that one guy300

well i found out my trailing coil is not firing at all............ well, before going out and buying a new coil, i checked the wiring going to the coil, i have power from the relay..., but none of the other wires show any voltage at all which would be in the 4 terminal connector on the trailing coil, i went to the pcm and checked voltage there, 2 have power and 1 does not, no pulsing at all, looking at the connector, the wires U and M have power, but the wire X does not.... and of course the fourth wire goes to the tach... which has no power going out and the tach doesn't work, is anyone familiar with the 87 gxl ignition system.... what controls the trailing coil... i know the computer does, but what components are used to control the coil? and what are the voltage values that are supposed to be found in this 4 prong connector?

HAILERS

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

that one guy300

does this mean that really the only thing that majorly controls the coils is the distributer?.... which really isn't considered a distributer.... but yeah..? this post you sent me to opposes another persons post... sayin the trailing coil is only used in emissions, someone else told me this trailing coil not firing could be the cause of my 3800 rpm cut out... or hesitation, which it was their problem on their car, once they replaced the T coil and the pickup coil it was fixed, i looked inside my pickup, all teeth are strait and look like brand new....? my T coil doesn't fire whatso ever, like i said, no power getting to the coil from the pcm, no pulsing nothing.... the T coil does have power from the main relay.... but the 4 terminal connector has nothing to it, when i was probing the pcm connectors, i did get a voltage, but im not exactly sure those were the correct wires, ( i forgot to get wire colors along with place in connector, i just got the connector veiw, and said these were it) but i am in the process of doing so, i was also going to attempt to ohm out the wires from end to end.... should work, and if my memory serves right, 0 ohms should be between these 2 points, or very little resistance.... also as i read this post, i thought to myself, would a rotary still run if the timing was 180 out?

HAILERS

If the hesitation at 3800rpm was a trail coil problem..............wouldn't a person kinda notice the tach isn't working???? Tach being dependent on the trail coil working is what I mean.

If the ECU pinouts for 1M, 1U, 1X are to the book (Control Unit, Fuel and Emissions section) and the bullet connector near the trail coil assy isn't accidently put to gnd (yellow/blue wire I think) then maybe try another trail coil assy. Junk yard item. Twenty bucks or so.

Trail and lead coil assys have to be bolted to the frame with at least one of their attach bolts because the ignitor in them gets its gnd from the bond b/t the coil assy and chassis. Not likely your problem.

The wires for the trail and lead coils are checked out with all electrical plugs attached and backprobing the wires AT the ECUs large plug. Key to ON, engine off and engine on both.

I seriously doubt the CAS is bad or any of its wires unless someone has been messing with it. I've never had a CAS problem..........so nobody else should have a problem with the CAS (HAILER reasoning at work).

When viewing a elec plug dwg, your looking into the wire side of the plug and it's labled from right to left in a up/down fashion. See jpg attached.

that one guy300

okay, so are you saying if i am not getting the correct voltages from the ecu, then its a bad ecu? btw... none of my idiot lights come on when i turn the key to the on position, just the parking brake light if the e brake is on..... could this be a clue to a bad ecu? i know in some other vehicles if the lights flicker or anything its a bad ecu... i dont know about these enough... i do have another ecu but it makes the vehicle run at high rpm all the time, still with the same problems as before.

that one guy300

i have checked these pin at the ECU... KOER
1X supposed to be .8V, is at about .002-.010V
1M supposed to have less than 2V, has 12V going to it
1U seems to have the correct voltage
1X and 1M are not correct....

that one guy300

my alternator is not charging either... i dont think that would keep the coils from firing

misterstyx69

iTrader: (142)

the ECU needs at least 10 volts to operate the car.any less than that your car wil Run Like ***...and eventually just Die.(no charging,running off the battery until the battery goes below 10 volts).

HAILERS

EDITED

I've seen the tach on my car(s) not work a couple of times. Both times had something to do with low volage.

As in the car needed to be jumpered off to start 'em. Tach still did not work while driving, but I coasted.....turned engine off, then key ON and dumped the clutch. Tach and trail coils now worked again.

I thought the low voltage caused a fail safe conditon that turned off the Trail coils during low voltage, but I can't prove that.

that one guy300

i am atleast getting 12.5 volts at the battery... it stays there all the time, even while running

that one guy300

soo... does anyone have any advice? i have made it to the computer... so now its either a sensor reading improperly, or the computer is messed up? anyone?, i was thinking about checking the pickup coil for its voltage... the fsm says the wires comming into the computer should all be under 1V, since circuits 1N 1P are for G and 1Q 1T are for Ne, i figured it would be easy... are these the correct wires...? i get a little shakey when im working with sensor wiring

HAILERS

Engine off. Pull the large plug off the ECU. Ohm out the N to P and then the Q to T circuits with the CAS connector on the CAS. It should ohm out to the figure given in the ENGINE ELECTRICAL section of the FSM. Something like 200 ohms. See book for real figure. Your ohming out the two coils in the CAS and the wiring inbetween when doing that.

