Tuners Rejoice! Free Tuning For M4.4!

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i have bench flashed the 607 p-part map to my spare ecu, i have set the injector voltage times etc (cant set for greens above 5 ms each time i try it re-corrects to 4.973) 

also it wont run unless i unplug the maf ! 

if i plug my original ecu in then run fine with no mil issues , so i no it's all fine , just really confused as to why it wont run with maf connected and with it disconnected runs but as you can imagine runs very poorly? 

car is a 1995 850 t5 already converted to 4.4 (uk)


Edited by Phillyc2003
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Attention: The first 30 or so pages of this thread are outdated. Please refer to the M4.4 Wikia article where all the relevant information is currently being collated. Before asking any questions p

Crush it.

After alot of testing and rewriting code, we finally got a useful new mod working. As we all know, some time ago my dad Piet found out how to convert to bigger maf housings with the maf factor. Conver

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3 hours ago, Phillyc2003 said:

i have bench flashed the 607 p-part map to my spare ecu, i have set the injector voltage times etc (cant set for greens above 5 ms each time i try it re-corrects to 4.973) 

also it wont run unless i unplug the maf ! 

if i plug my original ecu in then run fine with no mil issues , so i no it's all fine , just really confused as to why it wont run with maf connected and with it disconnected runs but as you can imagine runs very poorly? 

car is a 1995 850 t5 already converted to 4.4 (uk)


Have you set injector constant? is the MAF stock? the dead times at those voltages are irrelevant, you can't set them higher because 4.973 is the highest Hex value it can be (FF).
If you have more problems, try making your own thread if its not directly related to M4.4 Development.

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Fooling with Cams




Yet another tuners block…..

You have your tune. It looks ok. Comes in real nice, and there is plenty power.

But that knock....

At a given moment you’re on 4 deg ign. advance and the brick just won’t go in mid rev, and still there is that bloody knock…tuners block….

Reading reading reading, nagging and more nagging about it to everyone and anyone, and then they start nagging back about cam timing, also in tuners rejoice.

I already tried timing my cams with ex -2 and in +2, with only result a slow car. (-is advance and +is retard)

What the hell, well..let’s try something, there must be some truth in the story if “they” say so…. 

Rob, make us that tool Yits told us about, let’s go for it…



All right then, I’ve tried to get the same sample for every log, which isn’t easy by no means.

So, my bad if it doesn’t turn out exactly the same, but I’ve tried.



 All for science…

Oh, and please please pretty please don’t go nagging about knock in those logs, that’s just what we tried to get rid of heheh….

After the tuners block we made a bin with the original ignition map so there is a good reference to what’s normal.

Of course we polished a lot of knock by ignitionretard, but at the cost of power.

So, we started all over again to try and get rid of that knock by timing the cams.

All the rest comes later!



If you are fainthearted better pour yourself a good drink…..here we go!!!


(click right on the picture + view to see it full size)



For your reference.

EX is 0, IN is 0

On the left there you see that nasty knock!

Load is reached easily, power build up is nice, TCV duty 80%

At 4400 rpm it flows pretty nice with 790 KG/H airmass.

But none the less, there is that darn knock on the left you just can’t get rid of, even if you retard ignition by 4 degrees!!




As advised we tried EX-2, IN+2

On the left, 3000 rpm knock is gone.

At 4400 rpm you can’t even get to requested load....look at TCV duty 98%

Airmass at 4400 rpm: 788 kg/hr.

Left, no knock, right (higher rpm) lots more knock.




Now EX -2, IN 0

Left 3000 rpm knock

At 4400 rpm you can’t get load, TCV 95%

Airmass 793 KG/H

Left knock, right knock


Now EX 0 IN +2

Unfortunately, with a little less throttle, but still very obvious.

Left 3000 rpm knock = Check!

At 4400 rpm you can reach your load with ease! TCV duty just 80%

Airmass at 4400 rpm: 777 kg/h (65% TPS)

Left knock, right no knock.


So, for now EX -2 IN +4

Left 3000 rpm knock = Nope!

At 4400 rpm you easily get your load with TCV duty 90%

Airmass at 4400 rpm: 793 kg/h

Left clear.... right clear! HIT IT…..

For all you poor delicate people we didn’t mention the step EX is 0 and IN is +4

It’s not a perfect comparison but I think it makes a lot much clearer, right?

