Hissin need your help

[Methodical]

Hissin do you have detailed information about how the ignition system work from the moment you put the key in and turn to start the car. I need detailed information so that I can trace my no start problem. YOu may recall that my car won't start with the spout connected and using the stock ignition system but will start with the MSD system connected.

I tested a new computer and the computer is not the problem. So what I'm looking for is detailed descriptions, diagrams etc. of how all the ignition components, computer etc work to start the car once the key is inserted and turned (i.e. what sensors, relays etc that are involved) so that I can trace this problem.

If you have information or if anyone who reads this thread has any information, I'd appreciate it. I've researched and have not found anyone with this problem.

Thanks
Al

 

[Adam95GT]

he has all the ccrm info i know ****er is a wizzzard!

 

[HISSIN50]

Al, I'll post up what I can.

FWIW, I like your testing methods. With it only running in OEM form (no box) with the SPOUT out, that did suggest a bad EEC. With it running only SPOUT-out or on the box, that suggests a bad coil or resistive coil wiring.

I think I posted this before but the PIP generates a squarewave closed signal (it measures the rising and closing edge of the signal unless something goes wrong). The signal goes to the TFI, gets smoothed out, and thengoes to the EEC. The EEC modifies the signal for optimal timing and sends it back to the TFI (now it's called a SPOUT signal), which sends a ground-pulse to the coil. The duration of the pulse depends upon if the rising and falling edge (PIP signal) are both being observed (they normally are. This helps the coil last longer. Kinda like Desmodromic valves vs using valve springs to close a set of valves).

There is also a signal sent from the SPOUT wire between the TFI-and-coil to the EEC (this is the same wire that tells the OEM tach what RPM you're at). This allows the EEC to compare the actual SPOUT signal to what it thought it should be. If they don't match, an IDM code should generate. If it's off by a country mile, the car runs in FMEM, where it guesses at timing based only on the PIP.


I'd do some electrical testing on the chain.

Check coil resistances.

The dizzy body should ohm out at less than 2 ohms.

At TFI Pin 4, be sure you have cranking power reaching the TFI. One thought I had was that this was missing and the car would catch when on the box because of the multiple sparks.

TFI Pin 5 should be 1/3 to 2/3 of battery voltage while the car cranks or idles.

TFI pin 3 is run-power. Be sure it's full battery power.

TFI pin 2 is the coil output (ground pulse). This should flash a test light very very quickly even while cranking.

TFI Pin 1 is the ground. Look for less than 5 ohms resistance.

To test the PIP, you really need a 'scope. With the ig box connected, is everything with the ignition advance totally copacetic? Does the box get power itself from VPWR or did you use another power source? If you used another power source, something could be wrong with a leg of the VPWR circuit.

 

[Methodical]

...


I'd do some electrical testing on the chain.

Check coil resistances.

Coil is new

The dizzy body should ohm out at less than 2 ohms.

To make sure I understand you. The actual distributor body should be less than 2 ohms - am I understanding you correctly.

At TFI Pin 4, be sure you have cranking power reaching the TFI. One thought I had was that this was missing and the car would catch when on the box because of the multiple sparks.

When you say cranking power, do you mean at least 12v. Do I need to crank the engine while testing or just test for power?

TFI Pin 5 should be 1/3 to 2/3 of battery voltage while the car cranks or idles.

Will have to test this and report back

TFI pin 3 is run-power. Be sure it's full battery power.

Will have to test this and report back

TFI pin 2 is the coil output (ground pulse). This should flash a test light very very quickly even while cranking.

I tested this when the car wouldn't start back in January and discovered that the stator in the dist. was bad

TFI Pin 1 is the ground. Look for less than 5 ohms resistance.

To test the PIP, you really need a 'scope. With the ig box connected, is everything with the ignition advance totally copacetic? Does the box get power itself from VPWR or did you use another power source? If you used another power source, something could be wrong with a leg of the VPWR circuit.

Not sure what VPWR is - vehicle power. But the MSD is connected to the vehicle with the MSD harness, so no splicing was done.

Hissin I apologize for the late reply so much going on on the home front. I wish I could clone myself and send the clone to work so that I could get all the stuff done at home, including the 'Stang.

Thanks for the info.

 

[HISSIN50]

To make sure I understand you. The actual distributor body should be less than 2 ohms - am I understanding you correctly.

You got it. The dizzy achieves a groundpathway through the lower intake. Kinda like your starter and alternator.

When you say cranking power, do you mean at least 12v. Do I need to crank the engine while testing or just test for power?

