Cable's Thread of Ongoing Misery

[Cabletwitch]

I'm currently in Devon at the moment, sans Cav, but I'll check it out when I get home. I need to look up and learn about a number of parts on the 2.0 that don't exist on the 1.8, and try not to break anything in the meantime.

[Cabletwitch]

AAAAARRRRRRRGH!

So, I got me a nice 2.0i as noted before, and wouldn't you bloody believe it? The damned thing has the same sodding issue, low idle RPM with what sounds like misfires (thudding noise from the exhaust every so often). I've changed the plugs, no dice. Cleaned out the ICV, nada. Today was spent changing all but the manifold and the downpipe on the exhaust (I did the gaskets though), and still nothing. The 1.8 has this issue, even with a new O2 sensor, so I'm almost reluctant to change it.

The one thought that springs to mind is that of injectors. I don't know if either is overfuelling, but at the price that most injectors go for, I'm again reluctant to swap those out. It's just the idle, fer chrissakes... drops almost as low as 500 on the 2.0i, and it's really doing my head in now...

Also, I don;t rate EuroFlo exhausts... I can put my hand over the end of the pipe now and watch it blow condensation though the seams of the middle and back boxes...

[cavalier1990]

AAAAARRRRRRRGH!

So, I got me a nice 2.0i as noted before, and wouldn't you bloody believe it? The damned thing has the same sodding issue, low idle RPM with what sounds like misfires (thudding noise from the exhaust every so often). I've changed the plugs, no dice. Cleaned out the ICV, nada. Today was spent changing all but the manifold and the downpipe on the exhaust (I did the gaskets though), and still nothing. The 1.8 has this issue, even with a new O2 sensor, so I'm almost reluctant to change it.

The one thought that springs to mind is that of injectors. I don't know if either is overfuelling, but at the price that most injectors go for, I'm again reluctant to swap those out. It's just the idle, fer chrissakes... drops almost as low as 500 on the 2.0i, and it's really doing my head in now...

Also, I don;t rate EuroFlo exhausts... I can put my hand over the end of the pipe now and watch it blow condensation though the seams of the middle and back boxes...

Did you swap anything over from the 1.8 to the 2.0, like ignition parts? Can't believe you still got the same problem. What's the 2.0 out of? is it later or earlier model cav?

[Cabletwitch]

No, the two cars are completely separate, it's just the problem is present on them both. The 2.0 is from a MK3 L reg, so post-facelift.

I'm just hoping what eventually fixes one fixes them both...

[Cabletwitch]

Well, apart from the exhaust sounding like it's about to shake itself to bits (never cheap out!), nothing has gotten any worse. However, I DID score a nice brand new set of injectors on the Fleabay for 160 notes, MUCH cheaper than retail (yet still from MPD... strange...). I'll be fitting those the weekend after they arrive, and see if that solves anything.

Wish me luck!

[Robsey]

Good luck

[Cabletwitch]

Right, just a quick one, back in the right thread (maybe, I seem to be in several systems at any one given time). I've tried all sorts... new FPR, new injectors, plugs, CTS, leaning ground straps, etc.

BUT... I recently saw a few videos on how to overhaul and fix the Bosch AFMs that seem to be fitted to just about every car from that era, and one of the symptoms is... yes, you guessed it, crap running at low RPM etc. So this coming weekend, I'm going to open 'er up and have a cleanup to see if that helps. If it does, happy days! If not... well, shouldn't be any worse, right? Just running out of things to mess with now without admitting to myself it's a mechanical issue at the core of the engine, and that would make me very sad...

Also, a new picture to more accurately reflect my ongoing saga with these bastard things...

[Robsey]

Have you tried running the car with the AFM disconnected?

The car ECU will use default values to allow the engine to run.
The ECU light will illuminate, but the car should run.

Just as with the ICV, if running with the sensor disconnected appears to be an improvement over with the sensor connected, then it may hint that the disconnected sensor is not working properly.
But don't treat this as a definitive answer - just as an indication.

There are no guarantees with anything Vauxhall related.

[Cabletwitch]

While I haven't tried it again recently, pulling the AFM out of the loop when running kills the engine, haven't tried running without it disconnected from the start. I'll give that a go and see what happens after work.

