Jnsneu Posted March 8, 2015 Report Share Posted March 8, 2015 Hi! First of let me apologize in advance for my english (Live in sweden)I bought a VW Lupo 1999 1,4 a couple of days ago. The problem is simple, The idle is really unstable when the engine gets hot and it feels really "choppy"I have changed the sparkplugs with no result. Changed the tempsensor and that made the car alot easier to start but didnt fix the other problems. I have removed the TB and cleaned it and mounted it back still with the same result. Sometimes when i drive it feels like the car is loosing power and the ride is pretty choppy. Do anyone know what could be causing these problems? I really dont wanna spend a fortune on the engine! Please help!Best regardsJonas Neumann Quote Link to comment Share on other sites More sharing options...
lupo1.0se Posted March 8, 2015 Report Share Posted March 8, 2015 Have you tried changing the coilpack/leads? Also cleaning the egr valve helps (if I has it) Quote Link to comment Share on other sites More sharing options...
Jnsneu Posted March 8, 2015 Author Report Share Posted March 8, 2015 Have you tried changing the coilpack/leads? Also cleaning the egr valve helps (if I has it)I was afraid of this, due to my english i have no idea what the coilpack/leads are! HahaAnd the egr valve, where is that placed? Thanks! Quote Link to comment Share on other sites More sharing options...
Jnsneu Posted March 8, 2015 Author Report Share Posted March 8, 2015 (edited) Can add that the idle is around 1000-1100rpm when its cold but goes down to about 400-500rpm when the engine gets warm Edited March 8, 2015 by Jnsneu Quote Link to comment Share on other sites More sharing options...
Pete Posted March 8, 2015 Report Share Posted March 8, 2015 It's quite normal for an engine to idle lower once it's warmed up than when it's starting from cold. The spark plugs that you have already changed have leads attached to them, these are the leads that are mentioned, and if it's a 16v engine the leads will go back to a little box on the side of the cylinder head, that's the coil pack. Quote Link to comment Share on other sites More sharing options...
Jnsneu Posted March 8, 2015 Author Report Share Posted March 8, 2015 It's quite normal for an engine to idle lower once it's warmed up than when it's starting from cold. The spark plugs that you have already changed have leads attached to them, these are the leads that are mentioned, and if it's a 16v engine the leads will go back to a little box on the side of the cylinder head, that's the coil pack.Yeah i aware of that but dosent 400-500rpm seem very low? Only had it for a coule of days and its my first VAG.Thanks! Now i know what you mean! Will have a look at that and clean the EGR Valve aswell! Cheers! Quote Link to comment Share on other sites More sharing options...
mk2 Posted March 8, 2015 Report Share Posted March 8, 2015 My guess is it might be the fuel pressure regulator or maybe the fuel pump (or blocked fuel filter).When the engine is hot, the fuel gallery (the main pipe that connects all the injectors together) needs good flow to keep the fuel cool. If the fuel gets too hot it vapourises and then the injectors cannot inject fuel, only vapour= slow engine. You need lots of fuel to go through the fuel gallery to keep it as a liquid. A blocked fuel filter, faulty pressure regulator or faulty fuel pump 'may' cause your problems... Quote Link to comment Share on other sites More sharing options...
Pete Posted March 9, 2015 Report Share Posted March 9, 2015 Wouldn't a blocked fuel filter or duff fpr cause poor starting though?? Quote Link to comment Share on other sites More sharing options...
mk2 Posted March 9, 2015 Report Share Posted March 9, 2015 Wouldn't a blocked fuel filter or duff fpr cause poor starting though??Yeah it would... We really need more info on the problems- is it misfiring? Is there power (when pushed hard)? Slow idle for an injected car is a really unusual symptom. As soon as I read that it was ok when cold but bad when hot, it reminded me of a problem with a car I sorted a few years back on a really hot summer's day. It was a dodgy fuel pump, that only delivered "just" enough pressure, but loads of flow. Took ages to figure out. Very similar symptoms. Jags used to suffer from that a lot. They ended up using the AC to cool the fuel gallery on hot days. Quote Link to comment Share on other sites More sharing options...
