases.

 

You can't just run the secondaries unless you switch the primary pins w/the secondary pins at the ECU. If you don't do this then the 'only' injectors which work below 3800 rpm would be the primary injectors. You might want to switch out the plug wires w/the lead coil so you can try to isolate the arcing problem at the trailing coil and if it's arcing as you say then of course it could cause operating problems.

 

I'm aware of the test method. I figured you knew what I was talking about.

Will the trailing wires be too short to reach the leading coil when I switch them?

An FC friend of mine has a 90 GXL and had the same problem. Fixed his with a TPS. I'll have to put on my spare and see if it's any good.

 

I thought R.E. mentioned the switch was done at the ECU thus the reason to depin those specific wires.

 

No no, the trailing plug wires that you were talking about, satch. Did you mean switch the trailing plug wires for the leading as well as repinning the secondary wires in the ECU into the primary spots? I'm just going to tape off the primary injector wires like Karack said.

 

ohm test the ignition wires to test their resistance, check the boots and wires themselves for tears in the silicone and replace any with rips or tears. also check the spark plugs, a fouled spark plug will also cause the trailing ignition to stall and the tach reading to drop out. swap the plugs to see if the faulty ignition follows the plug, replace it/them if it does

trailing ignition wouldn't cause the major lack of power issue in the top end though. a fouled leading plug would.


at this point in time i would recommend checking the ignition, replace severely worn plugs/wires, make sure everything is firing and the tach issue is fixed. then replace the TPS with your spare, check it and make sure it sweeps cleanly with no spikes or dips in ohms/voltage. if all else fails swap those injector wires, with the ECU exposed it takes about 5 minutes.

on the left 26 pin ECU connector, on the far left are the injector wires:
primary 1- light green 3W
primary 2- light green/black 3Y

secondary 1- light green/white 3X
secondary 2- light green/red 3Z

Y/W are on the top row (primary)
Z/X are on the bottom row (secondary)

move Z/X to the top row and tape up Y/W that you took out. attempt to start the engine and see if it runs normally or has a much different tone to it, as if running on one rotor and a severe lack of power below 3500RPMs. if it runs much differently than normal, disconnect one secondary clip and alternate and see if the engine shuts off.

 

Will do. I haven't replaced the plugs or wires since the rebuild almost 11k ago now. I have removed the plugs once recently and cleaned them with a nylon brush wheel. Worked great and made it a little better. I'll be able to do them friday.

 

I swapped the rear spark plugs for the front yesterday, drove to Panama City today with some hiccup. The Lucas booster and full tank of 93 nonethanol had no effect this time, so I ordered plugs and wires together [platinum plugs, and all for like $50 shipped!] which should be here wednesday. The wires were on the car when I bought it so they are of unknown age.

I have a SUPER busy schedule the next three weeks, but I plan to do the injector wire test tomorrow after work. Will report back.

 

The wires were bad. New plugs and wires and she's noticeably better, but still just a little hiccuppy. I haven't checked to see if the 71 is gone. I will check that in the morning and actually do Karack's test tomorrow. I'm actually going to have a few days off.

Trailing coil definitely arcs though. No tach almost all the way home from work last night.

 

Replacing the plugs and wires made the code 71 go away. It doesn't hesitate hard or at all throughout the range.

My tach still goes out though, and it still burps holding a constant speed. Good idea to replace the trailing coils and ignitor?

 

Couldn't hurt.