Lack Of Power

[P1_Paul]

OK, so if subjecting the engine to certain conditions can affect the IAM value (e.g. when forcing fast ECU learning), and the IAM value affects ignition timing advance, then doesn't it follow that driving style can affect ignition timing? Perhaps not constantly, but at least under certain conditions - e.g. after a change in fuel, or after an ECU reset...

BTW - cheers for all the info, it is appreciated.

I suppose it does stand true that if your IAM was lower than the highest value and you maybe had some additional learnt knock, then pussy footing it around wouldn't do anything to help raise the IAM back up or remove the learnt knock values. I'm coming at it from the point of view that the IAM is at it's highest value, i.e if it's 16 and you have no learnt knock, driving like a grandad won't reduce the power of the car.

[P1_Paul]

Here's the learning table for learnt knock, this is how it builds a timing curve depending on fuel quality, conditions etc.

[thewelsho]

It's hard enough trying to understand the concepts and processes discussed in these posts/articles wihtout using acronymns minus the explanation! What is IAM, or what does it stand for? Once I know that, I can perhaps get a handle on the discussion!

[P1_Paul]

Aye, sorry, Ignition Advanced Miltiplier.

[thewelsho]

Aye, sorry, Ignition Advanced Miltiplier.

Ah cool! All makes perfect sense now

[Midnight21]

Ah cool! All makes perfect sense now

makes sense here too

[dipsy]

http://www.ecutek.com/tuning/ignition .It easy reading here and the advance multiplier is mentioned aswell

[mystery machine]

It's hard enough trying to understand the concepts and processes discussed in these posts/articles wihtout using acronymns minus the explanation! What is IAM, or what does it stand for? Once I know that, I can perhaps get a handle on the discussion!

Hey, I had a stab at guessing I.A.M. above - got two words out of three, not bad

Reminds me of scene from Only Fools and Horses:

Well-heeled gentleman: "We've got S.W.A.N.S."

Delboy: "What? Them big white duck fings?"

Rodney: "No Del, it's not a duck or a goose or anything like that - it's an acronym."

Delboy: "Oh, right...... What do you feed them on?"

Well-heeled gentleman: "What do we feed what on?"

Delboy: "Yer nacronyms?"

[mystery machine]

I suppose it does stand true that if your IAM was lower than the highest value and you maybe had some additional learnt knock, then pussy footing it around wouldn't do anything to help raise the IAM back up or remove the learnt knock values. I'm coming at it from the point of view that the IAM is at it's highest value, i.e if it's 16 and you have no learnt knock, driving like a grandad won't reduce the power of the car.

Cheers again for the reply, Paul.

OK, I understand.

Let's hypothesise for a moment and assume that fuel supplies aren't necessarily consistent - even within a particular brand and flavour of fuel. Imagine then, you top up with a good batch of V-Power, give your engine a good booting for a couple hundred miles, and your IAMs hit the big 16. Next top-up the fuel isn't quite as rich in octane, and your ECU detects knock - IAM is reduced a tad and the car doesn't pull as strongly. Tank three you're back to the good stuff, but - and this is the important bit - until you've given the engine a good hoofing, your IAM remains languishing somewhere below its optimum value.

OK, I've used (an assumption of) variable fuel quality as an example of a factor that may cause IAMs to be reduced, but would you agree that there are other factors that may increase the likelihood of knock, even after the ECU has decided that its current IAMs are 'safe' values - e.g. change in engine temp, air temp, humidity...?

You see what I'm getting at here? You pointed out quite rightly that sedate driving doesn't directly cause timing to be retarded - however, from a driver perspective it might appear to have that effect. I'm speculating that IAMs, rather than being values that hit their targets and then stay there for 'a long time' until something freakish and out-of-the-ordinary happens, perhaps they are being pulled down more regularly as a result of knock, brought on by varying external factors.

Therefore, to keep one's IAMs at or near max, one has to give one's Scooby a bit of a caning on a fairly regular basis - drive sedately and you might be allowing those values to drop...

BTW - this is probably just an overly-analytical way of saying the same thing as you just did - but hey, "the devil's in the details" as they say

Edited April 24, 2009 by Mystery Machine

[mystery machine]

Here's the learning table for learnt knock, this is how it builds a timing curve depending on fuel quality, conditions etc.

Cheers for posting!

Interesting to see how it's broken down across the rev range - perhaps that explains some of the 'stepping' I sometimes feel accelerating through the revs? (particularly after driving sedately for a week! ).

[mystery machine]

makes sense here too

Aye, I know what you mean

Probably should have just left it at this - says everything the vast majority of us need (or want!) to know:

Go on a good run that cleans them out .

[mystery machine]

Wouldn't it be just hilarious if, after all this detailed analysis, simboy73 came back and told us his turbo was gubbed?

OK, maybe no' so hilarious for simboy...

