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zob

MK2F 1.3 over rich / poor economy / cold-start issues

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zob

New to the Polo scene after buying a '93 Mk2F Bready reacently. Its got 145k on the clock and has its problems but mechanically seemed sound enough (for the price) when I bought it. First drive after getting the keys was Southampton back to Birmingham and it behaved fine so I was happy enough.

 

However I've noticed a few problems and they all seem to be inter-related. I'm trying to work through them using fixes I've picked up from these forums, however no one thing I've tried yet has done the job.

Problems:

1) Temp gauge never got higher than ~75 on a long run, although the fan did kick in when parallel parking (lots of revs to get up a curb!) after a long journey.

2) Starts ok but idle is lumpy and until its vaguely warm any light use of the throttle almost kills the engine. Have to keep revs high to change gear when cold

3) Loads of white smoke and the smell of unburnt fuel, especially when cold.

 

Tried solutions:

1) Coolant and temp gauge sensors relatively new (replaced by previous owner). Checked the blue coolant sensor when cold and has a high(ish) resistance - ~5kohms. Gauge sensor is similar (but a correct colour - black)

2) Tried warming up the engine and then blipping the throttle a few times past 3000revs (or what i believed to be - no revcounter on this car) with the blue sensor plug off, replaced it after. Supposedly to clear any error codes associated with the sensor after it was replaced.

3) New fuel filter put on recently by previous owner

 

Possible solutions (yet to try this weekend):

1) New thermostat housing put in a year ago (according to records) but no thermostat on the service bill - seems mad to replace the housing but not the 'stat but you never know. When heating the car up I tried to see if I could feel warm water entering the radiator earlier than it should but it was inconclusive. My feeling is the 'stat, if faulty is opening early rather than just being stuck open.

2) New plugs and leads - only pulled one plug so far (have to remove air filter housing off the top to get to the rest) and was pretty carboned-up. HT lead plug had some green corrosion around the nipple seat. Could it be simply time for new plugs and leads?

3) Throttle body clean - looks clean enough to me but worth a squirt. I found a link (unfortunately now old and dead) to supposedly a guide to adjust the Bosch monotronic SPI - anyone know if this is a thing? Something about throttle idle stop screws (I'm new to fuel injection here!)

4) Lambda sensor? No revcounter to test how it holds revs when warm but might be able to hear any fluctuations by ear. My feeling is this wouldn't have much to do with it running bad when cold

 

The car had its MOT last month and failed first time on emissions (v badly!) and I can see why now. Its definitely running too rich when cold and may well be all the time. Air filter was changed again recently too so its not that. Could most of these problems be down to poor plugs+leads and an engine that isn't getting to temp often because of a slightly dodgy thermostat? Could it just be that the ECU isn't switching to a closed loop mode because the engine isn't getting to temp / it doesn't think its getting to temp?

 

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steveo3002

id start with a full service , fuel and air filter , plugs leads and cap /arm , carb cleaner the tb , have the timing checked 

 

non genuine blue senders can cause trouble  , and make sure you only use a genuine thermostat , ive had massive problems with ecp ones

 

when its cold it wont use the 02 senser so wouldnt be totaly to blame ...once its warm if you have issues disconect it and see if things improve 

 

not related to your issues but has it ever had a cam belt?

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zob

Thanks for such a quick reply!

 

I asked when it last had a belt change but the seller didn't know - service history is great up until ~2000 and then theres a gap till 2014. Definitely on my list!

 

When you say non-genuine do you mean 'anything not branded VW'? Can't find any OEM VW sensors on all the usual sites, or at least they're much harder to come by.

 

I'll give it a full service myself then and at least we're starting from ground zero eh

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steveo3002

yes genuine vw are the best ...maybe take a chance on hella or some known brand if i had to 

 

dealer still sells them and avail on ebay   https://www.ebay.co.uk/itm/VW-Golf-MK3-GTI-VR6-Temperature-Sensor-025906041A-Brand-New-Genuine-OEM-VW-Part/161179299043?epid=648479365&hash=item258708ece3:g:ecwAAOSwyWxb2iDl:rk:3:pf:0

 

for cap and rotor get bosch or beru brand....some stuff is shocking quality 

 

you can also get a scanner software and cable to look for fault codes, but sounds like a full service is a good start https://www.ebay.co.uk/itm/Fits-VaG-GROUP-AUDI-USB-OBD2-KKL-409-1-Diagnostic-lead-2x2-Works-VCDS-Lite-V1-2/153126515006?hash=item23a70d313e:g:IlAAAOSwQc5bZciR:rk:9:pf:0

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zob

Cheers steveo, much appreciated!

 

Plenty of ignition timing guides about so I'll follow those if needed - I'm guessing I should check the ignition timing properly after fitting a new cap and rotor?

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zob

So far replaced the plugs, leads, dizzy cap and rotor. What can I say?

 

What a difference!

 

Its like night and day! I have to admit I wasn't totally sold on the Mk2f before (sacrilege!), but it turns out that I was driving a polo missing a good 25% of its nouse. Idles fine when cold, isn't guzzling juice and easily cruises at motorway speeds. Happy with that.

 

Next is the belt, timing and replacing some wet parts (temp gauge is working but 20C off - reckon the resistance of the aftermarket black sensor is too high for a given temp). That and a rear nearside shock that creaks like nobodys business.

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steveo3002

ah sounds like its getting there, not many receive the attention they need these days and then cheap n nasty parts dont help 

 

when you get round to the timing belt remember theres an early /late style 108 tooth vs 126?  i think , worth checking carefully that you have the correct belt and pump

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zob

Cool, thanks for the headsup - i'll check the current belt markings.

 

 

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