Jnsneu Posted March 10, 2015 Author Report Share Posted March 10, 2015 Hey! Was in the garage today and just tried disconnecting the plug that is located on the TB while the car was running, as soon as i did that the car became "normal" the idle was great and it felt really good driving!Is this supose to happen? Recorded a video that shows you everything!https://www.youtube.com/watch?v=GfTiQo8wOw8&feature=youtu.be Quote Link to comment Share on other sites More sharing options...
Pete Posted March 10, 2015 Report Share Posted March 10, 2015 Try another body then, the motors inside may be faulty, most likely to be causing it if you've definitely got your throttle body clean tho. Quote Link to comment Share on other sites More sharing options...
Skezza Posted March 10, 2015 Report Share Posted March 10, 2015 I think new throttle body needs adapting, if you do decide to replace. Quote Link to comment Share on other sites More sharing options...
Jnsneu Posted March 11, 2015 Author Report Share Posted March 11, 2015 (edited) Thanks! What is the purpose/function of that connection on the TB. Really want to make sure that its the TB thats broken. Pretty expensive to change. Edited March 11, 2015 by Jnsneu Quote Link to comment Share on other sites More sharing options...
Pete Posted March 11, 2015 Report Share Posted March 11, 2015 Putting it simply it's sending the readings of the motors positions inside the body down to the ecu, as it's an electrically functioning fueling system it uses those readings to make the engine run as efficiently as possible, and ultimately communicates with the other modules, engine temp, coolant temp etc, so they all need to know what's going with the throttle body regarding it's position, so if the throttle body starts to fault then it throws the whole engine smoothness out, causing issues such as your poor idle. So when you unplug it altogether it goes back to a certain preset of values as a safety override. And as mentioned once you've replaced the body, you'll have to teach in the new one so it can learn its parameters. But if it's a matter of cost just run it without it being plugged in, may cost more in fuel tho and possibly chuck up an eml. Quote Link to comment Share on other sites More sharing options...
Skezza Posted March 11, 2015 Report Share Posted March 11, 2015 Putting it simply it's sending the readings of the motors positions inside the body down to the ecu, as it's an electrically functioning fueling system it uses those readings to make the engine run as efficiently as possible, and ultimately communicates with the other modules, engine temp, coolant temp etc, so they all need to know what's going with the throttle body regarding it's position, so if the throttle body starts to fault then it throws the whole engine smoothness out, causing issues such as your poor idle. So when you unplug it altogether it goes back to a certain preset of values as a safety override.And as mentioned once you've replaced the body, you'll have to teach in the new one so it can learn its parameters. But if it's a matter of cost just run it without it being plugged in, may cost more in fuel tho and possibly chuck up an eml.Pretty sure it would throw up an EML on newer Loops but not older ones Pete. It would also fail an MOT miserably because the ECU would automatically go into a correction map which works regardless of all parameters. This will not efficiently, meter fuel and therefore, your emissions would fail quite badly, even if you gave it an Italian tuneup, you'd have almost identical readings. Am I right in thinking you might also cause excessive wear on your cat?The best thing you can do, in my opinion, is try and fix that throttle body one more time. Really give it a good clean. Spray a load of carb cleaner down while revving the car. You'll see a **** tonne of smoke and probably throw up an EML but it's about the best way you'll clean it.If that doesn't work, I'd fit a new throttle body or try and get a second hand one. You could always take a punt at a cheap pattern part. Quote Link to comment Share on other sites More sharing options...
Skezza Posted March 11, 2015 Report Share Posted March 11, 2015 Actually, I've just had a thought. You could try realigning your throttle body. A non-aligned TB would cause no end of problems.http://www.ross-tech.com/vag-com/cars/throttlebody.htmlGet your VAG-COM out baby. Quote Link to comment Share on other sites More sharing options...
Jnsneu Posted March 11, 2015 Author Report Share Posted March 11, 2015 (edited) Thanks guys! You are the best! Will take the TB apart again and really give it a good cleaning! Edited March 11, 2015 by Jnsneu Quote Link to comment Share on other sites More sharing options...
