max boost on 91 octane ? 14 psi ?

[burldude]

Here it is . I am at the point where I can run only 14 psi without inducing all sorts of problems . I am also saying that anyone that is running 20 psi on pump gas 91 octane is full of it . I have all the supporting mods . If I richen settings up with safc or maft to get rid of knock, then I run to rich and induce spark blow out. Feels just like fuel cut but more stuttering. With a fmic and fuel pressure turned up to 47lbs and 680 injectors and cold air intake . At 15 psi I will get knock , over 20 . Logging at 14 psi with 43 pounds of fuel pressure base , at 5000 rpm I hit 18.97 duty cycle on my injectors . This is way to high ,Iam only running a 16g evo and it is over running 680 and a stage 3 eprom burned for them . What Iam saying is that on pump 91 octane anyone that is logging and watching for knock and is running more than 15 psi is seeing plenty of it . I mostly notice the 2g guys talking about how they are running 20 plus psi and still seeing good timing , hahahaha sure you all are . Not with anything less than 100 octane . I have done the tuning and the mods and 14 psi with a large fmic is all it can give me on 91 octane and 20 degrees of timing . Bad knock sensor ,no been replaced . Carbon buildup ,no been rebuilt . Hot plugs ,no been changed . Running to lean ,no been monitored . Boost leaks , no been fixed .

My point is 14 psi with 91 octane that is it . Sure I will keep trying . Coil on plug will give me somthing with larger injectors . Phenolic spacer installation maybe Sunday ,that might be good for a degree of timing , or one less knock. When you put 14 pounds of extra air pressure in a chamber and then compress it quickly it heats up and there is know way to slow the burn rate down in the combustion without higher octane .

 

[kobykris]

Sounds like you have to just about figured out. Theres you should be able to push a lot more boost with that big of an injector though. Post some logs

 

[stock1g4g63]

Yeah, that sounds like it might be a tad off. I haven't been had my boost turned up in CA (awaiting my fmic install) past 15psi, but I ran 19psi on an 18G with 550cc injectors on 93 octane. I spoke with RRE, and they said 18psi on 650cc injectors on a 20g would be fine with 91 octane. I'd like to hear more though, as I haven't been in CA too long and would like to learn more about your experience with the 91.

 

[anconover]

id try at least 24psi on 91 octane on the 14b with your setup. Dont mind the knock and negative timing, it doesnt do anything.

 

[stage2eclipse]

Finally i have heard of someone getting a lot of knock when you try to turn the boost up with 91 octane. i was getting the same symptoms with 93 octane. i wasnt sure if something was wrong with my car, but now i realize that when i put 110 in my car i can turn it up to 22psi on my stock 14b.

 

[burldude]

id try at least 24psi on 91 octane on the 14b with your setup. Dont mind the knock and negative timing, it doesnt do anything.

Man you have got to be kidding me . In your profile you are running a 12.3 with a 50 trim ,not a bad time . But what would you run on pump gas 91 octane with your boost level ? Blown headgasket would be on the way :thumbdown

stage2eclipse , I hear you man and I am having to decide where to go next with this car . I have heard so many people saying how many pounds of boost they ran ,20 plus on pump gas 93 octane 91 ,94 . Just alot of kids blowing there cars up .

My tranny has just about lost the first gear synchro . I am going to have to find a rebuild or new one soon . Good bye 3 grand, putting the titanium buildup on hold this month . Shep told me he didnt have any cores and would have to use a new tranny to buildup . At least I know I would have a decent tranny then .

 

[slowAWDTSi]

You said you changed your plugs? Did you check your plug gap? From what you said (spark blow out) may be too much gap. Set them plugs down to 26 or so and try that. Unless of coarse you already have.

 

[Budget90GST]

Hey everyboby, what's up? I'm new to this tuning stuff, in fact I just got my 190 lph, EVO 8 560's, and MAF translator. I also have a 2.5 turboback on stock 14b and sidemount. Hardpipes all around though from lower to TB. Anyway, when I first tuned it with my pocketlogger, I would get the stutter (spark blowout syndrome) at around 5000 rpm (I had WOT knob richnened by 6 clicks) and I could not for the life of me figure out why. Then I realized that my FP solenoid was not working and was causing me to lean out as soon as I boosted. After bypassing it and retuning, I am now running 17 psi with about 12 counts of knock max (WOT knob is 2 clicks richened). I still want to tune some more and get it down to below 5 counts but I have been lazy lately. This was obviously on 91 octane. Like I said, I'm no tuning expert and in fact I'm still learning new things as I go along. Maybe it's just me, but good luck with your tuning.

 

[anconover]

burldude, if you thought i was serious, im sorry for you.

but, i run 25psi on 93 octane. But i was obviously joking in my previous statement.

 

[Budget90GST]

Alright, I went out and did a few WOT pulls and got my knock count to 0 all the way to 6500 rpms on 2nd and 3rd gear. Ended up with 4 clicks on the WOT knob. 18 psi with no creep on 91 octane.

 

[nine5raptor]

I regularly run 20psi on my 14b on pump.




The WI helps keep things safe

 

[burldude]

Iam going to go after water injection . It is obvious to me that some of the people here are oblivious to the truth :thumbdown

 

[hellotbone]

50 Trim 20 PSI plus no problem on the street sunoco 94

 

[GSX4LIFE]

Many, many people run 20psi on 91. Sure it pulls your timing some, not crazy though. I have been in Tucson now for 6 months. And I am now used to 91. I didnt let it get me stupid. I richened things up to low 11:1 AFRs and continued running 20psi on 91. I will say, my headgasket did just pop. Forget the fact that it is a stock mitsu gasket(not 4 layer metal). Forget the fact that I have been on this same gasket for 2.5 years. Forget the fact that I have countless 30psi runs on race gas, countless 22-24psi runs on 93, and a few runs of 27-30psi on pump gas accidentally. My headgasket popped because I run 20psi on 91, right?

