r400 duratec spluttering engine on low revs. then fixes itself.

[Tomiam]

Odd problem which started about a week ago. R400 duratec with roller barrel throttle bodies.

It starts fine but then as you drive at low revs the engine can splutter and start to die. Push down clutch, give it a blip of revs, release clutch and it will be fine.

It happens at low revs , anything less than about 2500

The weird thing is that it clears itself up with 15 min or so of driving In that manner.

If i drive at 3000 rpm or above its fine but that means I'm either accelerating reasonably quick on a normal road or its noisy.

 

I've driven it all day at Oulton Park without any issues. Went to drive out of the pits on way home and it did it again. Spluttering and close to the engine dying. Within 15 min or so it was cleared up.

engine was warm when we started.

 

It's almost like the ecu learns what it needs to do it low rpm driving and then forgets it when the engine is turned off.

I've checked the plugs and ht leads and they seem OK. Two plugs have a bit of rust around the middle but tops and bottoms are fine. I've cleaned them up and wd40 on connectors.

 

Any advice very welcomed. I'm not the most mechanically knowledgeable and this has me stumped.

[Tomiam]

Oh and at idle at will just drop the revs and die after a while.

[martyn]

Hmmm..  Something in the back of my mind seems to remember that this might be a common fault with the R400D.  If indeed it is the same problem then it is fixed with an ECU update.  Where do you have the car serviced?  Do you know if the ECU has the latest map?

[Tomiam]

HI Martyn, Thanks for the info.

I've only had it for about 4 months so havent gotten anyone to give it a service yet.  Its had an MoT at Millwood and its now booked into Williams Automobiles for a rear damper replacement in a couple of weeks though.

I have no idea on the ECU as to what map its got.  I suspect its not got the latest as the previous owner didnt appear to do much with it for the past 3 years or so.   Its got roller barrel throttle bodies, I dont know if this means it couldnt have the new R400D map or not?
Also being mechanically unknowledgable... if the battery was disconnected, would the ecu lose the latest map and have to relearn everything?  Sorry.. since getting the Seven Im learning fast, but there are gaps in my knowledge for sure. Only I disconnected the battery a while ago to clean up the earth lead on it.   Dont know if thats related or not.  

If I got Caterham to email me the map is there a simple way to update it myself or is it better to have it done by a garage, ie: Williams Automobiles in this case.

 

 

[martyn]

Nothing to worry about with disconnecting the battery.  The map is permanently written into the ECU so no worries about losing it.

I guess the car would only have received the updates if it has been into a Caterham main dealer for its servicing.

Best bet is to contact Caterham, explain and suggest about the ECU map.  The problem will be getting to someone technical enough to not just fob you off with excuses.  Might be a good idea to approach this through Williams Automobiles and ask them to contact on your behalf. I suspect they probably have some inside contact phone numbers they can use.

Hopefully someone else will be along with some more concrete info to back up my patchy memory!

[Jim 123]

You mention that your car has roller barrel throttle bodies.  If these are non standard fit, you may want to check that a couple of the fixing bolts aren't  working loose?  If the car has not had a lot of use prior to you buying it, maybe a induction system vacuum hose is perrishing/drawing air.  

What colour were the plug electrodes when you had them out?

[Tomiam]

Thank you both very much.  As a result of the info that Martyn said about this being a common problem with R400D's I went a googling and searched these forums for stuff related to ecu mapping + R400D engine problems etc.

I found a thread in which a chap had a similar issue and someone said "lambda sensor".    So I've jacked the car up, got underneath and unclipped the wire etc.
The connectors between the sensor and loom were completely covered in a green residue.  Think of the type of stuff you get on a leaking battery and you're not far off.   I cleaned them up and reconnected and it appears... to be perfectly fine.

When I go to start the engine it seems to be more urgent, starting on the push button only.  Whereas I had to blip the throttle to get it to start before.   Its not dying when left idiling once the car has warmed up.  Which it did before.
Im unsure if its even possible for the lambda sensor to effect this, but my car has never started on the push button alone and after cleaning those contacts up, it now does every time.

I've just taken it out for a 20 min drive without any issues at all.   Left it alone for 3 hours and then drove it home.  Zero issues.

Engine definately feels more responsive and is reacting well to throttle changes.

