1993 MX5 starts and then dies

Discussions about MX5 Alarms, Car Stereos, Lighting, Batteries or other Electrical related issues

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sprsta
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Post by sprsta » Tue Jul 14, 2009 4:34 pm

Im sure you would find a second hand one at mx5 mart

Habanero666
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Post by Habanero666 » Tue Jul 14, 2009 5:26 pm

Habanero666 wrote:Check the connection for the CAS.
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Euen
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Post by Euen » Tue Jul 14, 2009 7:36 pm

Hi Stuart

There is a possibility that these guys may be able to do the internal electronics for the CAS.

http://www.anythingelectronic.co.nz/front.asp

Otherwise, as Sprsta says, there is MXMart, Mazline, Mazspares at Rosedale. Even a 1.6 CAS will fit but not sure about the connector.
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Post by Trevor » Wed Jul 15, 2009 10:09 pm

stuartbuckle wrote:Thanks Trevor, I have had similar thoughts myself.

UPDATE: Tuesday 14th July.

Mazda dealer thinks that the Camshaft Position Sensor is faulty. A new one cannot be located in NZ or Australia and second-hand ones don't seem to exist, so we have gone for a new Aftermarket sensor, price $253. I assume that is plus GST.

Should be fitted on Thursday (15th).

Further bulletins will follow.
The tachometer receives its signal from the ECU/ECM. rather than the the CPS/CAS. If this what they are using as a clue, they are off target.

Surely at their hourly charge out rate they are fully equipped and can check the output of the CPS with a 'scope. I most certainly could here at home base. :o
Trevor.

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Post by stuartbuckle » Thu Jul 16, 2009 8:59 am

Latest bulletin:
The Camshaft Position Sensor has been fitted!
But the car still has the same condition. It's not fixed.

My thoughts now are that when VTNZ removed the Fuel Injection fuse and subsequently refitted it, at least one of these operations was done with the ignition left 'ON' and it spiked the ECU.

How about that for a possibility?

Trevor
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Post by Trevor » Thu Jul 16, 2009 10:46 am

stuartbuckle wrote:Latest bulletin:
The Camshaft Position Sensor has been fitted!
But the car still has the same condition. It's not fixed.

My thoughts now are that when VTNZ removed the Fuel Injection fuse and subsequently refitted it, at least one of these operations was done with the ignition left 'ON' and it spiked the ECU.

How about that for a possibility?

Exactly likely and possible. :( Did I not tell you so? :lol:
Trevor.

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Post by poison » Thu Jul 16, 2009 6:22 pm

stuartbuckle wrote:Latest bulletin:
The Camshaft Position Sensor has been fitted!
But the car still has the same condition. It's not fixed.
Well I'm sure Mazda will acknowledge their error and not charge you for the unnecessary parts and labour.... YEAH RIGHT!

We should have a vote as to which Mazda dealer provides the worst service. IMHO North Harbour Mazda is a winner here by a mile, the parts department is a joke. And on a positive note I have had great service from Canterbury Mazda, worth the courier fee.

Come on everyone I'm sure there must be someone on this forum who has upgraded and can lend an ECU as a test....
:twisted: Gazda in the white HOT Mazda :twisted:

Euen
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Post by Euen » Thu Jul 16, 2009 6:29 pm

I have a computer from a 96 1.8 but not sure how compatible it is. Stuart, PM me if you want to try it.
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Post by brownie » Thu Jul 16, 2009 8:54 pm

Just make sure ECU numbers match BPE8 or something like that,
No match,No go .
If you get stuck try me at Mazline and i will check the draw for a match.

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Post by Euen » Thu Jul 16, 2009 9:57 pm

My one is a BPS5. Part no. BPS5 18 881A
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Post by stuartbuckle » Fri Jul 17, 2009 1:41 pm

Hi again huys

I've been up in Northland for a couple of days, so haven't had much of a chance to reply on here.

My ECU is: BPF3 18 881

Underneath it has: 0797004571

That was read to me over the phone by the foreman at John Andrew Ford & Mazda. He did emphasise the 'F' for Freddy, so I haven't confused it with an 'S'.

If I can't get one, I'll try Anything Electronic in Nelson.

stuartbuckle
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Post by stuartbuckle » Fri Jul 17, 2009 4:40 pm

Friday 17th July.