 

[OnABudget]

hey we have similar names and cars...
your passed problems sound just like my own and i have tried everything(except increasing fuel pressure)on both my dsms so the deal with bypassing the fuel pressure solenoid sounds very interesting. what exactly did you do? any inconveniences?
thanks man

 

[out there]

my suggestions for a checklist (please just go along with any repeat info)
plugs (and gap)
wires
ignition system
fuel pump
fuel pressure solenoid

make sure your injectors are the size you think they are! i bought some 680s and they turned out to be 550s (obviously returned them), but i would've set things up initially for 680s instead of 550s... this definitely would have caused a few problems at first.

i can't give you any suggestions on any tuning device other than an safc, but we can discuss some other numbers. when this "spark blow out" occurs, what does your o2 voltage look like?
my theory is that you're running too rich, this is what happened to me when i tried to tune for 19psi on my 14b with stock smic and 92 octane. i don't really tune for knock (at this point) and just go for .88 o2 voltage across the rpm scale

 

[Budget90GST]

The FP solenoid is located by the driver side firewall between two other solenoids. I just bypassed it completely. Do a search, that's how I found out about it. In any case, I heard that it's sole purpose is to keep the pressure up for warm startup. I personally can't tell the difference between having them and not having them. If it fails close, then your regulator will not go up or down with vacuum/boost, in my case leaning me up top. Oh, it made my trims look funny too, like real far from each other. It's all good for now. Time for better intercooling.

 

[bastarddsm]

it could also contribute to bad gas mileage when cruzing.

 

[burldude]

my suggestions for a checklist (please just go along with any repeat info)
plugs (and gap)
wires
ignition system
fuel pump
fuel pressure solenoid

make sure your injectors are the size you think they are! i bought some 680s and they turned out to be 550s (obviously returned them), but i would've set things up initially for 680s instead of 550s... this definitely would have caused a few problems at first.

i can't give you any suggestions on any tuning device other than an safc, but we can discuss some other numbers. when this "spark blow out" occurs, what does your o2 voltage look like?
my theory is that you're running too rich, this is what happened to me when i tried to tune for 19psi on my 14b with stock smic and 92 octane. i don't really tune for knock (at this point) and just go for .88 o2 voltage across the rpm scale

I have a stage 3 dsm chip setup for my 680 and with my maft set to stock ma safc Is almost zeroed out . I have a cold air intake also so no hot engine air . My fuel trims are right at 100 for high, medium and low . I have logged a couple days ago (batteries came out of my palm pilot ) so I cant hot sync right now but I have logged a couple hundred times amd I know what my trims where reading last . I know that my injector duty cycle is maxed, 18.97 pulse width at 6000rpm . At right around 5000 rpm at 12-13 psi I watch my o2 voltage drop from .88 to .82 and knock commences . If I richen things up by turning up the fuel pressure I induce a stumble from running to rich . My car is pretty fast with 0-60 dropping under five when I have a quarter of a tank and a gallon of tolulene added with boost at 14 . Sure everyone can say Iam running lean at higher boost and its true but if I dump more fuel inthere to bring the knoch down I get a stumble at five grand . So for now Iam going to run 12-13 psi and look into water injection . This way I wont have to worry as much if my headgasket will go or if Iam going to spin a rod bearing. I still didnt think that I would max out 680 injectors with a 16g and a walbro 255.

 

[out there]

there is no way on earth that your 680s are maxed out below 400hp, there's a local guy running low 11s with 550s (about 42xhp i think)
i advise you to either a) talk to someone that knows how to handle the gm maf for tuning OR b) get rid of the maf in favor of a 2g mas and safc (because the knowledge base is HUGE)

 

[98spydert]

I run 18+psi in CA and I'm not "full of it". *shrugs*

Ran 15psi on the stock smic with low counts of kock around 5K. Put the front mount on knock went away. Went up to 18psi still no knock. Leaned out fuel 10% still no kock with more room to take fuel away. Creeps to about 20psi and no knock at all.

Are you burning massive amount of oil? That induces knock. Not much else I can think of expect for timing problems.

 

[forcedfed4]

You should really post those logs to see what going on. I can't see you maxing out those injectors. I've been running 22 pounds on a 16g with 93. So i can't see why you shouldn't be running at least 18.

 

[anconover]

18ms at 6k isnt maxed out, thats 90% isnt it? But anyways, i bet i can fix your problem right now. You way too rich. People dont realize this, but just because your o2 volts are .8x doesnt mean anything. Running overly rich ive seen o2's drop and as you lean out youll see them come up, then back down. What are your settings? i bet your about 10% too rich, the stumbling your seeing upping the fuel pressure, is you actually running even richer. Buddy did same thing, added fuel to get rid of knock, logs looks great, car was dog slow. Leaned it out about 15%, golden.

 

[OnABudget]

thanks budget90gst, i did it on my awd and its so much better. i was running such a low base timing and couldnt figure out why in order to get rid of knock, but now my base timing is set back up and im not knocking and timing advance is 23! thanks a lot, im curious why this fuel pressure solenoid problem isnt suggested more often when people are having problems.

 

[out there]

i wanted to suggest that, but i have no idea how to give advice regarding a maft. something similar occured to me when i lost to an evo w/catback and new filter... i then leaned out like 5-8% and it hauls now