Idle Issues... 1.8 16v

[Ash J]

Hi guys,

Had a new car delivered this weekend, 306 XS (2001, 1.8 16v engine). I haven't seen the car yet, been away and someone collected it on my behalf. Anyhow, the guy who picked it up said the only problem is it doesn't idle at all when cold, it cuts out. Idles fine when warmed up.

Obviously I will take a look at this when I am back and able to look at it, but just wondered in the mean time if anybody knows what could be causing this? Sounds like it could be the idle control valve to me?

Cheers

[Ash J]

Got round to looking at this tonight, started and idled fine from cold and has not been used for couple of days.

I know the battery was literally just replaced by previous owner as it wouldn't start. Wondering if the drive back has allowed ECU to reset itself after battery being disconnected.

Either way, doesn't appear to be a problem, so I am not sure what the delivery guy was going on about. Perhaps it is an intermittent fault, we shall see.

[Eeyore]

I had problems with the idle on my 1.8 and it was massively overfueling. Turned out to be the MAP sensor. Its the one that looks like this

[Ash J]

Right, finally had a chance to start driving my car.

First couple of days have been absolutely fine, kicked over perfectly, however have noticed the revs do hunt a little at idle.

Went to start it this morning from cold, and would not idle at all. Just instantly cut out as soon as it started. Started fine every time, and I eventually just held the revs at about 1500 for 5 mins or so for her to warm up and then she was fine.

Suggestions? Idle control valve? MAP sensor?

[vincent1]

do these have a the coolant sensor thats that usually plays up? green one?

[7057sam]

How news your icv? also sound weird but my mate had a similar problem and it was actaully his pas sensor.

[Ash J]

Had a look under engine bay, and I could see a brown, blue and green sensor all near each other with plugs on. So I guess that's the green on you mean?

As for how new icv is, I dont know as not had car long.

It's been fine since the car is warm, and each subsequent start after being in shops etc has been fine but it does hunt a bit.

[Niall]

Could well be a bad temp sensor.
Next time its cold and won't idle, unplug the green coolant temp sensor and try it again to see if it will idle. The ECU will default to -40 degrees if you unplug it so it will be massively overfuelling but it should idle. If thats the case, get that temp sensor changed asap.

[Ash J]

Started fine this morning and didn't cut out. It is a bit milder this morning, so I'm wondering if it is when it is really really cold?

Anyway, I let it run for a while this morning, and every few seconds it would dip in revs and then come back up, and a couple of times dipped to the point where it almost stalled but it came back up again. I unplugged the green temp sensor, and initially there was a rise in revs, and then it seemed to be a bit more settled. Still seemed to hunt a little but was better.

So I have now swapped in a new green temp sensor, and replugged it back in. Started her up and she does now seem to sit much smoother at idle, even if there is just the faint dip/hunt.

I notice there is a blow on the join between my cat and centre box, don't know if this isn't helping the situation? This should be sorted in the next week when she goes in for the MOT.

Anyway, going to go for a drive in a bit just to see how she performs, particularly when coming to junctions and dipping the clutch etc, and will report back.

Would it be worth changing the MAP sensor anyway? And if so, from memory a MAP from a GTI fits the 1.8 16v engines, correct?

Cheers for the help guys.

[Ash J]

It was particularly cold this morning, went to fire it up and as I suspected, cut straight out like it did previously. This is despite having fitted new temp sensor so that rules that out.

On the drive to work (only 5 mins) it didn't have enough time to warm up so I had to hold the revs up with accelerator when approaching junctions and traffic lights as the revs would dip too far otherwise and car would stall.

Have ordered another ICV today which is known to be in perfect working order, so we shall see what that does.

If that doesn't work, then I will change the MAP sensor. And if after that it is still the same then I don't know what it is!

[Ash J]

Last couple of mornings, it has had the same issues. Engine runs lovely otherwise, but just will not idle well.

It is the same even when the car is up to temperature and warm now. It doesn't always cut out or stall when warm, but revs do hunt and dip down to 500 then come up to 1000 constantly.

I am wondering if the blow on the exhaust also has something to do with this. I had a look under the car and you can visibly see the blow when started from cold, right on the join between the cat and the centre box. Wonder if this is throwing Lambda out or something? Will be going into garage on Friday for a few other things, so will get them to look at this too. Knowing my luck it will need a new cat and/or lambda!

Anyway, have another known working ICV and MAP sensor on the way, so will fit both of those. Green temp sensor already been changed so I know it isn't that.

If the ICV and MAP sensor don't sort it out, it has to be an issue with Lambda?

Have unplugged blue PAS sensor and it still cut straight out and would not idle, so I don't think it is this either (few people suggested these cause problems with the idle).

I have learnt to drive the car how it is when cold for now. If I approach a set of lights and just dip the clutch, it will stall. If I approach and dip the clutch, but hit the accelerator a couple of times just to increase the revs, then it seems to almost settle at 1,000 first and then fall to 500. Then it will just constantly hunt between 500 and 1,000 and occasionally it will stall instead.

Hope to get this sorted soon, as it is making me want to set fire to what is otherwise a very tidy and sweet running motor!

Cheers guys.

[C.A.R.]

I had this years ago with mine. In the end I couldn't determine whether it was the TPS or the ICV, but replacing both solved it. I think the ICV was about £60, the TPS was second-hand.

I would doubt the lambda to be an issue - I had lamda problems on my 1.8 caused by a blocked catalytic converter, the lambda never was able to establish that there was a problem until the engine had already warmed up - ie. it was never an issue immediately after start-up.

[Ash J]

I had this years ago with mine. In the end I couldn't determine whether it was the TPS or the ICV, but replacing both solved it. I think the ICV was about £60, the TPS was second-hand.

I would doubt the lambda to be an issue - I had lamda problems on my 1.8 caused by a blocked catalytic converter, the lambda never was able to establish that there was a problem until the engine had already warmed up - ie. it was never an issue immediately after start-up.

Cheers for the advice.

This is what I was thinking about Lambda too, so hopefully that is fine, as car drives absolutely fine throughout rev range otherwise.

Hopefully when I fit this MAP and ICV which arrived today, that will sort it. Failing that, I will give the TPS a go.

Cheers.

[doski]

you have the potentiometer (TPS) to try although when mine fell into pieces the car revv'ed a lot higher than usual

[Ash J]

Just thought I'd update this to say it's all running sweet again.

I fitted a brand new Magneti ICV, brand new Bosch TPS, and a good used Bosch MAP sensor.

Fitted them all at the same time so I don't know which one it was, most likely ICV, but she's now idling nicely.

[Eeyore]

I had this problem. It was the MAP sensor. It was hunting between 500 and 1500. I always carried a spare with me just in case it happened again.