Map Vs Tps Vs Rpm Woth Itb's

[Richie-Van-GTi 71 2 Cars]

The throttlebodies I have came with linked take offs to a single map sensor. Just wondered if its best to map the car with a map sensor when on tbs or just stick to TPS and RPM map? Also when the bodies get balanced there are other vac ports that could be used but would I be best taking the link out instead to get an accurate reading. Thanks

[petert 586]

All depends how good your ecu is, but for normally aspirated throttle bodies:

 

ie

good

fuel - tps

ignition - tps

 

better

fuel - tps

ignition - map

 

best

full tps/map blending

[Anthony 1,002]

better

fuel - tps

ignition - map

Out of curiosity, why would you use different load sources for fuel and ignition like that?

[welshpug 1,657]

different response times and requirements, feed it lots more air and you need the fuel before you can feed in more ignition if my understanding is correct.

[petert 586]

ie If you have the ability to tune via VE rather than just pulse width, both TPS and MAP are taken into account.

[Richie-Van-GTi 71 2 Cars]

Well its going megasquirt so will have a read up on the possibilities.

[Sandy 191]

VE is a misleading term when used in mapping. The fuel quantity injected and resultant lambda reading are significantly affected by many factors beyond the amount of cylinder filling (volumetric efficiency represents a percentage of the swept cylinder volume, for those that don't know the lingo). Not getting at you Peter, I just hate the use of the term!

I'm not the only mapper in the world obviously and don't doubt there are people more capable than I am, but I personally find, if the TPS is well mounted and precise, it works best on its own as load reference for both fuel and ignition on an ITB N/A engine. I've been all around the houses using it separately or overlaying pressure correction on TPS load and in each case it caused more problems than it solved. The theory is sound of course and on standard-ish engines, where the fuel and ignition requirements are pretty predictable and linear, it's less of an issue, but with tuned engines, particularly N/A race engines (which is what I specialise in mapping), speed of response requires a certain amount of anticipation and a high degree of repeatability in the settings, to get what you need in transient conditions and MAP plays absolute f*** with that; ditto live closed loop lambda correction.

Edited July 18, 2015 by Sandy

[petert 586]

Out of curiosity, why would you use different load sources for fuel and ignition like that?

 

As Sandy said, on a race engine it makes no difference, as you're at WOT most of the time. BDA-BDG in F2 for example, ran a dizzy fixed at 30 deg BTDC. Mapping the ignition against manifold pressure when using TB's with big cams has an advantage when there is vacuum at part throttle however. eg cruising at 80-100 km/h. It's more representative of the real load on the engine, as the load for TB is logarithmic, whereas manifold pressure is a linear scale.

 

Mapping the fuel via VE combines both TPS and manifold pressure. You would still select TPS as the load source. Because it takes into account injector size, injector dead time and engine capacity, it gives much better fuel economy. Again in race engine, where it's at WOT most of the time, it makes little difference.

Edited July 18, 2015 by petert

[Sandy 191]

I hear what you're saying Peter, but believe me I pay fastidious attention to how the race engines I map behave in all areas! I map a lot of RWD Escort/Darrian etc rally cars and the reason I get the work is because of the progressive throttle response I achieve, that makes them a lot more throttle steerable. Similarly look at the incar of Colin's 205 and you'll see how rarely he'll fully "let it have it" as he describes WOT; mostly it's being feathered for traction and it's incredibly precise on transient throttle, deliberately so, it's the flexibility of the chassis and engine which makes that car work so well on narrow bumpy roads.

Each mapper has their own approach and I can't second guess the logic others apply; but I know that MAP reference is an unreliable value on high spec N/A race engines and can make for inconsitent throttle response on any ITB engine.

 

I do however, commonly use an ambient Baro sensor reference on my own engines.

Edited July 18, 2015 by Sandy

[petert 586]

It's certainly a fascinating subject. As you can see from my setup, the fuel is still mapped from TPS as the primary source, but the method is VE. Haltech has only included this method in recents years. Motec & Autronic have always had it as the only option, even though it's not called VE, regardless of whether you choose MAP or TPS as the source.

[opticaltrigger 52]

Excellent discusion this,on a very contested subject.

Stuff like this is what makes for forum gold.

 

Personaly speaking, the only way that I myself have managed to find any peace with this subject is to accept that personal feeling and prefference on this is as an important a part as the relevent technical and theoretical merits.

My reasoning for this is that the tallented individual mapper finds a way to achive the end result with a blend of his own personal recipie and technical merit.To put it anouther way...