Just had a phone call from John Andrew Ford & Mazda.

They have got the car running.

They borrowed some coil packs from an auto electrician and away it went.

So it's not the ECU after all and the search is on for reasonably priced replacements. These coils packs have the 4 wire plug on them.

Apparently it is the igniters that are burnt out. (Built into the coil pack on a 1.8)

So now, the question is why did they burn out? Did someone leave the ignition on for a long time or was it the cranking done during the so-called 'compression test' with no Fuel Injection fuse fitted?

Either way, I am sure that if VTNZ had not touched the car, it would have been running just fine.

If anyone knows where coil packs can be obtained without breaking the bank, I would be grateful.

Also, can anyone confirm what sorts of things lead to igniter failure?

I know that leaving the ignition on for a long time can do it. Also, that cranking the engine with plug leads disconnected can do it.
But, would cranking without the Fuel Injection fuse cause it too?

Some good, solid advice would be appreciated for the upcoming battle
with VTNZ.

Trevor
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Post by Trevor » Fri Jul 17, 2009 7:03 pm

Sorry, I have now ascertained that the MX5 tachometer is first initiated from a signal derived from the igniters and the coils, and only then via the TCU, which is a rather back the front option, but does allow the use of an off the shelf component.

As as been pointed, out the MX5 does not have a separate igniter as such, the purpose of which is to switch high current as is required by the ignition coils on receipt of a low current signal from the ECU, i.e. so as not to overload the ECU. The required arrangement is built into the MX5 coil packs, hence the four wire connection.

As already posted, it is not advisable to operate a coil without a spark plug connected, as the HT voltage has no where to dissipate and could track past the insulation within the coil. Also if an igniter input is permanently energised this can overload the solid state components normally are exposed to only intermittent switching.

However it is difficult to accept that the TCU would supply a constant signal as would be required to cause this form of overload. Furthermore I can find no advice in respect of caution in regard to the above, in any MX5 repair data I have on hand.

Please note that I am not trying to impress with knowledge which is in fact universal, but am thinking out loud in order to somehow isolate the problem. What the hell did these buggers do?

In theory, surely opening a circuit by removing a fuse in order to stop the engine firing, should have isolated the igniters and coils. An applied short circuit would be required in order to induce an overload.

If only the igniter portion of the coils is the problem, a continual overload is the only logical cause. Good solid advice unfortunately is the problem. How can the culprit be nailed?
Trevor.

As a child, on cold mornings I was happy to warm my cold feet in a cow pat, but I detest bull$hit. LOL

sprsta
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Post by sprsta » Fri Jul 17, 2009 7:58 pm

i still cant believe they didnt take a plug out
i think theyre just hoping you dont call their bluff
maby you should check out their magic compression machine?
i know there is acouple of posts that state there is this type of thing but no guarentees they have one

stuartbuckle
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Post by stuartbuckle » Tue Jul 21, 2009 10:17 pm

Well at last the repair side of the saga is over. The car now has a new coil pack and runs sweetly. John Andrew Ford and Mazda even removed the Camshaft Sensor that they tried earlier and did not charge me for it. Some places would have left it on and charged for it regardless of it not fixing the fault.

Now I just have to sort out VTNZ.

Thanks for all the posts and support you guys.

Stuart

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Post by dynofiend » Wed Jul 22, 2009 2:48 pm

I would advise getting the tech at mazda to write you a short letter about the fault that your car had. Then approach VTNZ and point out that the car drove in without the fault, and got towed out with it. Then say that you know the fault can occur when the engine is cranked without the HT leads connected or with them having been removed. One of which would be necessary to perform a compression test (you cant have the engine firing when the compression test is carried out). You also know, from a previous conversation, that they only removed the fuel injection fuse, which will disable the injectors, and stop the engine running when the compression test is carried out. But will NOT stop the ignitor from operating.

The test they have probably done uses an electronic gadget to analyse cranking speed, but it still requires the cars ignition system to be disabled to stop the engine from starting mid test. I suspect that the tech did not disable the ignitor properly before running the test, hence burning them out.

Fact of the matter is, you drove in there, they had the car when it broke, and they were fiddling with the part of the car that broke, when it broke!

