Update to poor fuel mileage problem......

[Ian C]

If I was you I'd get your current problem sorted out before chopping out the whole ECU and remapping it.

 

Anyhow, if you are running too rich you'll a) be losing power and b) be using too much fuel. If it's a mapping issue, then backing off the fuel delivery will improve 'efficiency' as in stop wasting fuel and improve power. However, the stock ECU is pretty damn good at giving the engine what it needs when it needs it (in an unmodified state), so if it's *not*, then you have an existing problem. O2 sensor a bit tired, perhaps?

 

When you run boost, you need more fuel to avoid detonation, and you also drop in some extra to help cool the chambers down at higher boost levels. So a big single turbo will deffo hoover up more fuel, but on the other hand your cruise economy will actually increase - providing the mapping is good. This is because in the stock setup, your exhaust system is a restrictive and unequal manifold, going to two tiny impeller housings, to a twisty-turny exit, and a double catted narrow exhaust pipe. In fact it's even worse when you only have turbo #1 running as half the system is blocked off. With a single turbo, your engine exhaust has to go down equal length tubular manifolds, into a big impeller, and out via a decatted 3" exhaust system. So the volumetric efficiency of the engine goes up, which is a fancy way of saying less power is wasted forcing exhaust gas out of the whole system.

 

-Ian

[chris_bramley]

that's about what I thought Ian, with the difference of you knowing more of the technicals. Glad I wasn't on the wrong track there

 

I think, and a few ppl have suggested this too, that the issues I am having are directly related to the ecu - apparently tuning japanese told the last owner after they tuned in the evc and fcd (and whatever else, uprated turbos too I guess) that it was "perfectly normal for the engine light to come on".

 

Bollocks says I! after a short while the tc turns off too, and the car just isnt' running right, laggy goin to second turbo, sometimes running much under par, and so on. What I have been told by quite a few knowledgable ppl is that TJ probably messed with the stock ecu a bit, possibly trying to trick the car with a forced rich run, and they don't have a good rep with pretty much anyone I have talked to...

 

I want to chip the car anyway, and speaking to Dude for eg has formed the idea that I can get the car properly tuned, the traction control uprated, the revs delimited, the fcd made defunct, and have the whole thing running correctly in one fell swoop, with a power increase to boot - and the aem is the best base for the other big upgrades later, being powerful and relatively easy to tune.

 

the car has a full powerflow single tube exhaust from the manifold back, 3", so it should be much improved, and the hybrids are rebuilds capable of 1.4 bar.

 

I do plan on a full single upgrade one day (hah! The money) but until then this seems the best way to accomplish all of the above

[terawua]

*If I was you I'd get your current problem sorted out before chopping out the whole ECU and remapping it.*

 

I heartily agree... at least now I cna go about getting some more numbers out of car. I mean if I am going to get 13mpg then I will want to enjoy it a lot!!

 

James

[THOR Racing]

I think I need more info....

 

Are you saying that prior to fitting the E.L. dials that you had replaced your Jap spec dial POD with a UK Spec dial POD? i.e. the entire cluster

 

Then placed the E.L. dials onto the original Jap spec facias and then swapped the WHOLE UK POD with the E.L. dialed JAP POD.

 

Question.....

How is your Jap spec E.L. POD showing MPH ?

Does it have a speedo converter fitted to the back ????

 

The ECU will change fueling etc and gearing (if an auto) dependant on road speed. It's often a lesser load input than MAP and throttle but does have an effect.

 

This is why I always advocate doing a proper speed conversion from Jap spec which allows the correct signal to pass to the power steering, cruise, active spoiler and ECU and use a proper speed delimiter (a frequency clamp) and not a frequency scaler (i.e. cheat and use the MPH signal)

 

Regards

Pete

 

ps. THOR and TRL and Pete Betts are all the same

[terawua]

pete.. I was getting poor mileage from the UK spec dial cluster... it went back to 'normal' when the j-spec cluster was put back in..... and as for the speedo convertor.... it just seems to consist of a cut track on the PCB and a resistor soldered in.. not ideal... and I am sure its an SVA fudge....

[Jake]

in theory it should be more efficient if it's running rich atm... or at least provide far more power for the same amount!

Chris,

I think I misunderstood what you meant by the above. I realise now that it can read two different ways with completely opposite meanings. I thought you were saying your engine should currently be more efficient because it's running rich at the moment.

My mistake.