Mk4 Golf 2.0l bad fuel economy after timing belt change

[bixler]

Hi all,

I'm new to the forum and Volkswagens in general. Had my '03 Golf 2.0 for a few months now. Really happy with the car; fuel economy has been between 8-8.5l/100km city driving. Car has 115,000km so on Wednesday I had it in at Volkscare Boronia for change of timing belt/tensioners, water pump/coolant.

Since picking up the car my fuel consumption has gone through the roof. Trip computer is showing average consumption 12-13l/100km when driving conservatively. At idle it has gone from 1l/hour to 2-3l/hour. The exhaust smell is also very rich and is noticable in the cabin when sitting at the lights.

I took it back to Boris at Volkscare today and he did a diagnostic scan which did not show up any fault codes. He checked all the hoses etc that he had disconnected and all seemed ok. He said he's never had this happen before.

Hoping for some ideas around what might be the problem. Is there a sensor that is likely to have failed? Any help would be much appreciated as I'm currently drinking more petrol than my old falcon!

Thanks in advance.

[Jmac]

Thermostat stuck open therefore the ecu sees a cool engine all of the time and injection pulse width is extended, will throw no codes as the ecu is doing its job correctly, its dumb and is only doing what it is told. My take, bearing in mind its an internet diagnosis.
Cheers
Jmac

[bixler]

Thermostat stuck open therefore the ecu sees a cool engine all of the time and injection pulse width is extended, will throw no codes as the ecu is doing its job correctly, its dumb and is only doing what it is told. My take, bearing in mind its an internet diagnosis.
Cheers
Jmac

I've actually noticed in the last couple of days the car is not getting up to temperature. Barely making it out of the bottom cold zone. Might occasionally make it halfway up to 90' degrees on the gauge but then goes straight down again when cruising. Sounds like you might be on the money Jmac!

[marquee]

I've only been here for a few months and jmac is normally right.

I just had the same thing happen to me cost me 130 for parts and labour. Parts were about 80 from vw so I though 50 bucks to save me the hassle why not

[bixler]

I took it back to Volkscare yesterday and had thermostat and coolant temp sender replaced. Car now running at right temperature BUT when i went to pick it up took it for a test drive and car felt like it was hitting the limiter at 3500-4000 RPM. Took it back and they quickly swapped the MAF sensor with another one lieing around and it seemed to solve the second problem. Car seemed fine last night and economy seemed back to normal.

This morning I went to start the car and it would keep stalling after a few seconds of rough idle. After 5th or 6th try managed to keep going and warm up and quick test drive seemed to be OK. Driving home from uni today though problems started again. Stalled once at the lights and power cut out and in 3-4 times randomly/momentarily when driving.

Does this sound related to the MAF? or could there be another problem. I'm getting more and more worried and don't want to be paying labour charges for a problem that did not exist before the timing belt change. The car was running 100% fine before the service. I had to argue my way out of paying labour for yesterdays work. They seem to be accepting no blame as the computer is not throwing any codes to suggest anything is wrong, even though there clearly is.

If anyone any ideas, opinions suggestions on where to go next it would be great. If this newest stalling/loss of power issue sounds related to the MAF can anyone reccomend where to purchase a new one? Had a look on ECS tuning but engine codes are different? Any help would be great! Thanks

[JustCruisn]

To test the MAF simply disconnect the wiring. The car will run on default settings, if the problem goes away then the MAF has issues.

[bixler]

To test the MAF simply disconnect the wiring. The car will run on default settings, if the problem goes away then the MAF has issues.

Thanks for the reply. I did this test last night. With the MAF unplugged the issue completely dissappeared, apart from car running a bit rich.

Took the MAF out.. there was a bit of fluff stuck on the wire mesh which i got rid of.. blew on it and put it back in. Took it for a test drive and car running the best it ever has. All issues gone and economy back to being excellent! Drove to work this morning (aprox 30km) and car still perfect and trip compuer read 6.5l/100km. No idea if fluff/blowing on it had any effect but I would say I've confirmed the MAF was the source of the issue.

I think I'll be ordering a brand new MAF in the coming days for safe measure. ECS seem to offer a reasonable price on Bosch unit unless anyone has any reccomendations? Stealer quoted $$390 less $115 rebate on return (which I don't think I will get as the current unit I discovered is not genuine/bosch).

[RolfGolf]

I think I'll be ordering a brand new MAF in the coming days for safe measure. ECS seem to offer a reasonable price on Bosch unit unless anyone has any reccomendations? Stealer quoted $$390 less $115 rebate on return (which I don't think I will get as the current unit I discovered is not genuine/bosch).

Try Imparts if there's one near you - from memory my Bosch MAF cost around $150.00. Postage will kill you from ECS - I priced a temp sensor and postage was quoted at $47.35 - ie. not based on weight/volume or reality.

(the sensor itself was $4.99)