Engine Cut Out

[Mike Trout]

Hi Guys,

Advice needed please. A friend has recently bought an SE which is in lovely condition. The engine has been nicely presented with silicone hoses, a dump valve. It was obviously someones pride and joy, but the poor fella got killed on holiday by the awful sunami tragedy.

Anyway the car runs great other than when your driving it hard. All goes well in 1st and 2nd then as the revs come up to limit in 3rd it cuts out. The engine management light comes on, and power is cut. After the light goes out it's back to normal.

Having read a few of the posts on here it's obvious that there could be a number of reasons for this. My problem is that I have no idea whether the car has been chipped or modified in any way, so I really need to get it to someone with the correct diagnostics to pin point the fault.

I'm based in Ashtead, Surrey, near jcn 9 M25. Any recommendations?

MIKE

[Sy V]

Mike

I'm sorry to hear about the unfortunate history of your friends car - not nice. If the car has silicone hoses it may have been owned by an LEC member (we had a group buy, not long ago) which is even more alarming (but I'm fairly sure the group buy was post-tsunami).

On to your friend's problem.

This sounds like boost creep/overboost and is normally indicative of modifications of some sort - most often an oversized/free flowing exhaust.

There are plenty of owners in the Home Counties who could pop along and take a shuftie, but in the meantime, a picture of the tailpipe might give us a clue.

I wouldn't go taking it to a garage just yet...(awaiting the cavalry...)

[Sy V]

Another thing to consider would be a stuck wastegate actuator rod (especially if the car has been sat for some time pending sale).

The engine warning light followed by rev limitation and then sudden cure-syndrome is perfectly normal and part of the Elan's fail-safe system.

[Mike Trout]

Blimey that was quick!!.

Your right. It has got an after market exhaust so you may be on to something there. Any help would be gratefully received.

I'll take a pic of the tailpipe and post it for you.

Should this indeed be the problem, what's the cure?

MIKE

[Paul.P]

Mike, if you can have a look under the front of the car, where the exhaust goes over the subframe under the engine, the original had a flattened bit ( squish ) which caused back pressure, which in turn stopped overboost, if your exhaust hasn't got this, it will be an aftermarket one, & overboost will probably be your problem, what does it boost to on the gauge under full throttle ?

[Mike Trout]

Thanks Paul. I'll check that out as well.

It's throwing it down here at the moment, so I'll get on it as soon as it clears a bit and let you guys know.

I really appreciate your input.

MIKE

[Mike Trout]

Here's a couple of pics of the engine bay and tail pipe. I can't get under the car at the moment to check the exhaust, but I'm sure you're right about the after market system.

Assuming it's the system that's causing the overboost, what's the plan of attack?.

[Sy V]

Hmm... I think the SW Lotus aftermarket exhaust looks like that - anyone?

Not part of the Samco silicone hose buy. But has carbon fibre (I think pre-Darren vintage - I say that because Darren supplied his with a different make of hose union) main pipes and probably a K&N air filter fitted.

Somebody did like this car.

Check the turbo wastegate actuator rod is moving freely - you should get about 1/2" play. I find it easier to go in with a pair of molegrips from below.

The, if you're confident to pull the ECU, check the integrity of the security seal/sticker. If it's broken it has either been adapted for CO emissions early in its life (it may even have 'CO done' or words to that effect written on it) or, by removing the smaller end cover, you should see if it has a daughter board fitted - if so it's probably chipped.

Final way to rid yourself of all overboost is to port the turbo's wastegate from 16mm to ~21mm.

[Doug]

just to second Sy's responses above -- all correct so nothing to add on that!

sounds like you may need to port the wastegate (very rewarding if you are a DIY guy) and your problem will be gone -- then you can run the boost WOT and not get the boost/fuel cut.

after that you can look into one of Alan's Mountain ECU chips if desired . . .

there's certainly a thread in the Forum with pics and instructions on how to port the wastegate -- SEE THREAD HERE

[Mike Trout]

OK thanks guys,

How easily should the actuator rod move?. I've managed to get some swan neck grips on it from above, and it doesn't want to move from side to side (left to right from above) at all.

Where is the ECU located? I will check that next.

MIKE

[Paul.P]

How easily should the actuator rod move?. I've managed to get some swan neck grips on it from above, and it doesn't want to move from side to side (left to right from above) at all.
Where is the ECU located? I will check that next.

