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VRS Driving like ****


KTP

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Looking for some help, have searched various things but not managed to get anything that seems the same although i'm sure theres probably a topic in here i havent found.

 

so my car seems to have an issue. when accelerating hard it bogs down badly and makes the exhaust pop on gear change.

sometimes this also causes the car to go into limp mode, the epc light comes on and i have to stop and restart the car.
if i try rev it high and fast it sounds like its misfiring but any other time it sounds totally fine.
 

i've swapped out all the coil packs and also maf sensor and nothing has changed. if i take it very easily, it seems fine but it just doesnt want to accelerate quickly, so this is awkward for moving out a junction etc.

no dashboard lights are on, i did have the eml on but with the new maf thats now went off. asked a friend to use his vagcom to see what if any codes come up but havent had that yet.

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Has anyone done a fuel pressure check or a smoke test yet?. Is the car remapped or standard?. Does it have an aftermarket recirculation valve fitted?. Were the coilpacks and maf oem new or second hand?. Does the car temperature run at 90 degrees all the time or does it fluctuate and run colder at times?.

 

Need a bit more info to help you really,

 

All the best

 

Phil.

 

 

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1 hour ago, kentphil1 said:

Has anyone done a fuel pressure check or a smoke test yet?. Is the car remapped or standard?. Does it have an aftermarket recirculation valve fitted?. Were the coilpacks and maf oem new or second hand?. Does the car temperature run at 90 degrees all the time or does it fluctuate and run colder at times?.

 

Need a bit more info to help you really,

 

All the best

 

Phil.

 

 

no pressure or smoke test has been done.
car is remapped, has a forge dv, coilpacks came out my other vrs and are fine, maf is new but not oem.
temp is around 70 all the time, needs a new thermostat

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As we are in a very cold snap at the moment I would think it highly likely that your thermostat issue (assuming it is not the sender at fault) is telling the system to richen up as it thinks the engine is still cold, but the maf cannot weaken the short term fuel trims enough to compensate. 

 

Having said that, faulty thermostats tend to manifest themselves as an increase in temperature that is shown on the gauge when climbing hills or giving it lots of loud pedal action, then a drop in temperature if cruising down hils on light throttle. If the thermostat and sender are good it should be 90 all the time regardless of up or down hills once the car is warmed up.

 

A constant low temperature would tend to suggest a Coolant Temperature Sensor fault, which could well be your issue for performance as well. You can see what temerature the engine is seeing as against what the gauge is showing by checking it in VCDS - the sensor has two outputs, one for the gauge, one for the ECU. If they both appear the same, the sensor may be ok, if one is higher than the other the sensor is in question.

 

The fuel trims can be checked by getting your friend to log the temperature the ecu is seeing (not the gauge temperature as indicated) against the air fuel ratios being adjusted by the system in VCDS (Vagcom if you like). Just as an aside, what brand and grade of plugs are you running and what gap are you running them at as the car is mapped?. What colour spring are you running in the Forge valve, and when was it last serviced?.

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16 hours ago, kentphil1 said:

As we are in a very cold snap at the moment I would think it highly likely that your thermostat issue (assuming it is not the sender at fault) is telling the system to richen up as it thinks the engine is still cold, but the maf cannot weaken the short term fuel trims enough to compensate. 

 

Having said that, faulty thermostats tend to manifest themselves as an increase in temperature that is shown on the gauge when climbing hills or giving it lots of loud pedal action, then a drop in temperature if cruising down hils on light throttle. If the thermostat and sender are good it should be 90 all the time regardless of up or down hills once the car is warmed up.

 

A constant low temperature would tend to suggest a Coolant Temperature Sensor fault, which could well be your issue for performance as well. You can see what temerature the engine is seeing as against what the gauge is showing by checking it in VCDS - the sensor has two outputs, one for the gauge, one for the ECU. If they both appear the same, the sensor may be ok, if one is higher than the other the sensor is in question.

 

The fuel trims can be checked by getting your friend to log the temperature the ecu is seeing (not the gauge temperature as indicated) against the air fuel ratios being adjusted by the system in VCDS (Vagcom if you like). Just as an aside, what brand and grade of plugs are you running and what gap are you running them at as the car is mapped?. What colour spring are you running in the Forge valve, and when was it last serviced?.

i know the thermostat is needing replaced as i had it plugged into skoda's diagnostics last year and this was one thing that came up.

the technician said they were a pain to change so i haven't bothered to do it as it didnt really give me any issues.

the coolant sensor, i might change this anyway as they aren't all that expensive. would rule it out and i think it does act like its cold anytime i start the car so wouldnt do any harm, i should also just do the thermostat and be done with it.

 

the car is pretty much as it was when i bought it, its had a lot done to it, so all i've done is fit the forge fmic (approx 12months ago). i'm not sure what plugs are in the car and same with the spring in the dv, theres other springs in a little bag in the boot and since a green one is in there, i can maybe assume it has the yellow one fitted. my other vrs also has a forge dv that i fitted so i could remove that and try replace it or the spring to see i guess.

i've had the car for over a year now, aside from the 1/4 tank issue its been a good car to me, its always ran great apart from an issue with the alternator to battery cable which i had to swap over at christmas. i've kept the oil topped up but i haven't given it a proper service, i'm bad for that actually...

i found another thread where a guy had a similar sounding issue and it seemed to be a number of things, some of the hoses that are known to split, maf and his fuel filter seemed to be blocked.
my car doesnt appear to have the troublesome pipes fitted (its had a few things removed, i assume these pipes included), all the pipes i can see look fine. i've swapped the maf already so for the cost of a fuel filter, i'll do that asap. maybe it will fix it, maybe not but either way a new filter isn't a bad idea.

