1.4ss stalling

[p.mole1]

I have a 1995 1.4ss and it starts fine and idles ok but when you come to a junction it often stalls or refuses to tick over. It has the early type 56mm throttle body with the idle controlled via a stepper motor.

I have checked everything, sensors,lambda probe, TPS, etc and have done a TPS reset. It has been fine for months but has started to play up again. It has always had terrible throttle control when trying to pull away and either wants to stall or the revs soar, no control.I have a lightened flywheel which may aggravate things?

I have been thinking of replacing the ECU with an Emerald unit and replacing the the the throttle body with a later 48/52mm unit and loosing all the idle control rubbish, I don't see why a Caterham would need it.

Also the TPS for my throttle body is no longer available, my car has an early ECU with one connection and a built in MAP sensor with the vacuum connection and one ECU multi plug, does the Emerald need a remote MAP sensor? or does it have a built Map sensor built in?

[Englishmaninwales]

Almost certainly the TPS has failed. I had this exact problem, and when I disassembled the TPS the rotating electrical contacts had worn away. As you say they are no-longer available. I was lucky to get a TPS on eBay (with the whole TB).

However, I have succesfully used the 1400ss loom on an uprated engine, running Jenvys, an Emerald and a later TPS (EU 2 or 3 type).

But for your suggestion I think you will need to replace the old 1400 system with a later complete TB/IACV/plenum/engine loom/ECU; BUT I recall there are some connectivity  problems between the later engine loom and the earlier Caterham loom......Im sure there are old threads in BC from around 10 years ago on this.

Malcolm

[p.mole1]

Thanks,looks like its going to a complex job! Do you have a Map sensor on your inlet manifold, or is inside the Emerald ECU. I tried testing the TPS and it seems fine but it looks a bit Heath Robinson.

I may try and modify a later TPS but I'm sure that mine operates in reverse to all the later ones

[Englishmaninwales]

There was no MAP sensor. Thus I think it was mapped on TPS, lambda and air temperature alone, with a distributor non wasted spark ignition. I guess the Emerald takes an assumed average value when there is no MAP sensor?

Malcolm

[TomB]

I suspect eBay or Rover breakers will be your best bet.  Ive a spare on my old 1.4 plenum youre welcome to borrow, but before I converted to TB on the 1.8k, I had similar stalling issues, so I suspect it was on the way out.  At that time ~4-5 years ago, the old TPS was about £80-100 ISTR. I fitted the TB and went to the newer TPS and it solved the problem.    

[p.mole1]

Hi Tom, many thanks for your offer.

However I have managed to find a new throttle body (unbelievable! £129) and it is later variant which uses the newer commonly available TPS. The only problem being it does not have the brass breather tube fitted, but the casting is there so it will be easy to fit or build a body from the bits.

Thanks Malcolm that would make an easy installation, but looks like I may have found a cheap fix with bonus of being able to use easily available  TPS