Higher octane fuel - Page 2

rover54 · 18th May 2012, 00:47

My understanding is the ECU constantly tries to advance the ignition until it senses through the knock sensor that pinking is about to occur, then it backs off the ignition. This is to give maximum power and economy from the quality of fuel used.

SD1too · 18th May 2012, 06:45

I've had a look in MG Rover's official technical manual to try to find some answers to the points raised.

Quote:

Originally Posted by MangoMan

... the ECU has to learn the high octane fuel ...

There is no evidence of any "learning" process. MGR says:
"Once above idle the ignition timing will be controlled according to maps stored in the memory and modified according to additional sensor inputs."
None of this information is stored.

Quote:

Originally Posted by ROVERX501

... is there anything we can do as drivers to help the ECU learn quicker via our driving styles?

No, because the ECM doesn't "learn".

Quote:

Originally Posted by Brek

There is a knock sensor the KV6, however their is much debate on if it advances and well as retards timing.

There are two knock sensors (one per bank) and they only cause the ignition to be retarded. MGR says:
"The ECM is calibrated for 95 RON fuel but can function on a lower octane fuel (91 RON). Testbook is able to re-programme the ignition map information in the ECM memory."

Quote:

Originally Posted by rover54

My understanding is the ECU constantly tries to advance the ignition until it senses through the knock sensor that pinking is about to occur, then it backs off the ignition.

MGR seems to be saying that you get pre-programmed ignition timing unless knocking is detected whereupon the cylinder involved is retarded by 3 degrees (this is the first action in a sequence). It doesn't advance the ignition beyond it's programmed values.

I hope this is of interest.

Simon.

HarryM1BYT · 18th May 2012, 06:58

Quote:

Originally Posted by ROVERX501

I am curious now, is there anything we can do as drivers to help the ECU learn quicker via our driving styles?

The usual method is battery off for 15 minutes, then back on. That should restart the engine ECU's learning process from defaults.

HarryM1BYT · 18th May 2012, 07:02

Quote:

Originally Posted by SD1too

MGR seems to be saying that you get pre-programmed ignition timing unless knocking is detected whereupon the cylinder involved is retarded by 3 degrees (this is the first action in a sequence). It doesn't advance the ignition beyond it's programmed values.

I hope this is of interest.

Simon.

So absolutely no advantage to be gained by using a better grade of fuel than Rover specified.

My last, but two cars had a selector plug, where if you set the plug at a certain position you could use lower quality (lower octane) fuel where the correct one was temprorarily not availble.

HarryM1BYT · 18th May 2012, 07:07

Quote:

Originally Posted by SD1too

There is no evidence of any "learning" process. MGR says:
"Once above idle the ignition timing will be controlled according to maps stored in the memory and modified according to additional sensor inputs."
None of this information is stored.

I suspect MGR got that wrong, because going back almost 20 years, even the early engine ECU's could and would learn and store the engines optimum operating perameters. In fact it was obvious because the engines would run somewhat rough until the settings had been regained.

Canonite · 18th May 2012, 07:21

There is a T4 option where you can specify which octane fuel you wanted to run on. Lol
Needless to say I opted for 95RON during my last T4.

However in my ZT, if I use Shell V-Power in the car it becomes more responsive and generally feels a bit more lively. This could just be a placebo in the sense that by Shelling out (yak yak) 5p more a litre we convince ourselves it works.
A downside is that it's so much fun you guzzle whatever fuel you put in pretty damn sharpish and the joy is replaced with empty pockets.

Brek · 18th May 2012, 12:55

its not a placebo effect, it does perform better, I am going to get mine mapped for 99 ron soon, there is no 99 ron option in testbook unfortunately.

SD1too · 18th May 2012, 18:02

Quote:

Originally Posted by Canonite

There is a T4 option where you can specify which octane fuel you wanted to run on.

Alan, is that limited to 91 or 95 RON as MGR says, or could a higher octane be chosen?

Quote:

Originally Posted by Brek

it's not a placebo effect ...

How do you prove this claim without two identical cars and driving patterns?

Simon.

VVC-Geeza · 18th May 2012, 19:54

Am I right in thinking that the 1.8K (inc turbo) has no knock sensor?

SD1too · 18th May 2012, 21:22

According to MGR, you are correct.

Simon.

18th May 2012, 12:55	#17
Brek Gets stuck in MG ZT 180+ 2.5 V6 Manual Join Date: Dec 2011 Location: Darlington Posts: 643 Thanks: 0 Thanked 3 Times in 2 Posts	its not a placebo effect, it does perform better, I am going to get mine mapped for 99 ron soon, there is no 99 ron option in testbook unfortunately. Last edited by Brek; 18th May 2012 at 12:58..

18th May 2012, 19:54	#19
VVC-Geeza This is my second home 2005 Connoisseur SE 1.8 Turbo,2004 45 1.8 Connoisseur and my beloved 1998 VVC Coupe. Join Date: Nov 2009 Location: Derby. Posts: 8,815 Thanks: 2,022 Thanked 1,016 Times in 739 Posts	Am I right in thinking that the 1.8K (inc turbo) has no knock sensor? __________________

18th May 2012, 21:22	#20
SD1too Doesn't do things by halves Rover 75 2.5 Connoisseur Auto (1999) Dealer launch model. Join Date: Mar 2007 Location: Former Middlesex Posts: 20,554 Thanks: 1,587 Thanked 3,749 Times in 3,181 Posts	According to MGR, you are correct. Simon. __________________ "Whatever is rightly done, however humble, is noble." Sir Henry Royce.

18th May 2012, 00:47	#11
rover54 Retired rover 75 v6 Auto Conn. SE 54 plate LPG and 2006 Rover 75 v6 Auto LPG , 1.8 r75 Manual Join Date: Aug 2010 Location: London Posts: 3,379 Thanks: 0 Thanked 6 Times in 6 Posts	My understanding is the ECU constantly tries to advance the ignition until it senses through the knock sensor that pinking is about to occur, then it backs off the ignition. This is to give maximum power and economy from the quality of fuel used.

18th May 2012, 07:21	#16
Canonite This is my second home BMW 330d Tourer, MG ZT 180 SE XPG, VW Polo 6R 1.2 TDI Bluemotion Join Date: Jul 2011 Location: York Posts: 6,030 Thanks: 363 Thanked 574 Times in 319 Posts	There is a T4 option where you can specify which octane fuel you wanted to run on. Lol Needless to say I opted for 95RON during my last T4. However in my ZT, if I use Shell V-Power in the car it becomes more responsive and generally feels a bit more lively. This could just be a placebo in the sense that by Shelling out (yak yak) 5p more a litre we convince ourselves it works. A downside is that it's so much fun you guzzle whatever fuel you put in pretty damn sharpish and the joy is replaced with empty pockets.