problem with coil? does this sound right?

[CWGT]

Hi All

Could anyone offer any advice?

We are looking for some advice on my mother-in-laws Beat. Shes had it from new, its all original and has had very little use (from memory around 20k miles in total).

On a run out a few weeks ago the car wouldn't start after sitting in a car park for 15mins. The trip was short but enough to get up to temperature, less than 10 miles. On the way out the car was running fine but on return to the car it would only turn over. It was a very hot day!

It was towed home and sat in the garage for a few days. Still turning over but not starting - not even spluttering. Our local garage had a look but they weren't keen, they said they couldn't get a spark. They recommended another local garage that specialises in electrics so it went there. They have been tinkering and have sent through the following:

I have rechecked the wiring / ignition system and have found that it is the ECU that is holding the coil energised with the ignition on. When the vehicle is cranked it reverts back to normal switching and the car will start with a substitute coil wired in.

With a new coil the car will start and run but I cannot tell how long this will last. It is only a problem with ignition on, engine off so it should be OK as long as the ignition is not left on. This is unlikely anyway as generally the ignition would not be left on.

If you cannot get the correct coil for the car I should be able to get one that will work but will be a different type

Now, we don't know much when it comes to mechanics, especially the mother-in-law! so any advice would be much appreciated - firstly on the problem and secondly locating a suitable coil (if this is the problem). Also I have read lots on problems with ECUs on the forum and wondered whether that might be an issue?

Any advice that we could pass back to the garage would be much appreciated. Cant afford a huge bill. We realise the car is getting older but it has huge sentimental value as my father in law (who bought it as a surprise for mother-in-law) dead a few years ago.

Many thanks in advance
Chris

[Steve_M]

So are you saying the garage have diagnosed it down to a failed coil???

If so a Beat coil is still available part number 30500-PH1-026 @ £108.48 inc VAT (No stock in europe so would come from Japan ETA 20/09/13

[Steve_M]

Its not a beat specific part, its also used on a 1986-89 Accord and 1987 Prelude, so this may be useful.

http://www.ignitioncarparts.co.uk/PartLists.aspx?PerformSearch=manufacturercode&SearchValue=30500PH1026

[CWGT]

Hi thanks for the response Steve

I haven't spoken to the garage yet so only the note to go on for now. I'll call them on Monday and update. I read it as they think there is a primary fault with the ECU which is causing the coil to act oddly and fail. But as I say, I have no idea when a coil should be energised! or not! This might be normal for a Beat for all I know?

Your information on replacement parts is great I'll pass this on.

Sorry I cant be clearer for now

Many thanks

[Moriniman]

Judging by the size of the coil alone, the Beat uses an inductive ignition. A spark is produced whenever an energised coil is turned off. With traditional points (Kettering) ignition the coil is energised for a fixed number of degrees of engine rotation (the dwell angle). As the rpm rises the time available to 'charge' the coil gets smaller and smaller. You can compensate by changing the coil, but then it will overheat at low rpm. This is why Magnetos were used for racing long after they'd fallen out of favor for normal use. The first solution to this problem was CDI (capacitive discharge ignition) where no energy is stored in the coil, instead a capacitor is charged up and then 'dumped' into the coil to fire it. Modern inductive ignition measures the time between sparks and calculates when to start charging the coil. If the coil is charged for too long (you've stalled the engine for example) it turns the coil off to stop it overheating.

If the coil is being energised when it shouldn't be then it will either be the ECU that is at fault, or the ignitor circuit. On some vehicles this is integral with the coil, but looking at the Beat wiring diagram appears to be a separate module. If it is, does anyone know where it's mounted?

[Steve_M]

but looking at the Beat wiring diagram appears to be a separate module. If it is, does anyone know where it's mounted?

It is a separate unit and its mounted on the r/h side rail in the engine bay (if I remember rightly)

[Steve_M]

Ignitor location.

2283

Part number: 30550-PH3-004

http://www.ignitioncarparts.co.uk/PartLists.aspx?PerformSearch=manufacturercode&SearchValue=30550-PH3-004

[CWGT]

Hi all

Apparently it is a possible problem with the ECU, the igniter is ok. They have hooked a different coil up to the car and it started up first time. They are saying a new coil will get the car going and may well run for many years with the fault as is - especially now we know not to hold the ignition on without cranking the engine! At the moment this is the preferred option as I think I read somewhere on the forum a new ECU is VERY expensive.

If anyone knows of a reasonable secondhand ECUs out there I'd be interested!

Cheers
Chris

[LawrenceHarding]

Usual problem with ECU is duff capacitors, which an electronics repair shop ought to be able to deal with.

[robertobini]

Usual problem with ECU is duff capacitors, which an electronics repair shop ought to be able to deal with.

I have had a brand new, original Honda ECU fitted to may Beat for 4 years now and it has always performed faultlessly but for once, 3 years ago, when, while driving, the engine stopped and would not restart. After I was rescued and towed back home I checked the large fuses in the engine compartment, but they were OK. However, when in desperation I just blindly replaced all the fuses in the fuse box by the throttle pedal...joy unconfined! the engine started, the check light was fine and it has been fine ever since. Readers of this forum might also recognise a previous post of mine, when the same procedure with the fuses successfully corrected an erratic speedo, and I believe it was successful with another member and his speedo. Now, I do not believe in magic and either there is something unusual in the wiring of my Beat, or there is a bit of corrosion in the contacts of the fuse box, or the design of the electric circuit of the Beat has some fundamental weakness, but it is a simple procedure and its cost is negligible. Cross your fingers and give it a try.

[Moriniman]

Apparently it is a possible problem with the ECU, the igniter is ok. They have hooked a different coil up to the car and it started up first time.

No, the ignitor will fire the coil, but that doesn't mean it's OK.

I'd want to look at the Ignitor signals, the ECU input and coil output. Some ECUs directly control both the ignition timing and the coil dwell time, but some just do the timing and leave the dwell to an external module. Some let the external module do most of the work and just tell it how much advance to apply. The Ford EDIS module works that way and gives you fixed 10 degree BTDC timing as a 'limp home' mode. I suspect that the Beat ignitor does the dwell control and is energising the coil all the time because the dwell timing section is faulty. It must still be limiting the coil current or you'd kill a new coil in short order.

[CWGT]

Hi all

Thanks for the new responses. I'll pass them on to the chap at the garage and see what comes - I'll report back shortly.

Best regards
Chris