Hard start 87 328-need advice..

Steve and Mark,
You guys are great, thanks for the thoughts and advice. I've always been sort of a DIY kind of guy, but I definitely don't want to do something stupid and then be sorry afterwards! I do know a great shop up in Houston I can contact.

Mark--I like that wiring info you posted. Indeed, when I examined the M9000 main unit in the passenger footwell recently, the connector to it housed about that many wires, all different bright colors.

Where did you find that info? link? I may be able to perform minor surgery myself with this info. Hoping it'll stop raining in the next days so I can pull the car out of the garage and tear into it...

What are you doing this Friday or Saturday?

Greg

 

Greg,

Saturday I have the kickoff meeting for the robotics team I mentor. Friday if it's nice out I will take my car for a ride. What part of town are you located?

Mark

 

Mark, i used to be your neighbor in the Heights but am temporarily living near BW8/Fairmont in Pasadena. I'll be working on the car Friday if you'd like to drop by..
Greg

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This afternoon, the car again exhibited hard-start characteristics. Actually, I should differentiate between my no-start and hard-start episodes.

The alarm has been un-armed for a week, as a test. Yesterday, the car started on first crank. Today, it took 3 cranks. On the 3rd one, it slowly came to life. That's always how it finally starts on hard start days. Almost as if the fuel pressure slowly comes up.. But...I isolated the spark as non-existent when the car won't start. And I always smell fuel when cranking, no matter what. I still believe my problem is spark, not fuel.

I did test the pins Michael suggested on the Microplex ECU. I tested both sets of pins, to measure resistance of the RPM and TDC flywheel sensors. TDC: 878 ohms, RPM: 770 ohms.
Right in the middle of the suggested 650-1000 ohm range. So, the flywheel sensors have been eliminated as a possible cause.

I plan on powering down the alarm system this weekend. That might not be enough; can anybody tell me if it's common for alarm systems to have an inline relay post-ignition, pre-starter? Or maybe post-starter, pre-coil? Maybe the problem is a sticking relay? I'm having a hard time sorting all the wiring behind the ignition key.

I will next test for power at the coils and Microplex using the technique Michael described.

Greg
87 328

 

Greg,

I did a search on "typical car alarm wiring diagram" and saw that several alarms disabled the 12 volt line to the ignition coil. So yes it is possible that your alarm is doing just that.

Mark

 

Thanks again, Mark, i appreciate your help. i just wish i knew WHERE the alarm system taps into the ignition circuit. it would have to be either right by the ignition switch or maybe around/behind the fuse/relay panel. the Mirage alarm unit is positioned behind the passenger kick panel.

It's just very diffcult to trace where all the wires are going to, lots of wire spaghetti ....

Greg

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ther

it will not start at all well it shouldnt also there is usually a basic bosch relay near the steering wheel column or near the ign switch or they may have put it riin the passanger footwell up under the dash just pull it out and reconnect those wires back together you will still have your locks.

 

Greg,

Any updates on your car?

 

Hi Mark thanks for asking. the past week or so I've been busy with work, and when i haven't been, the weather has stopped me. the next few days should open for me; I'll update the thread...
Greg

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Mark,
Thanks again for this color code list. They do indeed match my Mirage M9000 unit. Had a go today with this problem. I traced all the wires coming from the M9000 unit out to various locations in the car. One possible pertinent wire seems to be the blue ignition wire in the sensor port bundle. This wire is tapped directly into the big yellow wire on the ignition switch. My guess is, this wire is supposed to send a +12VDC signal down the wire to the M9000, in the event of somebody trying to start the car. Seems a silly place to mount it, as it's easy to disconnect ( I did remove the lower steering wheel dash trim; probably harder to get to with that in place.)

I pulled this connection, just a blade connector tap(but very sturdy looking). Do you guys think this could be my issue? Car has started as normal the past few days. There are larger starter wires tapped into the ignition as well, but remember, my starter cranks very strong all the time. No issue with starter, or fuel, only ignition. Could this wire be responsible for KILLING the ignition? I don't see how, as it's not tapped into the coils. Runs directly from ignition to M9000 alarm ECU. Maybe the ECU intelligently knows how to kill the starter if this wire receives +12VDC if alarm is tripped.. ??

I think I'll leave it unplugged and see what happens.

The mystery continues.

Greg
87 328

 

After consideration of my exploration today, I've come to a 95% certain conclusion:

My occasional hard-start problems are NOT caused by the alarm. This is a "starter kill" alarm, not an "ignition kill" alarm. Looking closely at the wiring, I can only conclude that. I ran a test, where I disconnected +12VDC from the Mirage M9000 ECU, and the car would not not turn over, no starter, no nothing. This leads me to believe that the alarm interrupts starter operation, not ignition.

This is logical, really. I see no tap-into any ignition component, only the starter. The blue ignition wire I mentioned in the last post seems to be only a sensor that the M9000 receives when the starter is cranked. With it disconnected, but every other alarm connection active, the car starts as normal.

Remember, last week I tested both flywheel sensors and they are good.

