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loupdydoo

Coolant/High Revs/Ignition failure

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Hi all, 

 

Bought my car beginning of this year, It's a 1997 1.0 VW lupo.  It's done approximately 32,000 miles and pretty much brand new internally and externally for its age

So, 2 months ago i stalled it at lights, upon getting the engine back on the revs were creeping up really high on their own without pushing the gas pedal. It stayed this way through gear changes, to the point where i had to pull over and turn the engine off for a short while. Put it back on and the same thing occured while stationary, until it settled down and went normal - but the engine light came on! 

I got a local mechanic to look at it, he did the super duper machine analyser thing (sorry i'm absolutely useless at this stuff) and he said there's nothing wrong with it mechanically - him, and my parents basically were looking at me like im stupid. He reset the light on the dash. 

It was driving normally for a while -  then the engine light came on the dash again. Now, recently its started the process again - only more frequently now. Sometimes even at the first ignition of the day. 

Its like the car has an attitude and starts revving up 2000-3000 before settling normally. Or, if its being extra, it will not start at all, and i have to push the gas pedal and maintain revs over 1000 until it settles normally. 

One thing i've noticed too, the coolant level is falling rapidly - the light came on, i filled it with the matching colour (pink) up to the max level - one month later it is below the minimum level. 

Oh and i can smell something when i put on my A/C

So to summarise:  

  • Occasional ignition failure - have to use gas to get it going
  • rapid coolant leak - maximum to below minimum in a month
  • high revs without pushing pedal - sometimes random, but mostly at ignition. 
  • Smelly A/C - cant describe the smell - can only liken it to a weakened petrol smell? 

any ideas will be great, because im not taking it to a mechanic again to be told there's nothing wrong with it again!! 

Louise.

 

Edited by loupdydoo

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Revs - possibly an air leak.

Coolant, it isn't using enough; If someone has flushed it then it could just be self bleeding a bit, doesn't sound like it gets lots of use.

Hello btw.

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3 hours ago, loupdydoo said:

Hi all, 

 

Bought my car beginning of this year, It's a 1997 1.0 VW lupo.  It's done approximately 32,000 miles and pretty much brand new internally and externally for its age

So, 2 months ago i stalled it at lights, upon getting the engine back on the revs were creeping up really high on their own without pushing the gas pedal. It stayed this way through gear changes, to the point where i had to pull over and turn the engine off for a short while. Put it back on and the same thing occured while stationary, until it settled down and went normal - but the engine light came on! 

I got a local mechanic to look at it, he did the super duper machine analyser thing (sorry i'm absolutely useless at this stuff) and he said there's nothing wrong with it mechanically - him, and my parents basically were looking at me like im stupid. He reset the light on the dash. 

It was driving normally for a while -  then the engine light came on the dash again. Now, recently its started the process again - only more frequently now. Sometimes even at the first ignition of the day. 

Its like the car has an attitude and starts revving up 2000-3000 before settling normally. Or, if its being extra, it will not start at all, and i have to push the gas pedal and maintain revs over 1000 until it settles normally. 

One thing i've noticed too, the coolant level is falling rapidly - the light came on, i filled it with the matching colour (pink) up to the max level - one month later it is below the minimum level. 

Oh and i can smell something when i put on my A/C

So to summarise:  

  • Occasional ignition failure - have to use gas to get it going
  • rapid coolant leak - maximum to below minimum in a month
  • high revs without pushing pedal - sometimes random, but mostly at ignition. 
  • Smelly A/C - cant describe the smell - can only liken it to a weakened petrol smell? 

any ideas will be great, because im not taking it to a mechanic again to be told there's nothing wrong with it again!! 

Louise.

 

Hmm thinking coolant temperature sensor which can cause uneven revs ,and won’t let engine start from hot , easy fix but losing fluid defo sounds like a leak in the system somewhere new sensor only costs pennies is really easy to fit so that’s where I would start it may also be allowing fluid to seep out if it’s loose x

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Best advice I can give if you want to work on your car yourself is to get a Haynes manual they don’t do one for a lupo so you have to buy one for vw polo they are the same and buy a cheap vag scanner vag305  obd11 connector on  eBay think I paid about 15 quid for mine and it is basically the same as the scanners they use in the garage good luck let us know how you get on x

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feel the carpets below heater matrix, the smell is probably antifreeze / coolant. Passenger foot well and tunnel area dont think it is in the middle.

Revs could also be coolant related if the sensors are in air etc.

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Yes if your heater matrix is leaking under main central console that could be where leak is if  you need to replace this I have done this before and it is also not a hard repair to do 

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Basically whole system involves filler bottle ,leak could come from here, fluid goes into engine system so moves through temperature coolant sensor and into radiator pumped round by water pump and through heating matrix as well as being allowed into system by thermostat see the right up here

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After looking at coolant system which will defo sort out loosing fluid and needs to be addressed if fault has not cleared the only other suggestion I would have re irrational revs and non starting would be potentiometer info here 

CFCFA8FC-21BE-418C-8BCC-8355CD6BB161.png

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If it’s not the coolant temperature sensor none of the other parts of the coolant system would affect the functioning of the engine ie irratic revs and would only show overheating x

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Hi and welcome to CL! :)

Your Lupo is probably one of the oldest in the UK! Would love to see some pics...

Yeah sounds like more than one fault.

