Post modification depression

[Tony Martyr]

It's finished. The QED-TBs/dta ECU etc kit has been fitted and all the old K series bits are in a big box - anone interested in working spares including MEMS ecu and transducers. John Noble has mapped it and tidied up the wiring, including the addition of a relay to solve the problem of powering the ECU which is a K series problem you have to solve and I failed on.

I fitted a large aluminium radiator also. I have left porting the head and larger valves to next year.

Now it is back on the road and I am getting used to the differences.

First is thing noticed is that it is considerably noisier. Maybe I need to line part of the bonnet but I don't want the weight.

Second thing I notice is that I get some backfire on high gear overrun and that there is a momentary hesitation from idle to an opening of the throttle.

The temperature of the coolant is not coming up to 80 as it did which maybe caused by the larger cooling capacity but should be taken care of by the thermostat(?)

I have not had much of a chance to test the performance and am still trying to get used to the new sets of sounds but there are now two distinct power surges. The original 4000rpm + sound and surge then a second at about 5800 rpm that is new and can be seen as a gradient on the fueling map. From 5500 rpm it is noticably more powerful

I know I should be very pleased but all I have to do now is to find out why there is a strange ticking noise (tappet buggered during mapping? these full power runs without cooling air flow can do horrid things to tyres and engines)and how to route the serial cable through the bulkhead and keep the water out without taking the plug off. Then I have to get the MOT passed with an open loop control. I am thinking of going the whole hog and replacing the CAT exhaust with a four branch unit now that the lambda sensor isn't doing anything. On a P reg car can the resulting possible detoriation in emissions be deemed acceptable by my local MOT man. It must be so as I see much more radical 7s than mine - what story does one spin? Advice on both points sought.

What I need is a nice dry day and a blast across Wakes to get rid of the wet winter blues.

[Jason Plato]

Tony ,

Congratulations , I seem to recall from previous threads that if the car was self build and you have a certificate to that effect the car only has to go thru a visible smoke test . That was certainly the case with mine .It also helps to find an "enthusiastic" MOT tester .

Where do you live ?? , blasts thru Wales are my speciality !! , I'm hoping to arrange a regular meet from the spring onwards at Abergavenny Island cafe ( along with several hundred bikers! )

 

Dave

[mark.hall]

The loud ticking is probably the injectors. They can be fairly noisy. I can hear the injectors on my BMW bike at tickover,when I'm sat on the seat, with a helmet on!!!!!!!! If you are really worried, a quick check of valve clearances should suffice, although I'm sure PC will be along with a far more intelligent answer in a minute.

I would concur with the opinion above re engine emmissions. Tell Mr MOT that you built the engine yourself, and that it should be subject to a sight only test. If he disagrees, ask him to check his reference book. I have to every year...............

[Tony Martyr]

Thanks to you Guys I feel better already! I had used an ear-stick to try to locate the ticking and had hoped it was injector noise as they are now more exposed and mounted onto the short aluminium Tbs rather than enveloped in plastic.

I like the 'visible smoke' restriction for owner built cars but I don't know of a certificate. I have a local garage how deals with the local TVR dealership - if he passes those I should sail through.

I just hope my neighbours don't gang up with Peter C's lot as mine are already puzzled by me apparently sending emails from inside the engine compartment while making an un holy din. Think I'll give Sunday morning a miss

[Peter Carmichael]

Tony,

 

I checked the MOT manual before submitting mine for a check. What they say is true for the amateur built cars. Many MOT men don't know this, so just tell them to get their manual and read it to them.

 

The stumble just above idle is going to be fuelling. Either bump some more into the base map or give it a bit more acceleration fuelling.

 

I believe what Mark says about the injectors. Can't remember whether you were still on Supersport cams and hence hydraulic followers. When hydraulic followers aren't working you get a more obvious noise than a slight ticking. I reckon its the injectors and you are not the first person to suspect sinister things from the noise.

 

Cat exhaust? Open loop? I reckon that Cat isn't going to be doing much and will probably get wrecked quickly. Go to the 4-1 competition exhaust as soon as possible, but you will need to remap.

 

The temperature thing is weird and I don't trust the Caterham gauge and I never believed its scaling - the standard thermostat operates at 88 degrees not 80, confirmed by me with a pyrometer. Disconnect the cooling fan. Start the engine from cold and warm it up (to start with at a fast idle); take temperature readings every minute (borrowing a pyrometer might be helpful, but place it somehow on the radiator bypass circuit).

 

In the plot of temperature against time watch for the thermostat opening. The cold coolant from the radiator will bleed into the engine circuit a small amount at a time causing a plateau on the graph - this will show you the actual thermostat operating temperature. Once all the radiator water has bled into the system, the graph will continue to rise (normal idle at this stage). Let it go up considerably and then reconnect the cooling fan and see that bring it down to a settled temperature.

 

You now know two temperatures for the system. Thermostat controlled and fan controlled. The fan-controlled temperature will depend on ambient. The thermostat controlled one will not. If the car operates below the thermostat controlled temperature then the engine is being effectively air-cooled, which isn't a good thing.

 

There is a simple way of fixing this. Run an 82 degree thermostat available from Lotus for the Lotus Sport Elise. This will open earlier and the engine will need to flow more water at lower temperature to achieve the same cooling - the thermostat will be more open more of the time. In this configuration, you can think of the thermostat just existing for the purposeof giving a fast warm up.

 

Oh and Congratulations!!

[Peter Carmichael]

Tony,

 

I don't know about a certificate, but the chassis number indicates whether it was a kit build.

 

My number begins RDKSDK...

 

One of the K's stands for kit-built. If you don't have an original document I am sure Caterham could provide verification in a suitably official manner.

 

Peter

[EFA]

Tony

 

The V% registration document is what you need at MOT time.

 

It will state amateur built in the notes section. The refer the tester to HIS documentation if he is unsure regarding whathe should test. In the testing stations documentation it clearly states that amateur built cars are subject only to a visible smoke at idle test.

 

So you do not require a Cat or closed loop system. I have successfully passed 5 mot's like this with my Vauxhall which is on TB's.

 

Someone should have told you your car would be rather less subtle (as if a Seven is anyway) ith the TB's though!!! Just get th needle the far side of 6 and they will really grow on you...

 

 

 

 

 

Arnie Webb

Organiser- L7C Le Mans Trip

To book for this years Le Mans Trip see The Le Mans Trip Website

It really is very very very very full now!!!

[old captain slow]

Since I'm just about to save up my spare pennies to embark on a similar mod, can you get a closed loop EMS? My car is factory built (sorry) and therefore I need to retain the Cat. Also the co-pilot is getting nervous about reliability when we tour Belgium, Holland and Germany in August so keeping it looking similar is a factor.

 

(I'm lying about the last bit but had to put it in - she can always take the train if it breaks down)

 

C7CDW

[Mick Day]

Congratulations Tony. My K on TB's etc runs with a GEMS ECU which retains the closed loop system & lambda probe. In fact I'm still using the original exhaust with cat. However, just as Peter says, it's probably completely shot by now & does nothing. Bearing in mind that the cat. (supposedly) only chews up approx. 1 BHP, how much better would a 4:1 system be?

Mick Day

[Mike Bees]

Tony - the backfiring on the overrun is caused by not dialling in enough ignition advance to those load sites (throttle closed at medium/high rpm).

 

Mike