johny

i have a 97 WS.6 running a 94 Z28 motor and pcm. my mods are lt4 cam, shaved heads, long tube headers with x pipe and dual exhaust, 160 thermal stat ,stock ram air intake, 1.6rr and 02 ls1 injectors (28lbs).

before my car would always run rich, so i tried doing my own tune. i'm new to tuner cat and i've changed some settings and they are

the injector size to 28lbs
fans to turn on at 170
and %change to fuel/air ratio vs cool temp at 68c to 15.6 percent. i changed it because i guessed it would work better with the new operation temperature.

well the result are good when i was looking at freescan the blm was 128 and the integrators stayed at 128 while driving normal and idle. i havent had a chance to give it WOT to see how low the integrators get with free scan hooked up. but when i do give it WOT there is a cloud of black smoke behind my car indicating it running real rich. since i done my little bs tune it has been better but how do i tune fuel at WOT to make it a bit leaner? and how do i know my AFR is around 13.1 while in WOT without a wide band?

thanks for your time and help guys.

gregrob

iTrader: (8)

The answer is you dont really ever know without a wide band. The narrow bands just arent reliable at that range, but you can get close.

You need to do a LOT of reading here and soak up the information http://www.lt1pcmtuning.com/tips

The 2 tables you will use are %Change to Fuel/Air Ratio vs Coolant Temp at WOT
and %Change to Fuel/Air Ratio vs RPM at WOT

It's best to zero the RPM table and get it close to where you want with the coolant temp table. Then when you have a good wideband and logging capability (IE dyno sheet, or a wb in the car with software, etc) you can fine tune it throughout the power band with the RPM table.

I personally set my car to run in the low 900's on the narrowbands, and it was rich on the dyno. 11.9 AFR in some areas.

Some guys say to go high 800's..

My95Z

iTrader: (8)

Those injectors don't flow 28 pounds an hour with LTx fuel pressure, they are rated for an LS1. They flow about the same as stock injectors, so I highly doubt you were running at 128 blm and rich at WOT, if anything lean. Chances are you just didn't run the car long enough to get into closed loop so it was showing 128 for the blm reading.

gregrob

iTrader: (8)

Very good point, I didn't see that he said ls1 injectors.

Here's the math on that 28lb flow rate / 4bar (58 lbs) = .48275
.48275 * 3bar (43.5lbs) = 21lbs flow rate

The injectors you have in there now flow LESS than stock...

and that's IF they were actually 28lbs, the only engines that I know of that had 28.5lbs injectors was the LS6, which would be in a Z06 vette...

Why people think they are an upgrade is beyond me.... You could put your stock injectors back in and crank the pressure up to 4 bar and flow way more than you are right now...

gregrob

iTrader: (8)

It's irrelevant what the BLM's showed at WOT because it is in power enrichment mode and the pcm is NOT going to try and correct it. So your statement is a bit misleading.

I can see how he could have been at 128 at part throttle and idle like he said, because the injectors flow enough in that area, but when he goes WOT I agree with you, probably lean. Possibly dangerously lean with those injectors only putting out 21lbs.

My95Z

iTrader: (8)

He indicated he was running rich in his original post via the black smoke he saw when he floored it, nothing to do with BLMs there b/c they lock as you stated. I never said his BLMs indicated he was rich or lean see the "and" in the area you bolded?

And I still highly doubt the long terms were at 128 at any cell if he has the injector constant set at 28 with those injectors, the PCM would have to be adding more fuel (blm > 128) to compensate for the constant being set too high (pcm telling injector to open for too short of a period of time).

And for the record LS1 and LS6 injectors were 28 pounders, just not LS1 injectors from 99-00.

johny

wow, thank guys and yeah my blm was a 128 all the time in closed loop and the integrators was close to it. while just driving slow, and yeah its still throwing some black smoke at WOT (much less then when the setting where at 24 llbs). i will set them back to 24 lbs and check the blm to see and integrators since i never checked it with free scan in that setting. reason why i got these injectors is because it came with the 94 motor. man the ones that came with my car where 19 lbs (previous owner raped me). as far as WOT tune i'll see if i save up for a wide band. i forgot to mention i dont have emissions Florida FTW and i have the egr turned up all the way high on all settings. im really new to this and u guys are very helpful.