Octavia 1.8T VRS Fuel Economy - MPG Problem.

[Tiger_kpt]

Hi all. I am new to this forum, I have just purchased a 2003 Octavia 1.8T VRS. So a big HELLO!

50k miles on the clock - FSH.

TOTALLY standard apart from: -

Custom code phase 1 remap

Forge 007P DV

Green Cotton panel air filter

(all installed July 2009 at JBS, 7k miles ago - along with a new MAF and a new coolant temp sensor)

The car starts fine, idles fine, runs fine and drives fine - maybe with a little bit of boost surging when pulling away in lower gears and using partial throttle, but very very mild. I have driven the car for just over a week now. I am however, a little worried about the fuel consumption it is returning though, it seems to be a little on the awful side! Driving like miss daisy sees me at around 24-26mpg. Driving enthusiastically sees me at around 20-22mpg. This is a little worrying as this car is now my daily drive, acting as a replacement for my diesel Transit Connect, which I had to sell as more seats were required, due to a new born baby! I would expect that 30-35mpg out of these cars is not unreasonable. As it is using fuel at the minute, it is actually worse on fuel when compared to my weekend toy - a 6.0 V8 Monaro. A totally full fuel tank returned a only 270 miles - in the space of a week, mixed driving.

The other night, whilst driving the VRS down the motorway, I performed a WOT 5th gear run. Half way through which, the ASL dash light decided to illuminate constantly on the dash. The ASL dash light could not be switched off by using the ASL console button like normal. I had to exit the motorway, pull over, switch off the engine and ignition and key back on again - this reset the dash light and it has remained off since. The traction control works as it should do, when trying to regain traction (typically low gears and high RPM), the ASL dash light flashes on and off, so no problems in this system as I can see. As a precaution I got in touch with JBS and took the car down to them today to scan the car with VAG-COM for faults.

The VAG-COM scan at JBS brought up the following stored fault codes on the ECU: -

P0343 - camshaft position sensor - signal too high

P0103 - mass air flow sensor - signal too high

P1602 - power supply terminal 30 - voltage too low

The car had been stood over winter for a few months before I bought her, declared SORN. Had a flat battery as a result - so this would explain the P0343 and P1602 fault codes - trying to start and cranking the engine with a flat battery? I put the ASL dash light illumination incident down to the P0103 fault code. This combined with the very mild boost surging and the very poor fuel economy - I decided that the MAF may be on its' way out, even though the engine starts and idles fine, so I replaced the MAF today with a Bosch one from GSF car parts. The engine now seems to run a little better, revving a bit more freely, pulling a little better and the very mild boost surging "seems" to have disappeared. However, the fuel consumption is still the same. When data logging, the only anomaly that was spotted was that the turbocharger was boost spiking a little low, spiking at 1.35bar rather than 1.40bar?

Does anyone have any ideas? I am thinking that it could be an ECU mapping issue? Does anyone have any experience of the JBS custom code phase 1 remaps on a VRS?

It may be that these particular engine maps are heavier than most on the go juice? What average MPG readings should I be seeing on a VRS - before and after remap?

Any and all feedback would be greatly appreciated. Is it possible to get rid of the custom code phase 1 map and revert back to the OEM factory engine map on the ECU?

Thanks.

Kyle.

Edited 3 February, 2011 by Tiger_kpt

[RobClubley]

I was getting low 30s mpg with a Custom Code phase 1 map .

I'd check the engine for boost leaks, degraded pipes etc as that's very common and can cause all sorts of issues, though I'd expect you to see more fault codes.

I assume a CC dealer such as JBS would be able to remove the map.

Or Ben at Shark can do it - I replaced mine with a Shark stage 2 map.

[Tiger_kpt]

Hi. Thanks for the reply. I have been looking at a Shark Performance remap as a replacement map to the JBS Custom Code phase 1 remap, in case I do find that the issue is with the map itself. How do you rate the two now that you have had both?

I had thought about the possibility of a boost leak or a split vacuum hose/pipe. I have had a quick look and they all "look" fine.

[RobClubley]

I went from a CC stage 1 map to a Shark stage 2 map so it's not a direct copmparison.

But the Shark map definitely feels smoother, more urgent, faster, more tourquey.

Dyno comparison:

[VRS Mike]

take it to r-tech in leicester mate, they will do remap witb full rolling road diagnostics for £250, as far as our engines go there is no one better. Call them you won't be disappointed.