Skezza Posted March 11, 2015 Report Share Posted March 11, 2015 Thanks guys! You are the best!Will take the TB apart again and really give it a good cleaning!Give it a TBA as well buddy. Quote Link to comment Share on other sites More sharing options...
Jnsneu Posted March 11, 2015 Author Report Share Posted March 11, 2015 Give it a TBA as well buddy.Will do mate! Quote Link to comment Share on other sites More sharing options...
mk2 Posted March 11, 2015 Report Share Posted March 11, 2015 I don't know this particular model that well, but isn't there either a map or air flow sensor? If the disconnected plug is the tps pickup, the ecu will ignore the reading as it'll be outside 'normal' range, and rely on the main sensor (map or air flow). So long as crank pulse is present, main sensor is ok and the lambda is responding, the engine will run ok. Using just those, the ecu assumes the engine has warmed up and will try it's hardest to keep the fuel/air mix ok. The engine will be less responsive though... I'm just thinking back to the days of mechanical fuel injection, where there was no tps. The entire fuelling relies on the air flow deflection arm. A bit like old SU carbs! A few years back the americans used to swear by map sensors, where the europeans used to swear by air flow... I think the air flow method won the argument. My fav is map sensor as it's easier to work with. Quote Link to comment Share on other sites More sharing options...
mk2 Posted March 11, 2015 Report Share Posted March 11, 2015 Just had a thought... Is this engine drive by wire? Quote Link to comment Share on other sites More sharing options...
Adam077 Posted March 11, 2015 Report Share Posted March 11, 2015 Check engine wires conection . 3 connections are placed near thermostat. There are 2 conections (black and brown) with about 7 pins and one with about 15 pins. Disconect and check it's dry and without corossion . Quote Link to comment Share on other sites More sharing options...
Skezza Posted March 11, 2015 Report Share Posted March 11, 2015 Just had a thought... Is this engine drive by wire? pretty sure it's fly by wire Quote Link to comment Share on other sites More sharing options...
mk2 Posted March 12, 2015 Report Share Posted March 12, 2015 pretty sure it's fly by wireIf it uses a VDO/Siemens/Bosch throttle body and is DBW, then there are 8 connections. If he unplugged that connector, the engine will run at fast idle (about 1300) and there will be no throttle response at all. There are two motor drive wires and two sets of independent TPS sensors (or potentiometers), to get an average reading. One goes up in voltage and the other goes down.My SDI is DBW, and one thing I noticed when I was doing the central locking wiring is that if you stick your head right in under the cluster, you can see if the throttle works to it's limit. In my car, the throttle couldn't ever reach full throttle- only about half way... I pulled out the pedal and the little link wire and bent the whol epedal in a vice. Now the throttle pedal sensor can actually do its job and travel to its limit. The car is so much more responsive now... I think to change that sensor would be a really big job. You simply can't get to it. Quote Link to comment Share on other sites More sharing options...
Skezza Posted March 13, 2015 Report Share Posted March 13, 2015 (edited) If it uses a VDO/Siemens/Bosch throttle body and is DBW, then there are 8 connections. If he unplugged that connector, the engine will run at fast idle (about 1300) and there will be no throttle response at all. There are two motor drive wires and two sets of independent TPS sensors (or potentiometers), to get an average reading. One goes up in voltage and the other goes down.My SDI is DBW, and one thing I noticed when I was doing the central locking wiring is that if you stick your head right in under the cluster, you can see if the throttle works to it's limit. In my car, the throttle couldn't ever reach full throttle- only about half way... I pulled out the pedal and the little link wire and bent the whol epedal in a vice. Now the throttle pedal sensor can actually do its job and travel to its limit. The car is so much more responsive now... I think to change that sensor would be a really big job. You simply can't get to it.Common problem. I had the same issues. Do you have a photo of the part you bent in the vice grip? I didn't do it myself, I paid my mate an extra twenty when he MOT'd it so mines all sorted now but it'd be useful know because it's a recurring problem. Edited March 13, 2015 by Skezza Quote Link to comment Share on other sites More sharing options...
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