Mike, the actuator rod, is quite hard to move & think you need to have a go from underneath. The ECU is behind the glovebox, just open it up & you will be able to carefully prise it so it will open fully, then you can get at the ECU.

[Mike Trout]

Thanks Paul. Found the ECU thanks and the security sticker seems intact.

I wont get a chance to get the car up in the air probably till next weekend now, but I'm assuming that if the actuator arm is not moving freely the turbo needs attention anyway. Will this mean it's got to come off? cos if so I might as well take on the waste gate porting project anyway.

I'm a fairly competent mechanic, but without much experience with turbos. It looks like it might be fun getting the turbo off, so any tips would help. I've got an air grinder and stones to do the job.

You guys have been great. Thanks

MIKE

[John_W]

Mike,
I'd advise keeping it as simple as possible. Don't remove any bolts near the turbo unless you have to. The chance of shearing bolts is high.

Several people have managed to free the wastegate simply by moving the actuator rod, so that's what I'd advise trying first.

Anyway, it's not certain that the wastegate actuator is the actual culprit; it's just something to be checked. Other things can cause overboost also, and all that neat colourful plumbing might hide an MBV-type device or orifice.

John

[Enright]

Mike, there's an easy way to free up the wastegate which leaves you in no doubt that you've got full movement once it's done.
It just means unbolting the diaphragm bracket from the turbo housing and then moving the whole lot backwards and forwards. It's fiddly - expect skinned knuckes, but you can be sure that it's working properly once it's been done.
See this thread, which includes some handy pictures!
Unfortunately if you're still experiencing the same problems after performing this, then you're into the realms of potentially a little more expense and a LOT more time.

The first thing (as Sy has said) is to try to find out if one of ESM's Mountain Chips has been fitted. If it hasn't, get one.
They raise the cut-off limit which may just be enough to avoid the boost creep problem.
They are also the safest, cheapest and best way to add a heap of performance to your car. Up to 40BHP for £100!

Then if you're STILL getting overboost, you've got to either put a restriction in the exhaust (which is just plain daft after fitting a bigger system), regulate the use of your right boot (ditto), or port the wastegate.
Only porting the wastegate is a guaranteed fix. But it's a big job fraught with the frustration of siezed/snapped nuts, impossible gaps and possibly a LOT of downtime.
Make sure you can be without your car for up to a couple of weeks before embarking upon it.

[ailwyn]

I hate to point out the obvious, but have you tried the paperclip test? This will at least confirm overboost.

FWIW if you are planning on selling it, stick a restriction in the exhaust, IIRC a gasket with a 2" gap should do the trick.

If you are keeping it on the other hand... get a mountain chip in there then port the wastegate if that does not cure your boost creep.

[GeoffSmith]

FWIW if you are planning on selling it, stick a restriction in the exhaust, IIRC a gasket with a 2" gap should do the trick.

I think this was suggested after the Peco purchase, but I'm not aware of anyone actually trying it.

[Doug]

I think you guys mean a gasket with a 2" hole diameter?! (not "gap")
(or maybe I speaks the wrong English?)

this is such a bodge fix it is sick -- don't do that it might work but only for a short time as the gasket will not be stout enough to endure . . .

[GeoffSmith]

I think you guys mean a gasket with a 2" hole diameter?! (not "gap")
(or maybe I speaks the wrong English?)

this is such a bodge fix it is sick -- don't do that it might work but only for a short time as the gasket will not be stout enough to endure . . .

Me and the Welshy know what we're on about

Quite right young Doug. What was suggested some time ago was an OE exhaust gasket, as the OE exhaust had a 2" bore them the gasket would have a 2" diameter hole! As I said, I think it was more a bright idea rather than a proven solution. I still doubt whether it would work and as you say, I don't believe it would last for more than 5 minutes. I remain to be convinced.

[ailwyn]

ok, place a restriction in the exhaust which will reduce the bore at that point down to 2".

This has been suggested a few times, I'd be surprised if nobody has tried something similar - however I do not recall any evidence either way being posted.

Scratch that anyway, I misread the first post and thought Mike was trying to get it fixed to sell.

I'd definitely go the wastegate porting route.

Ailwyn

[GeoffSmith]