Engine Parts Identification

[KevW]

I'm personally not a great fan of the throttle jack solenoid system. On both my previous Excel (no aircon) and my current Excel (with aircon) I disconnected the electrical feed to the solenoid as Mrs W and I like to hear a little bit of burbling on the overrun during deceleration. What's more important to me is the feeling of having the engine revs drop quickly when I lift off the throttle rather than the damped effect the solenoid gives even when it's properly set up. I also find I don't need it to compensate for the times the aircon is switched on. At idle when I switch on the aircon my warm engine sees its revs drop slightly from 900 to 800 rpm which isn't a problem for me.

My PAS pipe insulation has seen better days too. On my previous car it was so perished I removed it completely and never noticed any negative effects even during hot weather.

[Tanz]

I'm personally not a great fan of the throttle jack solenoid system. On both my previous Excel (no aircon) and my current Excel (with aircon) I disconnected the electrical feed to the solenoid as Mrs W and I like to hear a little bit of burbling on the overrun during deceleration. What's more important to me is the feeling of having the engine revs drop quickly when I lift off the throttle rather than the damped effect the solenoid gives even when it's properly set up. I also find I don't need it to compensate for the times the aircon is switched on. At idle when I switch on the aircon my warm engine sees its revs drop slightly from 900 to 800 rpm which isn't a problem for me.

My PAS pipe insulation has seen better days too. On my previous car it was so perished I removed it completely and never noticed any negative effects even during hot weather.

When my car came back from Lotusbits a few years ago after having the engine out (new clutch & exhaust) I noticed Dave had disconnected the throttle jack - Guess Lotusbits are not fans either. I also like the sound of the overrun.
My pas pipes have never had insulation and I replaced them when I did the rack and pump - still no inssulation and seem fine.

[Phantasm]

So I did a little fumbling around the TJS. Turns out it is operating as expected when voltage is applied. I noted I had to hold the "plunger" that pushes on the throttle arm in the 'Up' position as it fires down and doesn't hold itself 'up'; Gravity prevails.
Then I noted that the Solenoid Plunger was always resting in the down position in situ, the Adjustment screw of the throttle arm was never in contact with the TJS, it was turned all the way down. So, I screwed that up to be in direct contact with the TJS in the full up position and found my revs held at 3000 RPM when electrified. Ooops, too far! So, I backed it down and now it holds the car at 1400 RPM. Then when power to the TJS is cut, it drops to the normal idle of 8-900RPM. In short, everything is working near as I can tell.

So, I now have my TJS doing it's job electrically AND mechanically. We'll see if I like it or not. I've been driving presumably for 2 years without it actually doing anything mecahanical. I might revert back to that operation if I don't observe any improvements with it in operation. Like Others have mentioned, I'm not super keen on the throttle being controlled like that without my input. I noted, it seems to hold the RPMs up on startup but the car wasn't starting like usual with the choke 1/2 on when cold - it stumbled/stalled and had to give it a little gas the second crank. It always starts first crank 1/2 choke when cold. To combat that, perhaps I'll install a bypass/cutoff switch, that way, if I find the TJS useful at times I can engage the cars ability to operate it (like once I get my A/C back in action), but can disable it for the moments it seems to be interfering - like cold starts.
Of course, I just did all this today and need to do some real world testing, so my assessments might be a tad premature.

Regardless, thanks to all for allowing me to realize an aspect of my car that wasn't quite to standard. I do appreciate you all!!!

[marky]

I have done quite a bit of investigation with the throttle jack over the last few years. When I first got the car it was not working because the speed sensing relay was dead. When I replaced the relay it came on randomly and stayed on for a long time and I quickly decided to disable it again.

I then gradually got the Carburettors working perfectly with all jet's clean and re-balanced along with several re-adjustments ( now runs beautifully and returns up to 29 mpg ).

I then turned my attention back to the throttle jack re-connected it and adjusted it following the procedure in the service notes. A spare battery is needed for this along with two wires and the procedure is simple once you have freed the adjusting nut on the arm with WD40. The throttle jack raises the idle speed to 1200 rpm by pressing on the arm slightly - note that it has some free-play and is always in contact with the adjusting nut on the arm. From memory I believe that the Speed sensing relay switches the throttle jack on at 1600 rpm and off again at 1400 rpm.

Once you have everything working correctly you find it is very effective at stopping the pops and bangs on over-run and if you stop gradually and don't dip the clutch too early then all is well. However if you stop suddenly then the engine will sometimes idle at 1500 rpm for about 15-20 secs ( rather annoying!) You can stop this by lifting the clutch slightly in gear until the engine speed drops below 1400 rpm and the throttle jack cuts off ( only takes a second ).

It is not perfect but better than all the pops and bangs. I suspect that what is happening is that with the throttle held slightly open by the throttle jack and some excess fuel is in the Carburettors the system is self perpetuating for a while.

It has been said that the correct way to fix this is by bending the support bracket upwards! This is miss-information probably started by mechanics who were two lazy to get a spare battery and two wires and check the adjustment. If you bend the bracket upwards in most cases the device will be effectively disabled as it will no longer be in proper contact with the arm. If you find that there in not enough adjustment on the screw then it may be necessary to bend the bracket slightly but I suspect that in most cases this will not be necessary.

Mark

[Phantasm]

So, Overall, I'm very happy with the Throttle jack working. The overrun is virtually eliminated on downhills and if I'm shifting in traffic (not shifting fast) it is just plain smoother/easier to drive with the RPMs not dropping off super fast. A less sporty feel, but more drive-able when I'm not trying to get on it.

I think I still need to adjust the screw down a bit because as noted above, the RPMs can get kinda hung up above 1400 and takes a long time for them to drop off, so much so that I can sometimes feel the car kinda pushing when I'm off the throttle versus coasting/decelerating at a preferred rate.

Even after I make that adjustment, I still think I want to install either a momentary normally closed switch to bypass the jack at will which will likely be on the steering column or a toggle to just turn it off all together. Probably both. Easy mod.

[MetBlue]

My TJS is unplugged currently ( as many seem to be). Seems that there may be an almost permanent 12v Supply to the solenoid.
Is the Engine Speed Sensor Relay discussed in this thread to the same thing as the Decell relay the wiring diagram shows?
Tony