Ok, well this only applies to people who are supercharged... and it isnt a 100% perfect fix, but hell its alot better than no tuning at all.... If it works then i wont have to run pig rich at 7k to be safe at 8,200k
So all i did during classes today was brainstorm how to fix fueling after 7k on my car, i had some pretty crazy ideas, including setting my stock shiftlight to always come on at 7k, run the wire from the light in the guages to a relay, which would open an air solenoid valve, which is fed by a vacum line from the manifold, then through a MBC, and into a FMU so that it would raise fuel pressure based on a fraction of the boost only at 7k and up....
Rigged,.,., I know.
But then i was taking a piss and the light bulb went on in my head, except this time it was more like a halogen bulb in one of my work lamps.
So, heres the new plan... Please dont flame me, but just let me know if you think it would work.
Well damn.... As i typed this i realized that the 2-bar tune doesnt change fuel... But it made me come up with a new idea
If we can rescale the tables for a 2-bar tune then couldnt i rescale the tables to bring my max RPM up to 8,200 RPMS as the last tuning variable???
Much simpler than what i was about to type up
<img src="http://memimage.cardomain.net/member_images/3/web/831000-831999/831395_11_full.jpg">
So yea, ignore the genious part in the title lol... I thought i was on to something big... New idea isnt so big, but hopefully will work.
Im also trying to do the 2-bar tune in excel but i still am unclear as to actually rescaling the axis for the tables
<img src="http://memimage.cardomain.net/member_images/3/web/831000-831999/831395_11_full.jpg">
Ok, well the bulbs out...
But im still not getting the 2-bar, im looking at your 2-bar tune write up as we speak but im still not getting how you change the map axis...
Or is it set so that when your viewing the table in the VCM editor, it still says 0-100 across the top, but you just change your numbers as if it said 0-200?? Im kinda lost
<img src="http://memimage.cardomain.net/member_images/3/web/831000-831999/831395_11_full.jpg">
The way its working in my head now is that as far as the PCM sees it, no matter if its a 1-bar sensor or a 2-bar sensor, it will read 20-100. However the ammount of voltage a 1-bar sensor sends to the PCM for say 50KPA, the 2-bar sensor will send the SAME voltage at 100KPA?
<img src="http://memimage.cardomain.net/member_images/3/web/831000-831999/831395_11_full.jpg">
I believe the scales stay the same. They are just changed in the write-up so you can keep them straight in Excel or whatever you are doing them in.
2010 Subaru Impreza WRX Limited
1999 Cavalier Z24 Supercharged
1999 Grand AM SE (Beater Car)
1997 GMC Sierra
2007 Honda CBR 600RR
2005 Honda TRX450R
Ben Brown wrote:The way its working in my head now is that as far as the PCM sees it, no matter if its a 1-bar sensor or a 2-bar sensor, it will read 20-100. However the ammount of voltage a 1-bar sensor sends to the PCM for say 50KPA, the 2-bar sensor will send the SAME voltage at 100KPA?
The scales are the same, I never changed them.
1 bar sensor at 50kpa = 2 bar sensor at 100kpa, thats right.
So you can "rescale" the MAP axis (doesn't change the values on the side), because you are using a different sensor with a different scale. There is no sensor you can change to rescale the RPM axis...
4cyltuner.com - Information Source For 4 Cylinder Tuners
Buy stuff from CarCustoms Ebay! Won't be disappointed!
Well then back to my crazy ideas,
What if i installed an AFMU, with a MBC in line to limit the amount of boost that reaches the FMU, this could allow me to have the fuel pressure raised a slight amount to compensate for the lack of tuning past 7,000 RPMS. It would be rough but if i tuned my VE tables with that system installed couldnt it work pretty accurately?
<img src="http://memimage.cardomain.net/member_images/3/web/831000-831999/831395_11_full.jpg">
Thank you Shifted for beeing so patient, its hard to find people willing to help Tuning n00bs like me
<img src="http://memimage.cardomain.net/member_images/3/web/831000-831999/831395_11_full.jpg">
Ben Brown wrote:Well then back to my crazy ideas,
What if i installed an AFMU, with a MBC in line to limit the amount of boost that reaches the FMU, this could allow me to have the fuel pressure raised a slight amount to compensate for the lack of tuning past 7,000 RPMS. It would be rough but if i tuned my VE tables with that system installed couldnt it work pretty accurately?
Personally, I'd pick up a BEGI adjustable FMU, and start playing with rising fuel pressure rates instead of trying to proportion the boost through an MBC.
4cyltuner.com - Information Source For 4 Cylinder Tuners
Buy stuff from CarCustoms Ebay! Won't be disappointed!
Ben, you've got mail
1989 Turbo Trans Am #82, 2007 Cobalt SS G85
Ben... your idea holds water until you consider this.
You hit 18 psi at 3200 rpm... and it holds until redline...
But as the RPM's go up your volumetric efficiency will go up demanding more fuel by sucking more air...
Yet your fuel won't raise because your boost isn't going up...
See what I mean?
We need a way to raise fuel from 6800-8200 via RPMs vs map or RPM vs TPS... but either way it has to be RPM...
