Cable's Thread of Ongoing Misery

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Re: Cable's Thread of Ongoing Misery

Post by Robsey »

Regarding the milk smell -
See if you can borrow a UVC light.
It is often used to kill bacteria etc, including pongy spilt milk. Do not point it at "living things" including yourself.

I suppose, the ongoing saga hints towards changing that temperature sensor.
In the general scheme of things, it is quite an inexpensive part.

Also check the cleanliness of the two pin connector that plugs into the sensor.

Poor running is usually due to an air induction leak, exhaust blockage or fuel starvation or too rich.

The exhaust would affect idling and general running at all times - so we can rule that out.

So fueling - if the engine ecu sees the engine as cold, when it is actually fully warmed up, it could cause an over rich mixture.
A bit like the choke being on in an older car.

Air induction leak - this would cause the mixtute to be too weak, and can potentially cause hot running and damage the spark plug electrodes.

There are lots of vacuum pipes and breather hoses that could all crack and perish over time.
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Re: Cable's Thread of Ongoing Misery

Post by Cabletwitch »

I've got a new temp sensor on order, so when it arrives I'll stick it in there and see what happens. It does make sense now you've put it that way, the exhaust smelling a lot of unburnt fuel would certainly point to it being way too rich... plus the fuel consumption not being great at this point does give credibility to this.

I'll fit and test once it's arrived, and report back when I know more!
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Re: Cable's Thread of Ongoing Misery

Post by Robsey »

I found that when the fueling was too rich on my Cavalier in about 2010, my plugs got so sooted up that the engine would not start when warm / hot.

Cleaning of the plugs sorted the issue, until they sooted up the next day.

That was before I converted from C18NZ to C20NE.
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Re: Cable's Thread of Ongoing Misery

Post by Cabletwitch »

When you say converted to the C20NE... full powerplant replacement, or is it just a few parts changed to give the extra volume? Either way, pondering it...
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Re: Cable's Thread of Ongoing Misery

Post by Robsey »

I did a complete swap...
From C18NZ to C20NE.

It is not a hugely complex job.

viewtopic.php?f=70&t=6685

It is 25 more bhp for no visible change in mpg.

Although after spending that much on the engine, I would be tempted to stick with the 1800nz.
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Re: Cable's Thread of Ongoing Misery

Post by Cabletwitch »

Ok, so changed out the temp sensor finally (about an hour ago), took her for a run, and she feels a lot better for it. Idle speed still seems a little low, but from inside the car there are none of the usual thumps indicative of the engine having issues. Listening at the exhaust however, still sounds like very minor ones, albeit a lot less frequently than they used to be. I'm also noticing a lot of moisture in the gas, so either it's just because it's a stupidly cold day today and it's condensing a lot, or I still have some water ingress somewhere.

Either way, seems like that was the main issue, and I'll keep an eye on water usage for a while. Good news at least!
Never use another Cav driver as guidance to a destination, unless you REALLY want to explore the country.

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Re: Cable's Thread of Ongoing Misery

Post by Robsey »

The C18NZ has always had a slight irregularity at idle...
It will idle smoothly with the odd random "flutter" every 10 or 15 seconds.

It is quite normal, and just needs getting used to.

With regard to low idle - not the same, but the C20NE was prone to revving at as little as 650 revs, giving the whole car the shakes.
It was common for Vauxhall technicians to program the ECUs to raise the base rpm.

Other than that, I found a very slight gasket leak between the throttle body and induction manifold of my C20NE caused a slightly slower juddery idle.

Not as many gaskets on the C18NZ, but a lot more vacuum pipes and elbows that snap or crack for fun.
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Re: Cable's Thread of Ongoing Misery

Post by Cabletwitch »

She's still doing it. I've noticed I seem to have a better fuel consumption overall (almost a 200 mile round trip, about half a tank used?), but the lump still sounds like it's not happy. It felt so silky smooth when I put the new temp sensor in, like it had sorted the problem, but after the 2nd run out, it started dropping to low idle, and the 'boofs' from incomplete combustion continued. No pops, nothing detonating where it shouldn't (that might actually be an improvement, after all this), just the gentle 'boof' as something is discharged into the pipe seemingly having not been burnt properly.

