aerobod - near CYYC

I just place the lower half of the doors on a flat surface, with the upper half vertical and touching each other at the top.

Yes, elevated altitude was the main reason, the standard 992 ECU defaults the air pressure to 1040 millibars, as I found out when adding the SBD pressure sensor. The 992 can see the air pressure and is wired to accept the sensor, but the maps don't use it. i also found that the standard maps didn't correctly use the full range of the TPS, perhaps due to the tolerances in either the throttle body or TPS manufacture, but I couldn't have both the minimum throttle site below 0.5 and the maximum above 14.5 when the throttle stop was set to allow the engine to idle. I also found inaccurate mapping around the temperature sensor curve and decided to use a wideband oxygen sensor that required mapping adjustments to get the best out of it. Overall the encryption and locking of the original ECU was too limiting for what I needed to do with the car. I do have the 992 ECU as a backup, which I did use I 2015 after I did a map update on the 9A4 and had Windows crash on me during the write to the ECU, causing it to be "bricked" and having to be sent back to SBD for a factory reset. Supposedly the crash happened during re-write of the communications block in the ECU, so I couldn't communicate with it anymore, just bad luck according to SBD.

A standard R400D setup will idle very well if the mapping is modified, I have a perfect idle at 1000RPM, but had to swap to the unlocked 9A4 ECU to get there.

Carbon can be removed to some degree with water spraying. Basically take the engine to a hot operating state, remove the air filter and idle it at 3000RPM by inserting a piece of folded cardboard of the right thickness under the throttle stop. Take a spray bottle with a fine mist nozzle of about 1 litre capacity filled with distilled water and pump the water spray into the throttle opening at a steady rate that drops the idle to 2000RPM, but not lower. If the idle drops too much, just stop spraying until the revs come back to 3000RPM again. It will take 10 mins or more to spray a litre into the engine, so no risk of hydro lock. Water / steam seems to work as well as any carbon solvent product, as seen in engines that have a coolant leak from a head gasket failure, leading to a carbon free combustion chamber. Best to remove the lambda sensor to avoid any fine carbon clogging while doing this and change the oil afterwards. Try at your own risk! I have done this several times (before each of the last 3 oil changes) and have seen a slow removal of carbon on the piston crown below the inlet valves, as viewed with a light through the spark plug holes.

1200RPM is quite high, I'm assuming you adjusted the idle stop screw to increase it?. It is worth checking with the MBE cable that your TPS site is still in the range of 0 to 0.4 while at idle, as you may experience idle hunting or lack of injector shut off at closed throttle when at higher revs if the TPS throttle site is 0.5 or above at idle, leading to drivability issues. You can make a very small adjustment in the TPS position by loosening the two screws (and potentially slotting the TPS screw holes slightly), to get it to the right throttle site. My Duratec R400 idled at 950RPM on the standard Caterham 992 ECU, but I changed it to 1000RPM in the map when fitting an unlocked 9A4 ECU, it idles flawlessly.

The default map for my R400 supplied by SBD with the 9A4 ECU had reverse TPS mapping (as used by Cosworth). The engine would only start and run roughly with a very narrow throttle position range. If you have the MBE cable, check the TPS throttle sites in Easimap start below 0.5 with a closed throttle and reach at least 14.5 with the throttle wide open (engine not running, ignition on). The TPS voltage should also increase from low to high smoothly as the throttle opens. If you don't have the cable it will be pretty well impossible to get things right without either taking to someone who has and knows the 9A4 ECU, or buying it yourself. Next I would check all temperature sensor values are plausible and relatively accurate, as even if the sensors are working correctly, the mapping curves won't necessarily be the correct ones for the sensors you are using, use an infrared/laser thermometer to compare Easimap temperature values with the temperature near the sensor to ensure they are within a few degrees of each other. if that all looks OK, If the engine can be warmed up I would check that lambda values oscillate from lean to rich at least once every couple of seconds to confirm fueling at least in the right post code. I have found it invaluable to swap the narrow band lambda sensor for a wideband one to give accurate fuelling feedback information (I fitted the Innovate LC2 system), making fuel adjustments from logging information quite easy.

Ideally checking the sensor values using an MBE cable with Easimap would show any implausible values. If you can't borrow or buy one, I would check the temperature sensor first. I believe the resistance should be about 2000 ohms when hot and 50000 ohms when cold, but basically it will change by at least an order of magnitude from hot to cold and become lower as the temperature rises. The air intake temperature sensor that is combined with the MAP (assuming plenum as opposed to roller barrels) should also vary in resistance as the temperature changes. The last resistance check is to see that the TPS resistance also varies smoothly with movement. I would also confirm the throttle idle stop screw hasn't loosened off.

The drag for a given body is proportional to the cross-sectional area, but a vertical plate has a Cd of 1.28, the slight inclination of the windscreen will make it slightly less than this, whereas the Caterham body will be somewhere closer to 0.7, so not quite just the effect of frontal area. Also, the drag with the roof on will be mainly affected by changing the windscreen from a flat plate to a bluff body from an airflow perspective, dropping the Cd of the windscreen/roof combination closer to 1.00. A flat plate is the worst profile for drag due to the severe vortices created and separation of flow as the air tries to wrap around the edges.

One thing that should be checked on the Duratec in an R400 is that the temperature that Easimap is reporting is accurate relative to the temperature on the sensor body when the cooling system has equalized to a somewhat steady state. I found on my R400 that the temperature gauge was actually showing a more accurate temperature when tested with a laser thermometer, compared with what Easimap was reporting, bearing in mind the gauge and ECU are using different sensors, although they are close together. Although the temperature sensor mapping curve can't be changed is the standard ECU, it can just be accepted that 98C detected by the ECU may actually be closer to the high 80s, if the thermostat and fan are operating correctly. I actually swapped the locked ECU for a 9A4 unlocked one and have accurately mapped the temperature sensor curve. Now my fan accurately cycles on at 90C and off at 85C, as indicated by both the temperature gauge and Easimap.

