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3.9 miss
Posted: Mon Oct 16, 2006 11:01 am
by andrew e
the 3.9 in my truggy has a small miss on idle, not to the point of stalling, but almost. I have it set up the same as the disco, accept for a VL commodore fuel pump, inline disposable fuel filter and pod air filter. I unplugged the airflow meter, and it went worse, so thats ruled out. will change the plugs and leads today, but is there anything simple i have missed or buggered up?
BTW whats the firing order of one of thse octocylinders?
Andy
Posted: Mon Oct 16, 2006 11:04 am
by RaginRover
reset the ECU and then tune the AFM to the right resistance, set the base idle then check the timing with a vacuum gauge - could be that the balance has slipped and the timing was last set via timing light and could be wrong.
Just some ramblings
Tom
Posted: Mon Oct 16, 2006 8:30 pm
by RangingRover
firing order is 1-8-4-3-6-5-7-2.
Beyond that, as Tom said - set base idle, check the timing....
Posted: Tue Oct 17, 2006 8:12 pm
by disco95
RaginRover wrote:reset the ECU and then tune the AFM to the right resistance, set the base idle then check the timing with a vacuum gauge - could be that the balance has slipped and the timing was last set via timing light and could be wrong.
Just some ramblings
Tom
Ok' now how do you reset the ECU and tune the AFM?
Posted: Wed Oct 18, 2006 5:45 pm
by RangingRover
You can set the hotwire style airflow meters off a 3.9 to a base spec, by measuring the resistance between the two end pins - should be 100 ohms. If nothing comes up at all (open circuit), you're out of range (normally too lean, try winding in 2 or 3 turns). Setting it to 100 ohms, with everything else in good condition, is generally pretty close to ideal.
Never heard of resetting the ECU though.
Posted: Wed Oct 18, 2006 6:34 pm
by RaginRover
RangingRover wrote:You can set the hotwire style airflow meters off a 3.9 to a base spec, by measuring the resistance between the two end pins - should be 100 ohms. If nothing comes up at all (open circuit), you're out of range (normally too lean, try winding in 2 or 3 turns). Setting it to 100 ohms, with everything else in good condition, is generally pretty close to ideal.
Never heard of resetting the ECU though.
I have had problems with the car not taking the new settings once the AFM has been re tuned, I have had to take the neg off the battery for a few minutes then reconnect.
That is what I call resetting the ECU
Tom