Ign Table options: TPS/RPM vs MAP/RPM
Turbo Mini Forums

In short - I'm wondering if we can have a little discussion about the two options used in aftermaket ECU's.

I'm waaaaaay more familiar with TPS/RPM and - in thinking about it - it seems to be a lot easier to set up, and picture what is happening.

But I'm guessing that OEM's take the MAP/RPM appoach? OR do they?

Basically - is one more favourable than the other, taking into account they were both mapped perfectly (working on the S**t in, S**t out rule)... How about speed of mapping? etc, etc, etc.

Looking to the 'usual suspects' for chiming in here

Hello,

I just can say that TPS/RPM is more accurate at full load (difficulties in tuning that device on small throttle opening) and MAP/RPM is better at low load.

But TPS/RPM is not compatible with turbocharged engine. It's due to unlinéar air flow.

French turbocharged 998cc

chime - lol

tps/rpm is not a good combination with a turbo. TPS is used to guestimate the load on the engine and with the CPS gives you a very very basic speed density system.

The load gustimate relates to the volume of air entering the engine. With a turbo the throttle position is no longer the only factor determining air flow!

Manufactures either use MAF (mass airflow sensors) or MAP (manifold Absolute pressure) sensor combined with TPS.

The reason being that neither system on its own can take account of sudden changes in load, such as dumping the clutch or flooring the accelerator. This gives better control of transient fuelling leading to better driveability.

AlexF

Hi,
Got to be MAP, for the reasons above. My Omex ignition setup uses the TPS also, for idle compensation.
Cheers,
Gavin :)

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oh, hang on folks - I don't know if you're all thinking the wrong thing here, but i meant the table itself... OBVIOUSLY there is a correction; For the TPS / RPM the correction comes fom the MAP sensor; Hence the 3-dimensions. For MAP / RPM the correction comes from the TPS; hence the 3-dimensions (although I understand MS doesn't have a TPS - so how does that mean it compares to a 3D Map/RPM (tps correction) system like Omex)???

Obviously (turbo) 2-d mapping really works only with Map vs RPM - but I don't know of any system that is just simply TPS vs RPM... ??? ... ??? ... ???

Sorry I didn't make that clear - I just assumed it was obvious going off my saying 'Ignition Table' in the title, rather than 'ignition map' (clearly not)...

Edited by TurboDave16V on 8th Mar, 2006.

Hi,
You've lost me here, don't take much I thought the 3 dimensions of the map were rpm, map or tps and advance? What's the table then?I'm running tps and rpm on my N/A at the mo. I'll add the MAP sensor when I add the boost!
Cheers,
Gavin :)

Edited by Bat on 8th Mar, 2006.

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hmmm - You're right. The 3-dimensions are indeed two input signals, and one figure inputted as the correlation between the two... So WTF was I thinking a few minutes ago?

Oh crap. I'm going to do some ironing and get my head in order. the 14hr day today and yesterday has puddled me. :(

Hey - come back here Peter... Enough of this 'leave it to the experts' nonsense. If any come along, then we'll have the answers - until then let's crack some skulls and figure it out

Edited by TurboDave16V on 9th Mar, 2006.

MS can use MAP and RPM only with TPS for acceleration enrichment- optional (speed density), or TPS and RPM only (Alpha-N) or a combination of the two (Alpha-N hybrid i.e. Ferrari F40).

The latter is aimed at folk running radical cam timing, or engines which produce erratic MAP pulsing (i.e. single cylinder engines).

Alpha-N and hybrid are not recommended for a turbo engine.

it gives your ECU a better idea of what is happening at low rpms/low load.

In that region there can be a lot of change in the engine without much change in just the map value.

Its all about drivability

Alex

AlexF

Lets re-open this can of worms!!!

Any new ideas?

I was running TPS vs RPM with MAP compensation, then my RR operator said just do it with the MAP sensor...

Now i wasnt overally convinced and i'm trying to make a new map as i originally intended before the next RR session.

Lots of variables in there at the minute but its slowly getting there.

I've got jim's map but it seems to run a fair bit of advance at high boost. certainly more than my engine seemed to like on the rollers.

As a rule of thumb, what sort of advance would you expect to run with a 8:1 ish comp ratio, and 15psi?

Mine is taking off about 10 degrees of advance at that point and has a table value of 27 so approx 17degrees.

I want to do some testing some point this or next weekend on the road (old airfield!) but i'm trying to get something that i think will work nicely before i get to that stage.

So dive in!

I'm adding/removing 1 degree of advance either side of 100kpa in 10kpa steps (so at 1.5bar (250kpa) i'm removing 15 degrees)

17 degrees??

I run 26 deg at full boost, 15psi and 8.5:1 with 101 RON.

Maybe you need to richen it up a bit.

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its running rich enough but we were getting this misfire hence the low advance as that seemed to cure it.

If anything it was over rich, 0.8 lambda.
I run optimax. Was thinking the 25 mark sounds right.

