L-jet Vs D-jet - Is D-jet More Responsive To Light Throttle?

[RB335]

Hi Guys.

Having a talk to a Tuner regarding whether to use D-jetro or L-jetro Power FC, he is recommending not to use AFM's and to tune with solution that uses Map Sensor.

He said that with L-Jetro and Tuning with AFM's, Full throttle power will still be good, but light throttle mapping wont be as good.

I'm wondering is this true and whether the difference is hugely noticeable.

I'm thinking to use a L-Jetro Power FC with Maybe Z32 AFMS on GT-SS Turbos, or Stock AFMS to begin with.

I went through PaulR33's Website Guide on the PowerFC and nothing was mentioned about this in Pro's vs Cons.

I'd like to hear your guys experiences.

Cheers.

[breaker1845]

Why don't you go to a more modern ECU and get rid of AFM's all together. Get a Link G4 or Haltech?

Power FC's are becoming old and might only cost you just a bit more (factoring the cost of buying Z32's and other shit) to get a modern ECU which would be better for your upgrades and has a huge range of features you might find useful.

Tuning on light throttle with a MAF sensor can be done but takes time to get it good/perfect with the resolution you have to work with, which is more money for tuning time anyway.

You can tune light throttle on a MAP sensor much easier and quicker.

Difference wise, a significant amount would be visible but not by a large amount, which also depends on the quality of the tuner's work.

[GTSBoy]

Yuh, I'd rather fit f**king Solexes than a MAP PowerFC.

[RB335]

What's so bad about PowerFC?

Edited March 29, 2015 by RB335

[breaker1845]

The fact that the ECU was made like a decade ago and there has been improvement in technology which does the job much better for a similar price.

There is better ECUs out there now that can do a much better job than the PowerFC, doesn't mean it's a bad ECU just getting old. There are things that are good about the Power FC and there are bad points too but no need to go into that detail or research unless you want to go with that ECU.

I have a L jetro in my GTR atm because that is what it came with and when I do an upgrade I'm not going to stick with the FC, going to move to a Link G4.

There was a thread here anyway about someone wanting to go from a Power FC to Haltech in a R34 GTT, dig up that thread and see what the comments were might give you more opinions.

[Blackkers]

After you factor in the cost of new AFMs an Adaptronic plug in ECU won't cost much more at all

[paulr33]

going back to your original post and problem statement, i cant see why the map sensor would be better at light load tuning

if anything, the airflow meters would be better as they measure actual airflow over the hotwire vs the map sensor that guesses load based on pressure (pressure != volume)

you need to remember if you go for twin Z32s these are 80mm each, whereas stock BCNR33/BNR32's are 65mm so you will get more airflow resistance on the std items, which translates to a more accurate airflow meter reading, which translates to a more accurate tune (more variance in the load cells).

if you go for twin Z32s then at 80mm each you might find it feel more dampened and sluggish as each intake is larger and it dampens the signal a little.

i would strongly think about what you are trying to solve before you do anything as you might find it worse

in my skyline i had the powerfc and i loved it and in my evo ive got the vipec and its pretty good also

the vipec is map sensor setup (previous owner changed setup) and it works pretty well but i can feel it is a little doughey on light cruise

i suspect thats due to the map sensor and large cams (270degs) and all the other crap done to the engine but either way, im not convinced map sensor "is better" for light load tuning

yeah sure the vipec has more features and is "this generation" but it doesnt have a simple hand controller which really sucks

but then yeah some of the other features are nice (launch, gear judge, logging etc) but it's a 20x20 ecu at the end of the day

[Piggaz]

going back to your original post and problem statement, i cant see why the map sensor would be better at light load tuning

if anything, the airflow meters would be better as they measure actual airflow over the hotwire vs the map sensor that guesses load based on pressure (pressure != volume)

you need to remember if you go for twin Z32s these are 80mm each, whereas stock BCNR33/BNR32's are 65mm so you will get more airflow resistance on the std items, which translates to a more accurate airflow meter reading, which translates to a more accurate tune (more variance in the load cells).

if you go for twin Z32s then at 80mm each you might find it feel more dampened and sluggish as each intake is larger and it dampens the signal a little.

i would strongly think about what you are trying to solve before you do anything as you might find it worse

in my skyline i had the powerfc and i loved it and in my evo ive got the vipec and its pretty good also

the vipec is map sensor setup (previous owner changed setup) and it works pretty well but i can feel it is a little doughey on light cruise

i suspect thats due to the map sensor and large cams (270degs) and all the other crap done to the engine but either way, im not convinced map sensor "is better" for light load tuning

yeah sure the vipec has more features and is "this generation" but it doesnt have a simple hand controller which really sucks

but then yeah some of the other features are nice (launch, gear judge, logging etc) but it's a 20x20 ecu at the end of the day

Having had a L Jetro FC with Nismo AFM's, a Link G4 (Map) and now a Blackbox (map) the difference on light load "crispness" is night and day. The FC feels like an old dinosaur in comparison, so although in theory the AFM's should be better in that area, it doesn't mean it always is.

A mate went from an Autronic SM4 back to an D Jetro and found exactly the same thing.