I posted this awhile back and got no response. Basically I tested nearly every pin on the ecu to try and track down my problem (car runs like **** basically). According to that, my intake air sensor, my AFM, and one of the three pins related to the trailing coil came up slightly out of spec. I've got two of everything (still can't find my coil in parts car) and I checked out the temp sensor first. they both read perfectly at 77degreesF and they are both off a good bit at 185 (but they both read exactly the same 6.5ohms while they should be 3.9-3.1) I suspect my thermometer i tested with is just off a bit and they're both good or else the readings wouldn't be so similar. The AFM tested out perfectly so I'll attribute it's error to old wiring but it should still be close enough to not cause problems. So now I need to find out what the different readings for the trailing coil mean. there are three: pins 1G, 1J, and 1V which are timing signal, select signal, and confirmation signal. apparently the first two are good and the third is off but I haven't got a clue what that means. Anyone able to shed any light on what could be wrong or what the difference in these three is?
Thanks,
Patrick

 

bump... someone has to know or at least have a suggestion... am i right in what i'm assuming and why are there three different readings for the trailing coil?

 

bump again

 

wut do u mean your car runs? more info on that plz

 

I know pretty much nothing about the topic you've posted about, but going by what I know regarding microprocessors, and computer communications I would suggest that the confirmation signal has to do with acknowledging that the the select signal was successfully received.

 

When posting about how your car is running, we need specific details. Does it lack power, does it idle poorly, does it lack power uphills, will it not go past a certain
speed,etc? All of our crystal ***** are on recall, lol. rx7doctor

 

Something is goofy about that series five Control Unit print out.

This is for a Series Four:

IGs-T.......is approx 4.4V switch to ON and approx 2.2 at IDLE (Select Signal)

IGT-T.......is 0V key to ON and approx 0.8V at IDLE (Ignition Timing Signal)

IGf-T.......is below 2V with the key to ON or at IDLE (Trailing)

There is an article at the FC3S site that addresses the ignition. I'll try to post that later.

Usually the trail ignition not even working won't be noticable. By the way, I don't understand the diff b/t the series four and five printouts.

EDIT: THIS.... http://www.teamfc3s.org/info/articles/demystifying.html

Or this from the article: Finally, the last trailing igniter signal to discuss is IgF. This is a feedback signal from the trailing igniter to the PCM. IgF is only produced when trailing primary #l fires. There must be actual primary firing!

It seems the IGf-T readouts b/t the series four and five are different ....for some reason. Typo???? Got me.

 

If I'm as interested in this tomorrow morning, I'll hook up my breakout box and take a look at my series four car and write back.

Tell me this: Just how much is the IGf-t ?????? That's pin V.

 

I get nothing with the key to ON and 1.3V with the engine idling. Series Four. IGf-T pin. If I put the meter on RPM I get 750rpm (meter has RPM 1 and RPM 2. RPM 2 is 1500rpm.) So my feedback for the trail coil is doing what the article says.

 

as for how the car runs... it won't idle well no matter what I do. I have replaced everything i can think to and tested nearly every sensor on the car. I have a new TPS set just right and the timing is set as well as I can get it. The car always seems to jump at idle over about a 300 rpm range constantly revving and backing off. It seems like a vacuum leak but I have searched and spent hours looking for one and have had no luck at all. As for the readings, here's what I got for each one:
Igt-T -- 0V at ign on and .75 at idle... should be 0 and ~.8
Igs-T -- ~5V at ign on and 2.2V at idle ... should be ~4.4 and ~2.2
Igf-T -- 1V at ign on and 1.1V at idle ... should be below 2V and ~4V

Thanks for that website, I definitely have a better understanding of the ignition system now, but I'm still having trouble figuring out what all this means and if it's contributing to the way my car runs.
Hailers - I'm not sure what you mean about your car doing what the article says... do you mean it's running badly or well based on the article? From those readings on igf-T (assuming s4 and s5 are the same) I'd say your car should be running badly since it's the same as mine, but since yours runs well maybe that's not my problem and it should run fine anyhow?
Patrick

 

My cars run Greatttttttttttttttt! I have no issues.....except I've seen better looking RX-7 in the wrecking yard (outter looks i.e. body).

For IGf-T....my readings are different than the series five but right for the series four. I don't understand why the series five would read different than the series four.

That article helps me understand things but I still get confused and have to return to it on occasion.

Hunting and pecking at idle. Just guessing. Could be a bad thing like one of the apex seals in one of the rotors is *weak*. Like if a compression test was done you'd have two fairly equal psi and the third weaker. Or the front rotor readings stronger by a lot over the rear rotor readings. Just a wild guess. Don't take it seriously.

Or I noticed once on my 86 n/a I had the two small hose crossed up. Talking about the three on the front of the trrottlel body. One big and two small ones below it. The two below were crossed up. That's a series four. A series five??? I suppose it has the same three vacuum hose.

Or maybe the *anti afterburn* valve in the ACV is leaking badly. The ACV isn't supposed to feed air into the intake, only the exaust ports. With one exception. The anti afterburn valve does feed into the intake upon deceleration, and only during deceleration. I've found the old ones leak a bit all the time....which means at idle also. I also found that instead of buying a new one I could remove the acv and plug the two holes that concern the anti afterburn valve with RTV and then reinstall the same valve with no noticable aftereffects

To test for that fault...remove the airpump hose b/t the air filter and the airpump. At idle spray starter fluid into the hose towards the airpump. If the idle reacts....then the antiafterburn valve is indeed leaking. There's no other explanation for the idle changing when doing that.

If you pull the plug on the trail coil assy and idle the car.....does the idle change? Stays the same, right? I don't think a trail coil problem is your problem. If the wires were crossed, yes it'd idle strange. Never done that myself. Just guessing. Done for now.

 

Also.................
look into the BAC valve, it is responsible for idle as well - there's a ohm check in the FSM, but do it with the engine warm!
I had a tough idle and the BAC multi-metered fine when cold, but when warm, it went out of spec, resistance climbed, computer couldn't cycle the valve properly, and idle suffered.

 

Dittos to slvr7

 

About BAC'S......Have you ever read this? http://www.teamfc3s.org/info/articles/idle.html

Forget about the title and the turbo talk. The bac work the same on either car. Just ignore all but the talk about the BAC. I did fix one of my cars by replacing the transistor in the ECU. Cost was about two bucks.

I don't know about the rest of the world, but I can take my bac off the engine, leave the connector on it....turn the key to just ON.....and look into the bac and see it vibrating. If it vibrates then that is a sign that it is good as far as the ECU goes. You might have to lift up on the tps to get it to vibrate. That's how I remember doing this several times in the past. If it vibrates, spray some carb cleaner into it and let it aggitate....dump that out and do it again several times. I don't recommend forcing the piston in either direction with a screwdriver etc. Sometimes you'll find one of the contacts in the plug that attaches to it is pushed back as described in the article. I had one of those also. Glued it in place. Don't ever short either wire to the other. POOF.

 

You got a vac leak or some other intrusion of unwanted air (which could be caused by a malfunction of a component such as the ACV as alluded to earlier), my guess... Took me two months to find mine. Turned out to be the block-off plate for the EGR valve, and only when she was hot (and mostly on bumps). Hailers gave me **** for not being able able to find it for so long, lol...