PM3 and Custom Fuel Mapping

[tjpatte]

Hey Folks,



Got a question mostly aimed at Briar and Steven St Laurent. What are custom mappings you folks have been working on with the Comp's? I know early on the Rough defueling was a problem and then you guys started working on custom mappings. Have they helped and what were your results? And could I get the same setup from Mark?



Thanks.



Tom

 

[tjpatte]

Anyone, Bueller, Bueller?



Tom

 

[Steve St.Laurent]

I had missed this post Tom - sorry. At higher fueling levels there is still a shudder that happens when backing off the throttle. What Tom and I are running is a box between the street level and comp box. Our boxes overfuel 100% at low boost #'s (which is what the comp box does) and backs off to 50% at normal-higher boost numbers (the norm for the street box). In my case if I run on level 7 I don't have the shudder problem when backing out of the throttle, but if I'm on level 8 or 9 I do run into it - unless I back off VERY slowly. For this reason I run on level 7 99% of the time and only go up to level 8 or 9 when racing. What we fiddled with was the fueling rate at low boost #'s (to spool the turbo faster) and the max duty cycle of the solenoid. The comp box has the max duty cycle of the solenoid set at 65%, Tom's is set at 60% and mine is set at 70%. We set Tom's at 60% because he was concerned about his injection pump lasting so we went on the conservative side (55% is the max duty cycle on the street box and the max recommended with little to no risk of pump damage). I had mine set at 70% because with my 4. 10 gears I wanted full fueling up to at least 2900 rpm and a duty cycle of 65%@50% overfueling started dialing back the fueling at about 2700 rpm (I'm recalling these numbers from memory so don't quote me on them). Basically the comp box set at 100% overfueling and 65% max duty cycle makes GOBS of power down low but would start dialing back the fueling rate at a pretty low RPM (around 2100 rpm I think). That's great for low end grunt - but not so good for 1/4 mile times. Here's a post that I made recently on another thread talking about fueling boxes and our custom programming:

Justin, it's hard to explain the fueling possibilities with a box over the net. The basic limitation is that there is a solenoid on the VP44 that is controlled by the ECM (and by fueling boxes) - the longer that it's open the more fuel is put into the cylinder. However, the longer it's open the more heat is generated in that solenoid and the greater the chance for a melt down, also the further the slide will move in the rotor in the VP44 - Blue Chip diesel has a great explanation of VP44 failures with boxes at http://www.bluechipdiesel.com/Bosch-VP44.htm . The true limitation of our VP44's is the solenoid duty cycle - you can increase the fueling of your box ridiculously down low and hit the wall on the solenoid duty cycle early and maintain that fueling level, or you could have it more level. Any of the boxes out there could set the max duty cycle at any level they wish - it's just what they feel comfortable with regarding heat in the solenoid! The max that I've been told they recommend is a 55% duty cycle before it can possibly get too hot depending on how long it's run. I have my box set at 70% - but I am aware of that and use my right foot to back off, but I am taking a risk. Tom and I are both running custom boxes that aren't normally sold over the shelf from TST. Both of our boxes do 100% overfueling at low boost #'s (to help spool the turbo fast - but also means TONS of smoke at low boost #'s) and then back off to 50% overfueling - comp boxes continue at 100% overfueling, however once the max duty cycle is hit then fueling is backed off. I had the fueling levels set on Tom's box so that his max duty cycle was at 60% (because he was concerned about his injection pump life) which was about 2500 rpm. In my case I have 4. 10 gears and hit 2800-2900 at the end of the 1/4 mile so I have my max duty cycle set at 70% so I would have full fueling until I was through the lights - but I'm taking a risk. Send me a PM or an email at -- email address removed -- and I'll send you my phone # and I'll be glad to discuss with you your options! Just remember that there are risks when you push the limits - myself, I decided that I didn't care about my VP44 warranty and was willing to take some risks on it - buyer beware and remember that YOU are your own warranty station!

 

[tjpatte]

Not a problem Steve I'll get in touch with you offline about my questions because it would take too much time and typing



Take care.



Tom