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Post by Habanero666 » Wed Jul 22, 2009 3:03 pm

Good point dynofiend, when I was manager of a workshop this most certainly applies to this situation....... although sometimes hard to ascertain the facts from "shy" Technicians and customers "trying one on" to avoid cost.

I would delight in setting things straight for customers, put it that way.

One thing is clear, things can break at anytime for no reason, but are more likely to break if someone is untrained on that specific product!

Take it to a trained professional and pay the money, or take it to a cowboy, and listen for the sound of hooves when something goes wrong.....

All the best with VTNZ mate, I hope you can get the result you seek.


Jim
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Post by Timmo » Tue Sep 08, 2009 10:41 am

For posterity, what is the correct method to avoid frying the coils?

Unplug the igniter/coil pack at the fire wall connection?

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Post by Euen » Tue Sep 08, 2009 1:51 pm

Hi Tim and welcome to the forum.

On the 1.8 the igniter is built into the coils. The easiest way is to remove each of the low tension connectors on the coils.
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Post by SLYDIT » Sun Oct 18, 2009 10:14 pm

the reason the coil packs fry is that they require the sparkplug on the secondary side of the coilpack to "drag down" the operating spark voltage (lets say 10,000 volts) if there is nothing connected to the secondary side of the coil the voltage generated by the coil pack will skyrocket to massive levels. the wiring and electronics insulation is nt designed to withstand this HIGH voltage and stuff breaks.it always makes me cringe when i see "mechanics" do the old 'pull the plug and see if theres spark' trick on modern cars.

A quick google search on "current transformer" theory will give you a basic idea of what happens on open circuit secondary windings.
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Post by Denys Roos » Tue May 13, 2014 6:16 am

stuartbuckle wrote:I think you are right, but when I challenged them on the spark plug removal two of them said in unison; "We don't remove spark plugs." Then one of the guys said; "We have a machine with a lead that clips to one of the spark plug leads and then we crank the engine and it takes a reading of all cylinders."

I haven't seen this 'machine' yet.

I towed the car home and have physically removed the coil packs and they LOOK OK. I emphasise 'look' because I have heard that they will show signs of melting if, for example, the ignition is left on for too long. I don't have a means of testing them though.

I have read elsewhere that there is an 'Igniter' or 'Ignition Control Module' that sends a signal to the coil packs and that it is located near the interior fusebox, but I can't find it. Apparently, this can fail and the coils won't trigger, but on initial start up the 'Igniter' is bypassed, hence the fact that it starts for a few second. Also, if this thing fails there is no signal to the tacho. That's exactly the symptoms I have, if only I could locate the darned thing, I have some test readings from a good one (off the internet) to compare with mine.

I've seen a picture of one in a Mazda spares Internet site, so I know what it looks like. It's a flattish black plastic gizmo a bit smaller than a cigarette pack but thinner.

If anyone can point me in the direction of that thing I would be grateful, then I could test it against the readings I have.

Thanks for your thoughts.
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Post by Skilfil » Tue May 13, 2014 6:37 am

Denys Roos wrote:I mostly treat vaping like smoking,and I don't have a problem vaping with the smokers, either. I'm lucky, I guess, that the smell of smoke doesn't bother me. Sure, I smell it more than I used to, but I'm okay with it. It's nice when there are other vapers out there, so we can talk e-cig.
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Post by Timmo » Tue May 13, 2014 9:42 am

Denys Roos wrote:I mostly treat vaping like smoking,and I don't have a problem vaping with the smokers, either. I'm lucky, I guess, that the smell of smoke doesn't bother me. Sure, I smell it more than I used to, but I'm okay with it. It's nice when there are other vapers out there, so we can talk e-cig.
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Post by marcellarius » Tue May 13, 2014 10:33 am

Relative compression tests can be done by looking at fluctuations in the starter motor current waveform. Its necessary to prevent the car from starting, pulling injector fuse would cut fuel. Their equipment may use a pickup on an ignition lead to allow cylinders to be identifird.

Running coils with HT leads unplugged or damaged, as SLYDIT mentioned can cook the coil packs. Each coil is connected to a pair of spark plugs and forms a circuit through one plug, the engine, to the other plug and back to the coil. If part of the circuit is broken, the secondary coil voltage will get very high and may find an alternative path and can damage the coil pack.

I wouldn't think that cranking with just the fuel cut would damage the ignition system though..

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