Loss of power today

[Hairyarse 10]

Got a lift home tonight!! lol

 

 

First time I've had to do this in over 25 years of driving which I guess should make me a little happier!

 

Anyway, driving along today I suddenly started to lose power to the point I could barely pull away from some traffic lights, and duly pulled over. The car still starts ok, idle is a little eratic/low. The main issue is you press the accelerator and revs are very slow and reluctant to climb up and wont go much over 3k typically.

 

Recently I've done the following;

 

-New dizzy cap and rotor arm

-Checked and re-gapped plugs

-Cleaned and checked ISV

-Cleaned and re-set metering head flap

-Replaced fuel filter

-Checked vac hoses for leaks

-Oil & filter change

-Air filter change

-Replaced both temp senders on the block

 

All of the above was done about a week or two ago and the car has been running well - with MPG going from about 26 upto 33 now :) Nothing seems/appears drastically wrong with the car, i.e. no signs of head gasket, oil and water all ok. I broke down in Leicester near to a friends garage so it's there overnight and we'll take a look at it tomorrow with his mechanics. However, any opinions are welcome on what the problem could be would be welcome!

 

Thanks in advance ;)

 

Cheers

Andy

[Jim 2]

Hm. Could be something to do with the throttle body perhaps? I have heard they can occasionally be problematic. Is it a 2.0 16v?

 

I'll also be interested to hear if the car runs OK for the first few minutes from cold and then starts to get lumpy and troublesome as it warms up. Keep us posted.

[ross k 10]

If it shows symptoms as jim says only when hot it could well be the lambda sensor ?

[Jim 2]

If it shows symptoms as jim says only when hot it could well be the lambda sensor ?

 

That's where I was headed :)

[Hairyarse 10]

Thanks for the feedback chaps - yes it is a 2.0 16v.

 

Funnily enough when I scanned OBD the other day I got error code 00525, which is 'O2 sensor voltage low - G39' so I did wonder about the lambda. The mechanic who saw it briefly last night didn't think that would cause what happened when I mentioned it. It's going on the ramp any time now so fingers crossed it's an easy fix.

 

I'll update once I know more ;)

[Jim 2]

Lambda can fail though it seems to be very uncommon - but what does seem to be more common is the wiring for it becoming brittle and breaking. So check that out :)

[Hairyarse 10]

Will do. Am I right in saying it's connected in to the cat'? I seem to recall reading that on here when searching for info on how to change one.

[Hairyarse 10]

Well after a lot of digging around it looks like it may be something simple. No signs of a vacuum leak, good spark although discovered that the cam cover is leaking a bit of oil down the plug bores, but whilst the car was idling badly, the mechanic disconnected the plug to the white, 2-pin temp. sender and it now runs perfectly!

 

I only replaced this and the other temp sender a couple of weeks ago, I'm wondering if this white one is duff? I've got a replacement coming out tomorrow so guess it must be this, or whatever it's connected to?

 

All theorys are welcome!!

[g0ldf1ng3r 14]

nice work andy

 

i know from my years of PC/application/server/network support roles that the first port of call of things to check when something goes wrong is always 'what has been changed recently' ;)

[Hairyarse 10]

It wasn't quite our first port of call, as got to a point of thinking it was a vacuum leak, but we soon got on to it. I've had it on a car before - changed a temp switch in a radiator and it quickly failed but spent too long assuming that it wasn't the issue as I had just replaced it!

 

Fingers crossed it sorts me out tomorrow when I fit the next new one ;)

[Hairyarse 10]

I've just fitted the new temp sensor and still have the same problem. Unplug it and it runs fine again (well, about 95% fine) Idle is a tiny bit lumpy and MPG down about 10%.

 

I'm guessing that the issue must be with whatever this sensor wire is connected to? Does anyone have any pointers please as I'm a little lost now!

 

Many thanks ;)

[Hairyarse 10]

Any takers on this one? I'm stumped as to where to look next.

 

To add, I checked for fault codes tonight and the only one was 00522, telling me that the temp. sender is disconnected.

