re

ive had this problem to a few times,give your throttle cable spring mecanisim thing a spray of wd40 stuff.
hope it helps worked for me.

 

ive had this problem to a few times,give your throttle cable spring mecanisim thing a spray of wd40 stuff.
hope it helps worked for me.

Is there a picture of this anywhere? I don't have a manual and haven't done any car repairs for 10 years or more.

thanks

 

Does this happen all the time or only when cold.

 

Don't do many long journeys so difficult to tell. I will take it for a longer drive tomorrow to test it out. Why what would this show?

thanks

Pete

 

My rover 600 used to do this. Turned out to be one of the engine sensors. You may need to take it to a garage and have it plugged into a diagnostic computer to give you a fault code that will tell you which sensor it is. It wont be anything to do with the throttle cable.

 

Thanks. I hope it is a sensor.

I have booked it in with a mechanic I trust on the 16th Dec - he's not cheap but I know he'll tell me if it's just a sensor. He said 9 out of 10 times it will be the control unit and they cost about £150 for a recon unit with warranty.

I've got to drive around with this problem for the next couple of weeks, hope that's OK.

So it's not;

the throttle cable
an air hose leak as revs would not go up and down

Any other things to try?

Thanks

Pete

 

My suspicions are with either

a) the coolant temp sensor - running the car on cold settings all the time

b) vacuum leak.

c) sticking TB

 

If it was a vacuum leak, wouldn't the revs stay high unless the leak kept sealing and reopening? I know next to nothing about cars tho.

 

I'm no expert but what about the throttle position sensor? I replaced my throttle body at the weekend with an alloy one and when I was all done my revs were going up and down until I realised I'd forgotten to put the multiplug back on the sensor! Just a thought...

Cheers,
Dan

 

spray some carb cleaner onto the butterfly just incase its sticking...worked a treat 4 me

 

Sorry to be thick but is there a photo of this or can you guide me to it and would WD40 do?

Cheers

Pete

 

take off the rubber pipe that come from the tb to the air filter and then squirt some carb cleaner into tb(ull see a silver metal flap) while opening and closing the throttle.try it with engine off and then with engine running.when u do it with the engine running make sure u dont squirt to much at once coz it will stall the car.

 

OK thanks.

It has been difficult to start the last few days, just cuts out straight away unless I rev it. It seems like it is running without any choke at all even from cold so revs are lower than they should be now (around 750rpm from cold start, would normally be 1000ish) - does that help diagnose the problems at all?

Thanks

Pete

 

that will be a coolant temp sensor then

 

How sure are you about that? Could it still be the engine control unit thingy? I mean, would this also make the revs jump from 1200 to 1500 to 1200 to 1500 etc etc when idling when it's pretty much up to temp.

I heard there were 2 of these sensor things, one for the dash and one for the control unit, is that right? Where is the one I need to change?

Could a novice change this easily enough?

Any guides anywhere?

How much do these cost?


Thanks

Pete

 

I would probably guess that it either

1) throttle position sensor

2) airflow sensor

3) a sticky TB

Phil

 

There is never a problem with the accelerator responsiveness if that helps, as soon as I put my foot down, revs go up and the car responds well so the problem is only ever at idle.

I did some stuff years ago; change a starter on my orion, gearbox on my cortina, water pump / thermostat on my metro etc. but it was a long time ago.

There seem too many things to try and I'm no mechanic so I expect I'll just leave it to my expensive mechanic unless I can get some more pointers on what to try first out of all the suggestions and how to do it. You have all been brilliant but I don't want to waste ages messing about with the least likely thing you all suggested and not realising it.

Thanks for all your time guys.

P.S. what's a TB?

Pete

 

just buy urself a haynes manual mate they are worth their weight in gold and will tell you most of what you need to know.ive leaned alot from owning them and wouldnt own a car without having 1.

i had the same problem as you mate with the revs and just ended up taking off all the breather pipes and cleaning them and also taking off the AICV(air idle control valve) taking it apart and giving it a good clean,cleaning all the breather pipes and cleaning the throttle body(TB).only took bout an hour to do it all and it cured it.

when starting from cold my car revs to 1500 and them once the temp reaches is running temp(just under half way) the revs settle down to 750.do only you have the revs problem when starting from cold or all the time because my revs are a bit irratic untill the engine warms up

 

to be honest i wouldnt worry too much,mine basicly does the same and it has done since the day i brought it.aslong as nothing else is affected such as power then i wouldnt loose any sleep over it.you could buy a new coolant temp sensor,they not that expensive bout £12-15 if i remember,but to fit it you would have to drain and re-bleed your coolant system

 

but to fit it you would have to drain and re-bleed your coolant system

No you don't. Just a quick swap will do or a bit of blutack in the hole when you take the old sensor out.

It does seem to be a dodgy sensor problem, very likely the temp sensor as it does cause all these symptoms such as bad starting in a morning unless throttle is pushed down first, fluctuating idle, e.t.c.

The ECU indexes the IACV depending on the input it gets from it's sensor bank. If it's getting funny data then it won't react correctly.

There is a little trick you can try as a temp solution. The IACV can be removed and a suitably sized bolt shoved in it's place (this has been done on here by someone). However it would take some trial and error to get it in the right position so that the idle stabilises and it would need to be secure.

Also unless the throttle is pushed down when cold starting you may have trouble getting the car to fire up and run correct until up to temp.


Also what happens to the idle when the temp sensor is unplugged?

 

hi Jay

you are right about the manual - I'll get myself one.

I noticed the problem couple of weeks ago when the car was idling, not long after starting up. The revs were going and down from 1100 / 1500 rpm, sticking for a second or two at each rpm.

I could live with that but in the last week it has gone as high as 1500 up to neatly 2000 rpm while idling at traffic light, when it's up to temperature.

The 2 rpms points seems to be random; i went out today and the revs were fluctuating between 800 and 900, not much above normal but a definate up and down every few seconds.

Thinking back to the summer, this was happening then but I thought it was the throtle cable or something like that. the problem was less obvious then though.

In the last few days, when the car is first started, it's been like there's no choke so I have to keep my foot on the accelerator or the car stalls.

The revs going up and down does not seem to be a hot or cold issue, it can happen when it's hot or cold.

Don't want to get into that whole draining the coolant / airlock area after my head gasket went last year.

thanks for your help Jay and everyone else too.

regards

Pete

 

just to mention: I've seen revs going up and down to a Volvo 440 turbo. Guess what was the reason: broken spark plug!

 

Thanks guys, lots of stuff for me to look into. I'm going away for a few days so I will post back as soon as I have some news.

Pete