1993 MX5 starts and then dies

stuartbuckle · Post by **stuartbuckle** » Sat Jul 11, 2009 3:15 pm

I have a 1993 MX5 1.8 manual. I took it for a pre-purchase inspection for a potential buyer and after they had performed the compression test it would only run for 2 to 3 seconds and then die. They told me that they had removed the 'Fuel Injection' fuse prior to performing the test, and that they don't remove spark plugs, but a machine records the cylinder compressions electronically when they crank the engine. After the 'Fuel Injection' fuse was refitted, the problem occurred.

Has anyone else had this problem?

I have tried bridging the F/P and GND connections in the diagnostic plug to make sure the fuel pump keeps running, and then starting the car, but the problem remains. The 'Fuel Injection' relay, which sits next to the fuse they removed, is also working correctly.

One more thing, you can keep the engine going by switching the ignition off and on again multiple times, and there is no rev counter movement except for the smallest flick of the needle on first cranking. When the engine is running the rev counter reads zero.

Post by **jif** » Sat Jul 11, 2009 3:26 pm

is the connection to the air flow meter ok? Disconnecting that will stop power to the fuel pump as a safety measure.

[Posted via external email]

stuartbuckle · Post by **stuartbuckle** » Sat Jul 11, 2009 3:50 pm

I have checked the connection to the airflow meter and it seems to be good. I have also tried bridging the FP and GND posts in the diagnostic plug, which forces the fuel pump to work all the time when the ignition is on. That didn't make any difference to the problem.

dynofiend · Post by **dynofiend** » Sat Jul 11, 2009 11:28 pm

In order to perform a compression test, you have to remove a spark plug. I have never heard of any machine that can read pressure inside a sealed combustion chamber by measuring it from the outside.

I have heard however, that if you do not remove the ignitors, or the fuse for those, and then crank the engine with a spark plug removed. That it can blow the ignitor/s.

It sounds to me like the garage that performed the compression check, didnt realise, or forgot, to disconnect the ignitors, fried them in the process of doing the compresion test, and are then spinning you a line about not removing the spark plugs in the hope that they can get away with having fried the ignitors.

My advice, call their bluff. Tell them you know that a spark plug has to be removed to do a compression check, and that you also know that cranking the engine with a plug removed can fry the ignitors, and thats now what you suspect has happened. Ask them what they intend to do about it.

stuartbuckle · Post by **stuartbuckle** » Sun Jul 12, 2009 8:07 am

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.

sprsta · Post by **sprsta** » Sun Jul 12, 2009 8:37 am

its by the fuse box in the engine bay
between fuse box and strut tower

Stevo · Post by **Stevo** » Sun Jul 12, 2009 9:14 am

Some garages use a machine to check compression without removing the spark plugs. It is not a true compression test, more of a "relative" test that checks for large variances between cylinders. Cheers Stevo

stuartbuckle · Post by **stuartbuckle** » Sun Jul 12, 2009 3:18 pm

Thanks for the latest replies.

However, my car definitely does not have an igniter in that location. In between the fuse box and that little emission thingy with the vac pipes on it, there is just an empty bracket with two (screw) holes in it. Presumably this is where an igniter would fit but I think my model has one in a different place, or maybe it is built in to something else.

(Thinks: Please don't let it be the coils or the ECU, they cost a fortune)

Mine is an 1800cc engined 1993 model. Perhaps the system is different on the 1800??

This whole fault was triggered when the guys at VTNZ disconnected the 'Fuel Injection' fuse to crank the engine and subsequently refitted it. It was driving perfectly up to then.

Habanero666 · Post by **Habanero666** » Sun Jul 12, 2009 3:41 pm

Simple tip, check the fuse for continuity ( is it in good condition) don't just assume, then check for oxidation at the connection where the fuse goes into the holder.
The ecu and ignitor will require consideration only after all wiring, connections and earths are checked.
Just stick with what the VTNZ guys have told you, untill you can prove otherwise.

Euen · Post by **Euen** » Sun Jul 12, 2009 5:21 pm

The igniter on the 1800s is incorporated into the coil pack. Is it running cleanly on all 4 when it runs?

stuartbuckle · Post by **stuartbuckle** » Sun Jul 12, 2009 6:29 pm

Hi Euen

Yes, it runs on all 4 and if I switch the ignition off /on/off/on rapidly it will keep running for as long as I do that. But all the time it is running, there is no movement from the tacho needle. It reads zero all the time.

dynofiend · Post by **dynofiend** » Sun Jul 12, 2009 7:15 pm

Regardless of what proceedure VTNZ have used, you drove into that garage for them to perform a task, you would expect to be able to drive back out again. This is obviously not a part on the car which has just happened to fail at the same time that the comp test was done, but is something that VTNZ technicians have had a hand in. I would fully expect them to be fixing it unless they can prove that it wasnt them that broke it in the first place!

