200 RPM increase when hot

Hello,

Slightly annoying change in my RPM range lately

Have a E2E carb on a 1800 EX engine running an LPG setup with radiator water heated LPG dampner

No more manifold heat shield collector or hose and air mixer at the inlet end of the air filter box - supposely to compensate for the slightly hotter running engine with LPG

OG air filter - closed up engine breather inlet tube

The first 7 seconds on startup higher revs never worked

Latelely - the weather is getting cold I noted that with a cold engine I have a very steady 900 RPM cold idle

When hot and I noted with the water up to temperature I get a slightly higher RPM rate of 1000 - 1100

Again very steady idle - just a bit higher !

What causes this ?

BerT3

I checked 12V feed at the auto choke

Isn't that supposed to shut out when the water is hot enough

I keep measuring 12V even after a high way drive of 30 minutes

Faulty water temp switch ?

BerT3

start here
http://www.vwgolfmk2.co.uk/forum/viewtopic.php?f=37&t=14917

the warm air system is essential when running petrol at least, otherwise the carb will ice up. on the LPG i assume its not an issue depending how the fuel is injected

Read it all through - did some tests today

Figured out what all 3 sensors do on the cooling flange - late EX engine

I can get the idle to be correct when I take of the plugs on the TTV and over-run valve when the engine is hot

How is this fed - is it really a constant live 12V feed - I mean: not controlled by one of the thermoswitches - either inline with the grey or red switch on the cooling flange ?

The auto-choke shouldn't be constant 12V too ?

Bert

the TTV and over-run valves just get ignition live at all times, the autochoke and inlet heater feeds are switched off by the 2 thermoswitches in the front flange once the coolant heats up a bit. red does the inlet, grey the choke

the 3/4 point unit and waxstat are the 2 main things that control the idle, so make sure both of those are working properly. if your inlet manifold oring is clogged the waxstat wont be able to do its job properly leading to increased idle revs, it doesnt do the autochoke any favours either.


If you click the link below in my signature i have the 2e2 section from the haynes carb manual scanned off, this covers the fine adjustment of the carb in much more detail useful if previous bodgers have been in there and messed up all the settings!

Thank you very much for your reply rubjonny

To test that grey switch - would it be enough to unplug it when hot to get the 12V off the choke ?

I can measure it at the red plug then

BerT3

aye if you unplug the switches this will kill the live feeds to the inlet and autochoke, to test the switch with a multimeter you put it on continuity mode and check between the 2 pins, they should pass current stone cold but stop once the coolant warms up a bit. i cant remember off hand how hot it needs to get but it should be well before the car gets to full operating temp. i woudl check in my copy of etka but i have no internet at home atm!

Checked again

Do have the retraction on start up of the 3/4 unit - can feel the pressure of the spring inside when trying to push it in

It retracts almost instantly - is that correct given it's rather chilly outside ?

On the other hand can't it be a reversed problem ?

I mean a low start-up idle (from another faulty component) compensated by a too much screwn cold idle bolt at the 3/4 unit

Or do I just screw on the 13mm nut at the back of the 3/4 unit to bring down the hot idle speed

Regarding the first step of those 7 sends higher RPM - is that entirely controlled by the waxstath ?

I mean does it bring cold idle down instead of up when heating up ?

Bert

I kept on reading

Might be a specific problem with LPG

Bad cold start / low idle since the LPG dampener need hot water to be fully opperational

I screwed up the cold start idle up a week ago when it started to get cold and had a low idle of around 500

I had a good hot idle of 900 then

To compensate I screwed the cold idle up to 900 and have the 1100 now when hot

Winter blues I guess

I'll test it on fuel this weekend to check the cold start idle RPM's

BerT3

On the other hand

Can't I close up the gap of the stage 1 of the choke by turning anti-clockwise at the PDU knob just for the winter ?

BerT3

are the vacuum liens all routed properly? mine always revved to about 1.5-2k for at least a couple seconds or so depending on the ambient temps. if its going down right away this suggests TTV is broken or the vac lines are not quite right.

with the idle thing, if its easier you could change the length of the screw that operates on the 3/4 point unit, maybe put a couple marks on it for 'summer' and 'winter'

are the vacuum liens all routed properly? mine always revved to about 1.5-2k for at least a couple seconds or so depending on the ambient temps. if its going down right away this suggests TTV is broken or the vac lines are not quite right.

