Low speed kangaroo 620

[nonturbo]

Hi again

ive got a low speed boggy running 620s and the idle speed is jumpy.

I know they have a cold map and a warm map but even when warm it smells rich and does not run smooth.

I'm thinking of taking it to Luke Stevens Developments for a remap but was wondering if anybody has had a similar experience with this fault?

I've always fueled up with Shell 99 

And when giving it beans it feels ok but I do think low speed 10-35 should feel smoother.

 

[Jonathan Kay]

Yes:

https://www.caterhamlotus7.club/forum/techtalk/620s-clutch-seems-go-‘floppy’-occasionally-when-depressed-stalls-when-cold

https://www.caterhamlotus7.club/comment/2228751#comment-2228751

Jonathan

[Benton]

Prime suspects are lambda sensor not working and/or TPS not adjusted correctly, been there!
What mpg are you getting?
Has it just started happening or has it been like this all the time?

Be aware the overall standard factory mapping is sub optimal which certainly doesn't help matters,  If you want to splash the cash then a new ECU and remap from the likes of PGM should certainly resolve the problem.

[SM25T]

Really shouldn't have to do this on a (very expensive) new car !! 

[nonturbo]

Thanks for the info.

I'll try a new lambada sensor as it's just started doing it.

mpg is not that good and I can defiantly smell it and so did the neighbour who gave me an earful this morning.

It's only done 3k and as you say I don't expect this from a top of the range model but it's all part of the experience I guess!

Anyone know the part number? 

 

[Benton]

On the 620R it's a Ford part  3M51-9F472-BC, Bosch 258006599 equivalent, however this may not be the same for the 620S.  Best take it out and read the serial number off the side. 
When mine went kaput whilst under warranty and was awaiting Caterham to replace it (they didn't have any in stock at the time!) I bought a used one off eBay for £20 which worked perfectly well.  New ones from Caterham were over £170 at the time .  
There were however other cheaper supposedly equivalent new lambdas available on eBay.   If you can find a friendly local Caterham owner with a copy of Easimap software they can soon check whether it's the lambda and look at the TPS setting.

[nonturbo]

Brilliant! I'll check the number.

And see if there are any Carrotland members with the technology about that are happy to help.

Many thanks 

[Phillip Meyer]

I had the same problem with my 620s twice last year (bought it from Caterham in July so they replaced it). Your problem sounds EXACTLY like my issue which was fixed by replacing the lambda sensor.

Oddly enough I popped mine out today as I want to buy a spare, just in case. Looking online you can get some from £25 by brands I have never heard of. I'm going to give one a try and see if I notice a difference. Mine looks pretty coked up.

[7 wonders of the world]

Rather than looking at the symptom you need to address the cause and get the cooling system to function correctly and then double check the mapping.

 

 

[aerobod - near CYYC]

There are quite a few cross-referenced Lambda sensors that can be used as opposed to the Ford one, sometimes Bosch sensors are easier to obtain at a more reasonable price: https://www.oxygensensor-crossreference.com/convert/ford/3M519F472BC, but beware of counterfeit sensors that may be sold on some online sites.

[nonturbo]

Nice 

thank you

[Phillip Meyer]

I was wondering, there seems to be a plethora of really cheap senors out there from brands I haven't heard of. As this seems to be a highly consumable part for the 620, why wouldn't you just buy a few really cheap ones? Other than it failing (which seems to happen every 3 to 6 months anyway), what could go wrong?

[Benton]

which seems to happen every 3 to 6 months anyway

 

After the initial problems I had with the TPS setup and duff lambda were sorted the current lambda has been working fine for over 12 months / 5000 miles with no problems.

[aerobod - near CYYC]

My R400D had too rich of a mixture due to not adjusting for my 1250m altitude properly, destroyed the initial Lambda sensor within a year. It has now been 32,000km and 8 years since the replacement. Several things to watch out for that will destroy the sensor quickly:

- continuous over rich mixture leading to carbon buildup that clogs the sensor or too much combustion in the exhaust system that shocks the sensor;

- sensor too low in the exhaust, leading to thermal shock from moisture soon after startup (as the sensor is already hot due to the heater element in it);

- oil burning leading to carbon buildup on the sensor;

- use of sealants that are not Lambda sensor safe, contaminating the sensor element.

[Phillip Meyer]

Hi,

Was this on a 620?

My understanding is that the 620 has a far too efficient cooling system and many (mine included) have no thermostat so cannot switch the cooling off.