I don't think much is going to come of it HPTUNERS has considered our platform basically finished.
-Chris-
-Sweetness-
-Turbocharged-
Slowly but surely may some day win this race...
Its a shame they jipped the jbodies on the axis rescaling feature that just came out in the most recent release, I havent messed with it, im not sure if it could do something like what hes aiming for
1989 Turbo Trans Am #82, 2007 Cobalt SS G85
Yea i will run into that problem when i go turbo, but for now with the vortech unit my boost will keep increasing as long as the rpms increase so it could work
<img src="http://memimage.cardomain.net/member_images/3/web/831000-831999/831395_11_full.jpg">
Ben what are you talking about? The FPR is vaccum controlled when it hits wot it goes up and stays there.... it doesn't keep increasing with RPM.
N/A cars hit 0 vac and the FPR stays and that's that. It doesn't go anywhere beyond that without a FMU and BOOST.
-Chris-
-Sweetness-
-Turbocharged-
Slowly but surely may some day win this race...
Thats what im talkin about, adding an adjustable FMU to increase fuel pres. just enough to keep the A/F ratio good past 7k.
I have boost, all i need is a FMU.
Ok, let me explain it better.
Ill tune for what i can until 7,000 RPMS. I figure ill be between 7-8psi at 7,000. Who knows how much more ill get from 7,000 - 8,192. I think it will be significant though, enough that if i have an adjustable FMU set very low, then the boost should raise fast enough in the top end to allow for the fuel pressure to be sufficiently raised and compensate for the lack of tuning past 7,000.
My other thought was add a MBC, set at say 7psi. So unless there is 7psi of boost, nothing will reach the FMU. That way it wont be doing anything under 6,500-7,000 RPMS. Then as the boost climbs past 7psi (also always past 7,000rpms) Then 1 or 2 psi will reatch the FMU, just enough to raise the fuel pressure and keep a good AFR
It would probably only work on my car, or others running the vortech unit
<img src="http://memimage.cardomain.net/member_images/3/web/831000-831999/831395_11_full.jpg">
Ben - and that's fine but what about part throttle? What if you part throttle it to 8200 rpm at say, 3 psi of boost? It's still not supplying enough fuel because the stock PCM is told to deliver xxx amount of fuel... sure your idea covers the 3 psi of boost but not the rest of the fuel needs over 6800 rpm. And if you purposely over richen it to compensate for the high rpm's all you end up with is a very over-fueled low RPM band when you're at low RPM's and boost.
And what if your supercharger maxes out at 7200 rpm giving you more boost and just creates more heat? You're stuck with 1k rpm of no more fuel added due to boost.
Sitting and thinking about it I don't really see it working as effectively as you hope personally - but that's one guy looking at it from one perspective. Lets see what the people who REALLY know what they're talking about have to say.
My vote is this isn't too much of a solution but good luck with it anyway.
-Chris-
-Sweetness-
-Turbocharged-
Slowly but surely may some day win this race...
I wont be richening anything up except for what is needed at the last variable, i understand its not a GREAT way to do it but it sure as hell beats doing nothing at all for that dead spot
<img src="http://memimage.cardomain.net/member_images/3/web/831000-831999/831395_11_full.jpg">
We need more after market support on this one, otherwise tuning is going to be very limited on a j-body. What im talking about is a replacement for the pcm, ecu etc...
I want to share something with you - the three sentences that will get you through life. Number one, 'cover for me', Number two, 'oh, good idea, boss', Number three, 'it was like that when I got here.'
This whole thing is really startin to bug me, the machine shop needs to get me my block back
<img src="http://memimage.cardomain.net/member_images/3/web/831000-831999/831395_11_full.jpg">
I think a dyno once you have the motor back to 7000rpm is a must, I made max power at 5800, despite the fact I made more boost at higher rpm, the power still went down, keep in mind there may not be any benefit in going past 7000
1989 Turbo Trans Am #82, 2007 Cobalt SS G85
Im running the comp cams stage 3 grind.... So i wont really be seeing impressive power till 5,000.
Plus i just called the machine shop and put a hold on boring the cylinders.... I just ordered the wiseco 10:1 comp pistons .020 over, so the machining is nmow put off till the pistons come in
<img src="http://memimage.cardomain.net/member_images/3/web/831000-831999/831395_11_full.jpg">
Ok so i think it is possible to modify a stock 95 pcm for boost, simply because you can fake a 2 and 3 bar map, also with some tinkering you can now adjust the levels at which tuning is adjusted, but to hit 8k my guess is going to be major code rewriting. If anyone is willing to try i can send them my sourcecode for the 16196285 $36 pcm.
Quote:
Ok so i think it is possible to modify a stock 95 pcm for boost
There is no change needed to the pcm.
There are changes needed to the code used in the pcm. Some guys have re-scaled the spark and fuel tables with some success, but there's likely to be plenty of "gotcha's" along the way.
1 BAR, 2 BAR, 3 BAR MAP all use same voltage range, 0V - 5V. PCM is ok with that.
-->Slow