Yes they are - new correct sized ones

The TTV gets hot - the idle over run valve clicks

with the idle thing, if its easier you could change the length of the screw that operates on the 3/4 point unit, maybe put a couple marks on it for 'summer' and 'winter'

You talking about the grub screw or the 13mm nut at the back ?

BTW - if I bridge the red water temp plug I hear a click from a relay in the fuse box
When I bridge the grey one - nothing - shouldn't it kill the 12V from the autochoke when bridged ?

BerT3

More testing and getting to know how it all works on a spare carb

I guess the TTV is dead (on the spare carb too) even it gets 12V but passes vacuum through instantly on contact

The autockoje grey switch is ok - the ckoke gets hot but when the the plg is bridged (simulate water hot) I keep getting 12V to it so I guess it needs a relay

Which one is it ?

I am either missing it or it's dead

Euro car EX engine 1.8 manal cabby fom '90

BerT3

I am actualy thinking it got wired in wrong

Since I bridge the plug I get 12V - if unplugged still 12V

I noticed the wires are screwed with - taped up

Anyone as a wiring scheme so I can check ?

BerT3

The over-run valve and both the thermoswitches are fed an ignition live from D/2, fuse 17. When engine is cold the inlet switch triggers a relay on the fusebox which then powers the inlet heater, the autochoke is just powered straight thru the thermoswitch so no relay clicky.

the inlet heater is fed from the large spade N on the fusebox, thick red/white you cant miss it. the autochoke gets ignition live from the fusebox to the thermoswitch, then a wire runs from the thermoswitch to a spade which the autochoke wire plugs into.

the TTV & inlet heater valves get an ignition live from D/7 on the fusebox, fuse 18.

I meant the grub screw, its easier to get to plus you can see any marks you make on it without having to use a mirror

Getting there

Found the wire from the auto choke !

It was cut of and found that the 2 jointed black/yellow and black wire were actually attached to the red plug from the auto choke

Both red and grey switches work - manifold heater works - relay and fuses are ok

Last problem:

The jointed black/yellow wire has to go to the carburettor heater - copper plug with male terminal above the wax thermostath according to the scheme below

While removing the air filter I noted that there is anotther plug even lower

Took out my old carburetor and it was removed - not there at all

On the setup I do have now I do have it straight wired to the carburetor heater plug

My questions:

- What is the lowest electrical part ?
- What does it do ?
- Is it needed ?
- How is it wired in since I can't find it on the scheme

Below some photos of what I am talking about

BerT3

the heater is the lower of the 2 electrical thingies on the front of the carb, the higher one is the thermoswitch for the rad fan after-run relay

rubjonny said

the heater is the lower of the 2 electrical thingies on the front of the carb, the higher one is the thermoswitch for the rad fan after-run relay

Ok - why would both be connected to each other ?
Makes no sense at all

Would the heater makes a big difference ?

The fan does after run though - I guess from the sensor at the radiator

Was the thermoswitch always wired in ?

Bert

they shouldn't be! the heater gets an ignition live feed as I mention above.

the thermoswitch for the rad fan after-run is wired to the after-run relay only, it triggers the relay to run the fan if the ignition is off and the carb gets to a certain temperature.

the thermoswitch switches to earth thru the carb body, so if you have an ignition live to it the fuse will pop whenever the carb gets hot!

rubjonny said

they shouldn't be! the heater gets an ignition live feed as I mention above.

the thermoswitch for the rad fan after-run is wired to the after-run relay only, it triggers the relay to run the fan if the ignition is off and the carb gets to a certain temperature.

the thermoswitch switches to earth thru the carb body, so if you have an ignition live to it the fuse will pop whenever the carb gets hot!

I see

I can wire the heater in - I have those doing nothing at the moment

The thermoswitch goes to pin 5 at the radiator control unit

Finally getting there

Final question though - is there a way to test the TTV ?

Last item I can't get to function !

BerT3