AFR's - Talk to me

[Lee P]

Yes mate - wouldn't want to run that lean on WOT ! What are your egts like ?

 

At WOT normaly just under 900 but if it goes up to 950 very max on those top speed runs

 

My internals are ceramic coated though which makes the reading a bit higher.

[Lee P]

Thats a good start

 

Who mapped it?

 

Dan turner mapped it.

[Matt H]

I found this word document helped me a few years ago to understand it a little better.

 

http://www.mkivsupra.net/vbb/showpost.php?p=536680&postcount=23

 

i was expecting a big document there! lol

[Lee P]

Mate you have one of my favourite Supras on here, be gentle to her and get those WOT afrs down to early 11's

 

Thanks Matt, It has worried me running it like this but SRR said it was fine and was probly running conservative ignition timing and thats why it was ok.

 

I have got water injection as well which helps.

[bromy]

Matt, so is there a big difference between the two different monitoring devices as Chris from 'Hyper' suggests or has your car been mapped 'safe'. Have you asked?

[Wez]

I have got water injection as well which helps.

 

Ahh ok, the water injection will make it appear leaner due to the higher oxygen content.

 

If it was my car I would disable the WI and check your AFRs carefully.

[Muffleman]

Ahh ok, the water injection will make it appear leaner due to the higher oxygen content.

 

If its was my car I would disable the WI and check your AFRs carefully.

 

Phew ! Didn't realise there was WI in there too, was starting to worry

[bromy]

 

If it was my car I would disable the WI and check your AFRs carefully.

 

 

Water injection failure could be catastrophic

[Muffleman]

Yeah but if the WI has been mapped in then you would need to retard the timing, not just switch WI off

[suprafan72]

12:5:1... On WOT is far too lean.. Mr Feckin Dan Turner can bullshit all he likes.. But you have to consider.

1) What happens if WI Fails (Pumps can Fail or run out of Water)

2) What happens if you fill up with Optimax and its substandard.

 

Yes you have a built engine but its no safeguard to what would happen...

 

Think you need your map investigating to be on the safe side! I nearly fell victum to an expensive engine rebuild after Dan had mapped it again after burning out a set of valves on my head... Lucky that Ryan on here saved my Bacon..

 

For your on sake mate get your Map checked out before its too late.

 

As Wes said only use W/I as a safety measure....

[rob wild]

OK Guys

 

Before 'slagging off' any more of our mapping work I'd like to explain why the tuning is done like it is.

 

Firstly, we use a laboratory grade Autronics, £1500.00 wideband, not a £200 AEM one that most of you guys are referring too! You wouldn't beleive the difference in the two...chalk and cheese. The sensor alone costs more than the AEM kit. The AEM's are OK if you want to keep an eyen things but I wouldn't take them as gospel and I certainly wouldn't map a car on one!

 

Secondly, if you run a car anywhere near 11.5 - 12.0 it will blow up. Period. I am certified by the EFI University tutored by Ben Shrader, who gave us a good example when on one of the courses. A 911 runs 10.7 AFR WOT makes 630BHP, and then remapped at 11.2 and make 640BHP, but lasts 500 miles before melting a piston.

 

A car will make very negligable power increases with a AFR of 10.5 or 11.5, though the car will be a lot safer at 10.5. There is no chance of bore wash on an engine that has 60,000 miles on it running an AFR of 10.0 or 10.5! All power if made through boost / timing increases and surprisingly little through AFR.

 

Please let us do what we do best, without any unsavoury comments from 'armchair critics'.

 

Thanks, Chris

 

I hope that wasn't aimed at me Chris? After remapping the car to 11:1 (and having the AFR's checked by a third party) it now comes on boost earlier and doesn't have the minor flat spot/hesitation around 3800-4200 rpm. The issue with the bore washing was after a conversation with one of the Senior PAG (Ford, Jaguar, Aston Martin etc etc) Race engineers who was visiting our engineering department and showing the engine development stages of the Ford GT/DB9. He was the one that mentioned to figure 11:1 afr. Also my car has not done 60000miles and neither has Matt's as Matt's has just been rebuild. Also since remapping my car i have done 1000's of miles and a santa pod and the engine has not gone bang yet.

