Polo Dune 1.4 16v Problems *One for the gurus!*

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Joined: Tue May 19, 2020 3:59 pm
Drives: 9n3 Dune
Location: Suffolk

Polo Dune 1.4 16v Problems *One for the gurus!*

Post by meadus69 »

Hi there people,

I have a problem with my polo dune 1.4 that has me at whits end and hopefully someone can help!

Ok so i will start at the begining.. i went to the car after a couple of days, the battery was flat, as in no lights on the dash flat.. charged it overnight and it cranked but wouldnt fire. I checked spark, fuel - the basics and eventually she fired up after a few mins of head scratching and cranking over. BUT wouldnt run right as i will describe below..
Ever since then it starts on the button but i have the running issue - it runs perfectly for about 20seconds and then the revs fluctuate up and down like a strong hunting but throughout the entire rev range. I have driven it but its got no power at all and just jerks around with the rpm fluctuation.
It runs with the airfilter removed and you can see the throttle body fluctuating causing the revs to hunt.
Does seem to be running rich which it never used to be..?

I have a basic dodgy vag-com and when scanned shows no codes at all. I have taken to a local garage who have also used their diagnostics and no related codes showing.
Have looked on VCDS at live values and no misfires detected, coolant temps to ecu seem to tally with guage - im no whiz with vcds just the basics!

I believe it to be electrical problem due to the battery drain and the fact that the fault doesnt occur right away from start up??

So far i have -
checked for vac leaks from throttle body and inlet manifold (pipes to servo and evap system)
replaced the electronic throttle body for a new item (no difference at all)
Sent the ECU to be tested for faults by ECU technologies - again no problems found

my local garage suggests the plastic inlet manifold may have a crack and it is sucking in air?? advised not to buy a second hand one.. vw want £750 for a new one! - no thank you! I am not convinced due to the battery drain!
I can get a second hand inlet manifold for £20 to try..?

I removed inlet manifold to have a look to see anything obvious and nothing really, all seals to head ports and throttle body seem ok and no obvious damage..

Going to carry out a compression test just out of interest!

Any other ideas would be greatly appreciated! im used to my classics (mk2 golfs) so not sure which way to turn next!
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Re: Polo Dune 1.4 16v Problems *One for the gurus!*

Post by alexperkins »

I’d agree it sounds like a leak somewhere. Maybe do a smoke test to validate the theory
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Re: Polo Dune 1.4 16v Problems *One for the gurus!*

Post by Cal844 »

Unplug the MAF sensor at the airbox, does the car improve? Give it a test drive. (reset the code if unsuccessful)

If you get the car running better like that replace the sensor.

As said above smoke test the inlet manifold and vacuum lines.

Hope this helps
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