Difficult Ignition Cutout Problem

[chromguy]

From some quick reading and looking at wire diagrams:
It looks like the LM gets power directly from the PM. The LM actually controls the ASD which supplies power to fuel pump, coil, injectors, and portions of the PM. If the ASD was turning off, fuel pressure would drop. That is why I would have a fuel gauge hooked up while driving.

Since you are losing the Tach... Either the HEP signal is dropping out, or the LM is completely shutting off. If the cluster was losing signal from the LM, the car would still run fine when the Tach drops out, so that is not the case. It sounds like the HEP circuit is pretty rock solid at this point after your repairs. I would backprobe the power feed
wires at the LM and see if I am losing 12v at any time when it cuts out. If so, trace those circuits back to the PM. If you are not losing 12v, backprobe all the LM grounds while driving and you should see 0v. If you see 12v on any ground, then you are losing the ground.

This reminds me....To check for 12V battery power you could use you scanner to clear codes. If code 12 pops up them you have a battery 12V power issue. I also need to do this as my csx never clears code 12.

[cordes]

I added another ground today. There is now a direct ground from the intake manifold at the fuel rail to the firewall. That does not seem to have helped any.

Here are today's screenshots from the testing.


This is the info regarding my 8v output. Seems pretty normal.


Here is the ignition voltage, Z1 voltage (power to injectors), the 8v power feed, and the O2 signal. Again, seems pretty normal.


If I really zoom in, I can see where there is a lot of noise when the coil fires. I'm assuming that's normal? It causes the scope to read some pretty crazy peak to peak numbers on things like the 8v feed. That also makes it to where I'm not sure how to trigger the scope when it's a falling voltage which I will assume will happen during cutout.

Any ideas on the triggering would be appreciated.

[jpcturbo]

I added another ground today. There is now a direct ground from the intake manifold at the fuel rail to the firewall. That does not seem to have helped any.

Take that grounding point on the fuel rail and run a line directly to the battery negative. Also ensure the head ground on the trans side is in good shape.

[cordes]

Take that grounding point on the fuel rail and run a line directly to the battery negative. Also ensure the head ground on the trans side is in good shape.

I've done that with the battery negative, and it didn't seem to help at all. I have a 6ga Tefzel wire running from the head to the battery negative.

I did just order up a new O2 sensor, as that's one of the few things I haven't replaced yet. This is really something, as I have so little actually hooked up, (just the bare minimum to run the car for the most part). I don't think that the speed sensor is hooked up, but I'll actually check that, as I haven't looked at it in so long.

[cordes]

Well, I double checked, and the SDS isn't hooked up. I removed the pigtail piece which is meant to adapt the odd 87 style intermediate plug to the later style connector. That made no difference.


I logged the ignition volts vs. Z1 circuit power vs. inj on signal vs. inj control signal. It's a neat pattern, but it didn't really tell me anything.

I'm not sure if, or how I can record this thing. Perhaps a screen capture program? I know it can output a table file with all of the values, but that hardly seems like it would be useful, unless I'm missing something.

Also, am I actually wanting to look at the Y7 circuit which is labeled Fuel Injector Sync Signal? I suppose I could lose the Z1 or Ign signals and have all three injector signals on there?

[cordes]

This one isn't very interesting. Does anyone know what the ASD relay output should look like? It's not a lot of millivolts, but it does seem to correlate to everything else while I'm driving along at higher RPM.

[Shadow]

Is the ASD relay just a separate replaceable relay for the LM based cars? Can’t remember if it was separate or integrated into the power module

[cordes]

Is the ASD relay just a separate replaceable relay for the LM based cars? Can’t remember if it was separate or integrated into the power module

It is integrated into the module. I've tried three different PMs all with the same result. At this point, I'm thinking it's got to be the O2 sensor, or perhaps the TPS. Those are about the only things I haven't changed.

I think I'm going to take this thing to SDAC regardless of where it's at by that time. I figure it would be easy for someone else to see something I'm probably missing. Get that fixed in about 5 minutes, and we'll be good to go!

[Aries_Turbo]

what circuit is the o2 heater on? so if it has an intermittent short to ground it could cut things out power wise.