My water temperature hardly gets up to 90c unless stationary and if it is cold weather I just get it out of the 'blue' section on the temp gauge. This causes the engine to run too rich (because it thinks it's cold) and so burns through the sensors. 

Could I ask what you did to change the TPS setup? (I have zero experience with this)

I'm very happy with the car, it is fantastic, especially on track when it is pretty much the fastest car there. I think I will get the PGM upgrade to the cooling system at some point soon but right now my car is under Caterham's warranty so I don't want to change anything big until that has run out.

[ChrisC]

I have noticed something interesting with my 420, and this may or may not translate to the 620.  
Each time I isolate the battery, which I do frequently to maintain my batter health, the ECU looses it's long term trims.  This wouldn't be such a problem, but the base map is rich, and the ECU lambda sensor value limits means it's ignored until a significant time / coolant temperature is reached.  In my 420 case from a isolator off start I need a coolant temperature of 98c before closed loop control is engaged, compared to a start without isolation where the typical 60c / 30 seconds is all that needed before entering closed loop. Once closed loop is established the long term trims are applied and the map is adapted to obtain the correct mixture. 
If this is the case for a 620, the combination slow warm up in comparison to the 420 might mean a 620 would fail to achieve closed loop and therefore fail to trim / adapt the map.

[Phillip Meyer]

I never disconnect my battery (I do connect it to a VTEC conditioner almost always) so I assume this would not apply to my 620?

I do think there is a basic underlying issue with Caterham's design for the 620, it just cools too well as there is no system inbuilt to stop or reduce the water flow through the radiator.

I have tried some masking tape over the top of the radiator but that had no effect, I'm next going to try covering a portion of the back of the front grill (where the big 7 logo is) to see if that helps. As mentioned, I think the only solution is PGM's mod (but it's expensive). Caterham just repeatedly say that they don't see it as a problem and it will not impact engine life.

[Benton]

On the basis that you've been back to Caterham twice with lambda problems I would have thought by now Caterham would have double-checked the TPS calibration alongside the lambda function by connecting it up to Easimap,

Because my car was originally under warranty I didn't go down the PGM cooling mod route and instead utilised some plastic correx board cable-tied to the nose grill, which I still do today. Through experimentation I've found I can quite happily keep the engine in the 80-90 degrees range (road usage) using this method, though I'm assuming my car does have a thermostat fitted.  Hardly ideal but seems to do the job.

The consensus seems to be to properly sort out all of the 620 "opportunities" you need to:-  get the cooling mod done, get a new ECU/remap, and whilst you're at it, sort out the suspension, replace the LSD and possibly the exhaust ....... maybe I'll set up a GoFundMe page 

[7 wonders of the world]

The 620 cooling system is inefficient in so much as it cannot maintain the correct operating temperature due to CC's poor design and instalation!

If your car is under warranty you should push to get it resolved asap.

[Mark w]

Ive had a 620R for 7 years now .

I would , in this order 

a) Replace your Lambda sensor. Ive only had one replacement in 7 years , they dont all fail provided b) below is set correctly.

b) Check that your TPS is set correctly at load site 0 at idle and that the air flow is correct at idle.You should be aiming for 0.43V fully closed ( i e with the butterfly shut and no throttle stop in place ) , 3.39V fully open and 0.57V at idle. You will need easymap to set this correctly. These values work on my car but double check what value your map gives for load site 0

c) Upgrade your cooling system  as set out in the article i wrote for low flying here here 

If you do this correctly you will find that your car runs pretty well on the standard map.

 You can then decide if you really want to spend significant sums on further upgrades ( or not !)  

 

[nonturbo]

Replaced the Lambda sensor today and the old one was pretty coked up so will see if tomorrows run yields better results.

I've booked it in with LSD just to observe the settings tps etc

I agree the cooling system is just to cool for anything other than track or a day with 19c plus air temps.

a load of tuition 

cooling system upgrade 

ecu and remap upgrade 

sadev and paddle shift upgrade 

suspension upgrade 

a few more carbon upgrades 

maybe some new wheels

happy days! 

 

 

[pgm]

Hi guys, if any of you require any help or just advice about the issues that your 620's are experiencing do feel free to give us a call on our workshop number, 01403713626. Alternatively do join us at our soon to be announced 2022 Open Day if you are within distance. We will do our best to chat if you call or if we aren't available we will give you a call back.

Kind regards The PGM Team

[nonturbo]

Lambda sensor replaced and running good again. 

 

[GulfSeven]

Lambda sensor failed in the first 3,000 miles? 

[Benton]

Lambda sensor replaced and running good again.   

 

Glad you got it sorted