I dunno... I need one of you lot to have a look at it, ideally. I'm running out of ideas and sensors to change. The thought had occurred that the position sensor for the throttle plate was off, and it may think it needs more juice than is actually required, so I'll see about ensuring that's all fine and good. The gasket between the throttle and the manifold... I guess a quick and dirty test would be wrapping tape around the joint (yeah, right... nothing on these things is built with ease of access in mind!) and seeing if that improves anything. Other than that... crank sensor would cause bigger problems, I'm guessing... the electronic ignition module would just work or not work, I figure... which leaves the ECU as the overall cause if there is nothing else.

Still, I'm learning, and once I've built up enough bitterness, frustration and hand-to-sharp-metal-and-plastic injury, I'll be well on my way to being a seasoned MK3 owner!

Shoot me now... (and no misfires!)
Never use another Cav driver as guidance to a destination, unless you REALLY want to explore the country.

"Won't SOMEBODY please think of the scones?"

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Re: Cable's Thread of Ongoing Misery

Post by cavalier1990 »

Hi Cabletwitch

The 1.8 CNZ (it is 1.8 you have right?), as Robsey mentioned, can be a bit erratic at idle and sometimes the revs can flutter up and down a bit, although it should rev cleanly through rev range and pull quite well.

The rich petrol smell from exhaust you get is something I have on mine too, yet plugs are clean, although I suspect that I need a new bosch oxygen sensor, not sure if running too lean or what. My MPG is fairly ok too. My mot guy has to use "another car" to register a pass for my emissions- he's a fine fella :D I really need to get to the bottom of this though.

Also check your manifold inlet gasket is not leaking. I'm assuming this was changed when you had head gasket changed? I had to change this twice on my 1.8, seems like a common problem. Can test it by spraying something like brake cleaner or WD (using a spray straw is helpful to concentrate the spray where you want it) along the join to see if you hear a change in engine note. No exhaust leaks either? Manifold can be farting and you might not hear it until you are up close.

Also go round the vac pipes with a very fine tooth comb - or your eyes will do just as well! Replace or trim any that are splitting at the ends, even worthwhile cutting the original ends even if not broke as they go loose and slack over time. Cutting a little bit off the end gives you a "new" tight vac pipe end. Also check brake servo pipe not leaking or worn/cracked. Mine was split under the elbow bend where it goes down to the manifold so you couldn't see it. Air intake trunking not split?

How's the oil breather system, not blocked?

Ignition - check resistance of leads/coil and the coil plug terminals are not corroded. Also check batter Earth onto body is not loose or corroded and wires not rotten.
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Re: Cable's Thread of Ongoing Misery

Post by Robsey »

If the MOT guy is having to use a different car to pass the emissions, I would say that the injector valve is getting worn or tired.

They tend to let too much fuel through causing an over-rich mixture.

Note that over-rich plugs will be black with a dry sooty look.
Lean plugs will show as very pale, almost white on the tips.

Usual weak spots on C18NZ in order or most likely to least likely are:-
1 - Oxy sensor.
2 - induction leak. - snapped vac pipe elbows.
3 - corroded or damp amplifier or HT leads.
4 - dirty or damp rotor and or disyributor cap.
5 - weak battery
6 - worn injector
7 - EGR valve.
8 - Vacuum sensor. (MAP sensor)
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Re: Cable's Thread of Ongoing Misery

Post by Cabletwitch »

To go through the list Robsey made...

1) Oxy sensor was replaced due to a different issue regarding that, fixed the 'choked' engine issue, but the persistent problem remains.
2) Induction... the intake manifold gasket was changed as part of the head gasket job, and as far as I can make out, all the pipes seem to be fine. I keep meaning to replace them all anyway, so that's on the to-do list.
3) Plug leads have been changed, as the mechanic did inspect them and found them in not such a great condition. The coil was also changed a while back, as that was my original though as to what the problem is. As far as I can tell, it's not an electrical issue with the HT system.
4) Rotor was changed, cap was intended to be changed by the chap at MPD got me the wrong type of cap to begin with, so that ended up being taken back and I kept the original. Listening closely to the distrib, I can hear a constant, even arcing, so again, the HT part seems to be working fine.
5) Just had that changed after running it flat in Halfords car park (at least it was in the best place to do so...), so that's just been swapped out. Nope, not the cause.
6) Increasingly likely, although I have a few other ideas I'll throw out after this part.
7) Still a possibility, but you just can't get the blanking plate anymore, apparently. Bloody GM. So the old unit is on there and a new paper gasket is holding it tight thus far. Can't rule out the valve itself is leaking though.
8) Got replaced, still no change. However, see #2, hose will be replaced.

