low O2s running lean stumble issues help please!

2dark2c

Member
Joined
Jul 21, 2012
1987 GN.
when (engine) cold, wont stay running without giving it gas.
once warmed up, its fine (can shut off & restart no problems).

when trying to do a brake torque, from 1-2000 rpm, stutter/stumbles/bogs & rpms drop, feels like it wants to die, O2 drops to almost zero.
(before, car use to blow away the tires at 2-3k rpm)
now it just feels like its lacking power.

its running lean (according to O2 & blm), but I can't figure out why!?

here's SM readings, in idle, in park, engine hot (loop blinking):

O2 576-590 (but see below)
af 5
l8 35
batt 13.3 (it does go up when revving)
int 128
blm 116
clt 167
ats 79
r 850-900 (always idled this high previously & ran great)
tps 44
iac 22
cc (initially ran up all the way & started counting again, but see below)
pu 1.8
sp 27.8-28.2
mal 0
map 37
bst -19

those were the readings after it was fully warmed up. left car running.
then I removed air filter (to check dirtiness, etc.) & kept it off:
O2 = 650-660
then tried brake torque to see if it made a difference (nope, still stumbles):
O2 now 790-820 when idling, cross counts very slow movement (even when revving), but when revving (brake torque) O2 drops to near zero.

WHY is thing going lean? Whats making it stumble? and why are my O2 readings all over the place?


What I've done / checked:

all grounds good (with many extra & redundants in place as well).
all power wires (at battery, alt & starter) ok & fuses good.
all vacuum lines (& pcv) checked & good.
all I/C couplers/hoses checked & good.
No egr, seal is good.
did the carb cleaner spray around hoses (etc) test, no change.

new O2 sensor (denso).
new fuel pump (racetronix 340 w/ hangar) [fuel pump ground wire + stock harness wire + hot wire relay (basically) tied together & grounded to frame & also gastank strap bolt].
new (bigger, full length #6 braided) return line.
new AFPR, 43 line off, 38 line on.
new FP hotwire kit.
new factory FP relay.
new Fuel injector harness, with hotwire, good.
(unplugging each inj, idle drops a tiny bit, but doesn't make that much a difference running, I can tell when plugging back in runs better though. Injectors are 72# low imp.)
new gas in tank.
new spark plugs (autolite 103 @ 28). {old plugs were very black}

cam sensor checked (took cap off, no wiggle on ring) & reset.
crank sensor, tight & clears, looks ok.
IAC cleaned & reset. (from 0 ref point procedure)
TPS checked & reset.
coolant sensor/wires look ok & seems ok based on SM reading (& fans come on at 160ish).
computer chips/plugs checked ok, not loose/no corrosion.
TT 5.6 chip, (with whatever settings are default) {I do have a 6.0 chip I could try, havent yet)

swapped out coil pack & ignition module, no difference.
(& extra ground added on IM base to firewall).
plug wires all ohm out within each other. good.
checked coil/IM plug, snug & good.

drivers side rockers (for cam lobe check) checked ok. (suppose to be roller cam, but never verified)
MAFTPRO, so NO MAF, connections ok, settings I believe are correct.
battery, alternator (& electrical connections) all checked good.

cruise control/brake switches (vac line) good.

-----
unplugged O2 sensor, reset comp., engine runs worse in general:

I READ THIS FROM ANOTHER THREAD, & CHECKED, {MY ANSWERS} IN CAPS:

so, you unplugged the O2 sensor, and reset the ECM, and it runs ok? {NO}
(The BLMs should all be stuck at 128 now). {THEY ARE}
the O2 volts should be stuck at .399 to .440 v (no cross counts) {MY O2= 176-184, NO C/C}
else to check:
check your ECM connector for corrosion? {DID THAT, ITS OK}
loose grounds on the back of the cylinder head? {OK}
replace the O2 sensor regardless. {ALREADY DID THAT}
(post from turbobob)

{MY VDO TACH READS STEADY 800RPM BUT SM SAYS 650-900 & ENGINE RUNS REAL LUMPY}

SO WHY ARE MY O2 READINGS SO LOW WITH THIS TEST?
DO I HAVE A LAZY/BAD O2?

-----

the below tests all done within 10 minutes, 1 right after the other:

1 hour later (from above), after warming engine up:
O2 560-580 int 120-129 bl 119

then unplugged cam sensor:
rpm doesnt change, then revving it up (1-2k rpm, in park) engine seems a bit stronger/quicker (sort of).
at idle in park:
O2 627-630 int 112 bl 115 cc slow moving
pu 1.2 mal 41 (unplugged C/S)
still having the stutter when brake torquing & O2 drops again.

shut off car (key off), plug cam sensor back in, reset computer, start back up:
O2 starts at 230 goes up to 600 then runs sporadic 100-600 (never more than 600)
int back to 128 bl 128

------

Maybe its the computer? Any way to check? It gets warm, but not hot.
With the crazy SM readings, thought maybe that was bad, but its relatively new too.