Edited by KTP
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Check the wiring loom for the coil packs on top of the engine. They have a habit of becoming brittle and breaking over time. When the wiring loom starts to break down it struggles to cope with the electrical demand required by the coils when you give it the beans.

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4 hours ago, KTP said:

i know the thermostat is needing replaced as i had it plugged into skoda's diagnostics last year and this was one thing that came up.

the technician said they were a pain to change so i haven't bothered to do it as it didnt really give me any issues.

the coolant sensor, i might change this anyway as they aren't all that expensive. would rule it out and i think it does act like its cold anytime i start the car so wouldnt do any harm, i should also just do the thermostat and be done with it.

 

the car is pretty much as it was when i bought it, its had a lot done to it, so all i've done is fit the forge fmic (approx 12months ago). i'm not sure what plugs are in the car and same with the spring in the dv, theres other springs in a little bag in the boot and since a green one is in there, i can maybe assume it has the yellow one fitted. my other vrs also has a forge dv that i fitted so i could remove that and try replace it or the spring to see i guess.

i've had the car for over a year now, aside from the 1/4 tank issue its been a good car to me, its always ran great apart from an issue with the alternator to battery cable which i had to swap over at christmas. i've kept the oil topped up but i haven't given it a proper service, i'm bad for that actually...

i found another thread where a guy had a similar sounding issue and it seemed to be a number of things, some of the hoses that are known to split, maf and his fuel filter seemed to be blocked.
my car doesnt appear to have the troublesome pipes fitted (its had a few things removed, i assume these pipes included), all the pipes i can see look fine. i've swapped the maf already so for the cost of a fuel filter, i'll do that asap. maybe it will fix it, maybe not but either way a new filter isn't a bad idea.

 

The thermostat is about a 40-45 minute job if you use 1/4 sockets or a 1/4 drive hex key, the important 2 tools that make it easy are a set of 1/4 drive wobble bars to enable you to get just enough room to get around the bits in the way, and a remote cable hose clip compresser. By the sound of it some of the deletes have been done, which can only make a thermostat change easier. Just put the little poppet valve on the stat in the right place before you box it all up with the clamp bar vertical. Also get new bolts for the housing, it makes feeding them back in so much easier.

 

If you do the filter, just take a bit of care when you compress the clips as they are easy to damage and can wreck a pipe in the process (waits patiently for the 10000 mind the clips post now:rofl:)

 

As has been mentioned above, check out your coil looms for cracking of the insulation where it passes over the cam cover, and check your earth tag to the coil loom attached to the camcover is in good nick too.

 

 

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i scanned my car today and these are the codes i have:

 

16621/P0237/000567 - Manifold Pressure / Boost Sensor (G31): Signal too Low
16490/P0106/000262 - Manifold / Barometric Pressure Sensor (G71) / (F96): Implausible Signal
17743/P1335 - Engine Torque Monitor 2: Control Limit Exceeded
16486/P0102/000258 - Mass Air Flow Sensor (MAF/G70): Signal too Low

17704/P1296/004758 - Error in Mapped Cooling System


so its either the map sensor or a split pipe although leaning towards map sensor.
i think the control limit exceeded is related to my fuel filter, new one arrived today but not had a chance to fit it yet.
maf sensor has just been replaced so this may be an old fault code, or maybe it doesnt like the new one either as its not oem.
replaced the coolant sensor but still need to do the thermostat also.

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Some info for your codes -

http://wiki.ross-tech.com/wiki/index.php/16621/P0237/000567

http://wiki.ross-tech.com/wiki/index.php/16490/P0106/000262

http://wiki.ross-tech.com/wiki/index.php/16486/P0102/000258

http://wiki.ross-tech.com/wiki/index.php/17704/P1296/004758

The 17743 code can sometimes relate to the intake manifold sensor wiring having issues, just as an aside, as you are having map sensor codes as well, you do not have any wiring loom damage down that side of the engine do you?.

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no damage that i'm aware of but i'll investigate it further before i order a sensor, i did look at my current fuel filter though and it looks like its been fitted for a very long time, its not original as its got a different clamp on but it certainly looks old enough. guess they get really weathered in that position though

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fitted new fuel filter, was hoping for great things but unfortunately not.

 

have cleared all the fault codes with vag-com and while still plugged in it just flags up the map sensor fault
16621/P0237/000567 - Manifold Pressure / Boost Sensor (G31): Signal too Low

i'm hoping all the other issues are clear but will plug it back in tomorrow once its had a good run and see if any of the other codes come back

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Ok, so my new map sensor arrived today, the supplier i bought from said Bosch had superceeded the part number and it would be the new one i would be sent out.

the middle part is a lot smaller and doesn't fit snugly into the adaptor plate, its from a Forge FMIC so i was a bit worried about that as it surely wont be sealed correctly.

i've had a quick look bit cant seem to find anything that would fit into this to allow for a smaller sensor.

regardless, i fitted it, cleared the fault codes from the car and ran it, now no codes showing and seems to be driving as it should again so i'm pretty happy with the end result.

map.jpg

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