The Corsa problem solver

OPEL used TECH 1 and Tech 2 then. I would hope a generic scanner nowadays covers that.
IACV pin(s): I mean the seat area in the throttle body. Treat it a bit like a valve and seat in the cylinder head when you look.
 
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I found an article that linked "dieseling" (and pre-ignition / pinking) to the possibility of the car running hot.

With nothing to loose, I flushed the cooling system (with a good engine cooling system flush - driving it for about 30km to ensure it had a chance to clean the engine passages and radiator) and then ran clean water through while the engine was running - i.e. thermostat open - until the water came out clean, before draining about half the water and refilling with anti-freeze to achieve a 50:50 mixture as reasonably close as possible. The amount of dirt (rust?) that came out of the engine / radiator was shocking!

So far so good. I had the dieseling about 2 or 3 times soon after I had done the flush, and not since.

I guess that it's worthwhile flushing the radiator / engine and replacing the coolant mixture as a general precaution on this engine? I have diarised it now as part of my "major" service routine.

PS I suspect I have a temperature gauge sensor fault - I never saw any "abnormal" temperature indicated, but that is another issue to fix now!

Thanks again to everybody who contributed ideas and tried to help! This forum rocks!!
 
Feedback

I found an article that linked "dieseling" (and pre-ignition / pinking) to the possibility of the car running hot.

With nothing to loose, I flushed the cooling system (with a good engine cooling system flush - driving it for about 30km to ensure it had a chance to clean the engine passages and radiator) and then ran clean water through while the engine was running - i.e. thermostat open - until the water came out clean, before draining about half the water and refilling with anti-freeze to achieve a 50:50 mixture as reasonably close as possible. The amount of dirt (rust?) that came out of the engine / radiator was shocking!

So far so good. I had the dieseling about 2 or 3 times soon after I had done the flush, and not since.

I guess that it's worthwhile flushing the radiator / engine and replacing the coolant mixture as a general precaution on this engine? I have diarised it now as part of my "major" service routine.

PS I suspect I have a temperature gauge sensor fault - I never saw any "abnormal" temperature indicated, but that is another issue to fix now!

Thanks again to everybody who contributed ideas and tried to help! This forum rocks!!
I missed this issue

Anyway, for it to keep firing after you have turned if the ignition it would need spark and fuel, or something already burning to accelerate with compression and clean oxygen, which can only be oil in the cylinder.

Or alternatively and more probably the wiring loom has seen some maak n plan and the coil and ecu are still charged with the ignition off, like they would do to bypass immobilizeres when changing keys and ignition barrels.

But lets hope it remains sorted with the coolant flush.
 
OK - my final update on this situation and hoping it can help other owners.

While the coolant flush improved matters it didn't solve the dieseling.

So as a final resort, I removed the injectors and had them tested. The results were quite interesting:
  • All injectors delivered the same amount of "fuel" (test fluid) into the measuring chamber in the test.
  • The spray pattern of one injector (cylinder 2) was perfect with fine mist / atomisation of the fuel.
  • The spray pattern of two injectors (cylinders 1 and 4) were OK but a bit more concentrated (probably dirty).
  • The spray pattern of the injector in cylinder 3 was almost a mere single stream of petrol - no spray pattern or mist / atomisation of the fuel at all.
I could clean the 2 dirty injectors from cylinders 1 and 4 by blasting lots of carburetor cleaner through, but no amount of cleaner or other attempts could fix the injector from cylinder 3. So I ended up replacing this injector (yes I know the recommendation is to replace all injectors, but it really didn't seem necessary after cleaning the ones that I reused).

The dieseling is finally solved - not a single (even mild) run-on symptom since. The engine is also smoother and the fuel consumption has dropped!

As to the original dieseling problem: I think because the fuel in cylinder 3 did not fully evaporate, there was unburnt fuel in the chamber which then caused the run-on. Maybe there was some carbon (caused by the incomplete combustion or whatever) that glowed and ignited the fuel. Who knows?

Moral of the story - I will add a can of fuel injector cleaner to the petrol every 10.000 km or so.
 
OK - my final update on this situation and hoping it can help other owners.

While the coolant flush improved matters it didn't solve the dieseling.

So as a final resort, I removed the injectors and had them tested. The results were quite interesting:
  • All injectors delivered the same amount of "fuel" (test fluid) into the measuring chamber in the test.
  • The spray pattern of one injector (cylinder 2) was perfect with fine mist / atomisation of the fuel.
  • The spray pattern of two injectors (cylinders 1 and 4) were OK but a bit more concentrated (probably dirty).
  • The spray pattern of the injector in cylinder 3 was almost a mere single stream of petrol - no spray pattern or mist / atomisation of the fuel at all.
I could clean the 2 dirty injectors from cylinders 1 and 4 by blasting lots of carburetor cleaner through, but no amount of cleaner or other attempts could fix the injector from cylinder 3. So I ended up replacing this injector (yes I know the recommendation is to replace all injectors, but it really didn't seem necessary after cleaning the ones that I reused).

The dieseling is finally solved - not a single (even mild) run-on symptom since. The engine is also smoother and the fuel consumption has dropped!

As to the original dieseling problem: I think because the fuel in cylinder 3 did not fully evaporate, there was unburnt fuel in the chamber which then caused the run-on. Maybe there was some carbon (caused by the incomplete combustion or whatever) that glowed and ignited the fuel. Who knows?

Moral of the story - I will add a can of fuel injector cleaner to the petrol every 10.000 km or so.

Can someone confirm if this actually works, or is it also one of those money making things that does no major improvement ?
 
"Can someone confirm if this actually works, or is it also one of those money making things that does no major improvement ?"

Good point!
 
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