Just wondering what everyone else has found to be the best method to tuning a supercharged car. I'm going to be using a P1SC procharger system.

And btw, how would you tune the PCM for the charger? The VE tables?

 

I voted for PCM tuning because using a FMU is hard to get the AFR steady and consistent. The FMU is just one more thing to break and cause problems. My car was extremely easy to tune using the mototron 60 injectors.

My tune is very similar to a stock tune. I've raised the timing at idle to about 28 degrees. I then reduced the timing in 95-100KPA areas to about 27 degrees. I also changed the WOT vs RPM table to make my AFR 11.8 at WOT. I never touched my VE tables. I'm using the MAF on the pressure side and showing no signs of it being maxed out.

 

Thanks, thats what i was thinking. Just wasn't sure if the MAF would be able to adjust for the extra air when you start getting into the boost at part throttle.

 

PCM here too. I've really only touched timing tables and WOT vs RPM table like 97WS6 and also have 60 pounders in there. I've changed other things also like the constant for the injectors, cooling fan temps, rpm fuel cut offs and such, but mainly when tuning, timing and the WOT vs RPM table is all i touch and i've been able to get A/F's spot on, until my fuel pumps started running out of fuel... Now my A/F curve has a nice U looking signature to it. Hehe. Putting twins in this week though, so that will take care of that.

Ken R.

 

pcm + dyno tuning

 

It's not either/or. An FMU can be a useful tuning aid, but using one is only "tuning" in the crudest sense.

Rich

 

That being said if you decide to go with an FMU you may consider the Vortech Super FMU (adjustable).

FWIW I ditched my sh!tty Powerdyne FMU (was only working at a 4:1 ratio when it was supposed to be 8:1) for 42# injectors and LT1 Edit. Tuning was pretty straightforward except for one thing, part throttle surge (cam surge really). It turned out to be a lean condition caused by closed loop, so I disabled closed loop and tuned part throttle via the AFR table ....no problems now.

 

I'm using TunerCat and dealing with the same closed loop cam surge issue. hopefully I'll get that cleared up soon.

 

Do a search on BLM's and max/min integrators in the computer forum, lots of discussion on it. You may be able to stick with closed loop by limiting integration. I tried lots of things and finally got fed up with it and just disabled closed loop. As long as you trim some of the fuel out of the Open Loop AFR table you will not have any problems going with open loop, I haven't anyway. I just trimmed some fuel out so I usually see mid 800mv's when cruising and low 900's for the extremely light loads (example, cruising in 4th at a steady 25 mph) as I needed more fuel to stay out of surge in those super light load areas. When I get on it the PE vs RPM table DOES kick in and I see mid 900 mv's ....so yes, the PE vs RPM table is activated even when closed loop has been disabled ...at least on my '94 it does (there are lots of arguments as to whether or not it is accessed, best thing to do is test it out for yourself. I did with extreme fueling on a test tune......I put loads of fuel in the PE vs RPM and got on it, saw .980+ mv's and rich knock so I knew for sure it was working).

 

It's funny you mention that you've disabled closed loop, because for the short term that's exactly what I've done, I do need to trim some fuel, but it sure does run better in OL. I was wondering if staying in OL, but tuned would be a problem, I'm going to play around with it some more but I think that will be my solution also.

 

As Rich noted, the FMU is a crude adjustment system. To insert a mechanical adjustment into a fully electronic arrangement seems retarded.

Go with the right size injectors (42#) and retune. The PCM tuners have sharpened their pencils a lot better in the last few years and their prgms are as good as you could get without your own test and tune equipment.

 

Another vote for PCM tuning. PCM's for less would be the direction I would reccomend. Although if you know more than me (not too hard to acheive) about the system, tuning the PCM yourself on a dyno would also be ideal. I am just lazy and have never learned, so I pay the pros to do it for me.

 

LT1 edit version 2.2 and Dynojet wibeband O2 sensor. Data log software and drive miles for low speed Closed loop and WOT tuning. I ditched the FMU.

 

Dyno tune with bigger injectors.

An FMU is like a band-aid for smaller injectors that dumps a **** ton of fuel.

Mike

 

Agreed. It just pinches off the return line to crudely increase pressure....hardly seems like a precise way to do things.