If memory serves, the CAS is creating a voltage when turning and inputs that to the ECU, not the ECU inputting a voltage to the CAS.

I doubt the LEAD coil *** would even work if the CAS was bad and those circuits were open. Your LEAD coil assy works and it's just your trail that does not work. Just an opinion. Like depin one of those wires mentioned above and try to start the engine. I bet it Ain't a gonna happen., Just an opinion. Never done it myself.

EDIT: The jpg attached from the ENGINE ELECTRICAL seciton of the FSM shows the CAS being ohm'd out from the CAS plug. It's better to do it from the ECU large plug. The resistance should be virtually the same and when you do it from the ECU plug you also checking out the wiring from the ECU to the CAS for contiunity.

that one guy300

i checked the resistance of the cas, and seems to be in spec.... 163.4 ohms and 161.7 ohms.... but i still have no signal for the trailing coil to fire.... it is getting the select signal just not the firing signal.... i am thinking its the computer, anyone else see something i might be missing? anything else that might cause the coil to not fire?

HAILERS

Edited for poor content. Deleted my remarks here is what I mean.

Back........if the wiring is good from the trail coil assy and the ECU, then most likely the ignitor for the trail coil is kaput imho. You've one trigger signal for two coils and that trigger is sent to one coil or the other by the transistors in the ignitor either seeing a zero volt select signal or a five volt select signal.

The ignitors electrical guts get THEIR gnd from the body of the assy being bolted to the frame of the car. If it's sitting on a pile of rags or foam the ignitors in the lead or trail coil assy won't fire/work. Just FYI.

I'd try another used trail coil assy myself. Twenty bucks at the wrecker and no more.

HAILERS

Sometimes I wonder. I wonder IF a meter was backprobed to the Select signal wire, and the key was put to ON, and you slowly rotated the engine by hand, would the meter at some point show five volts? and if the motor was rotated by hand again, would the voltage at some point go or show zero volts? I guess I'll just wonder on that one.

that one guy300

but i am not getting the correct voltage that should be comming out of the ecu to the igniter on pin M i have 12 volts there, which should be under 2 volts.... on pin X i have .002-.010 volts there, it should be .8 volts, on pin U i have close to 2.2 volts, which is where its supposed to be.... these are all while the car is running (KOER)
(reminder: my alternator is not working, that is why it says 12 volts at this wire instead of 14.4 or whatever the voltage should be)
i am getting battery voltage while it should only have under 2 volts!? this cant be right, and this comming strait out of the ecu.... i never knew that ecus used 12 volts, i thought they controlled stuff with 5volts or less? i am confused on this one, i know it was the corect wire, exact color, exact location... what is up on this one? tomarrow ill ohm it out and make definite sure that it is the exact wire , same with the other pin. i am also very poor lol, and i dont have enough money to be goin out and buyin parts that might fix the problem or not.

HAILERS

Pull the plug off the ECU and read 1M with the key to ON. What do you get?

This morning I backprobed 1U with a meter, and put the key to ON. The connected a spare CAS to the harness. Turned the bottom gear on the CAS to rotate it . The voltage on 1U changed from (memory) 4.3 v to 0 as I turned the CAS.

With the sparkplug wires AT the coils pulled out and just laying at the front of each bore in the coil, one coil would fire when the meter read zero and then the other would fire when the meter came back up to 4.5v as I turned the CAS. More or less proves the ECU is putting out the Select signal to the ignitor.

I'll go play with 1M for a while now.

HAILERS

Engine off, Key ON and backprobing 1M shows 0.99vdc.

Engine idling, key on of course, backprobing 1M shows 1.26vdc.

Key ON, engine OFF, plug off the ECU, 1M shows no voltage at the plugs blue/red wire in 1M. Well a tiny .03vdc which equals zip.

If you pull the plug off the ECU, and backprobe the blue/red wire in 1M, with key ON, and see anything like 12vdc, replace the coil assy.

There is one other thought. NEAR the trail coil is that single wire bullet connector with a yellow/blue wire in it. That wire should not be connected to anything at all, EVER (almost never anyway). Go look and see if that bullet connector is connected to SOMETHING.

You know what bullet connector I'm talking about?

