LOL and I need to learn how to use one and understand what it's telling you. I hate feeling stupid.

I know I was just stunned when I heard that, there was a huge pause and I just didn't know what to say after that. I went back the other day and looked at my invoice. That work was done 11-5-02. Total $1431.00.

And there is this little mice print that says: "The factory warranty consititutes all of the warranties with respect to the sale of this item/items. The seller hereby expressly disclaims all warranties either expressed or implied, including any implied warranty of merchantability or fitness for a particular purpose. Seller neither assumes nor authorizes any other person to assume for it any liability in connection with the sale of this item/items.

Nice huh. Service manager tells you, you get a lifetime warranty on the parts if it ever fails we will replace it. That doesn't cover the labor. Most people will go oh that's no problem as long as I now have a warranty. Of course they go through service managers like day old bread. I can't count the number of service managers there have been there since I've been going there over the years. Oh let's see what is that smiley say... oh yes

And you wonder why I was hesitant to go get that module from them. Full list I could have got two from Chris and still had change left over.

 

Damn. The downside of capitalism.

And I didn't like his constant claim of "Opti". That seems like someone who wants to sell a lot of crap and not fix it.

No wonder I do my own repairs...

I sure hope the ECU finally fixes this!

If the signals are getting hosed, it makes me think the ECU is freaking out. I assume you made sure the chip was seated completely???

 

There has to be something else wrong.

The yellow signal is the input from the ECM that triggers the ignition control module to generate the other/output signal.

With the LT1, the output signal cannot exist without the input signal -- that's because the LT1 has no way to generate the triggering pulse in the igntion control module like the LT5 does. The LT5 can determine a "fault" from the ECM and go into backup mode with a fixed timing advance -- the LT1 can't.

I agree with a previous post, check your grounds thoroughly -- especially, the one below the throttle body on the front and the ones on the left hand side behind the oil filter on the bell-housing.

Tom Piper

 

It would be interesting to see the oscilloscope waveforms for the new module that won't fire.

However, since the engine won't fire, you would be scoping at cranking speed of about 400 rpm.
(400rpm x 4 firings per rev) / 60 (convert from minutes to seconds) = 26 hertz for the frequency

At 26 hertz (cycles per second), this is a very low frequency and may require a "storage" scope to see the waveform -- these scopes aren't cheap.

Tom Piper

 

This may just confuse things more, but I think I should at least mention it.
During a conversation I had with Pete at Delteq (http://www.delteq.com/),
he told me during development of their system that they have seen '92 and possibly '93 ECMs that sometimes loose the ECM output signal to drive their system -- that is the same signal that is used to drive the ignition control module on the stock system. He has no explanation for it.

Tom Piper

 

This is saying the yellow trace (channel 1) is 5 volts per division and the amplitude is about one division, so it is about 5 volts peak-to-peak.

And, the blue trace (channel 2) is set at 50 volts per division.
So, if you forget looking at the spikes on the waveform, the square wave component is about 25 volts peak-to-peak, but the dampened oscillation high frequency component (ringing) takes the peak-to-peak amplitude to about 200 volts.

This all looks fairly normal to me.

When you connect the new ignition control module (the one that doesn't work), are you mounting it to the coil bracket or just plugging it in without mounting it?

Tom Piper

 

No I never opened the ECU up when I had it off, just checked the continuity for the wire coming from the ignition control module.

 

I will reverify the grounds. But the on near the throttle body, yes on monday that was the one I found loose (well loose in the sense that the moment I put a wrench to it to check it was loose) I removed the bolt and wire cleaned both and retightend. When I replaced the battery a few months ago I made sure the ground connection just beyond it at that location was good. I'll check the lower one on the engine too.

 

Did it both ways. With the first new module I had installed it expecting it to fire and be normal. While it was mounted Bogus had me just plug in the old one which it fired. Then when I got the second new one I fully expected it to work so it was mounted too, and the same thing also when the second one didn't work I just loosely plugged the old one and it fired. Yesterday while the old one is mounted back up, I did that so that I could run it the other night to duplicate and pull new set of codes, I just loosely plugged the second new one in like I did in reverse above. And it wouldn't fire.

So in all conditions except last night, the new ones were always installed.

 

One more thing I want to point out.

The width of the positive going pulse for the yellow trace is determining the "dwell" time of the coil. I actually expected a very short duration spike for this -- I was wrong. I thought the dwell time was determined in the ignition module.
The ignition "dwell" time is determined by the ECM with this yellow pulse width. This equates to the time the points are closed on an old "points" system.
Dwell is important and determines the intensity of the spark by making sure the coil has enough time to "saturate" -- usually, dwell time is more than sufficient at low rpm.
However, if the dwell time were very short, you could have a weak spark that would not ignite the mixture.
So, if you scope the new module (the module that doesn't fire) keep an eye on the pulse width from the ECM too and compare it to this graph.

Tom Piper

 

This has been suggested by others previously, but it is an easy check.

Just in case one of the capacitors in the tach filter decideds to break down and short out the output signal of the ignition control module, temporarily disconnect the tach filter from the coil.

If I remember correctly, there are two connectors on the ignition coil in a piggy-back fashion, both of them have a white wire in them.
One white wire in one connector is the output of the ignition control module to the coil.
The other white wire in the other connector is the wire to the tach filter.
The two white wires are actually connected together inside the ignition coil itself.
So, if you can determine which white wire goes to the tach filter, you can eject the pin for that wire from the connector to disconnect the tach filter from the circuit with a pin ejection tool that you can purchase at Pep-Boys.
After this is done, try one of the new ignition control modules again.
If it runs, your tach won't work and the ASR fault light will come on because they are driven through the tach filter which is no longer connected.

Tom Piper

 

That would be terminal A of the gray connector. There are two halves gray and black. The gray one is the passenger side of the connector assembly. Terminal B, the lower pin of that same connector half is the coil fuse/ign B+.

I'm waiting to determine when these parts will arrive.

 

If by chance you need a tach filter, I have one. It's got about 115k miles on it or so.

 

Just got home, and the new ECM, Ignition control module and coil were here.

Going to get started in a bit. Wish me luck!

 

 

 

Before I decided to start into this, I decided to take a closer look at the ICM connector and its wires. I did this because in the back of my head I keep hearing it has to be a ground issue. I removed the tape all the way back to the pigtail. Looking real carefully I noticed a blister on the C terminal wire (ground).

I checked the continuity again to several ground points from the connectors socket and by sticking the probe into this blister on the wire. I still got no ohms so it is showing good continuity but I sure don't like the looks of this.

Do you think maybe having this opening in the wire's casing could possible be a contribution to the problem?

The wire doesn't appear to be damaged inside. This is the best possible picture I could get. I used a 10x eye loop to look really close at this, sure be nice if I could take a picture through the eye loop. (This loop is one that I use for color proofing. Comes in handy sometimes for other uses.)


Lani

 

Opps forgot to ask, do you think that when things heat up this could be causing the problem.

Also, do you thing that wrapping each wire with electrical tape independently, then all four together would solve this issue?

 

yes. it is possible.

Get some 3M 130C tape. it's a high temp heat tape that won't shrink or melt.

 

You can use hight temp silicone on it.That one wire does not look that good.That is the ground right? Looks rusty from what I see.Use some electrical contact cleaner if you have it to clean your plugs.