Cloud9...68

Tama,

I think the fact that I'm getting +12V at terminal 86 of the DME relay in the fuse box (the ignition switch terminal), and that the engine cranks normally when I turn the key, rules out the ignition switch. Also, I would think the problem is more likely caused by things that I touched during the course of the project, as opposed to things (like the DME module, the alarm module, ignition switch, DME relay, etc.) that I didn't. But then, who knows? Anything is possible.

Cloud9...68

Doc,

Unfortunately, at the moment, towing isn't really an option, since I don't have the front suspension on the car yet (waiting for the machine shop to drill out the spindles to accommodate the larger diameter ball joint pins of my Racers Edge A-arms), nor do I have tires yet.

Maybe I shouldn't be so quick to rule out the CPS. A guy on the 924/944/968 forum described a method to check it using a 3V diode placed across pins 48 and 49 of the DME connector as an alternative to an oscilloscope. If the diode illuminates while cranking the engine, it means the CPS is working and is gapped correctly.

I next plan to check the wiring of the 14-pin connector in the passenger side footwell one more time, and check for a signal at pin 7 of this connector, which somebody told me needs to be hot. If it isn't, I think it means the alarm has immobilized the DME, although I can't see anything in the wiring diagram that supports this, but it's simple enough to check. If these all check out, I'll buy some diodes and do the CPS test.

Also, I know someone who has a Durametric. Do you think this could help troubleshoot my problem? The concern I have is that if there's no signal coming out of the DME, will there be anything for a Durametric (or a Bosch Hammer, for that matter) to read?

Cloud9...68

Not sure if this adds anything useful, but I confirmed that the wiring of my 14-pin DME connector is now correct. So, I tried actually cranking the engine, just in case it now has spark, even though the fuel pump still isn't turning on (it doesn't), but I did notice that the tach needle now bounces nicely and normally, so my guess is that getting the DME connector wiring correct not only eliminated the various warning lights, it cured whatever was causing the tach needle to not bounce. Also, I think this completely rules out the CPS.

In addition, I confirmed that my throttle position sensor works correctly, and I confirmed that I'm getting +12V at pin 7 of the 14-pin connector, which somebody told me indicates the alarm is not shutting off the power to the DME, which, along with the +12V I'm seeing at terminal 86 of the DME relay, completely rules out the alarm as the culprit.

So, I've ruled out a lot of stuff, but still have a dead car.

tamathumper

That is useful - it's just as good to rule something decidedly OUT as it is to rule something potentially IN.

Cloud9...68

Not so sure about that. I think I'd much rather have a car that starts when I turn the key, but which has left me with a few lingering questions as to whether I had ruled out every possible reason it wouldn't start, than the lifeless lump I have taking up space in my garage. This is getting very old, very fast

MB968

Cloud I can't imagine how discouraging this must be for you. If I were you, I'd forget trying to jumper items, etc. I'd concentrate on getting all the parts to put the car back together. I suspect you can get a lot of loaner parts off the forums, as there are a lot of sympathetic owners out there. Once you put everything back in if it doesn't run the fuel pump when you turn on the key, you'll be able to concentrate on what the real issue is. Or if it does work, then you can start taking things off one at a time, doing the jumpers, and insuring it will start with each change. When you remove something and the jumpered fix doesn't work at least you will know what to focus on. When you tore it down, you made so many changes it is hard to know which way to turn. It may just be me, but the process I describe, for me would be a lot less discouraging, as I could at least feel like I was on a sure path.

Good luck
Joe

Cloud9...68

Thanks, Joe. It's true that I took several items off the car, namely:

- The passenger side air bag module
- The air bag control unit
- The cruise control module
- The windshield washer reservoir
- The stock headlights

But I'm really struggling with how any of these items could trigger my symptoms, which I can summarize as follows:

- Based on the fact that every sensor I can test without an oscilloscope, or without running the car, check out OK, and the input voltages to the DME are all good, I know that I'm getting power to the DME

- Based on the fact that the blink test doesn't work, and that there is no spark, or voltage at the terminals for the DME relay that trigger spark or fuel, there is no signal coming out of my DME.

And you're right, this is epically (to use modern vernacular) discouraging and frustrating.

MB968

Thing is, if you put it all back together and it still doesn't work, you can at least start down the right path. Right now you have sooo many variables making it almost impossible to identify the one that is the solution to the problem.

And, if putting it back together does work then you have a very deterministic way to solve the mystery.

Just trying to get you to step back from the problem and take a different prospective.

Eric_Oz_S2

Might have missed this, but when you checked an alternative DME was that with the incorrect wiring? Is there a chance that both your DMEs were connected with incorrect wiring so that 12V was applied to an incorrect terminal within the DME? (ie both DMEs are fried)

Cloud9...68

Eric,

Good thought, but I was very careful to make absolutely sure I had the wiring of the 14-pin DME connector correct before installing the spare DME. I've since double-checked the wiring, and have confirmed it's now correct. I take the fact that the warning lights that were previously on no longer are, and that my tach needle now bounces when I crank the engine, as evidence the wiring is correct.

Cloud9...68

A possible clue (or maybe not...) - a new piece of data, anyway. With the key in the start position, I checked to voltage at the terminals of the coil. To my surprise, I'm seeing +12V at both the (+) and the (-) coil terminals relative to ground. So, if I'm getting voltage to my coil, why aren't I getting spark?

