Golf MK3 1.8 fuel consumption

[charbel89]

Hi,

I have a Golf MK3 1.8 petrol automatic transmission L reg (1994).

Over the last couple of months the fuel consumption has doubled. The car is doing 3 Miles to a litre.

Thats about 14 mpg.

I had the car recently serviced (Major service including fuel filter and plugs ) but this did not help.

I had the Injection unit sprayed with a cleaner but still no change.

I notice that sometimes the RPM plays up and down, especially at morning starts.

If I press the gas peddale down and up, the RPM stays quiet high for about 20-30 seconds before it goes back down again.

Currently I am spending close to £250 a month on petrol. A full tank is doing 160 miles.

Any ideas or thoughts on how I can resolve this issue?.

I am considering a new Injection Unit but the cheapest brand new ones I found were close to £300.. so I wanted to exhaust all other options before I spend that kind of a cash on a 1994 car.


Thanks a lot

Regards


Charbel.

[towcestervag]

check the base gasket of the monojet unit and the servo hose coming from the manifold for leaks

[charbel89]

Thanks for the response.

The injection unit itself wobbles a bit, I am not certain if this is normal, or not.

I am not certain about the servo hose? I tried check around all pipework I could see connected to the Injection unit. Nothing seemed obviously leaking, unless I am missing something!!!

Regards

Charbel

[towcestervag]

the base gasket splits through if it wobbles squirt some water at it whilst you wobble and see if it sucks it into the engine and causes a missfire (not too much at a time)

[charbel89]

I sprayed water all over the injection unit gasket and all the air pipes connecting to the air filter.

It did not make a difference.

One thing worth mentioning: the exhaust sprays some liquid that after just few revs the ground below the exahust is covered with watery like black liquid. (Could be not fully burnt petrol.??)

Also I could hear the Injection unit flapping rapidly.. is this normal?

Thanks

[towcestervag]

the flapping noise is probably the single point injector
can you get a diagnostic test done to see if there are any faults?

[charbel89]

Might be able to do it tomorrow.

[charbel89]

I had the diagnostics done.

Two faults showed up for engine and transmission.

Error code : 00515 Hall Sensor Camshaft position no signal.
Error code : 00518 Throttle position sensor (G69) outside tolerance.


Thanks.

[towcestervag]

hall sender fault is always apparent if car not running so dont worry about this one
check throttle valve
with a diag machine go to measuring blocks 08 enter 00 and zone 2 should increase in value until 1/4 throttle then remain constant
zone 3 should increase in value uniformly until full throttle
if not then pull 5 pin connector off of side of monojet unit and check voltages pins 1+5 =5volts
if car is a auto it has a 7 pin connector and its 1+7
if ok then base unit reqd
if not ok then full wiring test between that connector and engine ecu required

[charbel89]

Thanks for this.

I do not own a diagnostic kit. I will have to take it to the garage again.

Can I check the voltage without the diagnostic machine connected?

My car is auto so presumably I have the 7 pin connector.

The connector you refer to , is the blue or red arrow?

http://img822.imageshack.us/img822/6607/injection.th.png (http://img822.imageshack.us/i/injection.png/)

[charbel89]

I went ahead and checked the blue connector. Pins 1 and 7. The power is 4.98-4.99 volts.

There two other connectors on to the top and one to the positioner!! or whatever it is called (Just below the throttle cable.)

[towcestervag]

ok it sounds like the base unit is faulty

[charbel89]

Thanks for your response.

Something else I was told about today. I never took too much notice of this previously.

When I start the car in the morning a cloud of white smoke comes out of the exhaust.

But then it is fine.

Is this something to be concerned about? or is the result of the faulty Throttle body?

Regards

Charbel

[towcestervag]

if your not losing fluids ie water oil or brake fluid then it could be just the fuelling due to the throttle

[charbel89]

Thanks.

Coolant appears to be fine. Brake fluid is fine too.

Engine oil. I do not know what is normal consumption. (1litre to a 1000 mile!!?).

Today I monitored the temperature guage. After driving for 10 minutes temp was about 75. When I stopped the car for 5 minutes the temp went up to 95. I then drove away. While driving temp drops to 78-80.. when stopped at traffic lights temp goes up to 90-95 again.

I am not certain if this is a fault fan or engine temperature sensor!!!?

Thanks

[Jon Bradbury]

Can you not hear the fan coming on when the temperature is high (after pulling over)?

Anyway, the temperature sensor should be changed, just in case. I had a similar fuel efficiency problem with my 1.6 Cabby and it was fixed by changing the sensor. Although I didn't notice anything odd about the temperature gauge, the sensor itself was so cheap (from a motor factors, it's not a genuine VW part) it made sense. Since then I can get 40mpg out of it where before it struggled to achieve 30.

[charbel89]

Thats interesting.

But the diagnostics did not show a temperature sensor fault!!!?

I am told there are two sensors the Coolant and the engine.

The coolant is located on the expansion bottle?

Where is the engine one located?

Regards

[charbel89]

I checked the engine oil. It is on the min marker.

This means I need to top up probably it will take one litre.

I had the car serviced on the 17th of May. (done about 650 miles).

I guess this is pretty normal for a car this age.

[charbel89]

I am assuming this is my coolant sensor:

http://img638.imageshack.us/img638/6126/15062010076.th.jpg (http://img638.imageshack.us/i/15062010076.jpg/)


And the blue part is where the engine thermostat is located? Will removing the ring where the yellow arrow is be enough? Looks like I need to loosen the alternator for this!!?

http://img197.imageshack.us/img197/4461/15062010075mod.th.jpg (http://img197.imageshack.us/i/15062010075mod.jpg/)

[charbel89]

HI,

I have now replaced the Throttle Unit with a brand new one.

The car is much smoother now, owever Idling is a bit weird.

Sometimes it is all fine running about just bel0w 1000 I would say 900 and then at some point it will rise gradually till 1500 and up to 1800 and fluctuate between the two as if I am revving the car.

Ideas, and thoughts?

I now have ross-tech vag-com.

Thanks.

[DropKickMurphy]

hi there,

you will need to adapt the car to the new TB unit - if you have full version of VAG-Com you will be able to do this via the diagnostics. eventually they do settle down but it can take hundreds of miles and its best to get ti adapted. even a garage shouldnt charge much for this, its a 15 min procedure as far as i'm aware

DKM

[charbel89]

Hi Thanks.

Will this be how to do it using the ross tech:


[Select]
[02 - Auto Trans]
[Basic Settings - 04]
Set Group to "000"
[Go!]
Press accelerator pedal all the way to the floor and count out loud 3 seconds.
[Done, Go Back]
Release the accelerator pedal

If yes I tried that!!?

[charbel89]

An update:

I changed the Throttle body gasket and then disconnected the battery for few minutes, connected it back and started the car.

Lo and behold, the TB has been adapted and the RPM is stable at 850.

Took it for a drive and it is nice and smooth.

I could not really tell if the TB gasket could have affected this or not, but I must say it was pretty bad. So it is possible that my vag-com adaptation did not appear to work because the gasket was leaking when car gets pretty hot.

What is certain though is that the battery disconnection must have re-adapted the TB. (I did not have to do the vag-com adapation..)

I hope this will be of benefit to someone.

Thanks for everything.

Transmission oil and filter here I come ...

Regards

Charbel