At 160km/h / 100mph the windscreen on an S3 creates about 400 Newtons of drag, with the aeroscreen and two helmeted occupants, likely 2/3 of that drag force can be removed. You can definitely feel the difference in drag at higher speeds. I estimate the total drag at 100mph is not much more than 1000N, so an aeroscreen equipped car has only about 3/4 of the drag of a windscreen equipped car.

The BMW diff used on the E46 M3 and E85 Z4M is not the same as the BMW diff used by Caterham (as used on BMW 316/320/520 and similar models). That being said the 90,000km I put on my Z4M left not a spot of oil on the output flanges, neither has any oil exited the output shaft seals on my 22,000km R400. Check that the seals are not pushed further than flush into the diff casing and that the diff is centred in the chassis such that there is even spring tension from the CV joints holding each drive shaft against the bearing face in the diff and fully seated in the seal.

I have been very happy with the Pirelli DM radial slicks in 180/530-13 front size and 200/540-13 rear size. Designed for Formula Ford weight of cars and can be heated well in about a lap and a half to a very sticky consistency. I use 2.7 degrees of camber on the front and 1.7 degrees on the back, the tyres have worn quite evenly over five track days and still have one or two days left in them, although they are losing grip a bit now due to heat cycling.

For a permanent fix to avoid contact burning on the brake light switch, I would suggest fitting a relay, as the arcing produced at the contacts by the more than 3A brake light circuit can reduce the switch life considerably compared with less than 100mA with a relay.

I was using the Redline MTL in the 6-speed on my R400, but switched to the Redline MT90 which gives me slightly smoother gear changes and less noise when hot, at the expense of a slower gear change for the first few minutes when the oil is cold.

6" rears for all-round use. If more than 200bhp and there is a need to put the power down in slow corners with large throttle openings, then 8" rears. On my 210bhp R400, I use 15x6.5" wheels all the way around for road use (it is hard to get 13" road tyres in Canada), then swap to 13x6" front / 13x8" rear wheels with slicks for track use.

It isn't obvious in the real time display/dashboard, but it is obvious in the log file where all samples are collected, here is a graph of 20 seconds or so of sample log data, red line is battery voltage, blue engine RPM, green reset count (increments across the power cycle shown between suspend and resume):

With Easimap and CAN based MBE ECUs (992, 9A4), the sample time for data points is 50 milliseconds or better, so it is easy to see battery voltage drops during cranking. I don't know what the sample rate is on the 967 ECU, but it should be at least 10 times per second, enough to show a voltage drop issue. The ECU reset count in Easimap will also increment if the voltage drops too low.

Standard 210bhp R400D here with 21,000km on the odometer. Uses about 1 litre of oil every 200km on the track when continually thrashed to the redline, 10 times less in spirited road use.

When I removed the seals on my BMW diff, a large screwdriver used across the seal and levered outwards against the underside of the steel face of the seal easily removed it without damage to the bore. A flat piece of metal across the seal face and a mallet placed it nicely flush with the top of the seat in the diff casing.

I use a Motive pressure bleeder which has it's own pressurisation hand pump and gauge: https://www.amazon.co.uk/Motive-Products-Brake-Bleeder-System/dp/B0002KM5L0 I find that using over 10 PSI, but less than 15 PSI works the best and never causes a leak issue. On the Caterham with the 4-pot front brakes, I fill the motive container with 1 litre of fluid, remove the old fluid from the reservoir with a syringe, then bleed the 6 brake and 1 clutch bleed points in one operation (my car uses the same reservoir for brakes and clutch, with a divider inside between the circuits). To make sure all air bubbles are released, I gently tap the calipers with a dead blow mallet while the brake fluid flows into the catch bottle. Perfect pedal firmness and a quick and easy bleed every time.

Going by the noise that you recorded, I would carefully check the integrity of the weld on the deDion tube ear, it could be a hairline crack fretting under load changes.

I could have taken the car to the only Canadian service centre for it to be done under warranty, but it is an 1100km drive plus a 95 minute ferry crossing, each way - 2 very long travel days in a 7, or preferably a 5 day trip if the car is fixed in a day. It took me a day to do it myself at home, I combined the job with the diff cover replacement (the redesigned cover that doesn't hit the dedion tube), parts also sent to me as a upgrade from Caterham. We have to improvise here in the Colonies!

Caterham shipped an upgrade for the Titan LSD to the previous owner of my 2012 R400D in 2014. It contained a couple of shims about 2mm thick to go under the belleville washers, plus a couple of new driveshaft seals. This also got rid of the clunk in the diff under load reversal and hard cornering.

If the car feels lethargic below half throttle and 4000 revs and consumes a lot of fuel when used in that area (worse than 20mpg / 15 litres/100km when the engine is warmed up), then it is likely a contaminated lambda sensor that needs replacing. If you can borrow or buy the MBE cable for your ECU, Easimap would diagnose this in a couple of minutes - with a warmed up engine the lambda value should oscillate every 2 or 3 seconds either side of 1.0 at lower revs and throttle opening, if the sensor has failed it likely will be in the 0.5 to 0.8 range continuously.

Although shiming may be needed, the de-Dion tube may also not be perpendicular to the centreline of the car. 0.17 of a degree equates to about 4mm of displacement forwards or backwards at the ear relative to the perpendicular position. Best to confirm the measurement from the tube frame at the front of the wheel arch to a point on the de-Dion ear is even on each side, if it isn't I would check the bushings are not damaged and if you have a Watt's linkage it is evenly adjusted each side.