2 and 2 knock was gone, but also power was gone.

When we started retarding the inlet cam, the precious power came back

That is how we ended up with -2,+4

Rob is very happy, the car is quicker than ever, midrev very strong and it goes on for a pretty decent time

The logs also show that the 10.3 load is achieved very easy.

Max airmass is good above 900kg/h

Unfortunately, fuel trims are still running a bit, so it takes a little while before lambda 0.81 (sorry, we’re Dutch heheh) comes back, but as we speak, that is fixed as well

Hope you enjoyed our little endeavor, we surely did.



I can all hear you thinking where is this Beunhaas guy coming from.

On the dutch volvo 850 forum we have a thread (size10% of this) it's called "Tuners deugd" freely translated meaning the same.

This after I read al of this thread and trying to translate it to Dutch, not completely translate ofcourse but just to have our "Dutchie thread" about it.

A lot of people are interested and it's still growing, ofcourse it's much easier to have it in ur own language.

Piet is our big Guru and he asked me to translate my post about fiddling with cams to the Tuners rejoice thread.

My pro beun tuner friend Rob who's car the story is about was so kind to do this translation.

And ofcourse without this forum/thread we would be nowhere so I'm happy to do something back although it's a small effort ofcourse.


Edited by Beunhaas
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10 hours ago, Beunhaas said:

That is how we ended up with -2,+4

@Beunhaas  Which is -2 and which is +4?  Are you saying you found the best power and least knock at ex -2, and in +4?  I suspect the inverse maybe?

Assume this is with stock cams?

And are you measuring KRCOUNT?


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(-is advance and +is retard)

Measuring knock by BITS bits value above 128 is hard knock.

This is with stock cams, stock turbo (15G), white injectors, alu intercooler and 3 inch catback but original Downpipe.

Gearbox is slushbox....

Max injector opening time under load with lambda 0,81 ~ 86% duty cycle on whites.

Clipping 2.75 inch V90 maf just on the edge 4.67Volt.

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@Beunhaas, have you thoroughly looked at the influence of your AFR? In the top few panels I see a Lambda of 0.85 being targeted (Gasoline AFR of 12.5), while in the lower panels you're targeting 0.7 lambda (Gasoline AFR ~10). This might account for a big part for the reduction in knock at higher RPM.

For instance, in your EX-2, IN+2 run, you target AFR 0.85 (AFR 12.5) and report a lot of knock in the high-RPM regions. Then in EX -2 IN +4  you report no more knock at high RPM, however AFR is 0.7 (AFR 10) this time. That is a very big difference in AFR while only a small difference in cam timing. It is well known that more fuel will act as a knock retardant due to in-cylinder cooling, but will cost you some power, albeit less power-loss compared to a knocking engine. I'd be very reluctant to draw strong conclusions on the influence of cam timing with such big differences in AFR.


Also in your top-panels, where you have the 3000RPM knocking, similar things are going on. I drew on your images for a bit:

First off your EX 0 IN +2 panel, you see an spike in AFR to a lambda of 1.0 just prior to your 3000RPM knock, which hovers around 0.8-0.85 for the duration of the knock, while it drops to 0.7 for the rest of your run which is then knock-free.



Then in your final EX -2 IN +4 run, your AFR does not have such spike and targets 0.7 lambda from the beginning and throughout the entire run, which is then knock free:



My humble opinion would be that the big difference in AFR plays a bigger role than the changes in cam timing. I don't think such drastic difference in knock can be attributed solely to a very minute change in cam timing (ex-2 in+2 vs ex-2 in+4), especially when lambda differs by more than 20% between those individual runs.

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Hey Boxman as mentioned I tried to get the same values but due to LTFT takes some time to settle some runs are rich I am aware of that.

I can show you the same log but running 0,81 the car is performing best until now without knock with the latest cam settings. As mentioned.

I'm aware that my way of measuring and explaining leaves room for improvement.

But I'm 100% sure that this improved for knock and power.

Running stock (re-scaled) ignition map we hardly didn't make any adjustments to it but running loads of 10.6 at the moment.

Car feels torqie in al ranges power is released smooth en car is very powerfull.

Anyway it's running on wideband mod since a few days so mixture is spot on now.