[Tiger_kpt]

Thanks guys. Just thinking out aloud... but if the car had a proper flat battery just before I bought it - to the point where the starter motor wouldn't even try to turn over - would this be like disconnecting the battery and would a throttle body reset/re-calibration need to be performed? Would a throttle body "out of sync" return poor fuel economy? The previous owner swears he could return a better MPG than I can get. I got 28MPG average today on the trip computer - mostly glliding along and feathering the throttle.

[VRS Mike]

That is very poor MPG, Mine will return high 30's on a run. If you've got the time phone R-tech and get it booked in, it will be cheaper than just changing random parts in the hope of fixing it. I reckon you've probably got a boost leak, I had a code relating to the MAF, but because I had only recently put a new one in I knew it "shouldn't" be the MAF, it turned out to be a split breather under the inlet manifold.

[illegal_in_9_countries]

you should be getting high 30's driving like that have you tried ross tech with your codes might shed some light on it

[The Skud]

I had two oct vrs mk 1's, the first was remappped by JBS with a Ph 1 map, I could easily get 350 miles out of a tank driving normally, mixture of 70% Mway and 30% around town, average was about 28-30 with upto 40mpg indicated on a run so low 20's is very poor and is obviously running very rich, I would get it looked at sooner rather than later as running excessively rich can ruin the cat, the Pre and post cat O2 sensors and that little lot will set you back a good few hundred quid!!

I would recommend Ben at Shark for no BS advice and diagnostics, ( plus he is only local to you in Mansfield) should you decide to change the map then he does very good maps but to be honest you should not need to, for all the bad press that JBS get for service etc, the CC Ph 1 map is a purely generic map that is not tweaked or written specifically for your car so runs a safe set of parameters that is suitable for any standard car so in all fairness to the guys above promoting this or that remap, save your money get it properly diagnosed and I think you will find that the map is fine and its a problem with the car, look at boost leaks, damaged hoses, the N75 valve vcan be problematic, also the temperature sensor in the water bottle goes as does the temperature sensor on the inlet manifold, they are some of the common problems, along with the MAF which you appear to have renewed, failing that it could be a failed Sensor in the exhaust system.

One thing to check that is often overlooked is all the small pipes under the inlet manifold, if these fail ( which they did on both my Mk1's) then you get a drop in performance due to leaks. Battery being flat will only reset the ECU, not affect the mapping, my battery died completely and had to be replaced with no ill effects.

Edited 4 February, 2011 by The Skud

[RobClubley]

Excellent response ^^

[furry]

As above really, remove the top engine cover and check all the breather hoses, inc the 2 under the inlet manifold that sit in a rubber sleeve.

A throttle body clean out and reset will certainly help.

i reguarly see 350+ out of a tank and my best being 498miles on a trip to the ring.

even after a PROPPER hard thrash last sunday chasing a mates 480bhp P1 through the windy roads i saw an average of 31mpg.

my combined average is always around 38-39mpg.

i'm running a CAI, S3 N75, G60 fly, deleted EGR/N249/Pre-Heat system and superchip.

[LukeRs]

Obviously the poor weather won't help, but I still see about 27mpg around town in winter compared to about 31mpg around summer - usually 370 miles to a tank.

Mine is a totally standard vRS except for miltek system, forge DV and panel filter.

Hope you sort it buddy.

[Schern]

I get poor MPG too, I just put it down to a heavy foot. If I'm very very good I see somewhere around 35MPG on a 40 mile run of mainly A roads with a bit of light town traffic. I've hit 40MPG maybe once or twice. If I just do a short run to work (7 miles nearly all dual carriageway with fairly hard acceleration on roundabouts and slip roads) then I see high teens to low twenties. If I can do anything to improve this then that would be good! How do you check the state of the hoses? Will splits be obvious or is it a case of removing them and trying to pressurise them to check for leaks?

[dubDEAN]

That is very poor MPG, Mine will return high 30's on a run. If you've got the time phone R-tech and get it booked in, it will be cheaper than just changing random parts in the hope of fixing it. I reckon you've probably got a boost leak, I had a code relating to the MAF, but because I had only recently put a new one in I knew it "shouldn't" be the MAF, it turned out to be a split breather under the inlet manifold.

i had this hose split g from pro porsche sorted it for me and found the seal on the pipe to the pancake from the turbo had a seal leaking swapped both and as quick as my mates 04 ibiza cupra now

[dubDEAN]

And started seeing over twenty five to gallon too lol was poor on fuel before

[Tiger_kpt]

Thank you for the quick and good replies guys. Good stuff! Some really useful/helpful pointers and feedback there.

