'98 LS1, 402 ci, 85mm MAF... maxing it out
09-21-2006, 02:37 PM
#1
'98 LS1, 402 ci, 85mm MAF... maxing it out I'm running a '98 LS1 PCM/harness in my '91 GTA... the car now has a 402 in it with big heads/cam, 90/90 setup, and a 85mm zo6 MAF along with a custom 4" CAI setup I built. The MAF is maxed out, what are my options? We would go SD mode but with the '98 it would only be half resolution... correct?
LMK what you guys think... seems like us '98 guys don't always have the greatest options.
Thanks!
-Jeremy
LMK what you guys think... seems like us '98 guys don't always have the greatest options.
Thanks!
-Jeremy
09-21-2006, 03:38 PM
#3
Originally Posted by Magnus
You can use our 2bar SD solution for the 98's with a 1bar sensor, all you have to do is calibrate the MAP in engine diagnostics for the 1bar.
09-21-2006, 03:38 PM
#4
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You could do what all the 1bar FI guys do; just fudge it on the pe table and such, but I wouldn't recommend it.
How would running a 2bar setup on a NA engine help any?
How would running a 2bar setup on a NA engine help any?
09-21-2006, 03:51 PM
#5
Originally Posted by AzzHauler
You could do what all the 1bar FI guys do; just fudge it on the pe table and such, but I wouldn't recommend it.
*Once the MAF is maxed out, what actually happens in the PCM? Does it refer to something else or is strictly off of the PE table or what? Sorry to sound ignorant, just curious...
09-21-2006, 04:09 PM
#6
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Basically it's putting false numbers in the pe table to account for the air the maf can't read. The ve table can probably help a bit too. Once you get to the maf fail freq though the pcm ignores what the maf is reading in runs strictly SD. Found that out way back using nitrous and not upping the fail freq. A potentially costly lesson to learn.
edit: once the maf is maxed it it reads the last value in the table until either the freq drops back down, or you hit the fail freq.
edit: once the maf is maxed it it reads the last value in the table until either the freq drops back down, or you hit the fail freq.
09-21-2006, 04:15 PM
#7
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Originally Posted by AzzHauler
How would running a 2bar setup on a NA engine help any?
With our SD Enhancement, you can still use the primary VE table.
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09-21-2006, 04:19 PM
#9
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I don't see that this is a forced induction motor; is it? If
no then what about the 1-bar SD option? Not sure that
MAP resolution is a huge deal, VE really varies more strongly
with RPM than MAP from the tables I've seen. But the
1-bar should not sacrifice any table resolution?
Now, one option (if 470g/sec is killing you but 511 would
be all strawberries and champagne) is to port out that
85mm using a stocker as a reference piece, stop when
the 85mm starts to read the same frequency near the
topped-out airflow (this would need a pretty stout flow
bench) and make yourself a new MAF table using a few
low, mid, high flow points to refit. That's a lot of work
to gain only about 10% more range and could be that
you are also past 511g/sec and the more difficult MAF
limits in the PCM just mean, give up and go SD.
no then what about the 1-bar SD option? Not sure that
MAP resolution is a huge deal, VE really varies more strongly
with RPM than MAP from the tables I've seen. But the
1-bar should not sacrifice any table resolution?
Now, one option (if 470g/sec is killing you but 511 would
be all strawberries and champagne) is to port out that
85mm using a stocker as a reference piece, stop when
the 85mm starts to read the same frequency near the
topped-out airflow (this would need a pretty stout flow
bench) and make yourself a new MAF table using a few
low, mid, high flow points to refit. That's a lot of work
to gain only about 10% more range and could be that
you are also past 511g/sec and the more difficult MAF
limits in the PCM just mean, give up and go SD.
09-21-2006, 04:23 PM
#10
Originally Posted by Magnus
Its the SD Enhancement that is the help. With out it, you would be using the secondary VE in the 98 car when the MAF is failed.
With our SD Enhancement, you can still use the primary VE table.
With our SD Enhancement, you can still use the primary VE table.
How much for this upgrade? What is involved in doing it?
09-21-2006, 11:20 PM
#11
Jimmy, 512 g/sec is not killing me, the 98's 11250 MAX HZ reading is. Above 6600 rpm it'll near 1200 hz, thus going lean since its last reference is 11250. If it was a 99+ this wouldn't be an issue.
I could fudge the pe table but I don't like creating hacked tunes.
I may try out the 2bar SD enhancement if I can get it to behave like a 1 bar.
Keith, above 105KPa, should I copy that line all the way down to to 210KPa? Or does it even matter since I'll set MAP sensor linear to 105KPa?
I could fudge the pe table but I don't like creating hacked tunes.
I may try out the 2bar SD enhancement if I can get it to behave like a 1 bar.
Keith, above 105KPa, should I copy that line all the way down to to 210KPa? Or does it even matter since I'll set MAP sensor linear to 105KPa?
Last edited by SmokingWS6; 09-21-2006 at 11:32 PM.
09-26-2006, 03:47 AM
#13
I'm having the same issues with my setup. LS2 402 with large heads/cam/exhaust/90-90 intake setup in a '98 TA. Had it professionally tuned this summer, but it maxes the current airflow tables at ~5600 rpms (I'm using a de-resistored 85mm MAF). Under full throttle, it hits the frequency limit and won't command it to shift. Just sits there and bangs the rev limiter. What a PITA! Messing with this thing has taken all the fun out of having this car this summer. Can't race it, can't get on it...
I think I'm gonna contact Magnus and have my serial cable lisence upgraded and give this a try. It's either that, find someone to build a custom MAF, or move to a Bigstuff3
I think I'm gonna contact Magnus and have my serial cable lisence upgraded and give this a try. It's either that, find someone to build a custom MAF, or move to a Bigstuff3
09-26-2006, 12:47 PM
#14
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wow does the secondary VE table really scare that many people off?
The custom OS should solve that but 98's are prone to PCM death during the install, so it's risky.
Using a 2-bar table it would make sense to just flatline the table after 1-bar since higher values will never be reached.
The custom OS should solve that but 98's are prone to PCM death during the install, so it's risky.
Using a 2-bar table it would make sense to just flatline the table after 1-bar since higher values will never be reached.
09-26-2006, 04:40 PM
#15
Originally Posted by white2001s10
wow does the secondary VE table really scare that many people off?
09-26-2006, 07:24 PM
#16
Originally Posted by SmokingWS6
Jimmy, 512 g/sec is not killing me, the 98's 11250 MAX HZ reading is. Above 6600 rpm it'll near 1200 hz, thus going lean since its last reference is 11250. If it was a 99+ this wouldn't be an issue.
I could fudge the pe table but I don't like creating hacked tunes.
I may try out the 2bar SD enhancement if I can get it to behave like a 1 bar.
Keith, above 105KPa, should I copy that line all the way down to to 210KPa? Or does it even matter since I'll set MAP sensor linear to 105KPa?
I could fudge the pe table but I don't like creating hacked tunes.
I may try out the 2bar SD enhancement if I can get it to behave like a 1 bar.
Keith, above 105KPa, should I copy that line all the way down to to 210KPa? Or does it even matter since I'll set MAP sensor linear to 105KPa?
I am running the 2 bar SD OS on my 98 N/A (no FI w/ 1 bar map sensor) Camaro with all of the stuff listed below. I have all of the values higher than 105 zeroed out. I used to have it all evened out and stuff but it was very difficult to read in the "graph view". Now, I can see what is going on at a glance. It had no adverse effect on my tune.
