vl blowing smoke under load

[aussie_macca]

hey all, im only new here and ive looked at a fair few threads on this topic but cant seems to find one with the same symptoms so here goes, its a stock vl commodore on duel fuel and i didnt know it blew smoke until the mrs was driving behind me the other day. it runs smooth as anything and doesnt chew through fuel or gas and doesnt blow smoke when your just cruising along and i got the mrs to rev it while i stood behind it and still no smoke...the only time it seems to blow smoke is when i was going up a hill on the freeway and it kicked down a gear and she said it blew a few puffs of dark smoke...it does this on both fuel and lpg....i dont know if you need any more details but thats pretty much the jist of it...any help would be appreciated.thanks. josh

[leigh 7005]

is it black smoke if so its fuel might need to adjust the air flow meter a bit

[harry3]

black smoke usually means motor is running to rich, make sure air filter isnt blocked

black inside rear of exhaust pipe is normal when running on unleaded

[aussie_macca]

ok cool so ill replace the air filter but if that doesnt work how do i adjust the air flow meter? and yeah sorry it is black smoke

[Nackerz]

there is a screw on the side of the airflow meter next to the plug it has a black plastic bit inside of it and behind that there is a flat head screw,

in another post it tells you how to adjust it, i cant quite remember which post it is but i will find it and put a link here for you..

[VL Berlina 5speed]

1. Air flow meter: check the connections including rubber boot, clean with contact cleaner if necessary. remove the airflow meter (undo the clamp behind it and remove the top of the airbox and air flow meter together) and clean using contact cleaner or some other cleaner thats safe on electrical components. clean out the airbox and replace the air filter if necessary ($10 for a cheap one, $100 for K&N) reinstall everything

if the car is stalling after starting or seems to be choking still after this, check AAC valve, air regulator, make sure there's no air leaks, then replace the air flow meter ($20-$60 from wreckers, approx $150 reconditioned, about $400-$600 new)

TO CHECK AND ADJUST MIXTURE:
1. start and run the engine until its at operating temperature
2. set idle speed and timing to specified values
3. take off the passenger kick panel to view the LED's on the ECU
4. start and run the motor at 2000rpm for 2 mins
5. check the flashes from the LED's on the ecu while at 2000rpm, they should both flash together more than 5 times every 10 seconds. if they don't you have ecu or oxygen sensor issues (refer to the picture at the bottom explaining the interpretation of flashes other than what are stated)
6. if there are more than 5 flashes per 10 secs, stop the engine, disconnect the wiring connector from the AAC valve and the throttle switch
7. start and run the engine at 2000rpm for 2 mins
8. let the engine idle
9. the leds should now flash simultaneously
10. if the green light is flashing more the mixture is lean, if the red is flashing more the mixture is richer than it should be.
10. if the LED's do not flash together remove the plug next to the Air flow meter connector and adjust the screw until they flash together (clockwise raises the resistance and leans the mixture, anti clockwise lowers the resistance and richens the mixture)
11. replace the plug, replace the AAC and throttle switch connectors and return to instruction 4. do the test again to check that the mixture is now right
12. if the mixture cannot be adjusted so that the leds flash together, its time to test the AFM

TO TEST AFM:
pull back the rubber boot on the AFM connector revealing the wires. grab your multimeter and stick the probes on wire 4 (white) and 2 (1 being the closest to the airbox) with the multimeter on DC voltage. turn the ignition on and the voltage reading should be between 1.26V (lean) and 1.32V (rich). this is the base setting and if it is out then the AFM wont be able to be adjusted to a satisfactory mixture (meaning you need a new one)

and just for interests sake you can test the mixture by putting the probes on wire 1 and 3 with the key on and measuring the voltage. 3.6V is the factory setting which is lean, with 2.0V being rich. the mixture should be in the vacinity of 2.0-4.0i couldn't get the LED's to flash and therefore couldn't set it using the computer so i did it this way and set it to 3.5V (AFM resistance of 375 ohms) and then checked it using the computer and it was right, LED's flashing together.

........................

[aussie_macca]

you have my sincere thanks.....i replaced the air filter about an hour ago and just had a fiddle with the plug which came off pretty easy....then gave a quick clean and when i put it back on it clicked and now it doesnt just come straight off....now there are no dramas what so ever...thankyou very much for your time and your responses were very helpful so you have my gratitude...thanks again...josh