On the subject of spark plugs.  They were a medium grey.
Im also picking up a new set of plugs tomorrow morning from Williams Automobiles as a secondary precaution.

So thank you both once again.  Here is hoping that its not just a temporary fault and its actually been fixed.    :)

[John Vine]

Glad to hear you seem to have fixed it.  Just to reassure you, an R400D on RBs should start on the button without throttle input, and settle very quickly into a rhythmic idle.  If it doesn't, something is out of kilter. 

JV

[Tomiam]

And... bollox.

Problem is back. An hours worth of driving was fun and then going up motorway in 6th and it started spluttering and losing power again.

I had a complete set of new spark plugs on me. Changed them. No better.

Disconnected lambda sensor. It's gone away.

 

[SM25T]

Time for a new sensor. Hello Mr eBay.

[SM25T]

Time for a new sensor. Hello Mr eBay.

[Jim 123]

Here's a speculative thought or two.... The Green Residue is most likely the copper in the wire to the Lambda that is corroding. This could be linked to the fact that the car may have left it sitting around for a lot with the previous owner and in a damp environment.  It may be an idea to have a look at some other connectors (esp. in and out of the  ECU).  If there is some corrosion inside the connectors it may not be heavy or obvioius. I have used a dry tooth brush in the past to clean the male and also the insides of female connectors with some success, a soft wire brush would also do. You'll need to get the brush bristles inside the apertures of female connectors and don't forget to blow out any crud that brushing may dislodge inside  

Is there a Filter in the Fuel Line on your car?  It might be worth checking that you don't have some sediment that has formed in the Fuel Tank that's getting sucked through as you consume gasoline.

[Tomiam]

Just spent a couple of hours in the travel lodge car park working on her.

Bloke with a seemingly good knowledge of car electrics happened to walk past and help. Lambda sensor is apparently fine but we did find more corrosion on the female connector.

Cleaned it. Seems OK. ... but then it seemed OK last time too.

Will update in a day or so.

 

Your help is genuinely appreciated. :)

Thank uou

[Geoff Brown]

I have experienced the same problem not long after building my R400D in 2013. The car spluttered all the way from Southampton docks to Swindon after a fault free week in France!

I investigated by removing, checking & cleaning with a needle file ALL the electrical plug connections in the engine bay. I found corrosion/verdigris on the majority of the pins & the spark plug lead connections.

A liberal dose of electrical contact fluid (not WD40) on all & since then no problems whatsoever.

I assume the engine was not stored in a very dry atmosphere previous to its delivery to me.

The other component to look at is the Throttle Position Switch on the end of the barrels. Apparantly they can start to fall to pieces/ come loose over time giving the same problem.

[Tomiam]

Thanks Geoff!
It did a day of sprinting at Blyton Park without any issues, probably because it was foot to the floor driving.  Then on the way home it travelled for an hour with issues, I filled up with fuel and within 2 minutes we were on the hard shoulder of the M1.  
Disconnected the lambda sensor and the issue went away so Im pretty confident now that the problem lies wthin that area 

Had a quick look at the plug which connects to the lambda sensor again this morning and despite my best efforts at cleaning it, it still looks pretty shitty. :(    The male connector (on the lambda lead) is pretty clean.  Its the female connector on the loom side which looks rubbish. 
I shall have to source a replacement one.

I've got a week or so until I need to use her again so will do exactly as you've suggested and go through all connectors very carefully and take my time.

Thank you all once again.  :)

[Jim 123]

A call to these guys might be helpful.

http://www.lambdapower.co.uk/default.asp

They also have a FAQ page on their website.  Good luck.

[Smiffy69]

It would seem us Duratec guys might have an inherent design probem witht the way the sensors / mapping works when you have a RB Throttle set up.

I recently posted about the same symptoms on my car and ran various "controlled"tests to see if its a reapeatable set of symptoms given certain conditions. My finders were.

The car will start up and run from cold perfecly well with no problems.

If you stall "ahem!" or switch off breifly the car will start and run OK

if you let the car stand with engine off once it is up to temperature for a period of time and restart things get interesting.  Looking at the Map traces mine would start OK until the warm up timer expires (Lambda ignored and has a low value 0.4) once the timer has expired and with the lambda being low the ecu then starts to lean out the fuel mix until the point it starts to stall.  It then injects more fuel to try and recover and does this 2 or three times until it stalls.  Its only one you get the Lambda reading in its usual steady state of 0.75 - 1.12 (it oscillates around these values) that all things return to normal.