I got thinking earlier on the way home... the car starts and runs fine until it's warmed up, after which the ECU wakes up and takes over... and that's when the fun starts. It HAS to be something actively controlled by it, and given I've just about replaced all the sensors responsible for telling it things are all good... the only thing that springs to mind is the idle control stepper. I've tried running the car without it in the circuit, it goes to 3000rpm and sits there (some idle! Still, better than I'm getting now). SO I wonder... is it opening up the throttle enough at idle to keep it going... OR is the ECU pulling it shut too much instead? It might be the value for the idle RPM is a tad off somehow, probably cosmic bloody radiation or dark magic. I'm interested in getting a readout on the Tech1 at the garage, to see what the values are.

Humbucker, would you (or indeed anyone else) happen to have a list of all the default/correct values for the ECU to have stored, so I can compare? I'd be interested to see if something has changed, or has been changed in the past (unlikely, as it worked fine when I was bringing it home from Tamworth).

The other thought is that I may have a leak in the exhaust manifold, and if it's drawing in air and confusing the O2 sensor, then the ECU would dump more fuel in to compensate, causing the rich and uneven burning... I shall do some poking around and checking. I wish there was something like coloured smoke I could chuck through it to see any leaks!

Any further ideas?
Never use another Cav driver as guidance to a destination, unless you REALLY want to explore the country.

"Won't SOMEBODY please think of the scones?"

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1.8i (Given up, going for parts)
2.0i (WHY won't it work?!)
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Re: Cable's Thread of Ongoing Misery

Post by Cabletwitch »

I just had a horrible thought... if I keep this up, do I win the title of 'Owner of the most broken piece of crap' from Rage?
Never use another Cav driver as guidance to a destination, unless you REALLY want to explore the country.

"Won't SOMEBODY please think of the scones?"

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1.8i (Given up, going for parts)
2.0i (WHY won't it work?!)
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Re: Cable's Thread of Ongoing Misery

Post by cavalier1990 »

Fuel filter been changed recently? Check fuel pipes into and out of carb for tightness, assume you've probably done that. One of mine was loose. Also is there a vacuum when you open the fuel filler at all?
Robsey wrote:If the MOT guy is having to use a different car to pass the emissions, I would say that the injector valve is getting worn or tired.

They tend to let too much fuel through causing an over-rich mixture.

Note that over-rich plugs will be black with a dry sooty look.
Lean plugs will show as very pale, almost white on the tips.
Plugs are clean, at least last time I checked and not had any issues recently that would tell me they are sooted up. Will give them another wee look this weekend just to check if they are health light brown.
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Re: Cable's Thread of Ongoing Misery

Post by Cabletwitch »

I'm going to assume the fuel system is fine, because if anything it's over fuelling, not under. It really does seem like something the ECU controls is causing it, the more I think about it... cold start is fine, no lumpiness, no misfires, no problems... then after a short time, everything just starts to go wonky. RPM goes from about 800 to 600 or less at idle, and you can hear a 'boof' noise randomly from the exhaust, along with the smell of un-burnt fuel. I'd be up for swapping the ECU out with a spare if anyone has one I could play with, just to rule out that part going senile?
Never use another Cav driver as guidance to a destination, unless you REALLY want to explore the country.

"Won't SOMEBODY please think of the scones?"

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Re: Cable's Thread of Ongoing Misery

Post by cavalier1990 »

Cabletwitch wrote:I'm going to assume the fuel system is fine, because if anything it's over fuelling, not under. It really does seem like something the ECU controls is causing it, the more I think about it... cold start is fine, no lumpiness, no misfires, no problems... then after a short time, everything just starts to go wonky. RPM goes from about 800 to 600 or less at idle, and you can hear a 'boof' noise randomly from the exhaust, along with the smell of un-burnt fuel. I'd be up for swapping the ECU out with a spare if anyone has one I could play with, just to rule out that part going senile?
I seem to get the opposite a bit lumpy at cold although my thermostat is goosed so it will be running a bit rich at cold. I'm quite sure you changed the coolant temp sensor ? And that the engine is warming up ok? Something I did notice is that when you said you changed a sensor it seemed to be ok then reverted back to the problem. Maybe it is going to a default setting until it learns the new sensor into its routine. I'm not sure if there is a limp home or default setting for the ECU, maybe Robsey has a clue about that?
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Re: Cable's Thread of Ongoing Misery

Post by Robsey »

Hmm -
When you do anything to the car, it is good to disconnect the battery.

