1.8 8 valve single point for cold start high revs.

[Pilky]

Hi all

Just brought a new cav 1.8 8 valve single point injection and only on cold starts she will rev up to 3000 rpm but warmed up the car is 100%. The previous owner has changed ht leads, plugs, dizzy cap, icv and gave it a good de grease with carb cleaner. Does anyone know straight away what it could be or I could try?

Regards

Adam

[Rage]

i was going to say the icv but you say it's already been changed my c18nz and c20ne have done this before and it's been down to the icv throwing a fit

[Pilky]

Is there any way I can test it or will it show any signs that it needs changing?

[Cavalier342]

Did the previous owner fit a genuine ICV or a cheap aftermarket one? Not much to go wrong on them, they're basically a simple valve with a spring. If it's new, then it may be something else. Does it just rev by itself? And does it fluctuate or just hold a constant RPM?

So when the car is warm it doesn't do it...

[Pilky]

Ever since I've had its never done it when warm just cold start. From cold start it does fluctuate from 2500 revs to 3000 it dont get higher then that. Could it be automatic choke? Its not sticky throttle is it?

[Cavalier342]

Sticky throttle wouldn't do that, not sure about auto choke, try taking off the small pink/red hose that goes to the EGR valve and blocking it, see if it does it then. Could be ERG valve needs removing and cleaning, but could be other things, ECU maybe.

[planetc]

Throttle body gaskets maybe? Engine speed is dictated by air flow. There are two types of iac valve too, one has a pointed end the other is flat tipped. Nz should have pointed one iirc.

[Cavalier342]

Ye mine has a pointed cone on the end of the ICV, good point about the gaskets, it may misfire if the inlet manifold gasket is broken but I don't think it would fluctuate. Also have you checked the vacuum hoses and pipes around the throttle body?

[Robsey]

Hmmm - only had this when the idle control valve was clogged with semi-sludgey black oil.
A good clean with carb cleaner worked well for me.

Leaky gaskets always caused my cars to idle slower and more lumpy.

[planetc]

The lower throttle body gasket bypasses the throttle flap Rob

[Pilky]

Hi fellas thanks for the replies. Today I have taken off the icv in my opinion it dont look like it has been in there for a couple of months. When you have taken it out could you compress the pointed end in and out because doesn't move at all. Is it soppose to?

[Cavalier342]

I don't think so, I think just the spring it supposed to move, the pointed bit is what keeps the spring in place, or a least what the spring sits on...

[planetc]

They will move, but are very very hard to move and doing so is not good for it. Clean it thoroughly along with the hole it sits in and see how you go.

[Pilky]

The EGR valve the breather hose on the side took that off with the car running are you able to feel anything from that little pipe on the EGR like sucking or blowing?

[Cavalier342]

You should feel a little vacuum from the pink hose, put your thumb to it and it should stick to it, if it doesn't, take it off and check the union (pipe) on which it sits.

[Pilky]

I've done a little investigation when I have had time. What I have done is sprayed carb cleaner down the throttle body and let it set for a while. Starts the car and its running smoothly like normal but after a while driving it the revs start to creep back up again. Is this something blocked or sticky do you peeps think?

[planetc]

Spray carb cleaner all around the throttle body with the engine running, ideally when the idle has increased. If you have an air leak it will cause a change in the engine speed.

[Cavalier342]

Random thought but I had a similar issue on my auto once, it wasn't revving higher than usual but the gauge was, if that makes sense. While normal driving, the needle was showing higher than the engine was actually turning, someone suggested I replace the water temperature sensor, next to the alternator, I did that and haven't noticed the problem ever again. But your issue sounds slightly different.... I mean it's worth eliminating in my opinion.

[Pilky]

I've done some playing about and disconnected the TPS started the car and no high revs just very lumpy and throttle response was slow. Reconnected the TPS and was high revving again. Im going to find another TPS to see if that was the problem. What do you guys think?

[Cavalier342]

These blocks don't have such a sensor as far as I know. Which plug did you disconnect?

[planetc]

Tps signal must be below 2% for it to recognise idle and the idle control circuit to kick in. Feasible it could be the tps causing the problem and definitely worth a swap out.

[saucy_begger]

them cheap idle control valves are erratic. I bought one for my cav (same engine) it would act lazy so when revved it would take its time to idle. not a lot of time but longer than the genuine one. if I pulled up at the lights it sort of hung then fluctuated till idle. just put the old one back on n its reaction times was faster and idle was better n smoother.

[Pilky]

These blocks don't have such a sensor as far as I know. Which plug did you disconnect?

I disconnected this mate http://www.vauxhallworldparts.com/vauxh ... r=17106682 and it idle fine.

[Cavalier342]

Oh I see, that's the bit on the side of the throttle body, gearbox side... I thought that was some sort of vacuum related part.. Cool.

[planetc]

That is the tps