Sort of indepth ignition question

[CoBHC]

So after a couple years of my 87 turbo being in many pieces it's finally back together. I went to crank it Saturday morning and after a couple of silly ground problems I got it cranking.

The problem I'm having is a lack of spark.

The cps is sending G1 G2 and Ne signals to the ecm and the G- is a good ground. The ecm is not sending the IGdA IGdB or IGt to the igniter, and while testing the igniter with the 3v battery for momentary continuity to the coils, 2 of the 3 outs failed. Everything was working prior to disassembly and it has all just been sitting in bags and such for a while, so I'm having a hard time believing the ecm and igniter just up and went bad while they were sitting there.

Before I spend $750 on a new ECM and igniter I'm wondering if there are any special grounds specific to the ignition system or anything like that, as I would be much more inclined to believe my own lackadaisical approach at putting it back together is to blame.

If you need more information please just let me know, my buddy and I were troubleshooting all weekend and covered as much as we could.

 

[isnms]

Make sure you are testing the igniter properly:
http://www.supramania.com/forums/showthread.php?t=23689

I've got a spare that pass the TSRM test I could send you $50 shipped.

 

[CoBHC]

Wierd, I was doing the test as it is described in the manual, and came up with the same results you got. Same coil passed and the other two would fail.

Well I'm going to rule out the igniter for now and assume the problem is all in the ECM failing to send those IGdA IGdB and IGt signals.

If anyone knows a reason this could happen other than just the ECM being junk I would love to test it before I call it dead.

 

[isnms]

Then you were performing the test incorrectly, as I was.
I corrected my images to show you apply 3v trigger to:
pin 2 for IG2
pin 2&4 for IG1
pin 2&3 for IG3

Have you checked your codes?
http://www.cygnusx1.net/Supra/TechTips/engine_error_codes.aspx

 

[cjsupra90]

Hey, I remember that thread. Yeah the way that the TSRM has the test described, it is very confusing. Most likely your ignitor is good.

With out having a scope, its hard to test the IGdA, IGdB and IGt signals. Best bet would be to get another ECU and try it and see if the car starts. Are you hearing the Injectors fire (click)? Do you have the ground wire groups hooked up on the intake manifold?

 

[jetjock]

Interesting. Good post too. It'd be nice if everyone was as thorough.

I assume the ECU is powered at Batt, +B and +B1? Grounds at E1, E01, and E02? IGSW at +12 and M-Rel at ground? MIL on? Any codes?

Gs and NE need to be at least 1 volt p/p (referenced to G-) at the ECU terminals or the A/D converter will shrug them off. Cranking speed OK? CPS pickup resistance and air gaps OK? Pull it off the car and spin it hard by hand. If and when you get spark you can put it back in.

You can check IGt and IGdx during cranking using a cheap logic probe if you don't have a scope. Even an LED with a resistor if you have to. A volt meter should also show something at cranking speed. Use a 12 volt bulb or a test light to check igniter output to the coils.

 

[CoBHC]

Hey, I remember that thread. Yeah the way that the TSRM has the test described, it is very confusing. Most likely your ignitor is good.

With out having a scope, its hard to test the IGdA, IGdB and IGt signals. Best bet would be to get another ECU and try it and see if the car starts. Are you hearing the Injectors fire (click)? Do you have the ground wire groups hooked up on the intake manifold?

I'm borrowing a scope from an engineer friend Thursday and will be able to really test it at that point, what I'm going off of right now is just the frequency tester on my meter. Since it wasn't getting any reading at all I had to assume the ECU wasnt putting out the square wave to the igniter.

The injectors seem to be working fine at the moment.

As for the grounds on the intake, if someone could post a clear picture of the engine compartment and maybe circle the ground locations I would forever be indebted to you. Right now I just have about 5 ground straps going to random places on the body and motor.

 

[CoBHC]

Interesting. Good post too. It'd be nice if everyone was as thorough.

I assume the ECU is powered at Batt, +B and +B1? Grounds at E1, E01, and E02? IGSW at +12 and M-Rel at ground? MIL on? Any codes?

Gs and NE need to be at least 1 volt p/p (referenced to G-) at the ECU terminals or the A/D converter will shrug them off. Cranking speed OK? CPS pickup resistance and air gaps OK? Pull it off the car and spin it hard by hand. If and when you get spark you can put it back in.

You can check IGt and IGdx during cranking using a cheap logic probe if you don't have a scope. Even an LED with a resistor if you have to. A volt meter should also show something at cranking speed. Use a 12 volt bulb or a test light to check igniter output to the coils.

We tested every pin on the ecu that has to do with power and ground and they all tested out ok.

I'm not sure on the exact voltage of the G and NE outputs but Thursday I will make sure they are at least 1v. The battery was strong as far as cranking goes once I actually got the starter to work. All the tolerances on the CPS were within spec as well. I am going to take your advice and just pull it out and spin it by hand though, no reason to run down the battery.

The ignition system is pretty simple I was kind of hoping there was more involved so I could blame some unhooked connector, but the more I think about it, the more it seems my ECU just crapped out on me.

As I said though, I'll have an osilloscope on Thurs to really test the CPS output and the IGt and IGdA and B outputs.

Thanks for all the great help guys, it is much appreciated.

 

[cjsupra90]

Unless the ECU was dropped while out, I am thinking that you have something unhooked or a broken wire somewhere. I cant see something going bad while just sitting there in storage, but strange things do happen, I have an 88 turbo ecu sitting here that is locked at base timing. It will run fine just at what ever you set the base timing at and thats it.

Just to make life a little easier, dont even worry about the IGdA or B signals untill you have the IGt signal. Without IGt, IGdA and B are pointless. IGt is what controls the ign. event and the timing, IGdA and be just tell the ignitor which coil pack to fire.

 

[cjsupra90]

One other thing to not is that the G (1 & 2) and the NE outputs put out an A/C sinewave and the voltage will vary depending on the speed of the reluctor wheel.

 

[jetjock]

Timing belt gnomes

 

[CoBHC]

Unless the ECU was dropped while out, I am thinking that you have something unhooked or a broken wire somewhere. I cant see something going bad while just sitting there in storage, but strange things do happen, I have an 88 turbo ecu sitting here that is locked at base timing. It will run fine just at what ever you set the base timing at and thats it.

Just to make life a little easier, dont even worry about the IGdA or B signals untill you have the IGt signal. Without IGt, IGdA and B are pointless. IGt is what controls the ign. event and the timing, IGdA and be just tell the ignitor which coil pack to fire.

I may just have to aquire that ecu off you if things go poorly on Thurs. What problems would I run into having to use a set timing, and are there any compatability issues between an 87 and 88 ecu. Also the car is a 5 spd if that matters.