Volkswagen Golf V (2004 - 2008) - 05 1.6 FSI - Sometimes Lacks Power

Honest John Back Room » Technical matters
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Sat 15 Aug 2009 21:58
05 1.6 FSI - Sometimes Lacks Power - timp
My 2005 Golf 1.6 FSI usually goes very well and is smooth. On other occasions it is noisier with a rougher engine note and lacks power. This often happens on the same day - it can be fine in the morning, then I park it for a few hours and then start it again and it can be bad again. As an example, it is usually fine going uphill on a motorway at 70mph in 6th gear, but sometimes I've had to drop down to 4th gear to maintain speed on the same stretch of motorway.

Other observations:
-It seems to have more power when the weather is cold and is worse when the weather is warm.
-If I accidentally don't hold the ignition key in the 'start' position for long enough it coughs, splutters and chugs into life (probably unrelated).
-It is not remotely prone to stalling at any time - in fact it's quite happy to pull away at idle.
-I've tried 95ron and 98ron petrol - there's negligible difference between them in terms of fuel economy and performance, even after 3 successive tanks of each.
-Fuel economy is worse when it lacks power.
-Switching off the air-con makes no difference.

It's got its first major service (4 years old, 25000 miles) in 2 weeks, which will mean new spark plugs, oil, oil filter and air filter (I need to check what else is included).

Has anyone got any suggestions? Sorry for the slightly vague and long post.

Thanks,
Tim
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Sun 16 Aug 2009 00:07
05 1.6 FSI - Sometimes Lacks Power - meltonlad
if you have got VAG COM then use it and check for fault codes. could be lambda sensor, coil pack or fuel filter. mine did this so i plug in VAG COM and code was lambda sensor bad connection.
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Sun 16 Aug 2009 10:38
05 1.6 FSI - Sometimes Lacks Power - elekie&a/c doctor
It is not unknown for these Fsi engines to suffer with in-tank fuel pump and pickup filter problems.There is a modified unit to overcome this fault.hth
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Sun 16 Aug 2009 23:51
05 1.6 FSI - Sometimes Lacks Power - MikeTorque
What brand of fuel have you been using ?

For the FSi engine Super Unleaded is recommended.
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Mon 17 Aug 2009 20:07
05 1.6 FSI - Sometimes Lacks Power - timp
Thank you all for your replies. I'll see how things go after its full service in 2 weeks, and I assume VW will plug it in to check for fault codes when they service it.

I've been using Shell V-Power for the last 3 tankfulls to see if it made a difference and there's been no effect on fuel economy and I've not noticed any effect on performance. I filled up yesterday with normal Shell Unleaded so I'll see if there's any difference.
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Thu 15 Apr 2010 11:37
05 1.6 FSI - Sometimes Lacks Power - STEVEO7T

I would never again put anything less than 98 RON in my MK 5 1.6 FSI engine. When the valves failed last year at the cost of 1500 quid, VW stated to me that cheap fules can affect and damage the valve system.

I called them back a year later this week and asked if this still stands, their recommnedation still is the same, and only use V-Power/Supper unleaded.

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Thu 15 Apr 2010 11:50
05 1.6 FSI - Sometimes Lacks Power - WellKnownSid

How does that work in the rest of Europe where you're lucky to be able to buy 95 unleaded in some countries?

I certainly can't think of a petrol station that sells 98 unleaded within 30 miles of here, nearer the coast maybe, but up in the mountains we're all tightwads!

I think the distinction needs to be made between 'cheap fuels' i.e. no additives and a decent 95 which is probably fine.

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If you cover no more than 100 miles per day and have easy access to a charging point at home or work, then an EV is ideal for you.

Is an electric car right for me?