Also check the color of 1M in your ECU's plug. Should be blue/red. The sixth pin on top from the far left of the plug. Maybe got in the wrong socket???????

that one guy300

at pin M with (koeo) key on engine off, the meter reads 12 volts , on pin U i have 4.4 volts , on pin x it reads 0 , all these koeo.... i am not familiar with a bullet connector... is it basically a connector used for just one wire? i am probing the correct wires, i triple checked lol. what does pin M do? is it a feedback to the pcm saying if the coil is working or not? i am kinda concerned about pin X also... it is low... while running atleast, i just dont know what sensor controls these wires. pins X and M which the way you said it, makes it seem like M is a self check thing, making sure the coil is firing properly? if it is sending power back to the ecu.... pin X i have no clue... im guessing a signal telling crank position? wait a sec...if i have power at the coil, and only a select signal.... shouldn't that make the coil fire no matter what?, unless of course the coil is bad? but then why would they need 3 wires to run the coil ( not including the power wires and tach?), <--- i guess im thinking to myself out loud..... i am going to go check to see if i can find that single wire "bullet connector" just hangin out around that coil. EDIT: p.s. i found that bullet connector, and it is not plugged into anything

BTW.... HAILERS, thank you soo much for helping me this much... i couldn't have any better help. w/o ya i'd probably be stuck with a giant repair bill.

HAILERS

If M has 12v on it with key On and the plug off the ECU, then the ignitor inside the trail coil assy is shot to heck. You should not be seeing any voltage on M.

As for what M does in life, see the second jpg attached. See the small *F* I underlined in Blue? That F stands for feedback. See the article I attached earlier for what the F, T and S signals do. I really don't understand exactly why there has to be a feedback signal on the trail coil assy. The article says it only exists IF the trailiing primary coil 1 fires.

X is the timing signal according to the article I attached earlier in this thread. See attachment below. When there is a T signal sent to the ignitor one of the trail coils gets fired. Which one depends on the S (select) signal going TO five volts or going to zero volts. See article. T also exists on the lead coil assy but no S (select) signal is required 'cause there's only one coil there.

A bullet connector is a single wire connector. Some say it's shaped like a ....bullet. The one I'm talking about has a yellow/blue wire in it and should be connected to NOTHING. That wire is also spliced to 1X inside the harness. This bullet connector is near the trail coil. Probably under it somewhere. I don't remember but a handful of bullet connectors on this car. Only three that I can think of. One at each coil assy and one on top of the radiator that is connected to the low water level sensor.

HAILERS

Sorry, the post above was written before I read all you wrote in the post above that one.

You may have a select signal, but the coils won't fire unless there is also the T (timing) signal to go with it. Gotta have both. And it seems you need to have a F (feedback) signal also for reasons unknown to me.

Lead coil just has one T (timing) signal and no F (feedback) or S (select) signals since both lead coils fire at the same moment, unlike the trail coils which fire seperatley.

I don't know anything about coils and ignitors other than what is in that article, and hope it's accurate.

NZCONVERTIBLE posted the Training Manual for early RX a few years ago. It only has the information in the attached jpg as to how the coils/ignitors work. There's not much there to work with other than seeing two transistors to control firing in the Trail ignitor and one transistor for the lead coil assy.

HAILERS

Again, your engine sounds healthy. Have you ever taken a timing light to that engine with the engine fully warmed up?

Have you ever seen the threads on this site where the intercooler has been removed and replaced by some cheap PVC piping from HomeDepot? Gives you room to work on the throttle body and see the throttle body without the intercooler being in the way. With the intercooler removed and the engine hot, you should be able to look at the throttle stop screw and see if there is a gap b/t it and the linkage. Do a Search for PVC pipe on this site. Or PVC and use the name NZCONVERTIBLE.

that one guy300

my car is a gxl it doesn't have an intercooler, and no i dont have a timing light

HAILERS

Sorry 'bout the intercooler remark. Not paying attention.

Go to AutoZone or some like place and RENT a timing light or maybe buy a CHEAP one. One with none of the fancy features. Just a straight ole timing light that does nothing more than flash on and off rapidly when clamped to a Lead sparkplug wire.

And aim it at the marks on the pulley/fixed pin. With a hot engine the first mark to come around should be opposite the fixed pin. IF not, then unbolt the nut/bolt that holds the CAS down and turn it one way or the other til the marks on the pulley and the fixed pin are opposite each other. Then tighten the bolt down that holds the CAS in place. Done

Something like the jpg attached.

Like I say, the engine sounds pretty good to me on the video.

that one guy300

i dont think i ever made a video of it....