tuning for changing boost?

unijabnx2000 · 05-07-2008, 05:52 AM

I have a JWT ECU with 555 injectors @ 3bar, & Q45 MAF.
currently to run 13psi the car was tuned on a dyno and to compensate the afpr was adjusted to correct the afr.
questions:
1. is that the idea way to tune it or should the adjustments be made in the fuel maps on the ECU?
2. doesnt changing the afpr use more gas when your not boosting just b/c of the increased pressure? (makes me think the best thing to do is change the tune)
3. when you get a tune from JWT, the fuel maps they load are based on...? (the boost you tell them you will run, or stock boost level?)

Dont get me wrong, I love the way it runs/drives i was just wanting to help a lil more gas and be able to turn the boost up/down on the fly without going to a dyno. (but i dont have a wideband)

unijabnx2000 · 05-07-2008, 11:30 AM

since i dont know jack about tuning, if i got a calum, could any performance store tune it for me? and what afr would be best for the DET?

irf305 · 05-12-2008, 10:42 PM

Calum has 2 computer set ups. Basic and realtime. The basic is similar to JWT. In that it uses a preprogrammed set of chips that he installs on a daughterboard and solders it to the ECU. Where they differ ( this is a guess, i'm assuming this cause in 5 years of forum browsing i've never come across anyone changing "chips" in a JWT ) is that in order to redo the JWT you send it back to them, pay $100 or so, wait 1 - 3 months and they return it reprogrammed. Besides Calum being much much cheaper ( $105 for him to redo the ECU compaired to the $600 JWT charges )and faster, you have the ability to change the chips he installed. This is where the wideband comes into play. After a dyno run that uses a wideband you can send him the A/F results and he can reburn you a new set of chips ( for $5. Yes only $5 ) basing the new chips on the A/F results you gave him. Or if you can burn your own chips you can easily do it yourself. Plus if you change injectors, maf or whatever, same thing, he can burn you new chips.

His realtime ECU is a set it up and program it yourself ECU using a laptop. Obviously this is a little more complex but gives you change on the fly kinda like a stand alone.

I'm pretty sure the FPR raises as the boost raises. I don't remember exactly but it's something like 1 psi for every pound of boost. So idealy you can raise the boost a few pounds based on your current tune and should have no problems. But if it's tuned for 12 psi and you decide to crank it to 20, you might run into some problems, besides the A/F ratio...

So to answer the ECU question. No not any shop can retune the Calum. But a few solid dyno runs with a wideband ( dyno shops usually charge another $25 for a A/F printout ) or even picking up an Inovative or AEM Eugo to see what your A/F's are at and you can reburn chips for the Calum.

To answer the FPR as a tuning device. Yes it can lower your A/F by raising the F/P. And yes it makes the fuel pump work harder. The ideal thing is to have the ECU programmed right ( either JWT or Calum's basic ) and fine tune with the FPR.

JWT's programs are based on years of tuning and dyno runs, and i assume Calum's are the same. One conversation on the phone with him and you'll see he is quite knowledgable about ECU's and the ins and outs of them. Hope this helps a little.

Proper A/F is about 14.7 at idle. 15ish at cruising. And 11.5 - 11.8 at upper RPM/boost.