1.8t running better on 95 Octane. Strange.

RoyalBoob

RoyalBoob

Registered User
Joined
Jul 2, 2011
Messages
72
Reaction score
10
Points
8
Location
NULL
Got a bit of a strange problem. I was sure my 190 was being a bit sporadic with boost and some flat spots.

Through lack of choice I put some BP 95 octane in and performance and MPG is consistently better than with V-Power.
I've filled it up three times now and the result is consistent. Even running 95 straight after a tank of V-Power to see if the difference is noticeable. Boost is typical of what I remember and MPG is up to around 30.

In the past I've always had really good performance from higher octane, as one would expect so it's a bit strange.

I've run a dose of Red Ex through to see if it cleans the injectors and helps.

Anyone got any ideas what might be going on?

Cheers
 
Mine is mapped and really doesn't like v-power either, much to a lot of people's disgust I use Tesco momentum, from what ive heard in the past a lot of shell garages charge for vpower but Its just normal fuel
 
My 1.8 t loved shell v power ran so smooth and made the engine very quite
 
  • Like
Reactions: DrStrange
I do find that odd the ''better quality fuel'' would result in your car not running as good.

I hope you get to the bottom of the root cause but cant scientifically see how higher Ron fuel would be worse.

Hopefully, someone can explain?
 
I wonder if you have a weak fuel pump
 
It's possible. I thought either plugs, coil packs, dirty injectors or MAF values not playing well with higher octane. Further back, the pump could be an issue if there is a difference in viscosity between different fuels.

I think Momentum has had a similar effect but not used it recently. Previously all of the higher octanes were noticeable improvements.
 
It could be the more advanced ignition timing that 98/100 RON fuel allows, doesn't agree with your car?

As the car can push the timing up with a 98/100 RON fuel and will drop it back a bit for 95.

I haven't got the first clue why that would be, but it might be worth looking into?

The results you get from a tank or two of Momentum would help with the diagnosis. To see if RON is a factor in the car misbehaving.
 
I think it's down to the fact that the 98+ RON fuel burns so cleanly, resulting in a smooth power delivery, whereas the 95 RON fuel doesn't burn so well and it runs a little rougher BUT it feels like it's pulling better because of that.
 
In my car which is 1.8i non turbo it says to put 95 Ron in it and the same with my dad's b6 cab to use 95 both unmapped running a standard tune. Mine has a couple mods my dad's has none that's all I could think off

Sent from my GT-I9195I using Tapatalk
 
Off the top of my head, I'm not sure. I think it may have been done a while ago, but again, good point, worth exploring.

Pushed up to BP Ultimate and performance is still better than V-Power. Previously I've always thought it to be a pretty poor premium fuel.

I'm now coming into the service window so it'll be going in with a list of stuff I want them to look at.
 
Don't take it to Audi they don't replace fuel filters as part of a service
 
Just to update and wrap up. Service and MOT last week... followed by a sudden break down. I feared the worst.

Actually, it seems all of the performance issues I was having were down to pipes and hoses and their securing clips. I don't have the specific info to hand, but really, just stuff that had perished over time and stress.
Really not an expensive fix... car giving much better economy and performance. Boosting nicely and lapping up the high Octane fuel!

If you read this in the future, do get the plumbing looked at for leaks and splits!
 
  • Like
Reactions: DieselJake and QuattroCalum
RoyalBoob said:
Just to update and wrap up. Service and MOT last week... followed by a sudden break down. I feared the worst.

Actually, it seems all of the performance issues I was having were down to pipes and hoses and their securing clips. I don't have the specific info to hand, but really, just stuff that had perished over time and stress.
Really not an expensive fix... car giving much better economy and performance. Boosting nicely and lapping up the high Octane fuel!

If you read this in the future, do get the plumbing looked at for leaks and splits!
Click to expand...

All vacuum hoses and pcv hoses are the nemesis of the 1.8t they have to be in top condition or you'll have any number of intermittent issues regarding fuelling. I can't think of one that would cause the car to breakdown though. Any info on the actual cause of that?

Glad to hear you have it fixed though, any thoughts on moving back to Shell V Power now it's running properly?


Sent from my iPhone using Tapatalk
 
  • Like
Reactions: DrStrange
QuattroCalum said:
All vacuum hoses and pcv hoses are the nemesis of the 1.8t they have to be in top condition or you'll have any number of intermittent issues regarding fuelling. I can't think of one that would cause the car to breakdown though. Any info on the actual cause of that?

Glad to hear you have it fixed though, any thoughts on moving back to Shell V Power now it's running properly?


Sent from my iPhone using Tapatalk
Click to expand...

The boost hose pipe clip had corroded and pipe detached, this was the cause of its breakdown after some spirited backroad driving - which makes sense...
Breather hose and all filters changed on the service. Just wondering about replacing any other related plumbing now. How many exactly are there? Also, might not hurt to change the PCV valve. It's a simple job isn't it?
Yep.... she's got a nice fat shot of V-Power in the tank now!....
 
RoyalBoob said:
The boost hose pipe clip had corroded and pipe detached, this was the cause of its breakdown after some spirited backroad driving - which makes sense...
Breather hose and all filters changed on the service. Just wondering about replacing any other related plumbing now. How many exactly are there? Also, might not hurt to change the PCV valve. It's a simple job isn't it?
Yep.... she's got a nice fat shot of V-Power in the tank now!....
Click to expand...

Would that be the one that connects to the inlet manifold, the so called L hose? That would cause a massive air leak and a lean code.
I can almost guarantee that the crankcase breather ( below the inlet manifold) is broken or will crumble when touched. Good idea to change the pcv valve as well, you'll know if they've been changed before because they will have jubilee clips in place of the factory crimped ones.


Sent from my iPhone using Tapatalk
 
  • Like
Reactions: DrStrange
One I'll have to have a look for. Are there any photo/ video guides you know of to assist with that stuff?.... I know the mechanic who changed the pipe said it crumbled away and was a bit of a ballache to do because of that. Nothing mentioned about the crankcase breather. I would have thought most of this stuff is seen frequently for a VAG independent.
 
You must log in or register to reply here.

Similar threads

R
95 or 98 ron?
Replies
1
Views
765
CJ A4
C
P
Running temperature 1.8t
Replies
20
Views
9K
mazzaman
M
M4KTT
1.8t running problems
Replies
4
Views
1K
M4KTT
M4KTT
R
Strange 1.8T problem
Replies
4
Views
717
vr6gordy
vr6gordy
s-line stu
95 or 98 ron petrol?
Replies
21
Views
13K
Nilz
Nilz
Top
Back