I've been trying to figure out why my car runs rich after I had it reflashed. I've been making some dyno pulls at work while data logging with the Tech 2 and found out the reflash is causing my injectors to go static. From 5000 rpm and beyond the injectors are not pulsing and just dumping fuel.
At 5440 rpm with a map sensor reading of 148 kpa absolute (just under 7 psi) the ECM is asking for a injector pulse width of 17.3m/s. This calculates out to a duty cycle 78.43%. And by 6350 rpm with a map sensor reading of 160kpa absolute (just over 8 psi) the ECM is commanding the injector to stay open for 19.2 m/s which equates to 101.6 % duty cycle.
From what I've seen on my car anything more than 7 psi will cause the injectors to go static.
coo
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- Sold my beloved J in April 2010 -
get bigger injectors??? and lower base fuel pressure
I do nt think it is the program causing it, but the injectors are not big enough for your boost. What size injectors are you running?
FU Tuning
common sense would dictate that its time for a increase in injector size and a re-reflash to compensate for the added fuel.
SPDDMON wrote:I've been trying to figure out why my car runs rich after I had it reflashed. I've been making some dyno pulls at work while data logging with the Tech 2 and found out the reflash is causing my injectors to go static. From 5000 rpm and beyond the injectors are not pulsing and just dumping fuel.
At 5440 rpm with a map sensor reading of 148 kpa absolute (just under 7 psi) the ECM is asking for a injector pulse width of 17.3m/s. This calculates out to a duty cycle 78.43%. And by 6350 rpm with a map sensor reading of 160kpa absolute (just over 8 psi) the ECM is commanding the injector to stay open for 19.2 m/s which equates to 101.6 % duty cycle.
From what I've seen on my car anything more than 7 psi will cause the injectors to go static.
This is what i figure too. Since I got hpt and logged my 32lbs injections hitting 130% at certain points, ouch. But i have the 2.6' pulley and hitting a 10psi max. Time for some bigger injectors, and change the fuel inj. constant with hpt.
Nate
Evolution of Cavyboy-->C22t--> C24na--->c24s/c
1995 Cavalier W/2k1 Engine
GM S/C 13.940@99.78pmh w/2.068 60ft
its a conspiracy. werent you the one spouting off that you were losing boost due to a p& p head?
Chris Fontana wrote:Dont mean to but in but how the hell are you getting 7-8 PSI? I have the 2.6 and dont see that?
if you mean me, i don't know, it just does
I made a post last week when i noticed what the max kpa i was hitting in each gear at wot runs. Its in the tunning forum somewhere.
Nate
Evolution of Cavyboy-->C22t--> C24na--->c24s/c
1995 Cavalier W/2k1 Engine
GM S/C 13.940@99.78pmh w/2.068 60ft
gm uses 310s which are easily maXed at 3 or 4 psi so you will need at least 370s its not a reflash issue its injeccts
1989 Turbo Trans Am #82, 2007 Cobalt SS G85
i see 5-7 psi easily with mine just after 5000 is when i usually see 7psi
and i was maxed on the gm s/c injectors , it ran in the mid to low 13's for afr
when i added the 36lb and droped my fuel pressure to 30 psi from 50 psi , i droped from low 13's to mid 11's , and picked up about .5 sec in the 1/4 and a few mph
and i feel alot safer with it
ccfab wrote:common sense would dictate that its time for a increase in injector size and a re-reflash to compensate for the added fuel.
Common sense would dictate that he does indeed need new injectors. But unless he has HP Tuners, he cant "re-reflash" as you indicated. Just lower base fuel pressure with a afpr.
What about just swapping in larger injectors like 370s, without adding an AFPR, will the computer be able to control them properly?
14.330 @ 96.37mph
BlownBlackZ wrote:What about just swapping in larger injectors like 370s, without adding an AFPR, will the computer be able to control them properly?
Thats what 97cavie24ls has done. works well for him
Evolution of Cavyboy-->C22t--> C24na--->c24s/c
1995 Cavalier W/2k1 Engine
GM S/C 13.940@99.78pmh w/2.068 60ft
BlownBlackZ wrote:What about just swapping in larger injectors like 370s, without adding an AFPR, will the computer be able to control them properly?
The ecm will compensate up to 10-15% without setting a rich code (maximum fuel trim compensation is 15% before the ecm will set a rich code). But it can only compensate while in closed loop. When in boost it goes into open loop using the map and rpm reading to calculate fuel needs. If you install bigger injectors without adjusting the injector constant in the programing, the ecm will still command the same fuel injector pulse width for the larger injectors as it did for the originals while in open loop (ie boost).
Now what I still don't know is if the ecm is self learning, ie if long term fuel trim values effect open loop fuel demands.
C24s/c wrote:BlownBlackZ wrote:What about just swapping in larger injectors like 370s, without adding an AFPR, will the computer be able to control them properly?
Thats what 97cavie24ls has done. works well for him
Yeah but he has an AFPR...
[quote=97cavie24ls(JDM&00s/c sedans™)]i see 5-7 psi easily with mine just after 5000 is when i usually see 7psi
and i was maxed on the gm s/c injectors , it ran in the mid to low 13's for afr
when i added the 36lb and droped my fuel pressure to 30 psi from 50 psi , i droped from low 13's to mid 11's , and picked up about .5 sec in the 1/4 and a few mph
and i feel alot safer with it
14.330 @ 96.37mph
adjustable fprs are worth having
ive put alot of hard miles on the car , and alot of easy 1's , and the car hasnt set any fuel related codes
milage hasnt changed either
just the stupid cat code
factory computer can adjust for 10% to be safe, so up to 341cc injectors, find out if you can find someone around with HPtuners, to change you constant, and maybe even play with your VE tables a bit (c WBo2).
PP will lower your boost on a s/c engine because the engine as a pump will be more effiecent, but be getting the same amount of air. GTP guys when doing exhaust, P+P, and intake, will notice a significant drop in pressure. When doing up a s/c setup pulley size should be backed up by other mods.
HP Tuners | Garrett T3/T04B | 2.5" Charge Pipes | 2.5" Downpipe | 650 Injectors | HO Manifold | Addco front/rear | Motor Mounts | HKS SSQV | Spec stage 3 | AEM UEGO Wideband | Team Green LSD | FMIC | 2.3 cams | 2.3 oil pump swap | 280WHP | Now ECOTECED
pick up some greentops..... this way you you got fuel to play with and if u decided to throw a dry shot of nitrous at it you still have extra fuel to compensate to keep it safe