The odd thing I cannot wrap my head around is how the car can sometimes be "coaxed" into starting, with a long crank and a bit of throttle. And then other times I can crank till the cows come home and the car will not start. The other 70% of the time, the car starts fine.

So, I have come to believe it is something else that occasionally interrupts the ignition system, not the alarm system. I'm all ears, and open to all opinions and advice. Steve?

Greg

 

did you also check for power as suggested in my posting no89 ?

IF the above measurements check out o.k. and you see +12V on coils and microplex ecu
they are not part of your problem...that would also mean, your ignition switch works as it should

.

 

The resistance test is a simple screening that doesn't prove operation (i.e., bad resistance = bad for sure, but good resistance does not verify operation) -- the next level is to measure the AC voltage on each during starter motor cranking per the Rose, et Al document.

 

Michael,

In post #89, you recommended 2 procedures. I DID test the sensor contacts (resistance only) at the Microplex ECU harness connector. They proved to be good. I also saw +12V at pin 13 of same connector. I believe that voltage was present with key off.

I have NOT checked voltage at terminal 15 of both coils. It's a tough-access location, but I need to do that. That's where the yellow wire meets the coil, on both, correct? Do I check for voltage there only when cranking the starter? Or will it always be present?

Problem is, for the last week or so, the car starts as normal every day, so I can't test for a problem when it's not present.... Ghost in the machine, as it were...

I suspect we can eliminate the ignition switch, Microplex ECU, flywheel sensors and coils. If this holds true, where else should I look for a possible cause-intermittent ignition loss?

Thanks!
Greg
Houston, TX USA

 

Steve, OK, good info, missed that on the Rose document. I can try that. I should see +12VDC on both ECU contacts during cranking?

Again, here's the big problem that we all need to be considering: THIS PROBLEM IS INTERMITTANT! I can't re-create it faithfully. In fact, the past week, the car starts pretty much as normal, although I do recall once last week where it took a few long cranks, and then it caught and started.. During the long cranks, I always smell fuel, so we can rule that out. I also have tested for spark during no-start episodes and there was none.

Thanks for everybody's input!

Greg

 

no...voltage on pin 13 is only present with key on

see above...voltage will be present when key is on

to measure TDC and RPM signal (volt), car should idle

TDC sensor should read >0,2V AC between pin 1 and pin 2 with connector connected to ecu
RPM sensor should read >2 V AC between pin 3 and pin 16 with connector connected to ecu

(if the engine is running, the sensors normally deliver the expected values -
the engine would neither start nor run if either sensor failed)

yes...we know...that`s why this is so interesting
you have to wait and be ready - and in this case hope - for a sudden failure

and this is what makes it so difficult...(if both coils don`t fire)
this symptom would normally point to the problem beeing upstream of the ignition...
and that means: either the connection from coils to microplex, the microplex itself or one of the sensors...

 

I can explain this behavior from theory and also practical experience with other cars using passive TDC sensors. Of course the problem might be something else but this fits:

A shorted turn or metallic debris on a sensor causes its output voltage to drop. The output voltage is proportional to the speed of the flywheel and is often just enough to make everything work during running but not enough to work during the slower speed during cranking.
When cranking, if you open the throttle the crank speed increases slightly, which might cause the voltage to rise above the threshold.
Why does it easily start sometimes? Just down to temperature and/or humidity. If the sensor voltage is marginal a slight environmental change could render go or no-go. Once the engine is started there is plenty of margin in the sensor output.

The only way to test the sensors 100% is using an oscilloscope. Testing the AC voltage gives an indication but the TDC sensor gives only one pulse per revolution so you are trying to measure this one pulse using an AC meter which is designed to measure continuous AC. This is why the output of the TDC sensor, measured with an AC meter is lower than the RPM sensor. In fact the voltage of the pulse should be the same, there are just less pulses.

Its worth trying the AC voltage test but I would also visually check the sensor in-line connectors and the bulkhead connector for corrosion even though you have good resistance measurements and even remove both sensors (no easy task I admit) and check nothing metal is stuck to them.

 

Greg,

Did you get you problem sorted. I have a similar problem with no spark. I have been told it is the ignition control unit. I have a 328 Mondial and trying to find the part.

Den

 

Of course i have no idea about the particular alarm system but an alarm that only disables the starter isn't much use since you can still bump-start the car. If it doesn't disable the ignition and/or fuel, then it doesn't provide any real protection against theft. Also, aftermarket alarms are notorious for causing a variety of starting problems. Frankly, I would completely remove it. NOBODY steals a Ferrari...there is no money in it; they steal Hondas and Fords, etc, cars that you can actually make money on.

 

Wow, this goes back a bit. First off, my alarm was NOT causing my hard start problem. All you alarm haters calm down! . Mine is a high quality one, well-installed.
After replacing both coil modules and checking spark and fuel, the car was still hard to start periodically. Soon after, I took the car in for a full service and my tech found a few bad vacuum hoses. After replacement and the service, the car starts on the first crank every time! So my issue apparently was a vacuum one.


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thanks for getting back to this thread, Greg ... two years late