A few days ago my 2.5 petrol v6 started fluttering (best way I can describe it) when in drive but stationary, van drives as normal and sits at about 800 revs when in park but as soon as put into drive the revs drop down to about 400, drive off fine and gears are changing as normal but when pulling to a stop feels like it wants to cut out because of the revs dropping so much, just had it in the garage today for a full service and mot which it passed and the mechanic said he didn't know what I was on about ! And it was a good van but I know it is definitely different than how it has been for the past year I have owned it. Any ideas ? They didn't change the fuel filter on the service so is that worth changing to see if it's a fuel issue?
Bongowight
Strange idle / fluttering sensation
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bongowight
- Bongonaut
- Posts: 52
- Joined: Sun Jun 21, 2015 3:02 pm
Re: Strange idle / fluttering sensation
Hi
Generic information I am afraid, but it may point you in the right direction.
It sounds like an issue with the idle speed control mechanism.
Essentially, these work from the depression in the intake side of things so when the engine load changes like when you select a gear or load the alternator, the vacuum will trigger the ECU,in most cases that will signal a solenoid valve or similar device to open allowing more or less air in and so increases or decreases the revs to compensate and balance out against the load thereby regulating the idle.
I believe, is the valve on the top of the engine referred to as an air idle screw.
http://lushprojects.com/bongopartsmk2/c ... o=.html#18
the part is 23-6823 make sure that is clean and not partially or completely blocked.
Cleaning is best carried out using an aerosol carb cleaner. If there is an adjusting screw do not alter it.
Read trough this post it describes how this guy gained access the air screw valve
viewtopic.php?f=3&t=71967.
You should also check all vacuum hoses/air hoses and the air flow meter mechanically to ensure it is opening freely.
Whilst you have the carb cleaner in your hand you may as well clean the butterfly in the air flow meter. If there is a black ring around the area where the butterfly rests when closed or on the edge of the butterfly do not be tempted to clean off it it is there to prevent sticking of the butterfly, just clean the area around it and avoid spraying any cleaner onto any electrical looking sensors in that unit also.
And again do not be tempted to alter any adjustment screws if there are any.
Keep us posted.
Generic information I am afraid, but it may point you in the right direction.
It sounds like an issue with the idle speed control mechanism.
Essentially, these work from the depression in the intake side of things so when the engine load changes like when you select a gear or load the alternator, the vacuum will trigger the ECU,in most cases that will signal a solenoid valve or similar device to open allowing more or less air in and so increases or decreases the revs to compensate and balance out against the load thereby regulating the idle.
I believe, is the valve on the top of the engine referred to as an air idle screw.
http://lushprojects.com/bongopartsmk2/c ... o=.html#18
the part is 23-6823 make sure that is clean and not partially or completely blocked.
Cleaning is best carried out using an aerosol carb cleaner. If there is an adjusting screw do not alter it.
Read trough this post it describes how this guy gained access the air screw valve
viewtopic.php?f=3&t=71967.
You should also check all vacuum hoses/air hoses and the air flow meter mechanically to ensure it is opening freely.
Whilst you have the carb cleaner in your hand you may as well clean the butterfly in the air flow meter. If there is a black ring around the area where the butterfly rests when closed or on the edge of the butterfly do not be tempted to clean off it it is there to prevent sticking of the butterfly, just clean the area around it and avoid spraying any cleaner onto any electrical looking sensors in that unit also.
And again do not be tempted to alter any adjustment screws if there are any.
Keep us posted.