 

Also I've changed the LAG times on the injectors to lean the car off which allows the car to start when it was hot which i have then compensated with by altering the water temp map which was set to 5+ across the whole temp range to 10+ at the lower temperatures.

 

Also if you can't trust the AEM wideband what is the best way of road mapping?

 

Again Chris I'm sorry if you feel that i was 'slagging you off' and if you took offense that was not my intention. I was simply adding to the discussion hence why i wrote:-

 

 

Not saying that they are wrong but I was a bit worried about bore washing.

 

and

 

Saying that the car did run ok but it was really rich and i suppose safe.

 

Plus the multiple threads where i have recommend you! Plus the HyperSr sticker in the back of my car. Chris if you feel that what i have written or done to my map is wrong then please feel free to contact me.

 

Cheers Rob

[Guest HyperSports]

Hi

 

Sorry, not specifically targeting anyone in particular (especially you, Rob), but this game is mine / our profession and get very peaved when individuals preach that something is right or wrong when they are not in a position to do so. I wouldn't tell a plasterer how to do my kitchen ceiling etc. It's not here, or this forum, it's just the tuning industry in general. All I know is 2 things:

 

1. No two cars are the same, and there is no right or wrong way to tune or map a car. You have got to give a car what it wants.

 

2. I have mapped probably 200 - 250 Supras over the last 7 years and, to my knowledge, not a single one has blown up, so must be doing something right.

 

Where would this forum be without a bit of controversy...

 

Thanks, Chris

[Ian C]

 

Firstly, we use a laboratory grade Autronics, £1500.00 wideband, not a £200 AEM one that most of you guys are referring too! You wouldn't beleive the difference in the two...chalk and cheese.

The sensor alone costs more than the AEM kit. The AEM's are OK if you want to keep an eyen things but I wouldn't take them as gospel and I certainly wouldn't map a car on one!

 

Can you let us know what the actual differences are rather than just how much you spent on yours? Because that'd actually be useful. The thing is, I can't believe the AEM gauge is £1300's worth of 'wrong', to me that'd be it couldn't read an AFR value with a torch and a map. Now, clearly it can display a pretty accurate AFR value otherwise someone would have noticed by now as their 3rd engine disappeared out the exhaust, so unless the Autronic makes the tea and plants trees to offset your carbon footprint I'd say it's cost is irrelevant and it can only be, what, 5% more accurate at best. Also I had mine hooked up to an MOT tester and compared the results with an AEM gauge and they correlated, and I'm fairly sure the MOT testing thing is irritatingly accurate. And don't they all use that previously mentioned Bosch sensor anyway...?

 

Secondly, if you run a car anywhere near 11.5 - 12.0 it will blow up. Period.

 

Well that flies in the face of all the stuff I've read and all the experience I and a good few others here have had, for years, under some extreme conditions as well (trackdays, TOTB, drag racing, top speed runs, driving like complete nutters...) what are we missing? It's also quite a sweeping generalisation - what engine, what fuel, what ignition timing, what turbo, how much boost pressure, what ambient temps, what intercooler.... etc etc.

 

I can understand if you're in a mood and wanted to defend yourself for whatever reason, but I can't have statements like that bandied around on here as gospel just because you spent loads on an O2 sensor and went to a training course once. We had one plum come on here saying 14:1 afrs were safe once, imagine that left lying around in the search results without a bit of counter-argument

 

-Ian

[tDR]

Have to agree with Ian. What a fleeting statement to make RE: target AFR's. It really depends who you talk to on the subject - I've spoken with mappers who say they'd be comfortable going to 12:1 on a customer's car and as lean as 12.5:1 on their own car!

