Electrical gremlins return

Hello world!

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Remap number 2

Returned yesterday through the rain to Track’n’Road in Rainham for Steve and Steve to work their magic, without being hampered (as they were last time) by valve bounce and a dodgy camshaft.  However, not all went to plan.  5 miles short of arriving, the engine inexplicably dropped a cylinder, so I limped the last stretch, and after a bit of careful diagnosis, it turned out to be a wiring issue.  The injector loom has been on my list of things that need looking at, and has now jumped rather further up that list!  A quick visit from their tame auto electrician, and the running of a new signal wire direct from the ECU to the injector on cylinder no 1 has solved the problem for the moment, but really a new sub-loom is needed for it to be reliable in the longer term.  Really grateful to Jim for coming out so quickly, and to Steve and Steve for coping with another problem on arrival.  (see this post for what happened last time!)

But once that that was solved, Steve fitted the new injectors (Bosch items made for the Z20LET engine, so 21st century technology, rather than the early 90’s single pintel ones that I had), and we finally got on to the map, assisted significantly by the Emerald upgrade to K3 spec that was done over the winter.

On the rolling Road

On the rolling road

Two and a half hours on the rolling road, and lots of detail work in various parts of the map, the initial results are good.  Engine in certainly smoother and more tractable, with more power in the lower range, and revving cleanly past 7500 revs.  Interestingly though, peak power came out a bit lower than I was expecting, at 187.2bhp at 7550rpm, with a torque peak at 141.5lbft at 5476rpm.  However, given that the car still only weighs about 750kg, it still feels pretty rapid at the top end, and it is probably ample performance for the road.  More on this when I have a chance for a proper drive on roads that I know in the dry.  I hope to do something on the track this year too, but we’ll see what pans out.

Here’s the power run graph from the rolling road.

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Winter Works

Car back to Rob at Protune with a long list of things to do in the worst of the winter. This includes trying to get to grips with the wiring nightmare that was knotted behind the glovebox, (including removing superfluous stuff like the old ECU, wiring for removed intercom system etc), replacing and relocating the battery to under the bonnet, and upgrading the Emerald ECU to K3 spec. And, of course, taking off the head to investigate the valve bounce.

Suffice it to say that none of this was simple. Hours of wiring, removal of the immobiliser (I only had 1 nfc fob, which was a recipe for disaster), fitting a battery master switch etc all having to work through a letter box sized aperture, is not a straightforward task, but I think in the longer term, this work will be worth it.  Fitting a higher capacity battery should help too, and given that the previous wiring to the boot mounted battery went along the dedion tube (!!), this is a positive change.

In engine terms, once Rob had got the head off, the issue became clear

Worn cam!

Worn (or actually non-existent) cam lobes on one cylinder, so its no wonder that the valve was bouncing at higher revs.  If it was managing to open at all. So, new cams needed. These were ordered from SBD motorsport, but it soon became clear that there were none in stock, and they would have to grind some specially. Not an overnight sourcing of the parts.  Replacement buckets were also needed, given the state of at least one of the old ones.

Failed bucket

During this work, it also became clear that the coolant hose arrangement (which had looked a little ‘heath robinson’) was leaking something chronic. So new silicon hoses required, which were also out of stock at Caterham. For weeks.

This is what Rob took off the car:

Assorted removed parts

The car is finally back, and I have a date booked to go back to Steve Greenald for the remap. It seems to make sense to do the injectors at the same time (the existing ones are not high enough capacity to achieve the power claimed, and of a rather old design) and remap with the upgraded ECU and new injectors. I’m confident that the effect of all this will be pretty substantial.

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Bodywork damage

Really annoyed to discover today that, possibly on my way back from Potters Bar, I’ve had a double stone strike which has left 2 rather unpleasant looking spider cracks in the gelcoat in a really obvious place on the bonnet of the car.


Given all my work to get the bodywork back to clean and shiny, this is really frustrating.

I’ve bought a tube of MagicEzy Harline Fix, which is highly recommended by guys who have fibreglass boats it seems, so I’ll try to make some time in the next couple of weeks to have a try with this on the bit of bodywork around the exhaust silencer (which isn’t in a great state anyway) to see both how it works, and how the colour matches (I’ve bought the fix stuff in Strawberry).  I’m hoping that with some of this fix stuff, and perhaps a little T-Cut and a polish, I might be able to get a decent repair.  I’m really not that keen to go to the lengths of having to sand this back  and repaint (which is way beyond my abilities).

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Uneventful drive down to Rainham on Thursday for the remap, until my arrival. As I wasn’t sure where I was going, I decided to find the workshop first before going to get some fuel, as I reasoned that Steve would know where to get fuel too. However, having parked up, and found where I needed to be, the car wouldn’t start again – no juice in the battery. Not a great start.

Steve took it all in his stride, thankfully, pushing the car into the workshop to connect to his battery charger, and giving me a lift in his van with a jerry can to get some fuel. First issues solved. The lambda boss was the next problem, in that Steve couldn’t attach his sensor, given that the boss wasn’t correctly threaded. Again fortunately, one of the other guys in the workshop had the right tool to machine it, though that did mean that sealing it again at the end was a slight issue.

So, on to the remap with the two Steves. Quite quickly, it was clear that all was not quite as it should be in that despite having mapped countless cars, Steve couldn’t hold a constant throttle. Diagnosis – dodgy throttle pot. Thankfully, Steve had one in the van, though with the wrong terminations, so a quick bit of electrickery later, and we’re back on track, though several hours behind.

All then started to proceed, and good progress was made on the map (the two Steves agreed with Rob about the quality of the previous one – insert unmentionable four letter words here) until we got to the top end. Here is was clear that something wasn’t quite right – at about 6850revs, all of a sudden the compression would drop, and the car would blow black smoke out of the back. Prospective diagnosis of valve bounce, which need further proper investigation. So, new lower rev limit imposed, and a partially completed map, with the car needing to go back to Rob. All in all, not quite what I had been expecting from the day. But, all credit to Steve and Steve, it was a different car to drive after their ministrations, and despite the lower imposed rev limit. The lumpy running and propensity to stall was entirely gone, and power delivery was much cleaner and more linear. Very good signs, with the hope being that it might just be a worn/broken valve spring causing the bounce, which would make a much easier second trip to finalise the map.

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