[Midnight21]

Crikey you do some talking to yourself

[mystery machine]

Just keeping the conversation warm while everyone's away, Cathers

[Midnight21]

Just keeping the conversation warm while everyone's away, Cathers

Where are they all away to? out driving in their cars maybe

[mystery machine]

Where are they all away to? out driving in their cars maybe

Yeah - what's all that about?

Must admit that I don't really go for the 'twilight cruising'. Prefer to save my petrol for the weekend mornings when the roads are deid and the sun is (hopefully!) shining

[Midnight21]

Yeah - what's all that about?

Must admit that I don't really go for the 'twilight cruising'. Prefer to save my petrol for the weekend mornings when the roads are deid and the sun is (hopefully!) shining

What's the point in twilight cruising! You cant see the cars to wave at I usually have a drive in the afternoon after work at the weekends! Its the only chance I get

[P1_Paul]

Cheers again for the reply, Paul.

OK, I understand.

Let's hypothesise for a moment and assume that fuel supplies aren't necessarily consistent - even within a particular brand and flavour of fuel. Imagine then, you top up with a good batch of V-Power, give your engine a good booting for a couple hundred miles, and your IAMs hit the big 16. Next top-up the fuel isn't quite as rich in octane, and your ECU detects knock - IAM is reduced a tad and the car doesn't pull as strongly. Tank three you're back to the good stuff, but - and this is the important bit - until you've given the engine a good hoofing, your IAM remains languishing somewhere below its optimum value.

OK, I've used (an assumption of) variable fuel quality as an example of a factor that may cause IAMs to be reduced, but would you agree that there are other factors that may increase the likelihood of knock, even after the ECU has decided that its current IAMs are 'safe' values - e.g. change in engine temp, air temp, humidity...?

You see what I'm getting at here? You pointed out quite rightly that sedate driving doesn't directly cause timing to be retarded - however, from a driver perspective it might appear to have that effect. I'm speculating that IAMs, rather than being values that hit their targets and then stay there for 'a long time' until something freakish and out-of-the-ordinary happens, perhaps they are being pulled down more regularly as a result of knock, brought on by varying external factors.

Therefore, to keep one's IAMs at or near max, one has to give one's Scooby a bit of a caning on a fairly regular basis - drive sedately and you might be allowing those values to drop...

BTW - this is probably just an overly-analytical way of saying the same thing as you just did - but hey, "the devil's in the details" as they say

TBH, I'd be surprised if IAM dropped due to a bad tank of V-Power or T99, it might happen, it's more likely to drop if you change to 95 RON. A bad tank of V-Power will most likely trigger Fine Learning values to appear, shown in the table I posted. It's quite straight forward to raise your IAM all things being as they should(it's quite well documented), the fine learning values can take longer to clear.(especially if you're driving steadily and not reaching the cells with correction) The best thing to do if you think you've had a bad tank, or had to use 95, is to reset the ECU and make a few steady throttle runs into boost.

I agree btw, this probably has nothing to do with the OP's problem, probably just him getting used to it, lol.

[mystery machine]

What's the point in twilight cruising! You cant see the cars to wave at

Quite! Perhaps they're kerb-crawling? :crying:

I usually have a drive in the afternoon after work at the weekends! Its the only chance I get

It's always nice to have something like that to look forward to after work - makes the day pass quicker

[Midnight21]

Quite! Perhaps they're kerb-crawling? :crying:

It's always nice to have something like that to look forward to after work - makes the day pass quicker

Think we better stop stealing this thread

[mystery machine]

TBH, I'd be surprised if IAM dropped due to a bad tank of V-Power or T99, it might happen, it's more likely to drop if you change to 95 RON.

Fair enough - but it's probably reasonable to suppose that air temp, air humidity and engine temp can also affect the likelihood of knock.

I guess the only way to find out for sure would be to record the values of these multipliers over a period of time, while driving the car in various conditions... Emdy fancy loaning me a laptop and a Scooby ECU cable? (just kidding)

I agree btw, this probably has nothing to do with the OP's problem, probably just him getting used to it, lol.

Well, if nothing else, it's given me a better understanding of why the car might behave the way it does

Cheers for the info and for your insights, Paul

[Maxxed_Ross]

a bit of ECU re-learning possibly

Putting a link to Andy F's site was a bad idea... I can feel my credit card squirming already

[mystery machine]

Putting a link to Andy F's site was a bad idea... I can feel my credit card squirming already

A-HEM!

As an RB320 owner, you have no place in a thread entitled 'Lack Of Power'!!!

Just kidding Ross, join the fun - how's yer IAMs been keepin'?

[dipsy]

a bit of ECU re-learning possibly

Putting a link to Andy F's site was a bad idea... I can feel my credit card squirming already

http://andyforrestperformance.co.uk/index2.html .Here you go

[Maxxed_Ross]

stop it! lol

I know I know I can't really complain... but more is always nice!

My ECU knows it's a play thing, it never tootles anywhere