 

Personally, I've run close to 12:1 whilst thrashing the nuts off mine drag racing - believe me when I say my car doesn't get an easy time. That's on my DIY map for the occassion with ignition advanced 7 to 10 degrees on top of standard in the fun parts of the map (using race fuel) on a bog standard engine with bog standard turbos. Yes I may be a little extreme but according to you (hypersr) I should have blown it up the first time I put my foot down! Yet it continues to soldier on after numerous drag and mapping runs....

 

I have to comment, looking at that example map posted earlier - it doesn't look like much actual mapping was done at all. My own map is infinitely more varied than that - I run 11.7:1 AFR solid under full load every day on mine and I don't get a trace of det and again haven't managed to blow it up..... must be in the mapping

 

The comment about how all our cheap and nasty Bosch sensors are so innacurate is just comical

 

Cheers,

 

Brian.

[Guest HyperSports]

Hi Guys

 

Don't want this to get into a "My Cocks bigger than yours" debate, but would like to share a few of my findings over the last 6 or 7 years, with regards to widebands.

 

I have owned and used (in this order) FJO, AEM, Innovate and Autronics widebands and I beleive there are 2 main areas where they differ. Firstly the sensor, which usually either use the LTK L1N1 sensor or various types of Bosch sensor. The Bosch ones, or specifically the one in the Autronics kit, have better response times than the LTK ones, I beleive 10ms rather than than 40ms (I could be a slightly out on this, it's Saturday morning, and I'm dragging this piece of useless data from the back of my brain!). I have also noticed that some of the cheaper wideband sensors lose their accuracy and consistency after a rather short life, and throw the AFR's out ever so slightly.

 

I beleive the main crux of the difference to be in the processing of the signal via the Processing Unit & Display. Some systems tend to use a 'under damped' reading which fluctuates more before settling down.

 

 

This diagram kind of explains what I mean. I have found with the steady state mapping on the Dyno that AFR's do vary between my AEM that I use for quick road checks and the Autronics that I use on the Dyno.

 

Anyway, I guess we should just put this thread down to personal mappers preference, and leave it at that.

 

Thanks Chris

[Matt H]

Hi Chris,

 

Just to let you know the Defi Controller came through the post so ive got that now so were all good for next sat if you have the boost gauge and those little plugs for the stock bov pipes

 

Sorry if this thread has turned out to be a bit annoying for you, only wanted to find out more about how to read the AFR gauge etc.

 

Cheers

 

Matt

 

P.s loving the "A" pillar pod work, really does look the business, will look even better next weekend with the the extra defi kit in!

[JohnA]

...Secondly, if you run a car anywhere near 11.5 - 12.0 it will blow up. Period. ...

 

Bit of a sweeping statement this one.

So according to you mine should have blown up ages ago, since it runs 12.5-13.5 regularly (and silly boost figures on top).

 

But it hasn't;)

 

So maybe you should reconsider the 'period' bit and start listing assumptions.

 

This is a very interesting subject with no single answer that fills all the blanks.

[Ryan.G]

Since it runs 12.5-13.5 regularly (and silly boost figures on top).

 

 

What car is this on John?

[JohnA]

What car is this on John?

 

UKSpec Ryan.

Have a look at my garage, it's almost stock running 1.5-1.6 bar currently:innocent:

 

Without listing the assumptions made, any theory can be made to look silly.

 

There are conditions that allow you to run perfectly safe at almost stoich under high boost. (done it)

There are other situations where even at 10:1 you'll get your pistons perforated. (done this too)

That's why blanket statements with universal AFR figures need a bit of explaining:)

[rob wild]

What car is this on John?

