Mk1 Vrs intermittent fault eg.revs erratic

[ScottishDavey]

Hello,hopefully some you wonderful people could shed some light on what's wrong with my vrs.When I bought my car back in November the only fault code showing was 16486(maf) so replaced this with a new bosch one but over the past couple of months the car has an intermittent lumpy idle(revs will dip rapidly then jump up to 1200rpm) sometimes to the point of cutting out it will do this a few times before settling at about 850 when this happens if I'm driving off it will have a tugging feeling.The car can be totally fine driving at 60mph then when I get back into town and park up and let it idle the revs will sometimes start bouncing a bit.It seems to always come back with the code 16486(maf) every time after clearing it and randomly some other codes aswell the codes today are 16486,17705,17545 I have checked what they mean on Rosstech sometimes the traction control light will come on for no reason and stay on for a bit then go off.I have had the car to 2 different garages the first one found a split breather pipe(replaced) and slider pins on rear calipers seized so they were freed off.The second garage was a vw/audi specialist who kept the car 2 days scanned it for codes and got maf signal too low-intermittent,evap emission control system incorrect flow-intermittent and pressure drop between turbo and throttle valve they then cleared codes carried out 3 road test's over the 2days checked again for codes and no faults,they did replace battery as it was poor.Last weekend the car got a full service with all mann filters,new ngk pfr6q spark plugs and castrol edge 5w30 I always run her on v-power.One other code that sometimes pops up is 01304-radio no communication - intermittent.Thanks

[kentphil1]

Hi, welcome to Briskoda.

 

When you say all new filters, was the fuel filter changed?. as one of your codes can be fuel pressure related. It could also be that your fuel pressure regulator has started to fail, or that the vacuum line to it has perished creating the same symptom - check that first.

 

Your error code relates to fuel trim as the ecu struggles to make sense of the readings it is getting. I know you said you fitted a Bosch MAF, but was it from a good quality parts outlet, as this forum is littered with rapid failures of ebay sourced units. This is one of those items where OEM will probably be cheaper in the long run.

 

Also your throttle body may require cleaning, they build up carbon and restrict the smooth operation of the butterfly valve - not expensive to sort - about £7 for a new gasket and whatever a can of fuel injector cleaner costs at the moment,

 

Hope it helps a little.

[ScottishDavey]

Hi,thanks for the reply kentphil1 yes the fuel filter was replaced,the maf was bought at Dingbro who supply the trade and took pipe off at drivers side of throttle body and it looks clean. 

[kentphil1]

In which case I would start to look at the fuel pressure regulator and carry out a fuel pressure test to confirm it is fuctioning correctly.

 

While I was at it I would get the Lambda sensor readings logged to see what is going on with the oxygen sensors and the air fuel ratios.

 

Just as an aside, taking off the intake pipe does not fully confirm it as clean, unless another person operated the throttle pedal to check how clean it was with the butterfly open. Do not try to open the butterfly by hand, as the electronics in the body throw a real hissy fit at that and throttle bodies are HUGELY expensive - just get somebody to use the pedal and keep the cable attached to the body so that it can still function.

 

Do you or any of your friends have access to VCDS at all?.

 

Has your car had the coil recall carried out on it yet?

 

Your 01304 radio code is normal if you have a non VAG radio fitted, but may indicate an issue if your radio is still original Skoda fit.

Edited 12 February, 2018 by kentphil1

[ScottishDavey]

On 12/02/2018 at 00:55, kentphil1 said:

In which case I would start to look at the fuel pressure regulator and carry out a fuel pressure test to confirm it is fuctioning correctly.

 

While I was at it I would get the Lambda sensor readings logged to see what is going on with the oxygen sensors and the air fuel ratios.

 

Just as an aside, taking off the intake pipe does not fully confirm it as clean, unless another person operated the throttle pedal to check how clean it was with the butterfly open. Do not try to open the butterfly by hand, as the electronics in the body throw a real hissy fit at that and throttle bodies are HUGELY expensive - just get somebody to use the pedal and keep the cable attached to the body so that it can still function.

 

Do you or any of your friends have access to VCDS at all?.

 

Has your car had the coil recall carried out on it yet?

 

Your 01304 radio code is normal if you have a non VAG radio fitted, but may indicate an issue if your radio is still original Skoda fit.

Thanks for the reply,the car has had the coil recall and the radio is still original.I have found a member local to me with vcds so will try and get readings logged when I get a bit of free time also get a look in throttle body.