Leave it off for say 15 minutes or so.

Then reconnect the battery and take the car for an enthusiastic drive round for 10 or 15 minutes.

I believe that the ECU does go through a "re-learn" phase, and so really it should be the opposite to what you both describe.

A bit iffy at first, but then the ECU learns how to compensate for any minor anomolies.

I am tempted to think that both of you have more than just a minor anomaly.
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Re: Cable's Thread of Ongoing Misery

Post by cavalier1990 »

Robsey wrote:Hmm -
When you do anything to the car, it is good to disconnect the battery.

Leave it off for say 15 minutes or so.

Then reconnect the battery and take the car for an enthusiastic drive round for 10 or 15 minutes.

I believe that the ECU does go through a "re-learn" phase, and so really it should be the opposite to what you both describe.

A bit iffy at first, but then the ECU learns how to compensate for any minor anomolies.

I am tempted to think that both of you have more than just a minor anomaly.
I think with mine I just need to change stat as it takes an age to warm up, so is likely running quite rich for lot longer than it would. Actually Robsey do you know the one is it 82 or 92 c version? I think mine is 92oC
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Re: Cable's Thread of Ongoing Misery

Post by Robsey »

I would stick with the higher rated stat, if the car runs best when warm.

I would have thought 82 degrees would probably more like a diesel set-up as they tend to run cooler anyway.

(Apologies for the slight diversion from the original topic).
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Re: Cable's Thread of Ongoing Misery

Post by Robsey »

If you suspect the ECU,
Have you physically and visually checked it over in the driver's footwell / kick panel.

See if it is clean and dry.

Depending on the possible ingress of moisture / water through corroded A-pillars or windscreen seal, it has been known for some ECUs to get wet, corroding pins or damaging the ECU.

No consolation I am sure, but my C18NZ ECU survived about 18 years and 227,000 miles without a hiccup, before I swapped it to a C20NE.
Sadly I sold the ECU in 2012 on ebay and gave the rest of the whole engine away to a member on here shortly after.
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Re: Cable's Thread of Ongoing Misery

Post by Cabletwitch »

I'll have a look and see if there is anything outwardly wrong with the unit... kinda baffled why I never thought to check it until now anyway. I can get a replacement idle control motor for 15 quid all in from Germany, so might as well do that one as well. Could just be the spring on it is weakened, so can't quite push the valve open enough when idling... although it doesn't explain why it's all fine right at the start... still, 15 quid, might as well.
Never use another Cav driver as guidance to a destination, unless you REALLY want to explore the country.

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Re: Cable's Thread of Ongoing Misery

Post by Cabletwitch »

Well, bugger me... I think I found the culprit. I removed the ICV to check it over, figured an inspection wouldn't go amiss on it before I did anything else... and found the plunger was seized rock solid. No movement, nothing. Given the Haynes Big Book of Lies said you may need to depress the plunger on a new unit if it sticks out too far, it's apparent that this one is NFG. After a gentle bit of persuasion on the kerb (no hammering, just a gentle push from the back of it) the plunger freed up by about 2-3mm, nothing more. The net result of that seems top be that the engine fires up at a higher RPM than before, but settles down to about where it should, at least within 2-3 seconds of start. I've yet to take it out on a trip to check if it's settled after a decent drive, but I suspect it'll still misfire due to an overly rich mixture, maybe a little less than before. So, going to order that one of Ebay, and see where that gets me!
Never use another Cav driver as guidance to a destination, unless you REALLY want to explore the country.

"Won't SOMEBODY please think of the scones?"

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2.0i (WHY won't it work?!)
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Re: Cable's Thread of Ongoing Misery

Post by Robsey »

Good to see a possible solution.
Hopefully it should get sorted this time.

You have replaced everything else, so not much else it could be causing your issues.
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Re: Cable's Thread of Ongoing Misery

Post by cavalier1990 »

Where is the ICV valve on the C18 engine?
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Re: Cable's Thread of Ongoing Misery

Post by Robsey »

It is on the front of the throttle body -
Held in place by two small cap-head torx screws. Probably T25 or similar.

See this image from the Astra mk2 owners club.

Image

The valve is in the circle.
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Re: Cable's Thread of Ongoing Misery

Post by cavalier1990 »

Robsey wrote:It is on the front of the throttle body -
Held in place by two small cap-head torx screws. Probably T25 or similar.
Ah ok Robsey will have a butchers at that never checked it before.

Cheers

C
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