Brian

[chromguy]

what circuit is the o2 heater on? so if it has an intermittent short to ground it could cut things out power wise.

Brian

J2 - "key on"

[c2xejk]

This one isn't very interesting. Does anyone know what the ASD relay output should look like? It's not a lot of millivolts, but it does seem to correlate to everything else while I'm driving along at higher RPM.

I would assume that the ASD control line is a low side switched signal. Thus 200mV would be a turn on of the control side of the relay. (ie. current would be flowing toward the ECU.) 12v is supplied by other means

On trying to catch a falling edge, the scope should have a trigger configuration menu to allow you to set the edge and level. Note that for the ASD control line you would be looking for a rising edge for turn-off. When the ECU turns off the ASD voltage will rise

On the output, if it outputs a table, you should be able to import it into excel and graph the results...

[chromguy]

I would assume that the ASD control line is a low side switched signal.

Correct

[cordes]

I would assume that the ASD control line is a low side switched signal. Thus 200mV would be a turn on of the control side of the relay. (ie. current would be flowing toward the ECU.) 12v is supplied by other means

On trying to catch a falling edge, the scope should have a trigger configuration menu to allow you to set the edge and level. Note that for the ASD control line you would be looking for a rising edge for turn-off. When the ECU turns off the ASD voltage will rise

On the output, if it outputs a table, you should be able to import it into excel and graph the results...

Correct

Thanks guys. I should hopefully be able to use this info for some better tests and ways to display the data. I've been reading up on the trigger modes, and I'm wondering if the pulse setting might be the way to go. It should hopefully ignore the noise from the ignition system if I get it set correctly.

[chromguy]

Thanks guys. I should hopefully be able to use this info for some better tests and ways to display the data. I've been reading up on the trigger modes, and I'm wondering if the pulse setting might be the way to go. It should hopefully ignore the noise from the ignition system if I get it set correctly.

Which scope do you have?

[cordes]

I picked up a Hantek 6074BE. The price was right...

[RattFink]

I picked up a Hantek 6074BE. The price was right...

The more I think about this,

I think you should just hook up the clamp to the coil wire. Have that as your only input. Make it take up the whole screen so you can see it really big. Drive. I think you will be able to determine what is going on by watching secondary ignition. You could use a screen recording program to record it if you want.

[cordes]

Alright. Today I replaced the TPS, O2, and coil (also removed the terribly rusty resistor thing) and none made a change. I did test in between each thing I did to make sure that it kept running with problems each time.

Perhaps I should begin removing things which are unneeded from the LM connectors? For example, I'm thinking that there is no reason why cruise control stuff should be a variable.

I'm about at my wit's end with this thing. I thought I was last summer, but now I'm really straining my sanity. At some point in life we all have to move on...

[cordes]

OK, after having no good results with the previous tests, I went for the ignition waveform only thing on the scope. I'm really confused now, as I had the positive and negative on the coil hooked up the way I did on the last coil. However, my waveforms looked upside down, which I've read is indicative of having the coil hooked up backward. I reversed the wires going to the coil, and now it works. For the record, the wire that had continuity with the Z1 terminal at the injectors is now hooked up to the "negative" on the coil, and the other wire, which I think is the J5 wire from the PM is now the "positive" on the coil. I'm not sure if that's how it should be, or if the coils is labeled backwards. This is all very confusing to me.

Anyway, here are a couple from when the coil was hooked up the first way:



Here are the captures from the second way:



I'll be hating this car if anyone needs me.

[cordes]

Here is the ignition vs tach output to the cluster. I think having the scope ready to go, or at least hooked up is the key to getting this thing running flawlessly.

I just made a 6ga wire to use as an alternator ground. I'm disconnecting the 2ga wire from the alt case to the battery as it has been suggested to me that it could be causing a ground loop.

[cordes]

For posterity, the different alternator ground made no difference.




I'll order an amp clamp for my scope tonight. I guess it's possible that I have a bad injector or something. Sorry for making this thread more of a step by step, but I want this down so I and others can follow what I'm doing.

ETA: I have now eliminated all wiring not necessary for the car to run with the exception of the tach.

I'm going to look at how grounding systems are designed and what is ideal. I might as well eliminate that potential problem.