No spark when cranking

Our Elan (VD) DP-08 with MZR 2.0 and Pectel T2 ECU has no spark when cranking (cranks but does not fire, no spark to plugs). We have the luxury of 2 identical cars, so our diagnostics included swapping out parts from the other car. When we swapped the starters, the spark returned and the car cranked and started without issue. The starters are Super Start XLT from Tilton. We don't understand how a starter can impact spark. Any ideas?
P.S. The failing starter will start the car from time to time if we tap it with a hammer when cranking. Go figure.

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Originally Posted by Redawgleader

We don't understand how a starter can impact spark. Any ideas?
P.S. The failing starter will start the car from time to time if we tap it with a hammer when cranking. Go figure.

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Many ECUs require a certain rpm sensed before sending the spark command. I know the PE3 ECU used on SRF3 and FE2 has that as a condition.

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Originally Posted by LarryWinkelman

Many ECUs require a certain rpm sensed before sending the spark command. I know the PE3 ECU used on SRF3 and FE2 has that as a condition.

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Interesting, never thought of that. So, if that is whats going on here, put the "bad" starter on the other car and see if it starts? What is the battery voltage while cranking? A saggy battery may be enough to spin it up but be low enough to not have enough juice to create spark. I know that does happen on bike motors.

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Originally Posted by LarryWinkelman

Many ECUs require a certain rpm sensed before sending the spark command. I know the PE3 ECU used on SRF3 and FE2 has that as a condition.

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yes, and that's why pushing-starting an ECU equipped car is usually unsuccesfull, can't spin the engine fast enough

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Originally Posted by LarryWinkelman

Many ECUs require a certain rpm sensed before sending the spark command. I know the PE3 ECU used on SRF3 and FE2 has that as a condition.

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Good point. Someone else mentioned that perhaps the starter, if faulty, is drawing too much power and starving the ECU/electronic ignition.?

This is a fairly common problem on Zetecs, maybe it applies to the MZR's as well.

The crank sensor is very sensitive to electrical noise. If the heavy power wire to the starter is anywhere near the crank sensor, it's possible it's interfering when heavy current is passing through.

I didn't believe it until I noticed on my zetec there was no spark until I released the starter button, then it would spark a few times until it coasted down in RPM. I then ran a new wire from the master to the starter over the cockpit away from the crank sensor and got spark while cranking. Turns out the crimp on the ring terminal on the wire from the master to the starter was failing. I replaced that piece of wire and ran it further from the crank sensor and all was good.

the T2 needs to see 300 rpm before it will start the motor. My MZR with a PE3 does not seem to. Mike's comment about electrical interference with the crank sensor is also another issue I've seen on a Zetec, but don't know about the MZR.

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Originally Posted by Bob Wright

the T2 needs to see 300 rpm before it will start the motor. My MZR with a PE3 does not seem to. Mike's comment about electrical interference with the crank sensor is also another issue I've seen on a Zetec, but don't know about the MZR.

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Thanks, Bob. Didn’t know about the min cranking speed. Could be that a weak starter isn’t making the min.

I had a Nissan Altima with a crank no start issue, and it turned out the reduction gear starter would spin plenty fast (fast enough that I didn't perceive a slow crank), but with a bad battery the voltage dropped enough to hold the ECU in reset.

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Originally Posted by Redawgleader

Our Elan (VD) DP-08 with MZR 2.0 and Pectel T2 ECU has no spark when cranking (cranks but does not fire, no spark to plugs). We have the luxury of 2 identical cars, so our diagnostics included swapping out parts from the other car. When we swapped the starters, the spark returned and the car cranked and started without issue. The starters are Super Start XLT from Tilton. We don't understand how a starter can impact spark. Any ideas?
P.S. The failing starter will start the car from time to time if we tap it with a hammer when cranking. Go figure.

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Update: We replaced the solenoid and the brushes ring with parts acquired from Pegagus, and did a full bench cleaning and lube of the starter (it had been soaked in oil due to a prior oil line leak). The commutator plate looked rather worn/pitted. We buffed it with a 3M pad. Didn't see any obvious damage to the rotor, but then we can't see inside it. We have not yet fully tested the starter since then - that is scheduled for next week.

Will update again after the test.

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Originally Posted by Redawgleader

Update: We replaced the solenoid and the brushes ring with parts acquired from Pegagus, and did a full bench cleaning and lube of the starter (it had been soaked in oil due to a prior oil line leak). The commutator plate looked rather worn/pitted. We buffed it with a 3M pad. Didn't see any obvious damage to the rotor, but then we can't see inside it. We have not yet fully tested the starter since then - that is scheduled for next week.

Will update again after the test.

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FYI there is a guy, Marc Bushman, who does a nice job on rebuilding and upgrading racecar starters. 630-388-8880.

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Originally Posted by John LaRue

FYI there is a guy, Marc Bushman, who does a nice job on rebuilding and upgrading racecar starters. 630-388-8880.

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Thanks!

The failing starter might be causing a voltage drop or interference, affecting the ignition system. Replacing it should fix the spark issue.