cold start operating when warm

problem person · Post by **problem person** » Thu Jan 12, 2012 10:41 pm

Hi can anyone help me,i understand that the glow plug relay can be heard clicking on and of at low revs,but now it is clicking on and off seconds apart,some times after starting up ,the cold start cuts in and out after about 3 minutes into a journey ,on and off leaving the vehicle hunting at a junction,but then clears after the revs pick up.you can ,if you pull over, see under the seat where the throttle cable keeps hitting the throttle stop tap tap tap whilst it is hunting at the low revs.it has just had a new one way air valve to the egr,this hasnt cured it although the egr has been properly blanked of at both ends. can anyone suggest where to start looking.is it just a case that the glow plug relay or is there a switch or a faulty sensor that is causing the glow plug relay to come on and off in such short succession.
please help mark

jaylee · Post by **jaylee** » Thu Jan 12, 2012 11:40 pm

Hi Mark, this may sound like a silly question... You wouldn't have the heater on at the time would you..?
Hold on.. I'm leading somewhere... If while you have the fan on for the heater... You wouldn't inadvertently have the air con on too....?
That would cause the solenoid to lift the revs... But then your radiator fans would come on too..!

Driver+Passengers · Post by **Driver+Passengers** » Fri Jan 13, 2012 12:15 am

Sounds like there might be two issues.

Glow plug relay is controlled by the ECU (separately to the glow plug light on the dash). The operation of the relay should depend only on the water temperature sensor so that might be one to check. I have read that in very cold weather, you can get the relay opening and closing several times and be none the wiser if you can't hear it and 'trust' one the glow plug light (which is not representing the state of the relay, anyway). But it's not that cold right now.

Cold start operation into a journey and hunting at junctions - I may have missed something - assuming you're driving an auto, are you still in gear at junctions? My understanding is that cold start should only operate in neutral. I might be wrong, but there might be an issue with the gear select sensor/microswitch.

I speak with no authority, but reading your problem made me think...

Northern Bongolow · Post by **Northern Bongolow** » Fri Jan 13, 2012 2:57 am

i think jaylee may be on the right track.
where are you, someone may live local and pop round, failing that, video it happening and post the vid on youtube, then put a link on here then we can see whats happening better.

teenmal · Post by **teenmal** » Fri Jan 13, 2012 12:38 pm

Hi problem person,

It would probably be worthwhile checking/cleaning the glow plug relay connections.

Cheers.

problem person · Post by **problem person** » Fri Jan 13, 2012 8:05 pm

jaylee wrote:Hi Mark, this may sound like a silly question... You wouldn't have the heater on at the time would you..?
Hold on.. I'm leading somewhere... If while you have the fan on for the heater... You wouldn't inadvertently have the air con on too....?
That would cause the solenoid to lift the revs... But then your radiator fans would come on too..!

problem person wrote:Hi can anyone help me,i understand that the glow plug relay can be heard clicking on and of at low revs,but now it is clicking on and off seconds apart,some times after starting up ,the cold start cuts in and out after about 3 minutes into a journey ,on and off leaving the vehicle hunting at a junction,but then clears after the revs pick up.you can ,if you pull over, see under the seat where the throttle cable keeps hitting the throttle stop tap tap tap whilst it is hunting at the low revs.it has just had a new one way air valve to the egr,this hasnt cured it although the egr has been properly blanked of at both ends. can anyone suggest where to start looking.is it just a case that the glow plug relay or is there a switch or a faulty sensor that is causing the glow plug relay to come on and off in such short succession.
please help mark

Hi jaylee ,no it may not be when any of that is on ,to be honest i very rarely use the heater and the air con

problem person · Post by **problem person** » Fri Jan 13, 2012 8:16 pm

Driver+Passengers wrote:Sounds like there might be two issues.

Glow plug relay is controlled by the ECU (separately to the glow plug light on the dash). The operation of the relay should depend only on the water temperature sensor so that might be one to check. I have read that in very cold weather, you can get the relay opening and closing several times and be none the wiser if you can't hear it and 'trust' one the glow plug light (which is not representing the state of the relay, anyway). But it's not that cold right now.

Cold start operation into a journey and hunting at junctions - I may have missed something - assuming you're driving an auto, are you still in gear at junctions? My understanding is that cold start should only operate in neutral. I might be wrong, but there might be an issue with the gear select sensor/microswitch.

I speak with no authority, but reading your problem made me think...

Cheers bongolier will check the water sensor although the temperature guage does read normal would that matter,and yes sometimes i do sit in neutral at lights but sometimes in gear

problem person · Post by **problem person** » Fri Jan 13, 2012 8:18 pm

Northern Bongolow wrote:i think jaylee may be on the right track.
where are you, someone may live local and pop round, failing that, video it happening and post the vid on youtube, then put a link on here then we can see whats happening better.

not local ,east midlands,but if all else fails i will post video ,thanks

problem person · Post by **problem person** » Fri Jan 13, 2012 8:21 pm

teenmal wrote:Hi problem person,

It would probably be worthwhile checking/cleaning the glow plug relay connections.

Cheers.

iwill check the connections ,i suppose there could be a possibility that one of the connectors has frayed at the end

dandywarhol · Post by **dandywarhol** » Fri Jan 13, 2012 8:24 pm

There is no connection between the glow plug relay and engine speed. The click, click is perfectly normal in cold weather - the plugs can stay on for several minutes/miles. Turbo boost cuts the glowplugs off under acceleration and whenever you lift off the throttle, the relay clicks back in again - all perfectly normal.

I think you have a vacuum sensor fault.

problem person · Post by **problem person** » Fri Jan 13, 2012 9:14 pm

dandywarhol wrote:There is no connection between the glow plug relay and engine speed. The click, click is perfectly normal in cold weather - the plugs can stay on for several minutes/miles. Turbo boost cuts the glowplugs off under acceleration and whenever you lift off the throttle, the relay clicks back in again - all perfectly normal.

I think you have a vacuum sensor fault.

the clicking is rapid like a hazard light relay,i have heard the click on low revs previous to this problem,that would be the normal way of things but this has increased 10 fold,but a sensor on the vacuum could be a problem is there anyway of testing this ,other than replacing it.

M 80NGO · Post by **M 80NGO** » Fri Jan 13, 2012 9:28 pm

Have you unplumbed any of the pipes to the coldstart unit recently ie when the egr was blanked, incidently have you inadvertantly switched on the engine warm up switch ( next to the rear heater switch to the right of the steering wheel ) as i once done this and drove the van and it caused the van to hunt when i pulled up at the lights, i thought oh god whats wrong now

and then remembered that i'd switched the engine warm up on and forgotten to turn it off

Soon as i switched it off it ran like a dream

cold start operating when warm

cold start operating when warm

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