Talk Morgan Forums Morgan Sports Cars Maintenance & Servicing Roadster 3.0 2011 ECU advice

Hi All,

Couple of annoying symptoms and wondering if ECU upgrade would sort issues?

Starting car from cold and idling for a few minutes to warm up,idling revs are fine,But then drive car 200 metres on a housing estate road the revs are slightly high making smooth low speed driving erratic,then ok once on major road drives fine.

Another symptom when pulling up at junction/lights revs are around 1200,does not drop immediately,then drops to normal after few seconds ..is this the rev hang symptoms?

Any advice regarding this please and who would be best to get good results and rough costs involved? Live in North East.

Thanks in advance,

I'd start by cleaning the MAF sensor & throttle body and then checking for inlet air leaks.

As you’re in Durham
Peter Davidson
Peter Davidson Motors
10 Old Pit Lane
Framwellgate Moor
County Durham
DH1 5HL
Phone: 07722 157127
Situated behind BMS Quality Used Cars on Old Pit Lane.

Peter is Ex John Macdonald & Beamish Morgan

Remove your idle air control valve and clean it with an old toothbrush and some cab cleaner. If its on a drive by wire throttle clean the butterfly in a similar way, actually it's worth cleaning your throttle buterfly even if it's a traditional cable throttle.

All the above are easy and virtually free things you can do yourself and a little bit of careful cleaning should help the situation greatly, good luck with it

Yep I'm with Dave.... throttle body mechanical and electrical, idle control valve, notorious for sticking and throttle potentiometer/s. Unfortunately the throttle set up has only two sensors and these are well known to have odd behaviour patterns, next time switch the engine off and restart, if normal its the throttle . later vehicles of most marks upgraded to three which produces a more consistent function.

Also have you or anyone else recently disconnected the ducting to the throttle body, if so it may have been overtightened which can lead to air ingress around the butterfly and cause the idle control valve to behave strangely. The ECU thinks you have applied throttle and raises the revs to either hold at that perceived throttle position or in preparation to drive.
Ask Richard V6 as he has recently had such issues he also has a metal bodied throttle body now installed.

If your'e cleaning the throttle body with it on the car don't spay loads of cleaner in as you might damage the cat. spray it on a rag on your finger and wipe it that way. You can use gentle slow pressure to move the butterfly to access all areas but move it slowly as believe it or not you can create enough of a current to send a signal to the ecu and totally confuse it.

The early 3.0L Roadsters were traditional cable to throttle body, if yours is, suggest you check the return spring & exposed cable end are not gummed up with sticky dust, clean up and re-lube and try and get a bit to track down inside the cable.

The rev hang you describe is not uncommon on Roadsters, even the 3.0's, you can simulate this to test...

Handbrake on hard, 2nd gear, bit of revs, tickle the clutch to bite, hold, let the revs off & because the engine thinks it's under load & may stall it holds the revs even when you dip the clutch (it's a sort of anti stall) I used to be able to get mine to do it at tickover creeping out of the garage and up the driveway incline

Once you solved the issue. I want to add something to the excellent advice above.
For future: stop the habit of warming up engine by letting it idle for a few minutes. This is bad for your engine as well as highly ineffective to warm it up; Start and drive.

Thanks everyone,great advice and will investigate.