Problem found tuning a supercharger
09-20-2002, 12:04 AM
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Problem found tuning a supercharger Well, I am in the process of tuning a Powerdyne 6lb on an otherwise mostly stock 2002 Firehawk. I have upgraded the pump (340m) and injectors (36 lb) to supply the extra fuel. I have the L-Trims dialed in nicely - averaging a hair under 0%, and the timing has been reduced to 16 degrees for everything above .88 g/cyl and 3200 RPM. I have verified that there is no knock, audible or recorded by autotap.
The problem is, It stumbles at partial to full throttle under boost. I have narrowed this down to the MAF sensor going out of range high - (verified with a trouble code and ATAP). I think it could be fixed with either the VE table (for MAF failures, right?) or the PE vs. RPM table.
What would be the best way to add fuel here? And I can't figure out how to add fuel in either one. Do you just increase the numbers?
Thanks for any info.
Geoff
The problem is, It stumbles at partial to full throttle under boost. I have narrowed this down to the MAF sensor going out of range high - (verified with a trouble code and ATAP). I think it could be fixed with either the VE table (for MAF failures, right?) or the PE vs. RPM table.
What would be the best way to add fuel here? And I can't figure out how to add fuel in either one. Do you just increase the numbers?
Thanks for any info.
Geoff
09-20-2002, 01:01 PM
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Re: Problem found tuning a supercharger "and the timing has been reduced to 16 degrees for everything above .88 g/cyl and 3200 RPM."
Is this how you go about reducing timing for WOT? Somebody told me to reduce the .56 g/cyl from 3600 rpm up. Does this mean up to redline RPM or does it mean redline RPM plus every thing else going down the table like .6, .64, .68, ect.. Can somebody please explain this concept to me before I screw something up? Thanks for your help.
Is this how you go about reducing timing for WOT? Somebody told me to reduce the .56 g/cyl from 3600 rpm up. Does this mean up to redline RPM or does it mean redline RPM plus every thing else going down the table like .6, .64, .68, ect.. Can somebody please explain this concept to me before I screw something up? Thanks for your help.
09-20-2002, 07:59 PM
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Re: Problem found tuning a supercharger </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by Justin2000Z28:
<strong>"and the timing has been reduced to 16 degrees for everything above .88 g/cyl and 3200 RPM."
</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Yes, I go that tip from a guy who had tuned a similar setup (Blackbird). It was very effective at eliminating the knock reatrd I had with the stock timing while maintaining the responsiveness at part throttle.
I scaled the injectors and dialed in the MAF table previous to trying the partial throttle hits. It's not a matter of extending the MAF table, the MAF frequency from the sensor is maxing out (and coding before it stumbles). One of the local performance shops pointed out to me today that the MAF should NOT be maxing out at 2 lbs of boost with half throttle at 4000 RPMS. I have the MAF relocated with an extension harness down in the wheel well. So I am currently approaching this as a physical problem with the MAF, not with tuning.
-Geoff
<strong>"and the timing has been reduced to 16 degrees for everything above .88 g/cyl and 3200 RPM."
</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Yes, I go that tip from a guy who had tuned a similar setup (Blackbird). It was very effective at eliminating the knock reatrd I had with the stock timing while maintaining the responsiveness at part throttle.
I scaled the injectors and dialed in the MAF table previous to trying the partial throttle hits. It's not a matter of extending the MAF table, the MAF frequency from the sensor is maxing out (and coding before it stumbles). One of the local performance shops pointed out to me today that the MAF should NOT be maxing out at 2 lbs of boost with half throttle at 4000 RPMS. I have the MAF relocated with an extension harness down in the wheel well. So I am currently approaching this as a physical problem with the MAF, not with tuning.
-Geoff
09-21-2002, 12:11 AM
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Re: Problem found tuning a supercharger If the maf is going out of range (high) then you need to extend the maf curve out. The stock maf table (depending on year) normally go out to about 58 lb/min, before it maxs out and sets a code.
Several people have done it, but no one really wants to post the curve.
Gary
Several people have done it, but no one really wants to post the curve.
Gary
09-21-2002, 12:40 AM
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Re: Problem found tuning a supercharger </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by Justin2000Z28:
<strong>"and the timing has been reduced to 16 degrees for everything above .88 g/cyl and 3200 RPM."
Is this how you go about reducing timing for WOT? Somebody told me to reduce the .56 g/cyl from 3600 rpm up. Does this mean up to redline RPM or does it mean redline RPM plus every thing else going down the table like .6, .64, .68, ect.. Can somebody please explain this concept to me before I screw something up? Thanks for your help.</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Reduce all cells right and lower from your reference cell.
I recommended .56 g/cyl to another question.
Above .56 g/cyl and 3600 your WOT timing begins. I suppose if your boosted and want to ensure that your timing gets retarded ONLY under boosted conditions, then you could bump up the flow to somewhere around .8 g/cyl as 2k Hawk suggested, but I don't think it matters either way.... once you go WOT, boost will be there soon enough anyways.
<strong>"and the timing has been reduced to 16 degrees for everything above .88 g/cyl and 3200 RPM."
Is this how you go about reducing timing for WOT? Somebody told me to reduce the .56 g/cyl from 3600 rpm up. Does this mean up to redline RPM or does it mean redline RPM plus every thing else going down the table like .6, .64, .68, ect.. Can somebody please explain this concept to me before I screw something up? Thanks for your help.</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Reduce all cells right and lower from your reference cell.
I recommended .56 g/cyl to another question.
Above .56 g/cyl and 3600 your WOT timing begins. I suppose if your boosted and want to ensure that your timing gets retarded ONLY under boosted conditions, then you could bump up the flow to somewhere around .8 g/cyl as 2k Hawk suggested, but I don't think it matters either way.... once you go WOT, boost will be there soon enough anyways.
09-21-2002, 06:41 PM
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Re: Problem found tuning a supercharger I swapped out the MAF extension cable from a six foot to a three foot and the problem went away. I guess the extra cable length effected the ability of the cable to transmit the signal properly! Who would have thunk it?
As far as the timing, the adjustments I made were to affect the timing curve relative to boost, not to just generally change the base timing. That is why they were different.
-Geoff
As far as the timing, the adjustments I made were to affect the timing curve relative to boost, not to just generally change the base timing. That is why they were different.
-Geoff
