TurbochargedBerserker Posted November 19, 2004 Report Share Posted November 19, 2004 Couple of issues. My SD tune is stable, and the garage is now benefiting from running Mass Air on the shelving units, but I've lost 3-4 mpg. I also am leaning out after 5-6 seconds of boost. Now, Chris at HPT is saying SD tunes aren't very good for boosted applications I'm thinking of dropping the MAF back on... Any opinions? Link to comment Share on other sites More sharing options...
SSminneapolis Posted November 19, 2004 Report Share Posted November 19, 2004 well seeing as i am the resident idiot when it comes to tuning FI...i don't know what the hell to tell you. but, everything that i have researched leads me to believe that the MAF is the magical POS that can either make everything better...or screw everything up. and with regards to SD tuning - i have been without hptuners for sometime now so i haven't had a chance to screw with that. i found the greatest success with modifying the MAF curve, an overal adjustment in IFR and small adjustments in VE to get everything where i want it to be... since i haven't been to the track i have no idea what i am running, but how i am running is better than before. running on the highway results in great gas milage (18-21mpg, depending on weather)...in the city when i drive "normal"...i get 14-16mpg...right now my info center reads 12.6mpg, that includes a lot of "i am going to get infront of you no matter what cause you are driving way to damn slow in the fast lane and i have places to be..." type driving... Link to comment Share on other sites More sharing options...
zippy Posted November 19, 2004 Report Share Posted November 19, 2004 the only way you can get the speed density to work the way you'd like it to is with hours of tuning. when gm tunes a crate engine they have roughly 2,000 hours into tuning it. i'm not positive either, but i don't believe the map sensor on this truck can read much into boost levels. i remember looking into this, but i don't recall the results. i'd run this past kurt or parish honestly. they are the two guys i know that have worked alot with turbo programming and found solutions. Link to comment Share on other sites More sharing options...
TurbochargedBerserker Posted November 19, 2004 Author Report Share Posted November 19, 2004 the only way you can get the speed density to work the way you'd like it to is with hours of tuning. when gm tunes a crate engine they have roughly 2,000 hours into tuning it. i'm not positive either, but i don't believe the map sensor on this truck can read much into boost levels. i remember looking into this, but i don't recall the results. i'd run this past kurt or parish honestly. they are the two guys i know that have worked alot with turbo programming and found solutions. <{POST_SNAPBACK}> You are dead on there Zippy. The MAP pegs after one or two cells of boost... What I've been doing their is just adding fuel in those cells until it's happy. I know Parish is still running his MAF, but is looking at standalone 2-3 bar map units. I told him about the whole SD craze. He was going to look into it, but so far has nothing new to add. Link to comment Share on other sites More sharing options...
zippy Posted November 19, 2004 Report Share Posted November 19, 2004 you also may want to look into a big stuff 3 conversion once you get the 408. i wonder if a 3 bar map sensor would communicate properly in this truck? Link to comment Share on other sites More sharing options...
TurbochargedBerserker Posted November 19, 2004 Author Report Share Posted November 19, 2004 you also may want to look into a big stuff 3 conversion once you get the 408. i wonder if a 3 bar map sensor would communicate properly in this truck? <{POST_SNAPBACK}> I don't think it would without the stand alone. Is Big stuff the DIY kit (the one you solder together)? HPT is also releasing the Pro version to everyone so, I might build my own 3 bar map version. Depends on how ugly it looks when I get it. They are releasing a 2 bar version from the get go, but my goal is 18psi... Dunno if I can even get there though. Link to comment Share on other sites More sharing options...
XGMTech Posted November 19, 2004 Report Share Posted November 19, 2004 18 psi??? Link to comment Share on other sites More sharing options...
styleandspeed Posted November 20, 2004 Report Share Posted November 20, 2004 Call Pro-M and see if they make a maf that won't max out as easily as your stock one if that is what you are worried about. Pro M Link to comment Share on other sites More sharing options...
deezel Posted November 20, 2004 Report Share Posted November 20, 2004 bad gas mileage makes sense... you are pretty much forced to tune rich without the MAF compensating for changing ambient conditions. I think a SD tune can be made to work ok for a belt-driven blower because of the direct relationship between rpm and boost. Turbos would be less cooperative. You could probably dial in a good, consistent tune for the track. But street driving has so much variation that the tables you have to work with in the PCM do not allow enough freedom to cover all the variables. Supposedly you can hack a 2-bar MAP sensor into the stock PCM if the electrical output matches - involves re-mapping the VE table with half the original resolution and higher VE values on the top half of the table. (so with a 2-bar the 105MAP cells really mean 210kPa, etc.) I think a 3-bar MAP would cause you to lose too much resolution. But, 18psi is only a tiny bit above the range of a 2-bar... maybe you could get away with it - just tweak up the 210MAP cells a little extra.... Beats installing a standalone air/fuel system. good luck Link to comment Share on other sites More sharing options...
TurbochargedBerserker Posted November 20, 2004 Author Report Share Posted November 20, 2004 I'm impressed so far with the Pro-M stuff... The fact that they have detailed flow charts is pretty impressive. That solves a bunch of tuning problems. I think I'll be calling them on Monday Link to comment Share on other sites More sharing options...
TurbochargedBerserker Posted November 29, 2004 Author Report Share Posted November 29, 2004 Update: I plugged the MAF back in and did the MAF scaling. It worked like a champ, but I don't know about the mileage... Lost the TCC too soon Link to comment Share on other sites More sharing options...
chiel Posted November 29, 2004 Report Share Posted November 29, 2004 Update: I plugged the MAF back in and did the MAF scaling. It worked like a champ, but I don't know about the mileage... Lost the TCC too soon <{POST_SNAPBACK}> What are you worrying about mileage i have some good mileagecars too trade with your sss. i think your car is more in the garage than on the road Sorry i had too do it mine is in the garage too Link to comment Share on other sites More sharing options...
TurbochargedBerserker Posted November 29, 2004 Author Report Share Posted November 29, 2004 Update: I plugged the MAF back in and did the MAF scaling. It worked like a champ, but I don't know about the mileage... Lost the TCC too soon <{POST_SNAPBACK}> What are you worrying about mileage i have some good mileagecars too trade with your sss. i think your car is more in the garage than on the road Sorry i had too do it mine is in the garage too <{POST_SNAPBACK}> hehe - ever get that feeling that as soon as you get it fixed, something else if going to break? My truck = Link to comment Share on other sites More sharing options...
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