Stevo · Post by **Stevo** » Sun Jul 12, 2009 8:41 pm

dynofiend wrote:Regardless of what proceedure VTNZ have used, you drove into that garage for them to perform a task, you would expect to be able to drive back out again. This is obviously not a part on the car which has just happened to fail at the same time that the comp test was done, but is something that VTNZ technicians have had a hand in. I would fully expect them to be fixing it unless they can prove that it wasnt them that broke it in the first place!

I agree.
So how did you drive it home? Cheers Stevo

sprsta · Post by **sprsta** » Sun Jul 12, 2009 9:09 pm

stuartbuckle wrote:
I towed the car home and have physically removed the coil packs and they LOOK OK.......

i wouldnt have towed it away, i would be expecting it to be just as good as when i handed over the keys and not left without them fixing THEIR problem

stuartbuckle · Post by **stuartbuckle** » Sun Jul 12, 2009 9:36 pm

Thanks Stevo and sprtsa.

I agree with what you say, VTNZ have responsibility for the problem, however, their stance was "It's not anything we have done" so I knew that if I left the car there, they would do nothing but maybe push it in and out each day (their primary function being to do WOFs on cars). In other words, nothing would happen.

I figured that I was better off with the car away from their incompetent and uncaring hands. (it's already covered in their finger marks)

What I am trying to do is establish:
1) What is the fault, and fix it.
2) Did they cause the failure
3) Get them to pay for it.

You know the irony of all this? I went in there for a pre-purchase inspection and they haven't even completed it because they couldn't road test the car. So I have no inspection report, I'm down $125 which was paid up front, and I have a dead car!

BUT, they will pay for this, don't worry about that. I am biding my time and gathering evidence.

There WILL be repurcussions.

Euen · Post by **Euen** » Sun Jul 12, 2009 10:06 pm

Stuart

I have some spare coils if you are in Auckland you are welcome to try them. Only problem is that they are from a 96 and only have 3 wires to each coil. There are 2 types, the other ones have 4 wires. If yours have 3 wires you are welcome to give them a try.

Cheers
Euen

sprsta · Post by **sprsta** » Sun Jul 12, 2009 10:21 pm

you will probably want a mechanic to write you a report on the damage that has been done to it

brownie · Post by **brownie** » Sun Jul 12, 2009 10:40 pm

May not be of much help ,But at work(Mazline Partsworld) we do get a quite a few phones calls for 1800cc coilpacks,I would indeed suspect they have fried them,And yes they are expensive new ,($600+),Hopefully someone on the forum may be able to lend a pair to try,We unfortunatly haven't even got any to offer for dianogsis,
They do have to be NA 1800cc type.

stuartbuckle · Post by **stuartbuckle** » Mon Jul 13, 2009 5:39 am

Thanks for the latest replies.

Euen, thank you for the offer of spare coils to try. I would like to do that please. I live in West Harbour, but my current job takes me all over Auckland most days, so pick-up would not be a problem. Can you contact me please and we can sort out details. The forum won't let me put my e-mail address on here yet, but see if you can work it out from this.

My e-mail is, my user name on here: stuartbuckle, then it is 'at' hotmail dot com

brownie, thanks for the advice. I can imagine there would be huge demand for used coils as the new ones are so expensive.

sprsta, yes, I may have to get a mechanic's report. I will see what VTNZ's reaction is first. If they cover the cost without argument (Yeah, right) then that's OK, but if not, I will have to take it further.

stuartbuckle · Post by **stuartbuckle** » Mon Jul 13, 2009 6:05 am

The consensus of opinion now seems to lean toward the coils having been fried on my car and I am thinking that myself now, all things considered.

One thing still puzzles me, why does it start up and run for a few seconds?
Is there some way that perhaps the igniter(s) get triggered on initial start that is different from the normal way when the engine is running?

If another pair of coil packs fixes the problem, that's great. But I am just curious as to how the triggering works during start up.

Habanero666 · Post by **Habanero666** » Mon Jul 13, 2009 9:25 am

Check the connection for the CAS.

stuartbuckle · Post by **stuartbuckle** » Mon Jul 13, 2009 4:39 pm

I have now sent the old girl (on a truck!) to the local Ford & Mazda dealer for them to test it on their magic diagnostic machine. Latest report from them is that the car will not talk to their machine, so they were checking ECU connections manually.

Ho-hum, well it's only about $110+GST per hour.

Stevo · Post by **Stevo** » Tue Jul 14, 2009 6:32 am

Hope you quickly get it sorted and adequately compensated. Please keep us updated. Cheers Stevo

Trevor · Post by **Trevor** » Tue Jul 14, 2009 2:50 pm

It would appear to me based on probability and logic, that the ECU could have been damaged. I would suspect that with the engine running, the required fuse could have been ascertained by removing fuses on a hit and miss basis, thus generating some nasty EMF.

Trevor.

stuartbuckle · Post by **stuartbuckle** » Tue Jul 14, 2009 4:23 pm

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.