Sidelights causing car to Misfire....
Discussion
This is driving me absolutely mad, VW garage have no idea and I am going crazy. When the car gets up to operating temperature and either the sidelights are put ON or the AC is turned OFF the car begins to violently shake, not really a misfire but I don’t know how else to discribe it... there are no codes or check engine light, car has been perfectly maintained.
Video Attached
The car is a 2011 Polo TDI SEL 90.
Please Help!
https://youtu.be/p4aA6RxTqLc
Video Attached
The car is a 2011 Polo TDI SEL 90.
Please Help!
https://youtu.be/p4aA6RxTqLc
Sounds like the idle speed is hunting, which might indicate that the engine isn't responding to the idle control logic as expected. Does your engine have a throttle? If so, perhaps this is sticking. Switching on a small electrical load might slow the engine fractionally, but less than headlamps, fans etc. Do they have a similar effect?
Some cars will raise the idle speed slightly when the AC is on and perhaps this is why it seems to prevent the hunting.
Some cars will raise the idle speed slightly when the AC is on and perhaps this is why it seems to prevent the hunting.
GreenV8S said:
Sounds like the idle speed is hunting, which might indicate that the engine isn't responding to the idle control logic as expected. Does your engine have a throttle? If so, perhaps this is sticking. Switching on a small electrical load might slow the engine fractionally, but less than headlamps, fans etc. Do they have a similar effect?
Some cars will raise the idle speed slightly when the AC is on and perhaps this is why it seems to prevent the hunting.
I am not too mechanicaly savvy, I am not too sure if it has a throttle. I am however 99% sure it’s some kind of electrical fault. It’s something to do with the engines loading, it’s completely fine to drive however as soon as I come to a stop off it goes. Some cars will raise the idle speed slightly when the AC is on and perhaps this is why it seems to prevent the hunting.
The car runs perfectly while it’s cold, idling etc. But it’s just when the car is hot. I recon it’s something within the ECU...
CJG98 said:
Could it be the Alternator?
I am not too mechanicaly savvy
I am however 99% sure it’s some kind of ...
I recon it’s something within the ECU...
The systems involved are complicated enough that it is a waste of time and potentially money trying to guess at the cause without understanding how they work. If you want to resolve the problem, get a competent mechanic to investigate and track it down methodically. I am not too mechanicaly savvy
I am however 99% sure it’s some kind of ...
I recon it’s something within the ECU...
GreenV8S said:
The systems involved are complicated enough that it is a waste of time and potentially money trying to guess at the cause without understanding how they work. If you want to resolve the problem, get a competent mechanic to investigate and track it down methodically.
It’s been with Volkswagen for 2 weeksGreenV8S said:
Sounds like the idle speed is hunting, which might indicate that the engine isn't responding to the idle control logic as expected. Does your engine have a throttle? If so, perhaps this is sticking. Switching on a small electrical load might slow the engine fractionally, but less than headlamps, fans etc. Do they have a similar effect?
Some cars will raise the idle speed slightly when the AC is on and perhaps this is why it seems to prevent the hunting.
He says TDI....so presumably no throttle in the sense you are askingSome cars will raise the idle speed slightly when the AC is on and perhaps this is why it seems to prevent the hunting.
As for the problem....it needs someone at the car to diagnose.
GreenV8S said:
Are you saying this model doesn't have a throttle, or just pointing out that it is a diesel?
If by throttle you mean a blade that restricts air going into the engine as a form of power/rpm control...then no, very few if any diesels have that.if you mean a throttle pedal....I'd hope it has one.
GreenV8S said:
You may know them as intake manifold flaps, or pre-flaps, or swirl flaps.
And these are in no way whatsoever a form of power/rpm control as you would normally call a throttle.They are purely to alter airflow into the chamber for emissions nonsense. And those with a large throttle blade present, that is typically an anti-run on flap.
stevieturbo said:
And these are in no way whatsoever a form of power/rpm control as you would normally call a throttle.
I don't recall calling them a power or rpm control. You might know them by different names. The point is that diesel engines do often have flaps and valves in the intake and exhaust to introduce turbulence at low rpm, control EGR and so on. I don't know whether this engine has anything of the sort. However, if present and faulty they might change the behaviour at idle.GreenV8S said:
I don't recall calling them a power or rpm control. You might know them by different names. The point is that diesel engines do often have flaps and valves in the intake and exhaust to introduce turbulence at low rpm, control EGR and so on. I don't know whether this engine has anything of the sort. However, if present and faulty they might change the behaviour at idle.
Very unlikely as quite often they're broke, missing or removed because they're just nonsense. But they would never be regarded as a throttle in the normal sense.Unless the broken parts have screwed something else up...but then the thread would probably be on a different theme.
stevieturbo said:
they would never be regarded as a throttle in the normal sense.
If it has a butterfly valve in the intake which causes manifold depression then I'm happy to call that a throttle. I'm not alone in that. If you don't like that term then you're free to call it whatever you prefer. The point is that they exist, and affect the air flow, and could alter the engine's response to idle speed controls, and some VW TDIs have them.Edited by GreenV8S on Sunday 17th December 13:31
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