[Hairyarse 10]

Begging for help now PLEASE :)

 

Can anyone help at all? Either guesses on what the issue is or what the temp sender is actually connected to as guess that must be the issue? I've been digging around but no solutions yet :(

 

Thanks in advance ;)

[Hairyarse 10]

Ok even more baffled now. With the sender still unplugged the idle was starting to hunt up and down. Having a play around under the bonnet again I thought I'd plug the sensor back in and now it runs absolutely fine!I can only guess that the problem of earlier this week is an intermittent one. I'll run like this for now and see what happens.

 

Still happy to hear from someone....anyone!! lol

[Jim 2]

2.0 16v has always been a bit of a black art unfortunately :( Hope you can get to the bottom of it.

 

Where did you get the temp sensor from?

[easypops 8]

Not sure this will be of any help but I'll tell you anyway.

When I had my 9a 16v it was, for a long time a horrible drive due to idling issues. I changed fuel pump,metering head,ISV,leads,coil,dizzy,throttle body and still it played up, sometimes it would be ok but others it was a nightmare. I found the fault by chance. The wires on the plug for the throttle potentiometer had split inside the plastic sheath(2 of the 3) and as soon as I fixed them it ran perfectly. So, you may well have an unknown wiring fault that's not visible .

As I said probably of no help but it may be worth checking the state of the wires especially at the plugs?

[Hairyarse 10]

2.0 16v has always been a bit of a black art unfortunately :( Hope you can get to the bottom of it.

 

Where did you get the temp sensor from?

 

I hope so! My local trade motor factor who I get all my parts from. As I've fitted two new ones now I'd like to think that they're working ok!

[Hairyarse 10]

Not sure this will be of any help but I'll tell you anyway.

When I had my 9a 16v it was, for a long time a horrible drive due to idling issues. I changed fuel pump,metering head,ISV,leads,coil,dizzy,throttle body and still it played up, sometimes it would be ok but others it was a nightmare. I found the fault by chance. The wires on the plug for the throttle potentiometer had split inside the plastic sheath(2 of the 3) and as soon as I fixed them it ran perfectly. So, you may well have an unknown wiring fault that's not visible .

As I said probably of no help but it may be worth checking the state of the wires especially at the plugs?

 

That's actually really useful! Before this issue I had noticed the revs sometimes slow to drop and when you stopped at a junction, idle would be a little high. If you kicked your foot up under the accelerator pedal the revs would drop to a proper idle so I assumed that the throttle cable may be sticking a little and need lubricating (something I've not done yet) but the point you mention would be worthy of further investigation for sure.

 

I'd still like to know the link between unplugging the temp sensor and curing the issue though, that's what's really baffling me.

 

Thanks again for the info, that's a big help ;)

[Jim 2]

I would be tempted to source a genuine VW one just to rule it out. Actually I've got a bag of various 2.0 16v sensors that I bought as a job lot years ago for my old valver. They're all second hand / used but if you can send me a picture of your old one for comparison I'll see if I've got another spare I can send to you?

[Hairyarse 10]

Hi Jim

 

It's this one;

 

 

I'd like to think it's not the sensor but who knows!!

 

I did just get some feedback from a friend in the VW scene who knows his onions, he suggested with the temp sensor plugged in, unplug the lambda probe and if it runs ok it's new lambda time. However, with the issues gone right now, I can't check that at this time! lol

[Hairyarse 10]

Well to continue this saga, we at last got around to fitting the new lambda probe last night. It turns out it's had a replacement - probably not too long ago - with an aftermarket one as the wires had been spliced on to the old plug. However, one wire had almost disconnected as it was hanging on by a strand!

 

Problem solved we thought! So we reconnected the wire, fired up the engine then plugged back in the water temp sensor plug and it ran like a pig and stalled! :( Tried again and it now runs well. It's definitely too rich though so we'll look at the mixture later today and see where we go from there. Fingers crossed we may have fixed it ;)

[Hairyarse 10]

This afternoon we put the C on the gas analyser. CO was hovering around 0.7 and HC around 600 so all looks good to me! The car seems to have 'settled' since last nights fix, long may it continue and run without issue