Alarming misfire.....

[Jackonicko]

Accelerating modestly hard from about 65 (wife was behind in the old Peugot so not attempting to take off or anything) I had a severe judder (as though backfiring badly) and an orange engine warning caption, which extinguished itself after a few seconds. My wife reported a puff of white smoke, followed by slightly darker.

Everything under the bonnet seems fine, and in all other respects the car is behaving normally.

This symptom has repeated itself on four occasions in 200 miles.

The car is a standard, non CAT SE, with no chip, and no obvious mods.

I don't have Elanscan, nor do I have a PC (Mac, sorry!)

I hope to get Steve Williams to "look and quote" tomorrow, but in the meantime, I'd like to get an idea of what I'm looking at.

Coil?

Over-boosting?

Simple?

Costly as f*** (fish?) or cheap as chips?

The seller is willing to contribute towards rectification, or to take the car back. If it's going to be the latter, I need a quick decision so that I don't miss other cars on sale in my price range at the moment.

[Enright]

Do the paperclip test and then come back and report the code.

[TheBard]

For instructions on the "Paperclip Test" follow This link to Wiki LEC Check Engine Light Problems and read the "Paperclip Method" section.

Best of luck,

Ian

[Candles]

Following the incident were you limited to 4000rpm for about 30s with the CEL illuminated?

Could you tell us if the exhaust and airfiler are stock or upgraded?

Candles.

PS I'm thinking boost-cut.....

[Jackonicko]

It's my first Elan, I picked it up yesterday. It all LOOKS standard, though at 109,000 miles, of course the exhaust will have been replaced, and may not be stock. I don't have ramps here (my Dad has all of that stuff!). The filter looks stock.

I don't know if I was limited for 30 secs - after the 'bang' I didn't try flooring it!

(Call me a poof...... but)

I'm SO impressed by the diagnostics paperclip mode - thanks to the wiki and video I found it easily, and unplugged it, bridged the wires, and did the test. VERY straightforward, and very easy.

But 1 flash -brief pause - 2 flashes - longer pause was repeated ad nauseam (10 times, before I turned the key off) - and I think that the last incident was WELL within 50 starts.

However, I've made sure that the ALDL is properly plugged back in, and my paperclip is stowed in the cubby, so as soon as it happens again I'll re-test.

I may even stop and turn off first......

[WillB]

probably overboosting due to a sticking wastegate

[Jackonicko]

Thanks for the suggestion, Will. On reading it, I did a search for 'sticking wastegates' and now believe that it sounds a credible explanation.

Is it a big job for a pro to put right? Will it cost me:

a) a small and painless wedge (less than an hour's labour and cheapy parts)
b) a tooth-suckingly painful amount
c) a kidney
d) an arm and at least one leg

[dermotbell]

You just need to access the turbo (beneath the heat shield) and use some long nose pliers to wiggle the lever. I had this problem when I got the car, as it is now a daly user I no longer suffer the prob.

Regular use of the right foot helps once loosened off

[GeoffSmith]

Jon, since we spoke, the more I think about it, the more I think it's a stuck wastegate (although an overboost code should have been thrown up) as I don't think the turbo got much use in the mileage that Miles was doing.

The way to test for it is to floor the throttle and preferably get someone else to watch the boost gauge. If the wastegate is stuck, the needle will probably hit the end stop but watch out for when the ECU cuts the fuel as you'll likely hit your head on the steering wheel. If it is not sticking, the boost should be maintained at about half scale.

[Jackonicko]

Geoff - that sounds like what I experienced - a really alarming judder.

I will go out and replicate - I may see if I can do it on the disused runway.

[Monty]

You sure you got the engine light? as you would have a error code

Maybe you hit the rev limiter which is 7k, which wouldn`t give an error code

[Jackonicko]

Nowhere near 7k. NOWHERE near.

I'm pretty light-footed, and 4k is more like it.

I do wonder if the ALDL was pushed fully home when I found it, and whether that might make any difference?

I'm ABSOLUTELY certain that the yellow engine warning light illuminated (for a few seconds) - the same light which flashes when you bridge the ALDL wires.

[GeoffSmith]

The ALDL socket is only pushed into a holder and makes no connection. Mine is often seen dangling down into the footwell........ ooh urr missus.

[Enright]

Nowhere near 7k. NOWHERE near.

I'm pretty light-footed, and 4k is more like it.

In that case it sounds to me more like a coil-pack or leads breaking down.

I do wonder if the ALDL was pushed fully home when I found it, and whether that might make any difference?

Like Goeff says - nope. It's just a plastic retainer on the bulkhead.

I'm ABSOLUTELY certain that the yellow engine warning light illuminated (for a few seconds) - the same light which flashes when you bridge the ALDL wires.

That's very strange then because it should have generated a fault code.

If it's overboost then it should show up in any gear above 2nd when you floor it from about 30mph. But it's not like a stuttering misfire. It's lightning acceleration followed by a very violent cut and refusal to go any faster (which feels like huge deceleration because you're expecting it to do the opposite).

If you update your profile with your location then you may find a local helpful LECer who can help you to trace the fault by swapping known good bits.

[WillB]

My money's still on a sticking wastegate

Oh and if you do drop in and see Steve Williams, say hello from me!

[Sy V]

Mine too.

[Jackonicko]

I will indeed, Will.

Thanks to all for all the advice and opinions - it all helps me build up my risibly poor knowledge, and it has provided a really helpful degree of reassurance.

[Jackonicko]

Went out and replicated it again - got the 'bang' accelerating up through 4,000 rpm in fourth (same acceleration in 3rd had no ill effect). Tried to tell myself to keep my foot down and got 'stuttering' judders.

The engine warning light on for 12 seconds.

Paperclip test again gave a code 12.

[ailwyn]

Just checking, but you are waiting for it to flash 12 three times before it starts showing the CEL code(s)?

Once and it overboosts with no/lost code I can accept, twice makes me think that you have a coil/coils that are on their way out and failing under load, hence the misfire.

Failed coils do not produce an error code... when I broke down in Jan the CEL definitely came on, but no code stored, I put it down to me running the battery flat with the hazards going, which caused the code to be wiped, but it could have been just through ECU panic because the engine was stalling.

Check your plugs after a run/misfire, if it's failing coils then you may find the plugs are wet with fuel.

[Jackonicko]

Oh yes, I'm aware that you get three repetitions of the 12 code before a real code. Mine just goes on giving the no fault code.