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Model specific boards => Golf mk4 => Topic started by: olly1505 on 25 April 2015, 10:00

Title: MPG has dropped
Post by: olly1505 on 25 April 2015, 10:00
Ok so I had a coolant leak which pretty much emptied my coolant in 48hours, during this time my mpg dropped which seemed normal. Had the pipe replaced that was leaking, leak sorted. But mpg is still low ?? Not awful but a significant drop from pre-leak. Any ideas ?
Title: Re: MPG has dropped
Post by: Dalo Harkin on 26 April 2015, 06:59
Over how long a time frame are you measuring the drop, and what's it dropped by?
Title: Re: MPG has dropped
Post by: olly1505 on 26 April 2015, 18:06
MPG has probably dropped by 30% I would say over the last few days. Not weather related. Seemed to start at the same time as my leak which I had fixed. Not sure if related to that ? Or completely different problem..
Title: Re: MPG has dropped
Post by: Dalo Harkin on 27 April 2015, 12:41
did you replace the temp sender?
Title: Re: MPG has dropped
Post by: olly1505 on 27 April 2015, 15:23
No. Should I ?
Title: Re: MPG has dropped
Post by: olly1505 on 28 April 2015, 10:32
I am taking it into my VW dealer on Tuesday. Have never used them before. If they cant confidently identify the issue, would it be best for my tell them to change the temp sensor, air/fuel filter first? When I mentioned cleaning the EGR valve/MAF Sensor they said that probably wont do anything and asked if I had been on forums  :grin:

Also getting them to check a hissing sound(air leak) i seem to get in high revs.. Worried will be the Turbo

I have 170k on the clock fyi
Title: Re: MPG has dropped
Post by: Dalo Harkin on 05 May 2015, 13:12
if you're taking it to the stealers, then make sure you come back here before getting the work done would be my advice.

I've had a few issues with the stealers in the past myself, mentioning MAFs, here was one of my issues with the stealers.
took my car for mapping and the MAF was dead, it was a brand new one from VW. after speaking with VW about getting a replacement/refund they said that they needed my car for the day to test if the MAF was faulty, said no as the MAF is off the car by this point (nipped to GSF for one because VW didn't have one in stock) when speaking with VW they said that as the car is modified then their MAFs are not covered by any kind of warranty. After they sent it to Germany for testing it was indeed dead and I collected the cheque the following week! what a PITA!

Basically if you have any engine modifications its hard to justify a genuine MAF
Title: Re: MPG has dropped
Post by: olly1505 on 10 May 2015, 20:34
They basically didn't acknowledge the fault because the engine management didn't show any problems. My drive to work is getting 42MPG. It's normally 50-55MPG. Significant sudden drop. Like I said it started when I had a coolant leak(which is now fixed)

Just serviced it & had all filters changed. Still no better :(

Any ideas ? :(
Title: Re: MPG has dropped
Post by: Rhyso on 10 May 2015, 21:01
What car are we talking about?

What power diesel engine have you got? Mileage?
Title: Re: MPG has dropped
Post by: olly1505 on 10 May 2015, 21:19
Golf GT TDI 150 PD. 2003. Mileage 172k
Title: Re: MPG has dropped
Post by: Rhyso on 11 May 2015, 07:50
Golf GT TDI 150 PD. 2003. Mileage 172k

Any performance issues?? Strange noises?? Smoke on startup??
Title: Re: MPG has dropped
Post by: olly1505 on 11 May 2015, 13:30
No performance issues really, running like normal. No strange noises. I get white smoke on start up but always have done for last 4/5 years. Had camshaft replaced on car 50k mileage ago which is a common fault. Really have no idea.. Maybe there is an issue with the small pipe used by the garage to fix the coolant leak.. Hmmmm doubt it though they always been pretty good
Title: Re: MPG has dropped
Post by: Rhyso on 11 May 2015, 13:34
Weird then

Where was the coolant leak from?? Rad? EGR cooler??  I assume the temp gauge sits at 90 when its warmed up

Have you had it scanned for fault codes??

Just saw your previous post about no codes
Title: Re: MPG has dropped
Post by: olly1505 on 11 May 2015, 15:06
Weird then

Where was the coolant leak from?? Rad? EGR cooler??  I assume the temp gauge sits at 90 when its warmed up

Have you had it scanned for fault codes??

Just saw your previous post about no codes


Temp sits normal, no fault codes

It wasn't from the radiator. It was coming from right in the middle, the mechanic showed me the small piece of black pipe, roughly 15cm long I would say, it had a split under the metal clip at the end. Sorry im not the most car literate