28 degrees max is what I tend to run as a start.

then it need to be tuned to the engine!!

At low RPMs you can run as much adv as you like (it won't DET) but you will end up with misfires and poor performance if you over advance.

The more boost you run the less ignition advance it will stand before it knocks. So the solution is to back the timing off. This is usually required at peak torque.

Once your past that point you can start to add advance again, but you still need to be VERY careful as high engine speeds and Det means holed pistons very quickly.

Many tuners run about 3 degrees below the point at which an engine dets.


So the next question is probably how do I set my engine up... well without a rolling road you can only do a best guess and use trail and error.

With a rolling road you set it up so that regardless of the power the engine produces the speed of the rollers doesn't change.

With the engine pegged to a certain RPM you hold the throttle to a certain position and see what power is being produced. Then in the map, for that load site you change the ignition advance and see adv it and see what happens. If you hit Det you back off.


Does that make sense?

Alex

AlexF

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Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

Wideband

Yeah it wasnt massively too rich just a little but we were happy with it at that for now.

Cheers Alex,

Yeah i know the ideas behind the RR was just trying to get as much info down here as possible for those that dont. its turning into a usefull reference

im at the same point myself ian , the way i see it is ,

the tighter the chamber ,with the beak etc , the faster the burn and the less advance needed ,

the lower the octane the less tolerant the engine of advance ,maybe to the point of needed a lower numbers than would give best torque (bmt)

the lower the cr the more advance ,

the better the intercooler more advance

,higher the torque ,less advance ,

higher the revs more advance,

wider the valve seats and cooler the engine temp .more advance ,

and so on and on ...

im figuring on about 17 to 20 degrees at 15 on my 8.5 to 1 engine .
running pump fuel .if i have to go to water injection ill up it to 22 to 24 degrees .
regards robert.

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

oh 3 other things thatll have a big effect on timing ,are

the turbo efficiency (more eff means cooler air so more timing but also denser air means higher cyl pressure so less timing ,paradoxical huh)

,turbine housing size and back pressure ( more back pressure more heat ,less timing ),

and mixture ,(richer can allow more timing )

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

I'm monitoring the air temp and have a retard function on that should it go over 60 degrees i think it is, maybe 70.

Water temp advances up to 60 degrees but then retards above 100 degrees.

I'm using emerald BTW I couldnt get the data loger running but i'm hoping to sort that this weekend. I'd just like to say that the customer service is spot on, Karl and Leoni answer my emails quickly

virtually all aftermarket ecu's will run a boosted engine MAP vs RPM, and is recognised as the correct way to do it.


TPS vs RPM with MAP compensaiton can work too, but it cannot be mapped to give ideal fuelling and ignition at every MAP vs RPM site, simply because its using fixed compensations. engines efficiency will change at different rpm and boost levels. Fixed compensations cant account for that. ALthough if you intend running one boost level, then it really isnt a concern.

Most OE ecu's rely heavily on the airflow meter, and less so TPS or MAP, although they will play a part.

Consider that some Toyotas, and Mitis Evos dont even have a MAP sensor.

When I first bought my DTA back in 2002, it could only do TPS vs RPM with MAP compensation. It was pretty easy to set up that way, and did work fine.

Swapping to MAP vs RPM when it became available was a nightmare. But I feel its the correct way to run a boosted engine.


As for timing figures on different spec engines......

No guesswork allowed, as every one will be different.

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will

If I can delurk here for a minute. There have been arguments about which method is best for as long as people have been trying to tune ECUs. At the end of the day all methods can be used to give a good tune but some are harder to get your head around.

For example some people like TPS (aka alpha-N) plus boost. It was good enough for the ferrari F40 after all. Others like MAP (Aka speed density, or SD). Aftermarket support for MAF units has been slow, but is there now. If anyone is interested I can put together an 'engine load sensing 101' that goes through the main pros and cons of each system and what it means to you when you are tuning if that would help.

Bill

P.S. Blame Stevie for me being here at all

Good to see you here Bill ...... You views will no doubt be appreciaed.

Every day is a school day ...........

How fast and how expensive ...... the same question...

Weclome Bill

One thing that would be of assistance to road tuners ( as opposed to guys with access to a dyno )

An airflow meter attachment, used only for logging purposes would be a handy tool.
A suitably large, non restrictive AFM would be handy, to determine if an engine is actually consuming more air after mods. Even if you werent actually using it for controlling fuel/ign.

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will

Hello and welcome Bill... Nice to have you on board!

Alex

AlexF

On 24th of Feb, 2007 at 04:45pm stevieturbo said:
Weclome Bill

One thing that would be of assistance to road tuners ( as opposed to guys with access to a dyno )

An airflow meter attachment, used only for logging purposes would be a handy tool.
A suitably large, non restrictive AFM would be handy, to determine if an engine is actually consuming more air after mods. Even if you werent actually using it for controlling fuel/ign.

turbo 16v k-series 11.9@118.9 :)

Denis O'Brien.