7 posts / 0 new
Last post
Ngmatthews@me.com's picture
Offline
Last seen: 2 weeks 5 days ago
Joined: 05/05/2015
360R misfire

I've just bought a 2019 360R from Caterham, 5000 miles on the clock. 
I will add that I'm in Cornwall so a trip to Crawley is impractical. 
 

There is a misfire at 3500-4000 rpm which is a PITA as it's dual carriageway cruising speed. The car starts and runs fine and is great above and below that range. It's not cutting out, just a hesitation. 
 

Any suggestions as to where to start looking?

Jonathan Kay
Jonathan Kay's picture
Online
Last seen: 1 min 43 sec ago
Joined: 17/04/2014

Can you reproduce the fault while you're working on the car, not just on the road?

Jonathan

Ngmatthews@me.com's picture
Offline
Last seen: 2 weeks 5 days ago
Joined: 05/05/2015

Doesn't seem to do it blipping the throttle, it is very slight but noticeable on the road. 

John Vine
John Vine's picture
Online
Last seen: 13 min 10 sec ago
Joined: 17/04/2014

That could be tricky to pin down without some diagnostic kit.  What you really need is Easimap and an MBE985 cable to hook into the diagnostic connector under the dash.  Then you could log the actual problem on the road.

Without that sort of approach, you could be searching for almost anything: sensors, ignition circuits, earthing, injectors, fuel pressure -- the list is long!

Presumably the car is under warranty?  If so, perhaps limit your investigations to simple things like plugs, loom connectors and earthing points.   Earlier Duratecs had a habit of fracturing wiring, notably in coil-on-plug and TPS looms.  Perhaps your car came with uprated looms?

Re warranty, if Crawley is too far, you could try somewhere closer like Williams (near Bristol).  Or Millwoods (I imagine any charge would need to be negotiated with CC).

Good luck!

JV

aerobod
aerobod's picture
Online
Last seen: 5 min 21 sec ago
Joined: 17/04/2014

One persistent issue I had on my R400D was a low-load misfire at medium revs. It took a cheap recording oscilloscope to determine the connector on the number 1 coil pack had become loose and opened up the contact slightly, probably due to vibration of the loom. I replaced the sub loom (I already had the fracture-resistant silicone insulated race loom) and put foam tape on all coil pack connectors so that the cover contacts the tape, which should stop any vibration in the future.

In terms of diagnostics, if you can get the car to reproduce the problem while wedging the throttle open slightly with the car stationary, you can use an infrared contactless thermometer to check the temperature of each primary, the cylinder that is misfiring should cool down relative to the others, if the misfire is isolated to one cylinder.

James

John Vine
John Vine's picture
Online
Last seen: 13 min 10 sec ago
Joined: 17/04/2014

... the connector on the number 1 coil pack had become loose and opened up the contact slightly, probably due to vibration of the loom.

Yes, #1 COP connector is certainly the favourite.  Mine also seemed to get unusually dirty (due to a poor connection / sparking?), so you could try cleaning the terminals with meths or similar.

JV

Ngmatthews@me.com's picture
Offline
Last seen: 2 weeks 5 days ago
Joined: 05/05/2015

New lambda on the down pipe cured it. Caterham were brilliant and posted a replacement part under warranty during lockdown. 
Thanks guys