[Cabletwitch]

I'm wary saying this, but I think we've bloody got it! After a short trip home from work today, just long enough to get the engine warmed and doing the low RPM thing, I parked up, switched off and unplugged the AFM. First restart conked out, but the second ran smoothly, and because I know my base idle RPM has been adjusted upward in the past to try and compensate for this issue, it peaked at 1500 RPM at idle. I shut down and restarted, same thing happened.

SO... I think we're now at the fault, and as such, I'll be removing and cleaning/unsticking/sorting the ARM over the weekend. I've seen a few videos on how to do this, so I'll report back anything I find, and anything I do. If this cures the issue, I'll be so damn happy.

However... this doesn't explain the issue on the 1.8, because it has a MAP sensor instead of the AFM, and I know it's a good one because I replaced it, same issue. I'll have to do more work on that, but as long as the 2.0 works fine, I'm probably going to take parts of the 1.8 and send it to it's final resting place eventually.

We might be done in this bloody saga yet!

[Robsey]

On the 1.8, the map issues can be just as easily a cracked or leaky vacuum hose.

The 2 litre air flow meter just looks more complicated than it is.
A variable resistor controlled by a moving vane, that can suffer a dirty or worn rub-track.
The hard bit is removing the top cover without injuring yourself or breaking something.

[Cabletwitch]

So, I managed to kinda sort the issue somewhat... I got the AFM out of the car and opened up eventually... a lot of cutting silicone seal and trying not to slice up fingers in the process. Eventually though I had it open, and thus the innards were exposed for all to see...




After checking the vane was free moving and fine, and the airways were all clear, I set about going over the internals. The carbon track was somewhat worn, but not too much considering the age of the part. I cleaned up the track and the contacts as best I could (a sheet of paper apparently has enough abrasion to clean them without damage), and pondered how to reseat the contacts onto an unused are of the strip. As it turned out, undoing the three screws holding the PCB to the frame allowd the board to shift ever so slightly, resulting in the needed adjustment. After ensuring the contacts weren't drifting off the track, I did em up, and all seemed well.



I checked the air temp sensor in there too (and stupidly forgot to take a picture, but it's in there) by blowing and huffing on it, and checking the resistance changed properly. All seemed good, so reassembly and testing proved all worked fine. It seems to have given me smoother running of the engine overall, with less misfires, but ultimately they still persist with the low RPM issue, so I can honestly say the AFM isn't the cause. I did remember I hadn't checked the TPS on this car, so a new on is on order and I'm probably going to kick myself hard if that turns out to the cause. Failing that, I've still got the new O2 sensor to fit because lazy and it's been raining, so maybe somewhere in all this mess the cure lies.

We shall see...

[Cavalier342]

That looks very technical. Credit to you for digging around, I wouldn't have a clue how to do any of that.

[Robsey]

Thankfully there are lots of videos on YouTube for stripping and cleaning Bosch air flow meters.
Fitted to lots of cars and camper-vans with Motronic and Jetronic fuel injection systems.

I have done many of the jobs that you have done, or plan to do.
I too still have the low idle when warm.
In my particular situation, I have changed the idle control valve, throttle position sensor, oxygen sensor, octane plug and I have cleaned the ICV twice.
I haven't done the pcb in my air flow meter, but I did clean all the parts exposed to the air flow.

This potentially leaves two further checks.
1 - Engine ECU for having clean contacts and no signs of water damage.
2 - Air leak in the gasket between the throttle body and inlet manifold, and the inlet manifold gasket.

(I have already checked all the ground wires in the injector loom).

Hopefully you are not far from sussing the final culpret in this saga.

[Cabletwitch]

New TPS arrived, going to see if I can fit it either lunchtime, or later after work. Maybe it will, maybe it won't. We shall see...

[Robsey]

Fingers crossed of course.
I think there is a pattern forming here - lol

It really would be nice to get this thing nailed once and for all...
Well for about 12 months anyway.

There is virtually nothing left to try.
All sensors checked, cleaned or replaced.
All breathers and vacuum pipes checked, cleaned and secure.
Induction system clear of gasket leaks.
Engine ECU and connectors in good clean, dry condition.
All service items okay - oil not too old or dirty.
Plugs, leads, distributor cap and rotor all clean, dry and in good condition.

