still trying to get better than 20mpg on my 87 polo. i found that the mixture plug on the pierburg 2e3 had been removed and i suspect that the mixture was enrichened by previous owner to compensate for a torn rubber carb flange which i have now replaced.
what are the symptoms of a mixture which is too lean or too rich if i have a go at tinkering with the screw myself. i will keep a note of its current position to be able to revert if necessary.
thanks
You never mentioned if this polo has an O2 Sensor. I know someone mentioned that they were not used in Europe back then.
He has carbs ... I didn't think anything with carbs had O2 sensors. I work more with diesels though, so I could be way off.
My 1984 Nissan truck had carbs and an O2. Hondas have carbs and O2s around
1984 and up. They are one wire 02 sensors. I believe I am repeating myself...
electronic-controlled carbs can have O2 sensors. I remember my '86 Hyundai had a setup like that.
no O2 sensor
is there any way i can know that i have turned the mixture too lean? apart from piston overheating and engine running on after ignition off?
From Haynes:
"11 If an exhaust gas analyser is not immediately available, an approximate mixture setting can be made by turning the mixture screw to give the highest engine speed."
It is basically an idle low mixture adjustment. The jet size is what affects the higher engine speeds. Or put another way, the idle mixture will have little or no affect on pistons melting. I assume no affect.
If you were work>no O2 sensor
Jim B.
why does a chainsaw need low/high idle speeds and a car only 1?
In days of old most small engines had 2 mixture screws. Now you may find no mixture screws. That is true for 4 cycle lawn mowers. I have not touched a new chainsaw so I do not know that answer.
Why? Maybe sloppy manufacturing tolerances in days of old. Maybe adjustments for dirty air cleaning. The air filter on many chainsaws used to be sort of small compared to the filter of a car. The car also operated in a slightly cleaner air environement. In days of old you had manual spark advancement. I think some small airplanes may still have mixture and timing adjustments. Another area I am not familiar with. Richer for climbing and leaner for cruising while paying attenting to head temperatures.
I would guess a modern carb for a car has no mixture screw. I would guess that the lambda circuit would adjust all mixtures.
"beerismygas" wrote:
Jim B.
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