Trying to get the Boy going again

[jono]

Hey, I have finally got around to getting another starter motor after my troubles back in July 2008.
I still think the problem wasn't entirely fixed. I found the invoice and here is what it says:
(For those who don't know I am running an EFI setup)

Engine over advancing at times only during cranking
Tacho reading 12,000 rpm
During crank ECU picking up interference from pick up in distributor
Check on oscilloscope - signal at ECU
Distributor receiving excessive trigger pulses
Modify ECU wiring harness and fit resistor to loom
Refitted ECU - tests OK

Well, not long after that the starter motor got ruined and I couldn't be bothered trying to fix it again! Now, after putting in the new (second hand) starter motor it cranks but then makes an awful noise like it is cutting back on itself.

Any ideas???

[ToranaGuy]

I take it the basics like fuel at the rail & spark have been checked for?

Cheers

ToranaGuy

[Brayden]

Now, after putting in the new (second hand) starter motor it cranks but then makes an awful noise like it is cutting back on itself.

Sorry but I don't understand the description. The starter motor is making the noise, or the engine?

[jono]

The starter motor.

Yeah there is spark and fuel at the rail. It seems to be the same problem happening again

[Brayden]

Describe "cutting back on itself". Are you saying that it cranks, then kind of stops like the motor is pushing back against it? If so then it sounds like the ECU is advancing the ignition.

[jono]

Yep that is exactly what it sounds like. Sometimes the starter motor would get stuck and I would have to out into fourth and roll the car backwards and forwards till it 'clicked' out. But yes it does sound like an advancing issue, and the invoice said something about engine over advancing during cranking.

Since the resistor in the loom they put in last year has not fixed it completely what should I do?

Thanks for your hep.

[Brayden]

The starter sticking is probably the solenoid or throwout, but if the ignition is advancing and putting excessive force on the starter then it will lock, and eventually burn it out.

For the ECU to be receiving a dud signal from the CAS, I would be trying to source another dissy. It sounds like the CAS may be faulty.

[jono]

Hmm, that was one of my suspicions. Thanks for your help mate.

[jono]

OK, I logged some data and found ridiculously high RPM reading upon cranking. It shoots up to 12,500 RPM!!!

Is it easier to replace the actual sensor or the distributor? And where would I be able to source either of these?

[Brayden]

I'd say the entire distributor would be easier to replace, but before we get that far I just had a thought. You're using an EMS computer right? It might be that the ECU isn't compatible with the type of trigger in the CAS. Might be worth investigating.

As for the dissy, I'd say Cappuccino Sport, Monster Imports or Greenline would be your best bets. John Verban might also have something laying around if you're lucky, so you could give him a call.

[jono]

Yeah, an EMS. Interesting thought. In the software the trigger sensor is set to mag and the sync sensor set to mag too, not hall. I think I remember the mechanic saying the set up would work better with a hall pick up or something.

It has ran for a while with those settings without too much trouble so perhaps it is the sensor. Thanks for the details I will look into it.

[Brayden]

Your sensor would most likely be a magnetic reluctor, but converting the setup to a hall effect would be much better. When I bought my ECU I was advised that Microtech was the only one that would play nicely with a magenetic trigger.

[jono]

Much work involved in converting it to a hall effect? I'm not that familiar with this sort of stuff yet

[Brayden]

Potentially less work than trying to find another F6A dissy! I'd get an old F8B/F5A dissy and have a crack at building one using that. The MegaSquirt guys will probably be most useful at giving advice on constructing a trigger wheel/hall effect system.

[jono]

Thought I would post up a fairly informative response I got from the AEM Forum.

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Check your grounds. They can read ok with a meter but when the starter draw pulls on it it can lose its connection. Adding a second ground to the engine and or remove each ground connection engine to chassis and ecu to chassis/battery, sanding, then reinstalling may help.

You may need a stronger resistor across the pickup if its a mag/vr. Is this a hall or mag pickup? Make sure the resistor is on the ecu side, not the sensor side of the harness.

The other possibility is if it has a sync signal it might occur too close to the trig signal and play either way (timing belt slack, gear lash, etc) might make it select the wrong pin.

Another possibility is to turn the key on and wait until the fuel pump stops its purge. Its supposed to reset the sync after this, not sure the dualsport does this or not though, sorry. If its ok starting this way you have a noise spike at key on. Chances are the initial solenoid closing on the starter motor is making a spike and making the extra signal(s.) You could try grounding the ecu at the battery or on the chassis. This is all stuff EMS recommended to me when i was chasing similar problems.

If you have an oscilloscope try using different ground locations for the probe (ecu ground is probably ideal to find the noise.)

This is definitely not a fun thing to find.
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