SMO Q

i just got the capability to scan the car and i really dont know what im looking at here, but from what ive learned so far, i have a problem if not several. I see the BLMs are high, up to 150 at times, also o2 voltages are low on left bank, and getting knock at partial to wide open. I hope someone can review my log to see if they can point me in the right direction. heres what i think is effecting it currently, that i am doing wrong. 1st, i descreened and ported the MAF 17 years ago, also around that time i put in blue top SVO 24# injectors. recently i installed long tubes and there is currently only headers and ORY with a dump before the axle. no muffler. so that could be the knock. i have gone over exhaust bolts and vac lines for leaks and as far as i know there are none. what might be causing my BLMs to be so high? the things i have mentioned already?also, is there anything else that looks wrong? 1995 lt1 camaro, A4 stock heads and cam. no tune.

gaedbo

Pretty sure Injuneer will respond to your request for help, but I just had to Laugh when I read your Signature. Good sense of humor !

Good luck on the diagnosis for your machine.....

Injuneer

I'll take a look at it. Are there any issues with the way the engine runs?
And no mods other than what is described in the post (signature looks like it may be out of date??).

SMO Q

ugh. i was a punk kid when i made that signature lol.

SMO Q

yeah its got kooks off road 1. 3/4 long tubes with ory and thats it for exhaust right now. also, new o2s ac delco when i installed them. a racetronix pump and hotwire kit, recently did the intake oil leak repair everything still seems to be tight. i found out i had a dead o2 that was brand new when i first scanned so i swapped it. pass side is the one that was changed. converter is also currently a too big 3600 yank. thats it as far as i can remember. no issues that i can pick up on in the way it runs that i can tell since ichanged the bad o2. i also dont even get an egr service enginge light even though its deleted and thank you very much for your help

SMO Q

Any chance to look at this yet, injuneer?

Injuneer

I've spent quite a bit of time on it, but it's a huge file. Try to wrap it up in a dat or two.

Injuneer

Sorry, delayed again, but my son went to the ER Saturday evening, had emergency surgery early Sunday morning, and was in the ICU until today. Should ease up tomorrow.

SMO Q

no problem. thank you again

blown94

bro, i can tell you w/o even looking at your file. You got way too many mods that havent been accounted for in a tune. You say no tune,.....im assuming factory pcm tune. No way you can change svo injectors even 24 lbs. cause theyre rated at different pressure. Secondly youve heavily modified the exhaust to barely any backpressure with dumps and long tubes and no cats. You need a tune, end of story. Cam or no cam, youve made too many changes and the pcm needs updating.

Injuneer

The PCM is adding fuel in all cells, and the max BLM's (LTFT) are 145, not 150. You may have been looking at the INT's (STFT), which do go to 155.

Both banks of the engine are well balanced. The only cell where there is a difference of more than two "counts" left to right is the idle cell 16. That is 137 L/134 R.... not bad.

I wouldn't worry about the flow rate on the SVO's. The SVO's are flow rated at 2.7bar (39.15psi). At 3.0bar (43.5psi) they flow 5.4% extra, so 1.054 x 24 = 25.3 #/HR. The stock injectors (nominal 24 #/HR) are actually programmed at 24.9 #/HR. Not a lot of difference (1.6% higher for the SVO's). Yes, using the correct number and offsets is preferred, but I don't think it's causing your problem.

Running MAF rather than 1993's speed-density makes the improved volumetric efficiency (VE) of the high efficiency exhaust system less of a problem. VE goes up, airflow into the engine goes up, MAF sensor measurement goes up. In speed-density, you have to play with the VE tables to make that correction.

When you go into PE mode (~WOT) in at least one case, you get massive knock retard (11.9*). During PE, where the PCN is supposed to be richening the mixture, even given the inaccuracy of the stock narrow band O2 sensors, I look for high 800's on the O2 sensors. Left bank averages 796 mV, right 819 mV. Seems to low to me, and may account for the knock.

I need to look at it a bit more. The high load cells are not fully developed, with 129/129 in cell 14 and cell 15. Cell 15 is the one that was used during the PE pull above. I think if those cells had been driven in more, and were similar to cell 18 (which is a weighted average of other cells) at 141/140, you wouldn't have seen the knock. Cell 10 137/137; Cell 11 144/143.

You might want to check your fuel pressure with the engine under heavy load, say WOT above 5,000 RPM. See if it's dropping off below 40 psi.

SMO Q

thats great info. thank you. i was planning on checking over the fuel pressure this weekend. i want to make sure there is nothing mechanically wrong before i do any tunes.

SMO Q

Checked fuel pressure last weekend and it was well within spec. replaced MAF and intake pcv grommet now im running slightly rich at 123 ish. still got a ton of knock. still think its the exhaust but going to buy a barrel of 100 unleded and see what happens. thanks again guys.

ACE1252

Not trying to side track the thread, but wanted to mention that I pray your son is getting better.

Injuneer

Thank you for your thoughts. It was a week of concern, but he's home now and doing very well.