Engine Stutter at 5,500rpm

Hello all
Regarding the engine misfire at 5,500rpm. Was there ever a definitive fix for this as my Exige has this problem at the moment and I’m really struggling to cure it.Already spent alot of money at my local Lotus dealer in Germany, Speed Senser, Coil, Leads,Camshaft Senser,Thottle Body and I’m no nearer a solution. HELP!

I assume you’ve done the ECU upgrade?


Hello IDG
Having just spoken with Storm in Leicester, they have said that due to the new battery that iv’e had fitted the ECU could have lost it’s program and will need re loading.
Are you aware of anyone else suffering from this problem?

If it’s a stutter you can get through then reflashing the ECU will be the way to go…

If it limits at 5.5k then… Oh dear, where to start!

But sounds like a simple easy reflash is all that’s needed

Hello Mark
mmmm… it hits the limiter at 5,500 as I definitely can’t go through it.
This isn’t the answer that I wanted you to hear I suppose.
Is there anything else I can look at given the new bits Iv’e already tried?
(please don’t say Honda conversion)
Some xtra info…
I can drive all day long in 1st, 2nd,3rd gear no problem with limiter, as soon as I criuse in 4th or 5th gear it hits the limiter and the only way to clear it is by switching off.
Having read previous mails from a few years ago its seems this was quite an issue for a while.

Yes, it has been covered, and many possible solutions posted, but not all of them worked for everybody and some of them never worked for some people.
Definite solution: swap ECU, install an Emerald.

Basically the original one has detected a misfire (however small) somehow and is limiting the engine to 5.5K to limit the risk of fire by dumping more unburnt fuel into the CAT than it can process.

Emeralds don’t have this protection, but a constant misfire is rarely an issue, and besides, if your car catches fire, you can’t blame Lotus anymore.

It’s just protection from numpties.
Who in the world would not notice if the car was running in 3 cyls and continue ragging it!?
Only a numptie.

Yep, emerald ECU will cure it forever plus allow you to map the engine better etc…

However yo’ve done the wheel speed sensor and all the HT stuff (leads and plugs) then you either do have a genuine misfire somewhere, could be cause by cam timing slightly out maybe…

But the only other common cause and one I didn’t follow up was a sheilded cable that runs fromt he sensor to the ECU, basically on Peskys car it was chaffing against the bulkhead and so sometimes not reading… If you can replace this wire then you should be all OK…

Worth a go… Otherwise an Emerald ECU is well worth it!

Hello IDG
Having just spoken with Storm in Leicester, they have said that due to the new battery that iv’e had fitted the ECU could have lost it’s program and will need re loading.
Are you aware of anyone else suffering from this problem?

Yet anpther classic from Storm. They really are full of [censored]!

Changing your battery will not alter the tune in the ECU, the only way it could be removed is by someone plugging a Lotus tool or laptop into it. Have Storm recently worked on your car as it’s the sort of cock up they would make.

Can only agree with MarkA Storm are a real er … shower

Hello Again
First of all, I would like to thank you all for a fantastic response to my problem.
I can’t believe the new information regarding this, considering the local dealer in Germany was in consultation with Lotus directly and they seemed to be totally unaware of these obviously recognised problems - especially as I said to them that I thought it might have something to do with the engine management system !!
Sometimes you wonder if the hassle is worth it, and then I think to yesterday evening when the limiter didnt cut in on a sweeping bend on the local autobahn, 3rd gear, full revs, huge grin.
Even my girlfriend forgave Lotus for a time.
Anyway, back to my problems,
I think an Emerald sounds like the way to go.
I was hoping to use Storm to fit one. Not so sure now.
Is there a good, reliable garage in the Midlands that could M.O.T my car and fit and set-up the new E.C.U?

When it comes to Lotus always :confused

P.S Any of you fine gents going to Le Mans, for 50th anniversary and race ?

Re Le Mans… quite a few are heading down…

Im also heading to the Classic British Welcome - 50th Lotus celebration on the Friday…

Travelling on Thurs on the 11.15 HMS Speed Ferry.



You really need a specialist to fit the Emerald, the wiring has to be cut and spliced and the map loaded etc - thats something Storm :

a - Are NOT capable of
b - Most likley wouldnt know where to start anyhow

So you need to find a friendly MOT station, if you really want to take it to a dealer I would suggest Nick Whale in Bromsgrove and for fitting the Emerald maybe SeanB could offer some professional help or talk with the Edwards Boyz - www.Lotuspower.co.uk

Fitting the emerald isn’t to bad if you are good with a soldring iron and thanks Andy for mentioning me.

I had mine fitted by Dave Walker at Emerald and I would recomend this route to everyone for the following reasons.

  1. They have done trilions so nothing is a suprise
  2. Your going to have to have it mapped anyway so if its there it all gets done at the same time
  3. If they do the work and there is a problem, you only have one place to call, you won’t end up with Emerald blameing the fitting company or vica verca
  4. Dave Walker is super cool (Frankly this is reason enough!!)


Dave Walker is super cool

“He is also mad” - quote from Circuit Driver mag