[Cabletwitch]

Well, it's not the TPS, not that I thought it would be.

So, we're going deep now... going to visually inspect the ECU itself, and check all components are functioning and not age knackered. This'll involve digging it out and making sure all is well with the board itself... pics will follow, maybe this weekend!

After that... very possibly the loom itself. The thought of rebuilding had occured, but how big an undertaking that would be, I don't know. I'd rather get a spare, rewire that and then swap them over.

[Cabletwitch]

Well, sod that.

It seems that the ECU on the 2.0i model is the part they started with, then decided to build the rest of the car around. The Haynes Big Book of Lies™ states that there are three screws (wrong) holding it in (they're nuts), and that one it's undone it'll simply drop out (assuming the forest of thick cable bundles surrounding it aren't there) and then you unplug the loom from it when it's out (if your main loom bundle isn't like mine however, else it's the one thing in the way of both the screws and it simply dropping out).

However, there was just enough space after snapping three of my vertebrae to gain access to the area in the drivers foot well that I could see the whole shebang was dry, no corrosion, nothing. I felt around it as best I could (and gained several razor cuts in the process) and confirmed that apart from the blood, there was no moisture there. So, unless I'm prepared to dismantle half the dashboard to gain access to it, I'm going to rule it out for now, and focus more on the loom.

Which is connected to the ECU... which I can't disconnect because no room... yay.

On the other hand, I've managed to find a few more earthing points which I missed and will clean up once I have some emery paper and contact cleaner in the vain hope it's simply that causing it. and not something expensive or frustrating such as a mile long bundle of cabling that's likely to have one crumbly green mess deep within it that'll take ages to repair. Or something.

[Cavalier342]

I've always used a wire brush on earth points myself, contact cleaner dries up on metal and leaves a a white residue, at least around the engine bay earth points in my case. The ECU should come out easily enough, although there is a fair bit of wiring down there.

[Cabletwitch]

The point about the ECU is more that I can't get anything in the area to undo the nuts, and the loom tail is so tight against it that I can't get the box out physically without undoing it, but the tightness means that even unclipping the cable, I can't get the connector clear enough for that to happen. Hence the whole idea that they started with the ECU and built the car around it.

[Cavalier342]

Isn't there a bracket which holds certain relays and plugs which is in front of the ECU that is held on with 2 screws? I presume you have got that out of the way first?

[Cabletwitch]

I'll try and get a pic of what's there tomorrow. Too dark now.

[Robsey]

The ECU is sat up and back from the bonnet release lever.
(My release lever has been detached for access, and is dangling down left of centre in the image))

Below this is the central door locking module held in by a plastic strap.
Two hex head screws fix this strap to the inside body.
8mm spanner or socket.

On the front of this strap are three small square connectors. These supply ECU outputs to the instruments and air con if fitted.

Behind the strap towards the firewall is a relay. This is the fuel pump relay.

See Here -





If there is a lot of wiring covering the area of the kick panel, then you may have a factory fit alarm / immobiliser.

All manuals including Haynes will say that the immobiliser is up behind the glove box - but I have seen photos of electrical spaghetti in the driver's footwell for the alarm / immobiliser.
This nearly always relates to 1995 vehicles,
where Vauxhall finally rolled out it's "dead-lock immobilizer" in October 1994.

As for bolts holding the ECU in place -
There is one that you need to remove completely,
and another one that you only need to loosen a bit as the ECU hooks over it.
More fiddly than anything.

[Cabletwitch]

Part of me is now just hoping I can find a place that does loom rewires to either make a new one, or at worst redo the old one... I'm not thrilled at the prospect of doing it all myself at this point...

[Robsey]

If it is the loom as you fear, then the most likely culprets will be the injector wires / connectors.
A weak spot on many engines due to the localised heat.

As this has been a saga... have we covered rotor arm, distributor and ht leads?

On my 1994 C18NZ and 1987 13S the leads were often the weak spot, requiring renewal every 12 to 18 months.
On the 13S it would often burn out the rotor arm due to the green powdery copper oxide on the lead ends.