I am seriously starting to think that it either a remap issue or a leaking boost or vaccum pipe/hose somewhere on the engine. I have booked the car in next Thursday with Ben at Shark Performance, he was very helpful over the phone, seems like a nice guy. He even offered to diagnose the problem and look at the current map FOC, which is great. I have just had four new tyres fitted and the brakes (discs, pads and handbrake) were all done just before I bought the car, so no problems with those areas either. I did quite a bit of city driving this afternoon and I averaged 20MPG! More free flowing A-road driving is seeing an average of around 26MPG. Any sort of revs or use of the turbocharger boost really sees the MPG drop dramatically. So something is definitely amiss.

I am going to take a look at all of the boost and vacuum pipes/hoses tomorrow morning, looking for any loose ones, split ones, cracked ones, etc. Is there a diagram or an engine bay photograph that highlights the areas of all of these pipes/hoses I need to check somewhere on the internet?

Also... off topic, but take a look at the youtube link below, this is the weekend beast, that ironically returns a better MPG than what the VRS is returning at the moment!

Make sure you have your volume turned up! I would be happy to get 35MPG average from the VRS, any more is a bonus.

Edited 4 February, 2011 by Tiger_kpt

[Schern]

Also... off topic, but take a look at the youtube link below, this is the weekend beast, that ironically returns a better MPG than what the VRS is returning at the moment! http://www.youtube.com/watch?v=oYuOhZ5bZoEMake sure you have your volume turned up! I would be happy to get 35MPG average from the VRS, any more is a bonus.

Filth!

[dubDEAN]

My pipe was the small one under the inlet manifold, spotted by G as just behind the lower trim cover on engine there was a tiny oily patch where it had sprayed the vapours onto it, the small pipe to the top of the n75 valve had a small split just above the clip about a third the way round and is so much better

[Schern]

My pipe was the small one under the inlet manifold, spotted by G as just behind the lower trim cover on engine there was a tiny oily patch where it had sprayed the vapours onto it, the small pipe to the top of the n75 valve had a small split just above the clip about a third the way round and is so much better

Did you just tape the pipes up as a temp fix or did you replace them? Think I need to check all mine over tomorrow!

[RobClubley]

Useful engine diagram:

[Tiger_kpt]

Awesome engine diagram. Really clear and concise. Am I right in thinking that the hoses/pipes I should be checking, that are the most common to fault, are: -

1) the length of green hose running under the inlet manifold (from the cabon canister), connected to #7 valve's and around to the turbo side of the inlet trunking?

2) the blue hose assembly connected to cylinder head (breather), the inlet trunking (next to the MAF), somewhere on the block (oil return to sump) and #18 vent?

Or should I be checking some of the other hoses/pipes shown on this diagram?

Edited 5 February, 2011 by Tiger_kpt

[DBP]

What? How does everyone have such better MPG than me lol.

I had 28 as an average, soon as I fixed the Breather it went up to 31.6. I guess monday I will be getting under the bonnet!

[RobClubley]

Awesome engine diagram. Really clear and concise. Am I right in thinking that the hoses/pipes I should be checking, that are the most common to fault, are: -

1) the length of green hose running under the inlet manifold (from the cabon canister), connected to #7 valve's and around to the turbo side of the inlet trunking?

2) the blue hose assembly connected to cylinder head (breather), the inlet trunking (next to the MAF), somewhere on the block (oil return to sump) and #18 vent?

Or should I be checking some of the other hoses/pipes shown on this diagram?

Check all of the light blue ones - they seem to be most prone to going.

If they're definitely okay check the yellow/blue/pink ones as well.

Green probably wouldn't cause a problem but again worth checking.

[Tiger_kpt]

Does anyone know of a full aftermarket kit that you can buy, which will replace ALL of the boost and vacuum hoses/pipes on the VRS with the correct silicone/reinforced replacement? I may just change all of these and the associated fixtures and clamps.

[Tiger_kpt]

Does anyone know of a full aftermarket kit that you can buy, which will replace ALL of the boost and vacuum hoses/pipes on the VRS with the correct silicone/reinforced replacement? I may just change all of these and the associated fixtures and clamps.

I have just found these hoses/pipes - albeit a little expensive (any cheaper options out there?): -

http://www.forgemotorsport.co.uk/content.asp?inc=product&cat=200101&product=FMBH18T

http://www.forgemotorsport.co.uk/content.asp?inc=product&cat=200101&product=FMGOLFIND

http://www.forgemotorsport.co.uk/content.asp?inc=product&cat=200101&product=FMKT005

Would all of the above together act as a total aftermarket hose/pipe replacement kit? I am thinking that I would need some bulk silicone vacuum hose/pipe as well - what diameter vacuum hose is present on the VRS AUQ engine? Is it all 4mm OD? Or various?