 

His Supra:

 

http://www.mkivsupra.net/vbb/vbpicgallery.php?do=view&g=218

 

Hi

 

Sorry, not specifically targeting anyone in particular (especially you, Rob), but this game is mine / our profession and get very peaved when individuals preach that something is right or wrong when they are not in a position to do so. I wouldn't tell a plasterer how to do my kitchen ceiling etc. It's not here, or this forum, it's just the tuning industry in general. All I know is 2 things:

 

1. No two cars are the same, and there is no right or wrong way to tune or map a car. You have got to give a car what it wants.

 

2. I have mapped probably 200 - 250 Supras over the last 7 years and, to my knowledge, not a single one has blown up, so must be doing something right.

 

Where would this forum be without a bit of controversy...

 

Thanks, Chris

 

No problem Chris PS need to give Stu a ring sometime soon as its MOT time again

[Lee P]

So if mine is running 12.5 with no det should I leave it or make it richer? Not sure what to do as everyone says different things.

 

 

Lee

 

 

UKSpec Ryan.

Have a look at my garage, it's almost stock running 1.5-1.6 bar currently:innocent:

 

Without listing the assumptions made, any theory can be made to look silly.

 

There are conditions that allow you to run perfectly safe at almost stoich under high boost. (done it)

There are other situations where even at 10:1 you'll get your pistons perforated. (done this too)

That's why blanket statements with universal AFR figures need a bit of explaining:)

[JohnA]

They are different figures because the underlying assumptions are different.

 

Don't assume that your mechanical setup and usage patterns are identical to someone else's. In fact they might not even be comparable.

Even identical engines may respond differently to the same AFR at the same load conditions (if say the spray pattern of an injector is different)

 

Hell, even mentioning 12:1 AFR at WOT can mean different things to different people:

Someone means a five second peak on a hub dyno, while someone else means full throttle in top gear for much longer on a long stretch of road (autobahn, whatever). The 'safe' dyno AFR will be freaking lean in the second scenario (the load is different)

 

It really is down to the (long) list of assumptions if you want to make comparisons. Bit like comparing camshafts: just because a 272 set works well on your friend's single, would you automatically assume that they'll work well on yours?

[Ryan.G]

UKSpec Ryan.

Have a look at my garage, it's almost stock running 1.5-1.6 bar currently:innocent:

 

Without listing the assumptions made, any theory can be made to look silly.

 

There are conditions that allow you to run perfectly safe at almost stoich under high boost. (done it)

There are other situations where even at 10:1 you'll get your pistons perforated. (done this too)

That's why blanket statements with universal AFR figures need a bit of explaining:)

 

 

John i understand what your saying but have you ever tested different afr's and then taking it to MBT to see which makes the most power and torque.

 

Ryan

[Sean1933]

John, I assume those AFRs are with the meth injection?

[JohnA]

John i understand what your saying but have you ever tested different afr's and then taking it to MBT to see which makes the most power and torque.

 

Ryan

Yes of course. In my setup the difference between AFR 10.5 and 12.5 is around 20bhp at 1 bar.

Another 15bhp at 14:1

 

The variance is quite a bit more pronounced at 1.5bar but I haven't done lean runs at such boost so I can't quantify it. All it takes is one semi-clogged injector and you risk a ride on the AA truck.

 

John, I assume those AFRs are with the meth injection?

Yes, lots of it before and after the compressors. Lots of steam too.

 

Every setup is different, we can't just issue blanket statements like "at AFR 12 everything melts" without people laughing behind our backs.

In the same vein, we can't just say "at 11:1 everything is safe" because that can prove to be untrue as well. When I melted my kawasaki turbo pistons during a very long full-boost run it was running rich as hell, single figures. Don't know if at 11:1 it would have detonated to death half a mile earlier, but the lethal mix of high ambient temps and fizzled-out fuel took precedence. Maybe too much timing for those conditions, too. Rich AFRs didn't save me.

 

The bottom line is that generalising is dangerous without listing the assumptions made. It will look less impressive but it will be more useful, and people won't be able to pick holes so easily...