Basically yeah. 12 volts or close to it (whatever your battery is at while cranking. A semi-dead battery can still crank down to 11 volts or so). Yeah, you'd need to have someone turn the engine over (or use a remote starter. IIRC you once installed one. ). You can disable the ignition (pull the electrical connector off the coil) if you want to. This makes it easier to see a test light or DMM.

This one is always important because the TFI obviously uses this pin to start the car. When it is not seeing battery power while cranking, the car will not start. For some folks who have had this happen, a dizzy box had enough 'drag or run-on' that as soon as the key was turned off from cranking to run, the car would fire up even though the starter was on the very verge of quitting.


I hear ya about being busy. Put me on the list of wanting a clone too. Good luck with it Al.

 

[Methodical]

... Does the box get power itself from VPWR or did you use another power source? If you used another power source, something could be wrong with a leg of the VPWR circuit.

Hey Hissin, I read and reread this statement and started thinking - Uhmmm. Then I began looking at the wiring diagram and PCM pinouts and started seeing VPWR. I said Hissin maybe on to something. I do have the MSD box power cable connected directly to the battery and that's why it starts with the MSD box So there's a good possiblity that there could be something wrong with the VPWR leg. I will began the electrical testing, hopefully, tonight. I have the repair manual on disk that I purchased on Ebay and did not realize that it had all of the PCM information on it. So now I have the step by step diagnostics to help guide me but may not spare the questions though.

But one ? for you Hissin. I kept seeing where the diagnostics require the hook up of a Break Out Box (BOB) to the PCM harness for tesing. From what I can tell BOB is used, well for various testing of course, but it seems to me to be also used to not damage the PCM pins. Tell me I don't need this BOB to do the diagnostics and can just possibly poke the insulation on the wires for testing purposes. Any exposed wire I will either tape or put silcone on it.

 

[HISSIN50]

A breakout box was pretty nice back in the day. For those that don't know, it went between the PCM wiring hafness and PCM and would intercept the I/O's and tell the user what the PCM was 'seeing'.
You definitely don't need one. They just really streamline diagnostics (in the same way viewing PIDs really saves time).

I do as you do with the piercing of wiring insulation. Aftermarket piercing meter leads can really help a lot . And the hole they make is so small that one almost need not bother sealing it.

 

[Methodical]

A breakout box was pretty nice back in the day. For those that don't know, it went between the PCM wiring hafness and PCM and would intercept the I/O's and tell the user what the PCM was 'seeing'.
You definitely don't need one. They just really streamline diagnostics (in the same way viewing PIDs really saves time).

I do as you do with the piercing of wiring insulation. Aftermarket piercing meter leads can really help a lot . And the hole they make is so small that one almost need not bother sealing it.

Cool. The journey begins tonight.

 

[Methodical]

Update: Did some testing last night but will do more. I tested for power but noticed that my batter was low (11.5v) so I had to recharge and will retest for proper voltage tonight or at least this weekend. But below are results test results. Tell me what you guys think.


Initial Standard Tests:<?***:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" /><O></O>
<O></O>
TPS (KOEO): 5.02 Vref
Spark at the plugs:
Stock system: no spark
MSD system: spark
Spark at the coil:
Stock system: spark
Pulse at the fuel injectors (noid light): yes
<O></O>
Coil voltage: 9.77v (measured between + coil jack and ignition ground jack (distributor harness). Note: battery voltage was at 11.5v during test. Recharged battery but not yet checked again.


Checked for PIP signal at ICM<O></O>
Stock system:
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SPOUT connected, placed test light on pin 6 while cranking. Result: no flash
SPOUT disconnected, placed test light on pin 6 wile cranking: Result: no flash. Remove test light while car is being cranked and car starts, touch pin 6 car dies. Will retest.
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Checked for signal at SPOUT<O></O>
Stock system:
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SPOUT connected, back probed both sides of SPOUT with test light connector while cranking. Result: no flash
SPOUT disconnected, back probed wire going to ICM (need to verify wire though) while cranking: Result: flash and car will starts. Note: I tested with and with out the coil connected out of curiosity
SPOUT disconnected, back probled wire going to PCM (need to verify) while cranking: Result: no flash and no start. Note: I tested with and with out the coil connected out of curiosity

 

[Methodical]

It's been a minute since I reported. I followed Jrichker's diagnostics steps and decided to try another distributor (still under warranty) but the problem still exist.

I haven't had the time to really put more time into the car but I plan to check out the ground wires next. What'ya think?