ChrisC

Lets not speculate, lets let CC check. Most likely its the much discussed 620 over cooling issue, causing the ECU to resort to warn up settings which is causing the petrol smell. CC did discuss a fix on the evening web chat a few months ago, but there are is also a fix offered by PGM (as above). I bet it would pass an MOT (and IVA) if its up to temperature, and the cat is warm (5 min at 3-4000 rpm should sort that). This is exactly how its tested at all the IVA tests (only 3) I have been to. As for other models with cold starting / warmup issues, In my experience (4-5 Sigma 150, two 360R, and 4-5 420R, and a Supersport R, all stock setup) it always boils down to throttle stops/cable adjustment/throttle position sensor setting combination. It takes time to find that balance on a individual car, and that time, it seems, isn't always lavished on fixing this issue in a commercial environment. Also a combercial environment rarely get to see engines start from cold. I have also found throttle adjustment made within the first few miles isn't always appropriate after the first 2000 miles, and this has been the case for both my 360R and 420R I have built. Currently my 420R will hunt at idle if the coolant is lower than 15C, its only for a few seconds until the coolant is over 15C. I didn't start this behaviour until it reached 1400 miles. I will fix this over winter. However when it was first built my 420R, before I made my first adjustments it would hunt at idle until it reached 40-50C (but before the lambda sensor kicks in at 60). There are excellent specialist that can makes these adjustments, or adjust the ECU to your specific vehicle. Or (like myself) there are armatures that will gladly give their time to fellow club members to resolve these annoyances. Just don't suffer if you are annoyed with your engines startup.

I can't help other cars, only the noise I was diagnosing on my car. For reference this is my cars noise that was resolved with the spacer, and was diagnosed in PDC as TADS diff noise.

So for reference, my 420R, is now one year old, sintered plates, has lost no preload in 2000 miles (not as many as I had hoped) and one Trackday (also not as many as I had hoped). It's quite now my gearbox is no longer hitting the chassis, and I have RRT oil. The only noise I get from my diff is when the RPM drops below 1500 and you start to get driveline shunt, which I suspect is more to do with mapping that the diff. Personally happy with my sintered plated BMW Titan diff. I am planning no further diff changes apart from a magnetic titanium BMW specific diff fill plug to be delivered.

Yes - I did, and they are aware of the impact it had on my car.

I am guessing its the only thing it could have been.

I haven't been able to edit the video of the noise it stopped on my car (yet), but will post when I can. All I can say is my 420R build was predicted to have diff noise, due to the synter plates, and it did. However it was embarrassing bad, especially in reverse. The car was seen by CC during PBC, and again in videos highlighting the problem. All suspected to be due to the diff, ok fair enough. I had tried the RRT special oil, it improved most on the sound but not the clonking. I had discovered the spacer and had specifically asked CC if it would help, the answer can back as no. But for £3.75 plus some postage it thought I would give it a try. It resolved 90% of my noise problems. I now only get diff noise, when I expect diff noise, and no more embarrassing clonking while reversing. So this must mean the clonking noise wasn't diff, and was caused by gearbox chassis contact.

That would explain it.

Interesting a new "unboxing" 420R video posted on YouTube today shows a return to Ford Sierra diffs being supplied

Agreed, or connection problem.

It wasn't in my kit delivered October 2019, it was in a kit delivered January 2021. So sometime between those two dates. The gearbox angle may be different between a Sigma and Duratec engine cars, so might not have the same impact as it did on my car. The funny thing was, after I discovered it, I spoke to Caterham Gatwick to see if it assist with my problem, and they where unaware of it at the time.

When the club was shown the Caterham Technology Centre, I remember them showing the Bilstein development for the 160. At the time they said all Caterham shocks where mono tube, because the variance from a twin tube found in normal road car shock would be unacceptable give the weight of the vehicle. They even had one disassembled and showed its components and how the valves where changed for the 160. Do you know how to tell if the Bilstein fitted is mono or twin?

It is, but your never find it, it has no image and is listed under *Seats and headrest fittings*. Just search the part number 3E0G0002A. It's £3.85, fits any 5 speed post 2013. It fits between the gearbox and the gearbox mount, raising it by 3mm. It can be fitted without removing anything other than the gearbox mount, I just supported the gearbox with a jack. I believe the effect is most dramatic on Duratec cars, obviously I have only tried it in my 420R.

My new build had terrible bang and chatter. But its now all under control. First I swapped the kit oil to Road and Race Transmissions specifically formulated blend. Unfortunately it was as simple as that with my car. By chance I was speaking with a 2021 spec kit builder, who asked where the gearbox spacer went, to which I replied what spacer. It seem in 2021 Caterham introduced a spacer to lift the tail of the Mazda gearbox 3mm. This stopped 90% of my noises, which was suspected by Caterham themselves as diff noise, but obviously not. This only applies to the 5speed, not the 6speed. Sorry to say given the age of your car I would be checking the preload, and expecting a rebuild, unless you have a recent record of one.