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I saw you mentioned it, but you swept it under the rug a little while IMHO it's a very significant difference. I honestly think your AFR has a much bigger influence in these logs than your cam timing. It is general practice to enrich the mixture when trying to avoid knock, and this is usually by adding steps of 0.5 AFR points of enrichment or so - you have a difference of >2 full AFR points between the runs you show. Essentially that is the same as adding water mist injection, but it poops on fuel economy and gasoline is not really as effective a coolant as water.

If you have comparative logs that all show 0.81 AFR across the board (without spikes to 1.0 AFR), with different cam timings, then it's time to draw some conclusions. To be honest there's no way to be 100% sure of anything based on the logs you showed, especially due to those spikes in AFR where you still attributed the knock to cam timing.

It's not to be mean, but just urging to be careful with drawing hard conclusions on runs that had strongly varying circumstances. Users that are not scientifically inclined will otherwise take these kind of posts as a hard truth.

Edited by Boxman
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I'm trying but for some reason tinypic banned me...

Anywayz we are running this cam timing for the moment incl wideband mod and it works out well.

Ofcourse it is also only good for this specific setup, another setup can give different outcome.

Removing inlet overlap is giving more duration for filling the cylinders it improves power.

Removing overlap with exh cams reduces backflow of (hot) exh gasses reducing knock.

Stock cam timing is good for 225hp and emission. As soon as you install a better flowing exhaust than original you'll already be suffering from 3000 rpm knocking.


Finally managed to upload the log picture with imgur.

So as you can see knock free runs with even more load.

This is not the final tune ofcourse but just to see what we can achieve, running on slightly less than 99,6% tcv duty gives more power anyway.


Edited by Beunhaas
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Well, with comparative I mean that whole measurement series of different cam timings with otherwise similar conditions - on a different day ambient conditions changed as well. and you have to be meticulous on AFR between each run. I know, it's hard to do hard science on a car, but you have to be aware of this.

The one you just posted isn't really fair comparison material either, since you didn't actually go full throttle until after ~4000 RPM or so, but your conclusion is still that "standard timing = 3000rpm knock". The previous logs included - i assume - second-gear runs with a gearshift to third, where the 3000RPM knock presented on the 2nd gear run when you were spiking lean.

I'm sure your car runs fine now, but the logs you post simply don't allow generalized conclusions and there are alternative plausible explanations for the knock you observed. There's a lot of unknowns on the principles and effects of cam overlap in turbocharged engines still. "It works out well" and "i feel a lot more torque and power" unfortunately aren't valid arguments unless you have hard numbers to back up that this can be attributed to the cam timing.

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You mean the arguments aren't valid to you...

To me they do perfectly fine, I have whole logs for comparison not only the piece I post here.

The one driving the car while logging is happy with the results, the car has significantly improved in power and we don't have the shitty 3000 rpm knock anymore.

This is enough for me...

What you want is up to you.

If you are interested I can even send you the logs, but i don't know if it's really necessary to go on to me like that.

Doing like my explanation and measurements are completely useless.

I also have my doubts about your way of tuning with LDR completely off but I respect everyone's way of tuning on their own cars.


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You take it personal while I'm just trying to constructively criticize your work for better future results. Do with it what you will, but you guys always take it as a personal attack somehow.

"You mean the arguments aren't valid to you"

That's just not how science works.

Edited by Boxman
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Not sure if it's completely science boxman tuning is also still a work of "feel, hear, smell" if you'd ask me.

It's always a compromise you never have the perfect conditions for that you need an engine test stand, and even then you design/tune for average circumstances.

Ofcourse I take it personal if you criticize my work that's what makes me human I guess.



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It's fine to try out new stuff and report on what you did here, everybody welcomes that. But if you do acknowledge that it's not as much science and more "fear, hear, smell",  you should refrain from saying things such as "I'm 100% sure that [this particular thing] is the cause and this is what happened" and drawing hard conclusions, or present things as though they're 'the truth', because that's when your work will be scrutinized and criticized. 

As for you taking that personal, well there's little I can do about that. When I see something that's questionable, I'll address it.

In the end discussion about results is the only way to move forward, if everybody just takes things for granted there will be no further progress.

If you have any further personal problems with me, always feel free to PM me as to not clutter up this thread.

Edited by Boxman
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