Hi guys,

Got a bit of a problem with my little NZ. Before I start, its not fitted to a polo, but it is a standard engine for a german model golf mk2. I was recommended you guys would be the best place to come to as I hear it was a more common engine in the polos?

My problem is this, if the car has been sitting for a while, it starts fine with no problem at all. I'm guessing this has somethig to do with the engine being cold???

Anyway once I get the car up to temp and try to start it up it can be a bit of a pita. It some times starts up, splutters and dies, starts up and idles badly, unless I give it a few revs, then the idle goes back to normal. I can always get it to start, but it takes a fair bit of turning the engine over.

Once the engine has settled down, it doesn't die, or anything like that. I've also noticed that when you let off the throttle its a bit jumpy and not smooth.

I've had the throttle body off and cleaned it all up, replaced all the plugs, new dizzy cap and arm, put an injection cleaner through the system and made sure the vac pipes that are there, aren't split (once I can get a picture ill need someone to check that the vac lines are right). It helped a tiny bit, but the problem still persists.

Could anyone point me in the right direction for curing this problem? Whilst its not stopping me using the car, its annoying and I would like to get it fixed.

My other question is - what kind of modifications can I do to this engine to get a little bit more power out of it? I heard changing the throttle body to a different one helps and also a cam change, but I don't know which engine to source these off. I know its only a 1.3, but having a bit more poke about the city would be useful.

I don't think Ill go down the exhaust route yet, or major mods, as I'm in germany and every single modification needs to be TuV approved which costs :(

Thanks :)

ISV - Idle Stabilisation Valve. Do some readibg up on this and give yours a clean.

Try unplugging the blue temperature sender (if there are two different ones) and see if the engine runs differently or starts more easily. They are common to fail and if it's a temperature related running issue, could be giving you your issues

id try a new blue temp sender , preferably a genuine vw one as ebay ones can be poor

as for upgrades , a gt (3f) cam would be ideal

Okay cool, I'm currently at work, but once I get home I'll have a look and let you guys know how it goes. Fingers crossed.

I'm unsure whether that's worked. I got the engine warmed up and fiddled about unplugging blue plugs and actually plugging one in properly and the car seems to start right up now. I think it may have to do with a dodgy plug that wasn't plugged in and seems a bit loose.

Next is to sort out the vacuum system. Pictures to follow

So, hopefully you can make out the pipes for the vacuum lines from these pics. Doesn't look completely right to me, due to the 3 way connectors. Anyone fancy drawing coloured lines over the picture or sending me in the direction of a proper diagram, so I can see how it is supposed to look (if its wrong).

Pics are here :) ...

http://m.imgur.com/a/9SLrc

Make a new tb to inlet gasket from a breakfast box or get the proper gasket paper to make sure its not leaking air

All the vacuume hoses need to be a tight fit

Have you adjusted the idle / fuel mix and dizzy position toake sure its running spot on.

Isv is a good call, if the clips are loose itll leak air and make the engine erratic

It might sound like a stupid question, but where exactly is the isv on the NZ?

I'm really unfirmiliar with these engines :( if it were a 9a or kr I'd be ok lol

It might sound like a stupid question, but where exactly is the isv on the NZ?

I'm really unfirmiliar with these engines :( if it were a 9a or kr I'd be ok lol

Hi

Put up a picture of the engine, a birds eye view.

The ISV is under the inlet manifold bolted onto the metal water pipe at the back of the engine.

It turns out that the blue temp sender is fubar. After plugging it back in the car started straight away every time and seemed to run smoother, even the throttle seemed a bit smoother (could have been in my head). But after a prolonged trip, so the car could get a longer warm up a new problem came about. With the blue temp sender plugged in the car will eventually drop off, splitter and die... Not fun in the middle of traffic. Unplugging it removes this problem and the car is fine again!

So I'll need to be getting a new sender I think. What exactly does the temp sensor control? Does a broken one assume the engine is running too cold or hot and mess with the fuel, causing the car to stall?

The blue temp sensor is a common fault get a genuine one if you can, it sends a 0-5v to the ecu to tell the ecu what temperature the water is in the engine and controls the fueling as in slightly more fuel if its cold like a choke ect.

Fuelling and ignition timing is usually adjusted to suit temperature, to aid warm up etc, faulty readings from the sensor could essentially try running the car on a map for cold temps when its warm, or similar, basically the ECU is getting an incorrect reading from the sensor, causing it to actually fuel/adjust ignition timing incorrectly to its true conditions.

Unplugging the sensor makes it run in a default mode, which is kind of like a safe mode, so it still won't be right, but it will eliminate spurious readings causing the issues you're having.

Well worth buying a new genuine one as people have said, even though they cost slightly more.

The black temp sender next to the blue one is literally just for the temp gauge in on the clocks, blue is for the management system.

Ordering one right now! Thank you for the explaination. It's always good to know how everything interacts.

If the car is running in a 'default' mode, will it be making less power? As I assume it isn't really the optimal settings?

It might be me but it did seem smoother and pulling off was easier. With the blue temp sender disconnected it does seem more sluggish on pulling off and a bit rougher. Until it started acting up with it connected it was lovely to drive.

Sorry for double post, but does anyone have the part no for the sensor? Don't want to end up getting the wrong one

025906041A temperature sensor 2 pin blue 20MM / 3F,PY,NZ, AAK,AAU,AAV

Yeah obviously having adaptive management on cars allows them to be optimised to the conditions, if you take away a sensor which gives feedback you lose that optimisation, but will generally be safe to use for a short while.

So yeah, performance won't be at its greatest, it could be over-fuelling slightly or running lesser ignition advance, popping a new sensor in should allow it to work how it was designed to once again

Nice. Thanks for all the help guys, I really appreciate it.

Sorry to resurrect an older thread...

So, I ordered the new blue temp sensor ages ago but due to working flat out, haven't had a chance to fit it. Fitted it today and the problem still occurs.

The car will start fine but the idle will slowly get worse as the car warms up(I assume) and then the car will cut out....Unless I blip the throttle at about half second intervals.

 

Keeping the blue sensor unplugged remedies the problem.

 

Should I be looking at the ISV now? Or could the ECU be knackered? Also I was wondering if anyone had a diagram of the vacuum system. I found a tube that is blocked off with a screw (near the bottom of the tb at the front) and also all of the t connections worry me. I want to get new tubing and correctly connect it all up.

 

Really scratching my head now. I was hoping the genuine replacement blue sensor would fix the issue.

 

Suggestions would be massively appreciated!

 

EDIT I did smell fuel with the blue sensor plugged in and the car bogging out.

Edited 15 June, 201610 yr by rez

Ruled out isv. It is spotless!

 

And here is how the vacuum system is hooked up... Bit of a mess 

 

Can anyone draw on it how it is supposed to be connected?

 

I forgot to mention that this is a cat version of the need and has a lambda/o2 sensor. If that is shot will it cause the idle and engine death problems?

Edited 15 June, 201610 yr by rez