There hasn't been a connector for my 2011 Sigma and 2016 360R or 2019 420R. On all these cars the number plate wire is just a single long wire supplied with no connector (as shown on the wiring diagram). The connector will be added by builder during the build. The 2011 and 2016 cars had a bullet connector added for the number plate light, that got a little more complicated with the 2019 car, where the LED number plate light had two wires already. In that case I added an Econoseal connector. You can see a factory (late 2019) build photo of the number plate wiring in my blob post, but this crimp spade terminal isn't supplied in kit, so it will all depend on who built your car. https://caterham420detailedbuildblog.co.uk/2020/02/15/number-plate-light/

I have recently discovered something interesting after looking into a noise problem. Everyone that heard the noise I was investigating suspected diff, but the solution was a spacer added between the gearbox and the gearbox mount. If you have a Mazda gearbox, and your car is pre 2021, I recommend 3E0G0002A spacer if you have any unexplained drivetrain noise.

Depends on the model of Sigma, 150, 140 and 310 definitely are not connected to anything. I think my 125 was connected to the plenum. I have never worked on a 270 so for that I can't be sure. I like to add a small piece of hose, open one end, and angling it down like a U bend, so a direct water attach wont end up in the MAP sensor, however remote that may sound.

Sounds classic lambda sensor to me. But agree with Tom, unplug it and test. It won't pass an MOT without it, and it will still be rich, but it won't be at the extreme of the possible adjustment. If it is faulty, try to stick with quality Original or OEM replacements (Ford or Bosch) and avoid fakes.

My experience is with a fair few Sigmas 150s mine and others, and one 125. The 125 once set seemed to say set, but my 150 liked a tweak about once a year.

Is your Sigma a 150? The idle speed is controlled by the ECU, but the throttle does need to be open enough to maintain that engine speed, which is a mechanical adjustment.

The Mazda 5sp normally has a 3.91 BMW diff. But I assume the CWP isn't for sale, because its a part that's not available as a spare part from BMW. So if that needs replacing you have to start with a new diff. The 3.64 was fitted to 6 speeds. Edit 5/5, I miss read the Caterham Part site, change 3.62 to 3.64.

I think its going to be a £35k (ish) by the time it's on the road. Which seems heavy, but not outlandish. The buyer has over paid, so will loose some money. The big can of worms is the IVA. Personally, the sun is out and I would want something to drive, not something stuck in the garage for another 6 months, for example there is currently a 420R 2018, with 2000 miles for sale on pistonheads at a well known dealer, for that type of money. It's more honesty, more powerful and drivable today.

Oh as for spec changes between 2015 and 2019 (assuming both are R models) Carbon plates (known to wear out) replaced with sintered plated Weather gear and boot cover factory fitted Rear badge style change (twice) Nose badge style change Key stock changed from aluminium to plastic (I think for safety) Speed sensor design changed Rear calipers are new items instead of refurbished units Cut down nut replaced with Top hat on upright Headlight design changed Instruments changed from 1/4 sweep to 3/4 sweep Loom design changed (modular 3 loom introduced , chassis, dash and engine) Dash control module introduced Swap to later ECU (from MBE 992 to 9a4) Washer bottle relocated to boot (from under plenum) Plenum design change Radiator deign changed Fan moved from behind radiator Thermostat (my 360R needed a 82c stat to make the fan / ECU combination to work properly, but not 100% sure on this one) Exhaust and primaries are now supplied polished Exhaust heat shield is no longer supplied Tyres CR500 to ZZSThink that's it, but happy to be corrected

The kit (based on the vin), was from 2015. The 360R was released around April time, so kits ordered before April (bare in mind kit lead times) would be Supersport R. I built a very early 360R. Early 360R cars have 1/4 sweep instruments, by 2016 they where using the 3/4 sweep instruments. My early 360R was an October 2015 kit with vin 72503, that car is 72093 nearly 500 cars before my first built kit. I have never seen an earlier 360R than my build, let along one nearly 500 chassis before. It's also missing all the R bits, Instruments, Gear Knob, and there is no picture of the key stocks. These parts are controlled by Caterham, they won't release them unless you have a R model. The stickers (rear wing, bonnet and dash) don't look right, but they can be purchased from the online store these days. Other red flags, why hasn't it got a genuine Caterham badge on the back? Only the Caterham receipt will tell the full story, but I will eat my hat if it's a 360R from the factory. It also doesn't have an IVA, and from the photos my list of rectification work would be as follows (and this is only what I can see): IVA trim missing on front wings, IVA trim incomplete on front suspension, IVA trim incomplete on indicator pods, IVA trim missing on exhaust heat shields, grommets missing in head light brackets, headlight wiring requires rework, repeater wiring requires rework and routed incorrectly. IVA wing mirrors missing, Speedo in KPM (needs to read in MPH and KPH), Wrong rear brake pads (so potential brake bias problem), Rear lights (need to be red not white), You also won't be able to claim amateur build, because you have to be in the build photos submitted. Which means the rules are different, but not 100% sure on the effect of that, I have only IVAed under amateur build rules. Either way it's another £600 to get a test, and wait before you can use the car on the roads. I suspect this is a kit build in the bad old days when builders where hit with big rectification bills at PBC, and the owner decided to go their own way.

Also not a 360R, especially not a 2019 360R. Kit from 2015 which would make it a Supersport R.

I posted the links for information. It's your post from 10th May 2018 that announced the release of the Tracsport BMW offering. I feel you should read my post properly. I have NEVER said the Titan design is the same for BMW and Ford, because obviously they are not. Thanks for being insulting; I have published the information on my Titan diff on this forum. I have nothing more to add.