happyhapka

So just got my afpr for my 86 TA auto LB9... My mods are as posted

CAI
MSD Wires and plugs
160* therm
Ported plenum (base is just matched with runners)
Hypertech cap and rotor
Relocated mat sensor
Hooker comp headers 2055-1
3" y pipe no cat
Air foil
BBK AFPR set at 50 psi at wot
Custome tune from john (freaking AWSOME tune)
Stock injectors
NGK 02 sensor
Egr delete
Air pump delete


So when I go wot it sticks at 128 but anywhere else its around 158.. It never goes higher than that but damn the car screams.. Runs really well.. I guess I'm asking is if this is normal.. I'm using an ethos scan tool from snap on... But when I just start the car (doesn't matter rather its warm or not) it starts at 128 than creeps up to 158.

Is this normal?

Tuned Performance

iTrader: (92)

158 wow that's lean ! , 160 is max blm programming limit based off how the ECM interprets the o2 signal . IMO it's a bandaid fix to tune bye increasing fuel pressure. Wot will lock to 128 it doesn't bye any means mean you are close to stoicometric. Only a wide band o2 feedback will show wot or hard acceleration higher tps gps feedback.

happyhapka

OK so any idea what I need to do to fix this?
Do I need to bump the fuel pressure up or does it sound like I need bigger injectors?

Tuned Performance

iTrader: (92)

If it's tpi maf you need to adjust your maf tables, speed density ve. you may not be at the limit of the injectors. Having the engine alittle lean at idle and just off isn't that bad but 158 is real excessive. Looking at your list of mods your tuner can see injector pulse width with a datalog tunerpro rt or tts datamaster is a good way to capture what's going on lv8 vs rpm , gps vs a average blm is how I tune tpi maf.

Tuned Performance

iTrader: (92)

Bumping the fuel pressure will help on tpi I really don't like more than 50 . The chance of a crossover o-ring blowing is a concern. Increas fuel pressure on bosh 3s yes they can handle it. Multecs and older bosh injectors the spray pattern and longevity of the injector can suffer .

happyhapka

OK so ill keep it at 50 psi... next question.. I've been doing the best I can for research... Some people had this problem and fixed it by resetting the computer is this accurate?

happyhapka

OK... Open loop fine.. Closed loop is when she gets lean... Also what information would help you guys know what's going on...

The scan tool I have is an ethos from snap on... Its a nice tool.. I'm almost thinking its a bad ecm but don't want it too be... I could be wrong.

Tuned Performance

iTrader: (92)

The fact that you can connect to the ECM is a good sign of a good ECM. OL your blm is locked to 128. If you do increase injector size say from 22-24's you may be to rich without tuning to compensate for the change. There are some tricks to keep the engine in open loop to see if added fuel helps. Adding a potentiometer to the cts feedback to keep the cts reading below 160.

happyhapka

I have 19 lbs inj....and I've heard a way is to unplug the 02... Is that correct

Tuned Performance

iTrader: (92)

I'm sorry I missed lb9 305 In the first post, I'm not sure if unplugging the o2 will cause the ECM to go into limp home mode if unplugged. Trying 700 ohms- 1.2k across the cts wires with the cts unplugged.If the butt dyno feels good then I would Persue a tune (maf scaler , or tables recurved ).

happyhapka

Oh ya I forgot to mention if this is normal... I was watching my O2 readings on my scanner and noticed that it would fluctuate between 500-650-700 than drop to 200-250 than go back up. Is this normal as well.

Tuned Performance

iTrader: (92)

That is normal, a non moving o2 will be at around .450 vdc. When the o2 is warm 5-600f it will become active and swing up and down. The longer it peaks over .450 the engine is running rich below is lean. The normal wave pattern on a good running tune is a nice wave up and back down but the longer it's at one side the o2 is seeing more or less oxygen. A exhaust leak near the o2 would cause a false reading of the o2.

Tuned Performance

iTrader: (92)

Without a different cam swaped, or heads have you allways noticed the high blms ?
Has this been something that just arose after a tune ?
I have heard of one tuned port injection tuner who likes to enable the lean cruise mode on all tpi maf vehicles using a 89 calibration. Without realy knowing the tune up condition of the engine and mechanical shape I would really advise such a change unless you have a wideband oxygen sensor installed so you can see the fuel ratio on a gauge.

onefreakz

question and i dont mean to high jack the post but what should the blm readings be around, i ask becuz my 92 z28 5.7 readings are at 150 this normal??. thanks

ploegi

Should be around 128 I do believe. Your PCM is richening up the mixture.. How old are your O2 sensors?

onefreakz

02 sensor was replaced few weeks ago, i forgot to mention i recently installed slp runners ported plenum and bbk 58mm tb, can this be the cause