So, I followed the procedure in Clark's Garage for testing the coil:

Ignition Coil Test
1. Disconnect the ignition coil output wire at the distributor cap.
2. Connect a spark plug to the end of the ignition coil output wire which you just disconnected.
3. Connect a ground wire to the threaded portion of the spark plug.
4. Disconnect the ignition coil ground wire from the negative terminal on the coil (Green Wire).
5. Connect one end of a ground wire to the ignition coil negative terminal.
6. Turn the ignition switch to the ON position.
7. Tap the other end of the ignition coil ground wire jumper on an good grounding point (for example the battery negative terminal) and look for sparks at the spark plug that correspond to the frequency of your tapping of the ground wire.
8. If you have a good spark at the spark plug, the ignition coil is good.
9. If you don't get a good spark, check for approximately 12 VDC from the coil positive terminal (black wire) to ground with the ignition switch in the ON position. You should also get approximately 12 VDC from the coil negative terminal (Green wire) to ground

I'm getting a spark, alright, but not at the spark plug - I get a healthy spark between the wire I have connected to the coil's ground terminal, and the ground on the car, when I tap the wire to this ground. So, I measured the resistance between the two coil terminals, and got the prescribed 0.4 ohms or so, and also between the coil output terminal and the coil ground terminal, and got about 6K ohms, which is right in the center of the prescribed range. I called my local Advance Auto, but they say they can't test a coil (at least not reliably).

So, does any of this mean anything? I wish I understood the current pathway in this car. In other words, where is the +12V at the coil coming from? The DME? Or straight from the battery through the ignition switch?

Eric_Oz_S2

The ignition coil feed comes from the DME terminal 1. This is connected to pin 1 on the 14 pin plug (the one in the engine bay). The DME applies 12v to terminal 1 computed using the ignition maps and flywheel sensor.

This might be a dumb question, but are you sure the distributor rotor is correctly orientated?

Cloud9...68

Eric,

Thanks for the quick reply, and for the information. So, this is the first indication I've seen so far that something is actually coming out of my DME, which I interpret as a good thing, and as confirmation that there's nothing wrong with the DME itself. By the way, how do you know this? Is it described in the manual? If so, could you point me to where, because I'd like to learn a lot more about this stuff.

And there are no dumb questions here. If it's possible to put something in backwards, I'm guaranteed to find it. But I thought the rotor only goes on one way. Also, should I check to see if there is anything coming out of the coil before tracing possible problems with the distributor and/or rotor? On much older cars, I've taken the coil output wire and placed it near a ground and looked for a spark while an assistant cranked the engine, but I'm leery on trying that on a more modern, microprocessor-controlled engine. Is it safe to test for output from the coil this way? Or is there a better way you (or anybody else) could recommend? Thanks.

MB968

I don't know the DME, but knowing a little bit about modern microprocessor based systems, I can't see how you'd create any issue with doing the coil wire to ground spark test.

The info below is out of my TECgt ECU manual. I know that most of it isn't pertinent, but may give some food for thought. It does refer to the spark test like you mention having done on older cars. I know that I did this test on my Mazda once when having issues. Watching for a spark across two coil towers would be equivalent to placing the coil output wire near a ground as you mentioned above. The led test is similar to the one you've been told how to do.

_____________________________
M.2.c. Spark-Related Starting Problems
• The crank sensor is the first thing to check when an engine will not start.
o Crank the engine. The LED on the TECgt ECU should flash red-green-red-green in a fairly steady fashion (see Section A.4). If the light is not functioning in this manner during cranking, and there is no RPM reading when viewed on a laptop, there is likely a trigger problem.
�� Check the crank sensor alignment and air gap with the trigger wheel.
�� Check the crank sensor resistance (should be between 600 and 700 ohms across the red and black wires).
o If the LED is functioning normally, check for spark at the coils. Remove the two spark plug wires from the coils, and watch for a spark between the coil towers during cranking. BE EXTREMELY CAREFUL NOT TO TOUCH THE SPARK!! It will really be painful, and can be deadly to people with pacemakers!
�� If there is no spark, check the wiring to the DFU and to the TECgt. Pin D on the DFU should have +12volts with the ignition key on.
�� If the wiring is good, and the coils are still not firing, look to the software. Make sure the appropriate calibration file is loaded.
�� If there is spark across the coil towers, but the engine will not run, check the plugs and plug wires. Also be sure that the coils are firing the appropriate cylinders (see Section C.3.)! An engine will not run (or will run very rough) if the plug wires are not going to the appropriate cylinders.

Eric_Oz_S2

The wiring diagram for the engine shows the dme pin connections and what they are wired to, so it is simply a matter of tracing the links. Terminal 15 on the coil is connected to terminal 15 (ignition on). Terminal 1 is the trigger from the DME terminal 1. Terminal 4 is the HT lead to rotor. You may have power at terminal 15, but terminal 1 is the signal from the DME to switch on the coil. So the DME may still be the issue. If the crank position sensor is disconnected the DME will not energise terminal 1.

On the s2 you can put the rotor on 3 different ways. The correct position at tdc for cylinder 1 is about 11 o'clock.

I wouldn't see an issue with grounding the ht from the coil, but I don't see the point as it is unlikely the rotor or cap itself is the problem. There are some guidelines in the manual about this (24/28-3). Just be careful!!! You don't want to zap yourself!

If you crank the engine and there is no spark to the plug when grounded then the issue is likely to be the DME terminal 1 is not firing a signal.