Backfire after cleaning throttle body adding fuel cleaner
04-25-2005, 09:28 AM
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Backfire after cleaning throttle body adding fuel cleaner
Hi,
Thought I'd post this one in case anyone had any ideas. I had my engine '75 ROW 911 running well. After having difficulty adjusting the idle adjust screw I decided to take off the throttle body and clean it up. I re-attached it (o-ring seated in groove well) and also added some fuel injection cleaner to the tank. After this, the engine backfires lightely at idle about every 10 seconds and more quickly at about 2000 rpm. Gets a light pop, pop, pop out of the exhaust.
My thoughts are that it is not so much the throttle body. As my tank is not full however it probably has about 8 gallons in it I added about half of the fuel injector cleaner. Can too much cleaner cause this? Fuel filter is new and hasn't seen more than 30min. of run time on it. And I have adjusted the throttle screw and air/fuel mixture again. I tried richening the air/fuel mixture but this does not help.
Thought I'd post this one in case anyone had any ideas. I had my engine '75 ROW 911 running well. After having difficulty adjusting the idle adjust screw I decided to take off the throttle body and clean it up. I re-attached it (o-ring seated in groove well) and also added some fuel injection cleaner to the tank. After this, the engine backfires lightely at idle about every 10 seconds and more quickly at about 2000 rpm. Gets a light pop, pop, pop out of the exhaust.
My thoughts are that it is not so much the throttle body. As my tank is not full however it probably has about 8 gallons in it I added about half of the fuel injector cleaner. Can too much cleaner cause this? Fuel filter is new and hasn't seen more than 30min. of run time on it. And I have adjusted the throttle screw and air/fuel mixture again. I tried richening the air/fuel mixture but this does not help.
04-27-2005, 10:20 AM
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Assuming U have a CIS car, usually the misfire/ backfire is because af a lean conditin in A/F ratio. Maybe WUR is not so good. I just drowe a couple of days with a AFR meter (actually lambda reading), and observed that at idle the mixture is lean (lambda 1.15-1.20) especially from 2 to 5 minutes after cold start, after the WUR is heated up, and befor engine is at full operating temperature. But at cruising 2-3K rpm mixture is OK.
Maybe try to ajust a little ritcher and up the idle rpm a little.
Remember CIS mixture is reacting different at cold and warm wather, so if adjusted OK for summer, might be to lean for winther or vice versa.
Maybe try to ajust a little ritcher and up the idle rpm a little.
Remember CIS mixture is reacting different at cold and warm wather, so if adjusted OK for summer, might be to lean for winther or vice versa.
