1.8 Kr sensors

[Wild-Animal 0]

Hey I have been having problems with my 1.8 16 valve running properly during the warm up thase.

 

The car idles drops to 200rpm when ever the throttle sits against the idle switch.

 

I know the KR engine has 3 sensors below the distributor and I have tested all 3.

 

I was wanting to find out what the brown plug, below the 3 sensors, what is it for ? and also the there is a sensor on the back of the block in the engine bay with a single wire.

 

I am trying to know what they do so either I can test them to see if they are causing the problem

 

Any info would be great, thanks

[CazzaVR 0]

The bigger one with the brown plug is the thermotime switch- pretty pricey! This can affect the start up- can't remember exactly how- been a while since I sold my valver ;)

 

Have you tested/cleaned the ISV?

[Wild-Animal 0]

Hey thanks for the reply, I have cleaned the ISV out numerous times and I have tested the voltage to it, and i the ISV does seem to work I can here it buzzing.

 

Thermotime switch thanks for that bit of info! I have tried everything I could think of so I may try and pick one up second hand and see if it does the trick.

[CazzaVR 0]

Think they are around £45 from VW. I'd go for a new one TBH.

[Wild-Animal 0]

Okay I will do thanks

[tony_ack 0]

Pretty sure the thermotime switch controls the cold start injector only, which only fires when you start up. A dodgy thermotime switch or cold start injector would make the car struggle to start, but it would be fine once it fired up (unless the cold start injector is leaking, which would cause rough running)

 

If it only does it during warm up, it may be worth checking the wiring to the WUR, and check the resistance across the terminals on the WUR itself (should be about 22-28ohms iirc). If that checks out, try swapping the wires around on the 3 temp senders.

 

Think the sensor on the back of the block is the oil temp sender for the MFA

[Wild-Animal 0]

Hey I tried swapping the the WUR and the cold start injector for other items, to of which came up with the same results. I will check the resistance of the WUR

 

The 3 temp sensors I have swapped the wires about and I have checked they all work, due to the same reading of the temperature gauge.

 

Thanks for the info about the sensor on the back of the block

 

I will try and check the resistance on the Overrun cut-off valve, its something I have not tried yet

[aide 0]

as above the brown thermotime sensor allows the cold start valve to function for a preset time, i believe its rated at 50degs/ 20secs. i.e. it functions only for 20secs max and only if the engine temp is under 50degs. its basically an automatic choke for fuel metering. when cranking and if the above conditions are met the cold start injector should receive 12volts, check its delivering fuel after that.

 

the WUR controls a plunger on the metering head, and in turn the fuel system pressure. its heated in two ways, firstly by a heating element through the two wires, secondly by the transmitted temp of the block, it uses both to ensure system pressure is low (i.e. leaner) when the engine is restarted warm. its basically an equivalent of modern ECU emissions control, only mechanical. symptoms vary depending upon failure.

 

bear in mind continuous over fuelling would lead to a progressively worsening idle from cold to warm, faulty WUR could lead to progessively better or progressively worse running cold to warm, yours seems sudden so i don't think it would be either of these.

 

the idle switch triggers the ISV, even if the ISV is buzzing it may not be metering air efficiently as it opens/ closes so many times per second that 1 cycle failure/ sticking in 20 could have an effect. the fact it idles fine when warm suggests its okay anyway.

 

there is a further possibility which is the auxillary air valve, and this would be my hunch, its located near the airbox, its a disc with a sensor plug and two small bore plastic pipes. this valve allows air to bypass the throttle body butterfly during warm up, like the WUR its contains an electric heating element which leans off the air supply as the element is heated. you can test it by chucking it in the freezer and looking through it. cold = open and warm = closed. check its getting power when cold, it shouldn't receive any power when warm, if its not getting power it could be a sensor issue.

[Wild-Animal 0]

Hey thanks for the in depth detailed reply!

 

I will pop in it the freezer when I can I will keep you posted on how I get on