 

If you were to ask two seperate chefs at the top of there game to both cook you the same dish,both would come back to you with the same excellent finished product i.e. a great dish...They would have arrived at it with similar theroetical and technical abillity but in different ways that are unique to them as individuals and the differences should be subtle one's that are better described as a signiture.

I have found that this paticular subject matter is very similar really.

 

Great stuff guys.I agreed with everything you Both said.

 

All the very best

O.T.

[Richie-Van-GTi 71 2 Cars]

Damn its frustratring when wveryone that has the knowledge to map a peugeot properly is so far away. Tempted to drag the car to Sandy and just have a week on holiday while he does it

[opticaltrigger 52]

Hi Richie,

That would certainly just get it sorted for you.

 

O.T.

[aldworth33 45 1 Cars]

Heard good things about orange Grove in Newcastle for pugs, worth a chat to them. They've done na and turbo 205's from what I can see on their Facebook

[Sandy 191]

Thanks for the positives, there are a lot of issues like this, that it would be good to discuss and give a lot more depth on, but I limit the time I spend online, to avoid it absorbing too much of my day and it can be very hard to fully convey the details and reasoning why/how certain methods are favoured. Mapping by numbers (Target AFR, "MBT" igntion evaluation) is pretty simple, but going beyond that into what the target AFR should be over the whole speed/load range and evaluating the ignition mapping with a broader view of its effect on how the engine drives and how it will continue to perform under different conditions and over the long term; becomes a much, much bigger topic! It's inevitable that different judgements will be made on that and an engine builder or self builder taking a long view, will have different priorities to someone looking to sell engines on top line bhp figuires/graphs.

I favour MAP over TPS and TPS with MAP compensation for SC and turbo engines, varying what I choose to use as to what seems to work best on each installation. I do still get some bother with light load and idle AFR stability over time, it's very difficult sometimes to establish settings on a single session with a boosted engine, that will perform totally consistently. I have much more success with TPS only on ITB N/A engines! It's not always possible to nail a perfect map in the time available, but I certainly dig deep to try and achieve that, which hopefully my work illustrates.

 

Recommendations of mappers to use is all you have to go on really and there's unfortunately no minimum standard in this work. However, I've seen a mapper in South Wales recommended on here very recently, who I know to be struggling to do a good job. Several cars that he's failed to sort out properly have since come to me, telling tales on specifics would not be pleasant, but suffice to say it's difficult for me to remain tight lipped, when I see such appaulling work, with much bigger bills than I would have charged.

Similarly Colin and Dave met a particularly cocky and arrogant mapper the other day, who is hailed a something of an expert in his field (drifting). As that kind of mapper often does, rubbished anything less than Life/Pectel etc ECUs. By chance I got a ZETEC on OMEX in a few days ago, that he'd mapped. I was slightly baffled and surprised to find it had 3x 377cc Picos and 1x 330cc fitted, which the customer assured me have always been there from the supplied kit, he clearly hadn't noticed. The maps looked smooth and reasonable enough, except for a mid throttle 11.8 degree line through the igntion table; but the common fail on OMEX of a quirk in the acceleration (Transient) fuelling settings, that disables acceleration enrichment most of the time, made me wonder if he really knew his way around the software. I hope having all these details corrected, will make a tangible difference that the owner appreciates, once it has four even injectors and I'm able to map it properly!

Edited July 20, 2015 by Sandy

[Richie-Van-GTi 71 2 Cars]

Out of interest Sandy what kind of costs do you expect to charge for mapping? If I brought to you a running base map gti6 on megasquirt with working tps map sensor and crank sensor? I know its hard to give a definate figure but just a ball park? Pm if you want as I would seriously consider bringing it as I can go stay at my cousins in yeovil anyway so wouldnt be just a journey for mapping.

[Biggles 65]

You're only an hour further from Plymouth than me (according to Google) and I went down just for the mapping. Well worth the trip.

[Sandy 191]

Thanks!!

 

For a full session, DTA typically £300, other systems £350. That's assuming there's no exceptional mechanical attention etc needed. I like people to bring the car ready to run, rather than a montage of unsolved problems; but I don't give up on things I can fix if need be either.

[dcc 855]

First time visiting sandy he picked up on a fault with the throttle body butterflies not being in line, which resulted in him stripping the bodies down and straightening them as best he could.

 

Rather pleasing seeing him fix your car for you

 

Attention to detail is why you pay your money, couldn't imagine going elsewhere for the same level of detail for the money! (And he makes a tidy cup of tea)

[Richie-Van-GTi 71 2 Cars]

Well i think as soon as its built and running enough for.me to be confident the build is good I will bring it down. ☺