Vauxhall Vectra tick-over trouble?

egr valve would be quite a likely fault given those symptoms and that vehicle

Crankshaft or cam position sensor?

Chris

EGR's are outside my comfort zone. I found it (near side of the engine block), had him take it off and it looked a little sooty. Sprayed it with carb cleaner, then a little oil, refitted and it made no difference. Whilst it was off I tried to push the valve centre in gently, but it would not budge. Not sure what to really expect.

possible, but crank sensor failure usually kicks in when hot IME, cam sensor is more vague and it usually runs, but not so well. but whichever fault it is then the engine problem light should be on and there should be some codes stored, so a code read is the first thing: iirc the vectra codes can be read by holding the accell and the brake pedals down and turning on the ignition, the multi function display then shows the codes (all models?)

Ah, that's interesting - some built in diagnostics.

Would it help to confirm the EGR as faulty, if I were to cut a bit of plate to completely blank the EGR off? A bit of reading has suggested it should run fine without the EGR.

blanking it off is an option, BUT the engine/emissions warning light will come on. This is where you need the ECU reprogrammed to disregard the signals from the ecu flow valve. Vauxhall dealers do a blanking off kit and a reprogram service.

on 30/04/2010, Mrcheerful supposed :

Thanks, I will pass all of that information on.

EGR sticking open (can be removed + updated software to cope) or dirty and sticking ISCV. I assume this has had the breather update?

Tim..

What I had him try this afternoon, was to make a thin steel plate to fit between the EGR manifold and the EGR. He then road tested it and found it made not one jot of difference - it still ran irregularly three times, before settling to a steady tick-over, when he came to a stop.

I also got him to try (something I read works) getting the ECU to indicate any fault codes, by pressing both brake and accelerator several seconds when switching the ignition on, but not starting the engine. That did not work.

No idea - the car is the grandsons and he bought it last week. What is the breather update.

In article , Harry Bloomfield writes

Sounds like the idle control valve. A common problem on Cavaliers with the Ecotec engine, which I think was also fitted to some Vectras.

Recommended fix is replacement, but I gave mine a thorough clean with carb cleaner off the engine and it was OK thereafter.

In article , Harry Bloomfield writes

It's a modification to the engine breather system to stop oil getting into the air intake (IIRC). It's a small plastic separator box which is inserted into the breather pipe at the front of the engine.

Also make sure that the other breather pipes running to the top of the rocker cover are clear of crap and have not collapsed internally, and that the connecting pipe on the rocker cover (onto which the breather pipe pushes) is not clogged.

Mike Tomlinson explained :

Thanks, I'll get him to take a look at both of those suggestions.

Tim.. formulated on Saturday :

The ISCV - Might this be the unit in the air intake close to the bulkhead, which also has the throttle cable attached to it and what looks like a motor between it and the actual bulkhead?

Assuming so, watching its operating arm move the throttle - it is moving in perfect time with the engine almost stalling. As it moves to the closed position, the engine speed falls away and the engine speed increases as it rotates clockwise. It then (usually) finally settles at the peak position it actually reached whilst running unsteadily, after which there is little if any movement and the tick-over is rock steady.

Harry Bloomfield explained on 02/05/2010 :

Oh, one more thing, which forgot to mention...

We tried unplugging what I assume is the air flow sensor (in the air duct between air filter and the throttle body ?). This turned on the engine light and its tick-over became permanently unsteady, until it was reconnected and restarted.

have you checked for vacuum leaks? that could also give your symptoms.

Yes. The only problem I found was a split rubber going to a unit on the left side - a small electronic unit with two such pipes to it, one pipe seemed to head back through the bulkhead. They didn't seem to contain any vacuum though and I repaired it.

Sorry this is coming in small doses, but he prefers to drive it than sort it out.

Harry Bloomfield laid this down on his screen :

Solved!

I don't know the correct name for this, but I had him remove the throttle body / butterfly and give it a good clean out with some carb cleaner. All running as it should now.

The butterfly is operated by both the throttle cable and by a small unit which looks very much like a motor between throttle body and bulkhead. The motor thingummy operates the butterfly opening at tick over and it certainly looked as if it was controlling it as it should.

In article , Harry Bloomfield writes

That's what fixed my Cavalier. You've just described the ISCV (idle speed control valve). Be warned though that some people find the problem returns some time after cleaning, in which case it's best to replace it with a new one.

I'm more accustomed to the solenoid type, which is repeatedly opened and shut to maintain the idle, the type which bypasses the butterfly. These can stick and you cannot see from the outside that they are sticking.

On this Vectra one, you could see the operating lever appearing to work fine, with the butterfly opening as intended - so I remain puzzled as to how it was failing. My best guess at the moment is that as the butterfly closed, its edge was sticking to the side of the throttle body.