TR6 EFI Sanity Check

[Emile Bergeron]

Hello,

I'm a new member to this site and would appreciate some feedback from the wealth of expertise I've seen regarding EFI.

I converted my '74 TR6 some 2 years ago during a frame off restoration to address some serious rust issues.  During that

time I had the engine bored .020 over and had the head skimmed to achieve a 9.5:1 CR, I installed a GoodParts GP2 cam

and Ford EDIS 6 ignition an ASPX wideband 02 sensor and MegaSquirt MS2.  My first go around was a two throttle body

setup with 2 injectors which worked but I found that fueling was uneven across the cylinders, so that setup was scrapped

and I designed and built a new intake manifold using 6 18 pound injectors and a single 63mm throttle body, this setup is

much better with all cylinders getting equal fuel.  I've spent countless hours generating AFR and ignition maps and would

like the Gurus out there to critique, offer improvements or point me in the right direction as to what I have done.  I'm including

my current tune and maps and also a few pictures of my setup.

Thank You,

Emile Bergeron

Falmouth, Massachusetts, USA

 

CurrentTune.msq

[Nick Jones]

Hi Emile, 

Welcome! That’s a nice looking install which should be capable of good things.

Do you have a particular running issue? Have you been using the auto tune feature in Tuner Studio with wideband?

Looking at your tables, my first impressions are

AFR table looks to have the right general shape but is probably a bit rich below 4000rpm/above 80kPa. Will certainly be safe and probably run well but be a bit thirsty.

VE table has a couple of “lumpy” areas especially the top three lines up to 2400rpm. This (the other areas) may just be where auto tune has not had enough data to change things as it quite a challenge to cover all regions of the tables when driving on the road.

Spark table looks safe but maybe a little conservative. I’m sure the engine will take more advance especially at lower rpms and part throttle. In some areas (cruise), quite a bit more, which will make throttle response sharper and improve fuel economy.

I have table from my PI saloon which had a pretty similar engine spec to yours. It has been posted on here before but not quite sure where offhand so will post again when I’m at my pc.

Is the exhaust manifold a single down pipe (US standard I think) or twin downpipe as used on the PI cars?

Nick

[Nick Jones]

At PC now so table below.

There is no reason why the numbers on the VE table would anything like yours.  You have different size injectors will will affect the absolute values (though not necessarily the general shape) and a completely different exhaust manifold, which will affect the way the engine breathes and could alter the general shape.

However, the AFR table and timing table will have some relevance.

PI ignition table

PI target Table

PI VE table

Also meant to ask why you have 5º in the two top-left cells of your ignition table?  This is where the engine goes when it's about to stall and dropping the timing numbers will tend to encourage that.  Most people do the opposite as a crude "anti-stall"

Nick

[Emile Bergeron]

Hi Nick,

Thank you for the quick response.  The car has been running well but the gas mileage has

not been what I expected, it is a bit thirsty.  The exhaust system is stock with twin down pipes

similar to the PI setup.  When I generated my AFR and ignition maps I was conservative as I

didn't want to harm anything during tuning.  I do use auto tune in Tuner Studio although I do

not generally use it while driving but log the data and then later let Log Viewer make the

changes.  Although I have put the car to bed for the winter I will modify my AFR and Ignition

maps to more closely resemble what you have and give it a go.   I must say that this is the

first website that I have been to that has actually had any really useful information.

I thank you again and Merry Holidays.

Emile

 

[Nick Jones]

 

Been playing this game with Triumph 6s for a while now.....

Yes, I think your fuel map is richer than it needs to be and you could run more ignition advance, especially at part throttle. The fuelling map is likely the main problem.

You are right to be cautious but you can afford to take a few liberties, even at full throttle, up to about 3-3,500 rpm and beyond that at part throttle. Indeed you have to do this to an extent to establish what the engine wants.  AFR from 4000 upwards at full throttle does need to be in the mid 12s but that’s too rich elsewhere. Timing wise, don’t go over 31 above 4000 rpm unless chassis dyno proven.

Do you have an AFR gauge you can see while driving? If so, you are looking for mid 14s to 15 at cruise. 12.5 to 13 under hard acceleration (lower numbers at higher rpms) and 13 to 14 the rest of the time.

Dont be afraid to drive around with auto tune on. It is a magic tool provided your AFR targe table is ok, just make sure the car is up to temp before setting off so it’s actually working. It will take a untuned car from barely driveable to pretty good in about 10 - 15 mins driving (though I don’t recommend trying it in city traffic!). Takes longer (and some good steep hills) to cover most of the map and really takes a chassis dyno to cover the full throttle, high rpm areas safely as you can’t usually go that fast on the road. Wideband and auto tune make it so much quicker. When I first did mine nearly 15 years ago I didn’t have either and it took many miles of data logging with narrow band and having a good friend drive while I fiddled with settings to get it right.

Nick