EFI no spark

Pedestrian · Apr 28, 2010

Ok, throwing this one to the experts.
Installed an 89 A9L computer and harness from an 89 Mustang into an early Bronco. I have no spark. There is power 12V to the coil, but no PIP signal. Have replace the pickup coil in the Distributor, replaced the TFI module, installed a known good coil.
According to the literature I have been reading, I should be able to eliminate the ECM from the equation by disconnecting the SPOUT connector. Still no spark.
I should also be able to mimic PIP by probing the PIP wire with a test light. Still no spark.
The Engine harness is unmolested so all connections in the spark circuit should be intact.
I am looking for any input

Viperwolf1 · Apr 28, 2010

No pip out is the key. Sometimes it's hard to see it with a digital voltmeter. You can use a 12v test light and should be able to see if the pulses are there. Make sure you have 12V on pin 4 with the key on, pin 6 needs to be grounded, and make sure pin 5 is not grounded.

Also make sure the rotor is actually turning with the engine.

Pedestrian · Apr 28, 2010

Pin 4 5 and six on the TFI? or on the ECM?

Viperwolf1 · Apr 28, 2010

Pedestrian said:
Pin 4 5 and six on the TFI? or on the ECM?

On the TFI.

Pedestrian · Apr 28, 2010

If I am not mistaken, pin 16 is ignition ground. Should this be a constant ground? or is it a ground signal to trigger the spark?
The PIP wire goes directly to the ECM. What exactly triggers the spark, and can it be triggered manually?

70_Steve · Apr 28, 2010

This help?

Pedestrian · Apr 28, 2010

Thanks Steve, you have a PM from Bill

Pedestrian · Apr 28, 2010

Ok, I can trigger spark manually with a test light. Coil good
I can also trigger the fuel pump by rotating the distributor. Stator signal good
I can not trigger spark by rotating the distributor. TFI??? it is a new TFI
All wiring to ECM passes continuity test.
I am down to either a bad, new TFI. Or a bad ECM. Although I should get spark without the ECM in the loop????

needabronco · Apr 28, 2010

Just for giggles, try a another eec. That's the 2nd tfi your on I have a hard time believing that you'd have 2 bad? I know autozone can test a tfi module to verify if they are in fact bad.

Viperwolf1 · Apr 28, 2010

I think you need to narrow it down a little more before buying expensive parts. I do believe you need the ECM to get spark. Does the ECM power up at all? If it does you should hear the fuel pump for 2 sec when the key is turned on. If it doesn't troubleshoot the ECM power.

yjzonie · Apr 28, 2010

The ECM does in fact power up the fuel pump as well as the injectors. The check engine light works as well. All power and grounds from the ECM check out good..Still no spark at ignition.

yjzonie · Apr 28, 2010

needabronco said:
Just for giggles, try a another eec. That's the 2nd tfi your on I have a hard time believing that you'd have 2 bad? I know autozone can test a tfi module to verify if they are in fact bad.

To much money just to though one on, not knowing if it is the ECM or not...

67EB_in_619 · Apr 28, 2010

As I understand it, the TFI provides the ground (TFI pin 5) to coil that completes the circuit for spark... the same wire that goes to EEC pin 4 thru the resistor as pictured above.

Can you put a noid light (or similar) on a fuel injector plug and see if it lights up when the dizzy rotates? If so, then I would say the dizzy know it is spinning and the EEC knows too. That is how I would test a dizzy/TFI.

Pedestrian · Apr 28, 2010

The injectors fire, the fuel pump fires when cranked. Everything powers up and works except spark.
Note the spark I am getting when triggered manually is pretty weak. It won't jump a gap, but will shock me ;D I know this isn't a scientific test, but good spark should make me not want to volunteer to hold the coil for a second test.

67EB_in_619 · Apr 28, 2010

Ok.. then I vote for:
"Borrow a known good EEC and dizzy setup and test swaps!"

yjzonie · Apr 28, 2010

Pedestrian and I are working on the same truck and it is mine....It is baffling us all to hell...everything is there but the blasted spark from the coil??????

Viperwolf1 · Apr 28, 2010

Pedestrian said:
The injectors fire, the fuel pump fires when cranked. Everything powers up and works except spark.
Note the spark I am getting when triggered manually is pretty weak. It won't jump a gap, but will shock me ;D I know this isn't a scientific test, but good spark should make me not want to volunteer to hold the coil for a second test.

Can you test the coil with an ohmmeter? 0.3 to 1.0 ohm on primary (tewo small terminals) and 8K to 11.5K on secondary (little terminal to high tension terminal).

Pedestrian · Apr 29, 2010

Didn't do a resistance check, but did replace with a known good coil out of a running vehicle.

DirtDonk · Apr 29, 2010

Is the second TFI module a known good one off a running vehicle too?

Something bleeding off power to the positive side of the coil then? Can't imagine why the spark would be weak even if you're only twisting the distributor to get it. Every spark out of a coil like that should lift the hair off your head!!
Could a defective TFI do that?
Are you using an old radio noise suppressor somewhere in the system by any chance? I know that's not common practice, but figured I'd ask.

Paul

needabronco · Apr 29, 2010

Bill I meant to 'borrow' an eec to see if that fixes the problem. I would also have that tfi tested to see if it's not 'weak'.

EFI no spark

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