Engine problems?

[dannypatrol]

Received such good help in the past that I am trying my luck again.

I just drove 20km, stopped for 20min and so and started the car but it didnt start smoothly. The car shaked and with driving it sometimes had a drop in power. 10min later I tried again, just starting was fine but without driving, revs dropped several tines from 1000ish to 800 resulting in a short shake. I have this on lpg and petrol.
It is redicously hot today in brisbane and the aircon is on max. Thermostat doesnt give any problems and was replaced shortly, same as battery and coolant etc. Unsure if it is a fuel thing or something else. Before I bring it to a mechanic I figured I might ask you guys if you have any ideas. Didnt had any problems this morning.

[4bye4]

If its that hot you may be getting vapourisation in the fuel lines. The 1000 to 800 RPM drop at idle may just be your air con compressor kicking in and out. Is it only on hotdays?

[dannypatrol]

I had starting problems ages ago when the car actually overheated. This is the first time since that. It sounds like it almost stalls. And starting takes a couple of tries as well, while it normally just goes. So you reckon it isnt any big thing? When I accelerate it goes well, so you might be right about fuel evaporation

[threedogs]

what fuel is it doing it on ??

[dannypatrol]

Both fuels. I was mainly driving on lpg but when I switched to petrol I got the same issue with starting and idle

[dannypatrol]

No problems today so I guess it was just the hot weather. Still bit unsure if it is normal or a problem. Do more ppl experience this when it is hot?

[mudnut]

I take it your engine has a carby? I have had a look on my RB30, but would expect it to be similar to a TB42 in this respect.

It has a solenoid valve which is operated by the air conditioner circuit. The solenoid is mounted near the brake booster and has a black wire and an Orange/blue, or Orange/purple wire.

This solenoid operates a vacuum line which pulls on a diaphragm that raises the engine revs whenever the air conditioner kicks in.

Check that the hose is connected, and that the diaphragm is intact and working as it could be causing a vacuum leak as well as not raising the revs when it is needed.

[taslucas]

I take it your engine has a carby? I have had a look on my RB30, but would expect it to be similar to a TB42 in this respect.

It has a solenoid valve which is operated by the air conditioner circuit. The solenoid is mounted near the brake booster and has a black wire and an Orange/blue, or Orange/purple wire.

This solenoid operates a vacuum line which pulls on a diaphragm that raises the engine revs whenever the air conditioner kicks in.

Check that the hose is connected, and that the diaphragm is intact and working as it could be causing a vacuum leak as well as not raising the revs when it is needed.

I think that's called the idle air control or IAC valve.

[Extrimal D]

In consequence of the extreme heat is more rapid evaporation of the fuel. I think the failures because of this. It is possible to cool the intake manifold water.