So this led me to believe that I had a Faulty Lambda probe.  I have swapped it for a new one and now change with the same results and traces ( ) 

My conclusion is that the warm up timer is not long enough for this configuration.  I did some research on how these probes work and they only start to read properly once they are in the right operatng temp band and you can see this from the Map traces.  When starting from cold values start low when 0.4 for about 90 secs then settle down to low .60 for 90 - 255 secs and then suddenly switchs on.

Every time the probe is cool and the engine map thinks the car is warm i.e. coolent is over 60 degrees the car runs lmpy until the Lamda switchs on then all is good (hence when after a few mins of driving or revving all is good again) .  As I can only read from the ECU I can't change anything so I can't prove this.

I also did consider the other side of the equation regarding air temp and that if the car is sitting hot but not running the airbox sinks heat from the engine bay and causes an artificailly high reading so as a result the ECU leans out the fuel until the temp in the airbox dropped due to flow.  However I have discounted this for 2 reasons - I saw no noticeabe change in temp after running and the Lambda should have compensated.

This looks to be a TADTS problem for this particular combo.

[John Vine]

Very interesting.  I had RBs fitted by CC Crawley last December, and cold starts, hot starts and general running have been impeccable.  Mainly for my own education, I'd like to do similar tests to yours, but don't have the necessary equipment.  Can you advise what I would need?

Edited to add that I don't have an airbox, just the standard Pipercross filter.  I don't know whether that would make a difference.

JV

[Smiffy69]

Hi JV

I just use easymap and the CAN adaptor to my Laptop.  ( The CAN can be a bit pricey though bt a useful investment for this kind of issue ) 

Where in Dorset are you ? I could pop over of you could come over here or we meet in the middle  if you want to use mine?

I also have the Pipercross Filter mounted on a CF box (hence why I called it an AIrbox but might have oversold it )

cheers

[John Vine]

Hi Smiffy69, YHM.

JV

[john aston]

MIne is a 40k R400 D and for 10k has had RBTBs. Early days- plenty of low speed stuttering after the car had been restarted from warm-  a coffee stop for example. Symptoms would persist for 3 or 4 miles and then would clear- as they would if it was possible to accelerate hard in 2 or 3 gears. 

Before RBTB car wouldn't idle when really cold so for first minute or two of manouevring   out of drive it got fiddly.. And sometimes even when warm tickover would drop  and car would stall

 

Post RBTB ticks over perfectly hot and cold; no stuttering . Mine was fitted by CCM  and no subseuqent settting up/mapping at all.  Also goes like a belted dingbat.

[Tomiam]

Update: Have removed Lambda Sensor. Unfortunately it was so tight that no amount of plusgas / tighten * untighten or levers would remove it.   Ended up welding a lambda socket to it and even then it wouldnt budge.   So I've drilled it out and am waiting on a new sensor to arrive from CC.
Unfortunately there is so much crap in the thread, in the pipe, that I need to realign the thread. Either a tap or a high tensile bolt (I think its 18mm diam & 1.5mm pitch) is needed.  Going to gently use the HT bolt first as I dont want the tap to get catch and mess up the existing thread.

Why do I think its the lambda sensor?
Car runs fine when its unplugged.  Repeated this test several times.
The spluttering / dying / minor hesitation only happen at 4000 rpm or below when its connected.   Above that it instantly clears.
Only happpens when the engine is warmed up.
The existing lambda sensor has zero markings on it.  Possible that previous owner used a cheap one but either way Im getting one from CC to ensure its the right one and rule out any possible problems.

Will update once Ive got the sensor in and have done a few miles.
 

[SM25T]

After all your investment ..... get a tap of the right size and clean the thread with it. Or take the primary or whatever bit has the socket in to a garage or exhaust centre. They should have a tap.

[SM25T]

If you use a HT bolt and it picks up on a bit of swarf, you could soon be back to Square One !

[John Vine]

Agree with SM25T, but if you do use a bolt, first cut grooves into it every 90 deg. This will help pick up crud and swarf.  And a lube like WD40 will help.

JV