OK, well, umm, hmm.
For those following my saga of the rich running engine / poor starting etc. So far I've swapped over the MAF, the TB, spark plugs, and checked all temp and pressure sensors (which all give logical impedance readings on the voltmeter). I can't find any inlet leakage. I appear to have good sparks. The tacho is working correctly. The temp gauge is apparently working as it should.
Today I changed to another O2 sensor, which has made no difference to my problem. Well, not quite, the 'new' sensor seems to have improved the economy, which (with old sensor) was around 20-22 L/100 km and is now around 12 L/100km (suggesting the old sensor was faulty, but not 'the' problem). This is about the same as I was getting when I disconnected the old sensor completely.
The engine runs fine once up to temperature (albeit a bit thirsty considering it's rural driving), and starts easily / idles well when hot. However, it's still a pig to start from cold. When attempting to start from cold it seems very rich, and it will fire up and idle for some seconds, then just dies, which it will do repeatedly.
If I even touch the throttle pedal it usually dies immediately, but sometimes I can keep the revs up during which time it runs rough with fluctuating rpm on a steady pedal. If I keep this up and re-start it enough times and manage to keep it running (badly) for long enough for the engine to get a bit warmer it will idle better and stop stalling at idle or if I try to give it a rev, but will die as soon as I select D or R.
More idling / revving and a bit more temp and I can keep it going in gear and drive off. After a very short driving time it will now drive apparently normally, and I can switch it off and then on with no issues. Once it's cooled down it's back to square one.
I have a new theory. Perhaps there is an intake air leak that exists when cold but disappears when hot. Maybe the manifold gasket leaks when the manifold is cold, but when the casting heats up it also expands enough to place some compression on the gasket and seal it....????
Grasping at straws here, any other ideas?
At any rate, tomorrow's job; have a go at tightening the inlet manifold nuts (I'd do it now, but I'd rather not get under there until it's cooled down, and off to work shortly).
Regards,
John.
For those following my saga of the rich running engine / poor starting etc. So far I've swapped over the MAF, the TB, spark plugs, and checked all temp and pressure sensors (which all give logical impedance readings on the voltmeter). I can't find any inlet leakage. I appear to have good sparks. The tacho is working correctly. The temp gauge is apparently working as it should.
Today I changed to another O2 sensor, which has made no difference to my problem. Well, not quite, the 'new' sensor seems to have improved the economy, which (with old sensor) was around 20-22 L/100 km and is now around 12 L/100km (suggesting the old sensor was faulty, but not 'the' problem). This is about the same as I was getting when I disconnected the old sensor completely.
The engine runs fine once up to temperature (albeit a bit thirsty considering it's rural driving), and starts easily / idles well when hot. However, it's still a pig to start from cold. When attempting to start from cold it seems very rich, and it will fire up and idle for some seconds, then just dies, which it will do repeatedly.
If I even touch the throttle pedal it usually dies immediately, but sometimes I can keep the revs up during which time it runs rough with fluctuating rpm on a steady pedal. If I keep this up and re-start it enough times and manage to keep it running (badly) for long enough for the engine to get a bit warmer it will idle better and stop stalling at idle or if I try to give it a rev, but will die as soon as I select D or R.
More idling / revving and a bit more temp and I can keep it going in gear and drive off. After a very short driving time it will now drive apparently normally, and I can switch it off and then on with no issues. Once it's cooled down it's back to square one.
I have a new theory. Perhaps there is an intake air leak that exists when cold but disappears when hot. Maybe the manifold gasket leaks when the manifold is cold, but when the casting heats up it also expands enough to place some compression on the gasket and seal it....????
Grasping at straws here, any other ideas?
At any rate, tomorrow's job; have a go at tightening the inlet manifold nuts (I'd do it now, but I'd rather not get under there until it's cooled down, and off to work shortly).
Regards,
John.