The smell is probably the aroma of antifreeze G12 or G13 additive evaporating very slowly from the heater matrix as already suggested. The correct solution is to replace everything, but you could do a 'jolly' fix and bung some "stop leak" in your coolant system. Yes I can hear all the purists shouting at their screens, but hey, if you have no time to fix it, it does work... In winter the inside probably steams up the windows?

The revs would be easiest to diagnose from the fault code that the diagnostics system gives you. But being a very early model, it might not report everything. The ECU (engine control computer) is trying to get the car running normally, so it keeps trying out different scenarios, but knows something is wrong. So it is running, but one or more sensors is playing up providing unusual readings. Most of the time, the ECU will use the sensor data, but then that faulty sensor goes so wacko the ECU disregards it then the engine bahaves itself again- but not running perfectly. So the solution with diagnostics is to find the code. Without diagnostics, simply go round unplugging all the sensors one by one, the try starting it again (you won't damage anything). When nothing changes, you've probably found the dodgy sensor.

My guess is TPS.

Respect to @lindylou! I've never had ti change a Lupo heater matrix, but heard it's a major operation 👍🏻

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I know what your saying mk 2 about bunging in a stop leak fluid which is a really good move if the leak is tiny  and is not in any of the pipes x I agree that the use of the scanner can help with fault codes and that is most definitely a first move x as suggested you can get a scanner really cheaply from eBay x but I’m still going with the coolant temperature sensor to start with I’ve had to change mine twice and it defo affects the smooth running of the engine as you say the ecu tries to compensate but can’t and it doesn’t show up as a fault on the ecu reader x

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I to would love to see some photos inside and out what a lovely find to get such an oldy xx

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Just a thought as well does it have a service history it might just need a blooming good service if the air filter hasn’t been changed that can send in some right nasty smells through the heater system x

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On 5/24/2019 at 9:25 PM, lindylou said:

I know what your saying mk 2 about bunging in a stop leak fluid which is a really good move if the leak is tiny  and is not in any of the pipes x I agree that the use of the scanner can help with fault codes and that is most definitely a first move x as suggested you can get a scanner really cheaply from eBay x but I’m still going with the coolant temperature sensor to start with I’ve had to change mine twice and it defo affects the smooth running of the engine as you say the ecu tries to compensate but can’t and it doesn’t show up as a fault on the ecu reader x

Firstly thank you all for the suggestions and information! 

I didn't even consider a sensor as being a probable cause! Thinking about it - my temperature gauge doesn't move up from the lowest temp - i've never thought about this before until you mentioned it. The revs do happen more often when the weather is warm, or if i have recently turned the engine back on after a short break. Sounds like this could be the issue. Would that be something to cause the engine light to crop up? 

The coolant leak is a given and that will have to be narrowed down somewhere. I checked the oil in the engine, and its at a good level, and on the lid is normal oil residue - no 'mayo'. I was concerned about that after reading a few other threads... 

As for pics, stand by. I'll take a few more tonight. He is so cute and i love him. lupo.jpg.9ec5500c23356744833c6c7d5b98b39f.jpg

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On 5/24/2019 at 8:57 PM, mk2 said:

Hi and welcome to CL! :)

Your Lupo is probably one of the oldest in the UK! Would love to see some pics...

Yeah sounds like more than one fault.

The smell is probably the aroma of antifreeze G12 or G13 additive evaporating very slowly from the heater matrix as already suggested. The correct solution is to replace everything, but you could do a 'jolly' fix and bung some "stop leak" in your coolant system. Yes I can hear all the purists shouting at their screens, but hey, if you have no time to fix it, it does work... In winter the inside probably steams up the windows?

The revs would be easiest to diagnose from the fault code that the diagnostics system gives you. But being a very early model, it might not report everything. The ECU (engine control computer) is trying to get the car running normally, so it keeps trying out different scenarios, but knows something is wrong. So it is running, but one or more sensors is playing up providing unusual readings. Most of the time, the ECU will use the sensor data, but then that faulty sensor goes so wacko the ECU disregards it then the engine bahaves itself again- but not running perfectly. So the solution with diagnostics is to find the code. Without diagnostics, simply go round unplugging all the sensors one by one, the try starting it again (you won't damage anything). When nothing changes, you've probably found the dodgy sensor.

My guess is TPS.

Respect to @lindylou! I've never had ti change a Lupo heater matrix, but heard it's a major operation 👍🏻

Thank you! 

I'll take it to the garage and see what they can do with the information yourself and LindyLou kindly provided! 

As for removing each sensor and trial running it - i don't have the skill or knowledge for that unfortunately! :(  And even still, the car doesn't misbehave in a regular pattern - some days he is fine, others he kicks up a storm until he settles down again shortly after. I'm definitely thinking coolant sensor now you and LindyLou mention it! 

For pic, see above! :) I'll take more later! 

 

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Omg you have got a beauty there and with the blue seats !! I was only commenting the other day I haven’t seen the blue or red for years x sorry I get a bit geeky about the early ones having a yellow one myself w reg. I think that it is the coolant temperature sensor from what you say and I have to tell you that even though he hasn’t done many miles and therefore the engine should be sound ,providing the oil was always topped up ,unfortunately the main problem I have experienced is that the sensors and switches do fail basically because of age. Wether it’s because of plastic going brittle or electric failure my first instinct if something goes wrong would be to do with sensor or switch.. I am so glad you have found our site and I think we collectively will always be there to help you whatever the problem xx please keep in touch and let us know how it’s going 

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