Tuning success!

I’ve got good news to report! The parts from Caterham arrived the Wednesday after Thanksgiving and was able to get them into place the following weekend, Saturday the 5th (I think).

Idle issue is improved greatly after doing the TPS reset procedure. To reset the TPS, turn the key from position O to position II but don’t go so far as starting the car. Repeat moving from position O to position II 10+ times (I did it 30 just to be REALLY sure it was done enough) and that will reset it. The idle is still VERY high, over 2200 RPM, but it is super smooth – no more pulsing.

Speedo sensor replaced and the wiring short resolved. You can see the old behavior in the video below – just a slight tug on the wire and it would turn off the LED on the sensor. Speedo is now functional and normal.

James from Caterham was incredibly helpful and sent over some pictures of the proper wire routing for the sensor. It follows along the radius arm then down to the bulkhead as shown below.


Speedo wiring 1

Speedo wiring 2

I also replaced the crappy automotive weather stripping on the nose cone with the “official” padding material Caterham sent over with the speedo sensor. Clearance is much better – I don’t believe I’m getting any rubbing on the bonnet and engine anymore but need to monitor it with some tape to see if I still have contact. Note, WD40 works awesome for getting sticky residue off the painted nose cone.

Removing old automotive weather strip

Correct padding in place.

Correct padding on nose cone

The last thing I worked on over the weekend was to secure the 7 grill in the nose cone. Under certain conditions it will vibrate with an unbearable harmonic. I added a dab of clear silicone to the bottom pins on the inside of the nose cone and that seems to have helped a bit with reducing the vibration and noise.

Silicone on inside of nose cone to secure grill

Next up on the list to resolve is to get the idle lower. I need to adjust the idle set screw then reset the TPS, making small adjustments until the idle is near 950-1100 RPM. I played with it a little this past week but anytime I get below 1500 it stalls out. I was NOT doing the TPS reset while adjusting the idle screw which was causing the stall (I think). Will have to spend a bit more time driving it and adjusting.


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