I do have a PL if that'll help (its hooked up), and can run tests, what do you want me to do / what do you want to see?

Also have a WBO2, not installed yet, (but will if that'll help narrow down this problem!)

Any help/suggestions appreciated! I'm lost at this point...
 
Lazy o2 maybe? Buy a denso and change it to see if that helps

Posted from the TurboBuick.Com mobile app

it had a heated O2 in it, so I removed it & replaced with the denso to see if that would help, but no, same low O2s & stumbling issues as before.
(also thought I remember hearing that the heated O2 with Maftpro might cause issues, so that was another reason for replacing).
 
can you watch the fuel pressure while driving? that would be my next test.


what version software is in the Pro?

step thru these MAFt Pro menus, config and setup, post all the settings.

set the Pro on the sensor monitor screen, look at MP, UT, DC, TPS, RPM, MT, VE.

post readings for all of these, engine off, and idling.

get some PL logs and post them.

B
 
heated o2 will not affect the Pro at all. the issue guys have is connecting a wideband, the plug-and-play harness cross connects the stock O2 and wideband, so that just needs to be fixed.
 
at part throttle, the O2 is supposed to move around, to tell if you are rich or lean you look at the BLM.

your BLM is lower than 128, so the ECM is removing fuel (because things are rich).

this is a separate issue from the bogging when you try to give it throttle.

Bob
 
can you watch the fuel pressure while driving? that would be my next test.
what version software is in the Pro?
step thru these MAFt Pro menus, config and setup, post all the settings.
set the Pro on the sensor monitor screen, look at MP, UT, DC, TPS, RPM, MT, VE.
post readings for all of these, engine off, and idling.
get some PL logs and post them.
B

Maftpro vers 4.40 speed density conversion
config select:
aux1 mode 0 f-in mode 0 afr source 0 v-out2 mode 0 v-out1 mode 0 f-out mode 11
baro mode 1 dens scrc 0 map source 0 airfl srce 0 displ 3.80 #ofcyl 6 vehicl sel 0

config select / system setup:
main scale 0.0 v-out1 set 2.500 v-out2 set 4.000 afterstart 0.0
lo load pt 36.4 mi load pt 100.1 hi load pt 143.0
f out max 0 tm base 0 tm correct 1.27 af trdelay 0.0

monitor screen, KOEO:
bstcfg mp100.6 dc% st aux 10.0 gain 6.0 psi aux 21.0 psi set 21.0 dc% start 24.0
psi start 8.0 tps start 3.000 rpm spool 3200 tps spool 1.700

AFR tracking:
min tps .440 min rpm 3200 min map 166.4 lean lim% 10.0 rich lim% 10.0 gain 4.0
afr2000r (& 3000 & 4000) 11.0 afr5000r (&6000) 12.0 afr7000r 11.0 afr8000r 11.5 aux% 0.0

air tmp: all = -64.0 aux trigger: all = 0 tune high load (& mid & lo) all = 0%

tune response:
map tps min 0.400 map decay 1.20 map enrich 0.70 tps spare2 0 tb size 7
tps decay 0.80 tps enrich 0.50

sensor monitor:
asc 100 mp 100.6 ut -64.0 afi 0 bd 0 mt -39.7 O2 0.20 fe100.0 afr 0.0 cf 100.0 taf 11.0
spk 16.0 ba 100.6 bp -0.1 ax1 0.00 tm 0.0 rs 0 egt 0 rpm 0 dc 129.8 afl 0 afi 0
ve 76.0 cel 77 fi 0 fo 30 tps .45

spark wot: 2000rpm 16.0 2500 (thru 8000) 15.0

spark aux: 2000rpm 15.1 2500-8000 15.0

---------

Engine warmed up & idling: main screen:

bstcfg mp 68.0-72.0 dc% st aux 10.0 gain 6.0 psi aux 21.0 psi set 21.0 dc%start 24.0
psi start 8.0 tps start 3.000 rpm spool 3200 tps spool 1.700

afr tracking:
afr/wot mp 68-72.0 aux% 0.0 afr 8000r 11.5 7000r 11.0 6000&5000 12.0 4000&3000&2000 11.0
gain 4.0 rich lim % 10.0 lean lim 5% 10.0 min map 166.4 min rpm 3200 min tps 0.440

tune mid load: all = 0

tune low load: @400 -2.5% @800 -2.0% @1200 -2.5% @1600 -1.5% @2200 (up to 7600) all 0

sensor monitoring: cf100.0 mp 68-72 afi 0 taf 11.0 afl 13-18 afi 0 ve 64.0-65.0
cel 0 then 40 then back & forth between those 2 #s

spk 16.0 vt -64.0 tps .46 bd 0.0 mt -39.7 O2 0.16 fe 100.0 asc 100.0 afr 0.0 cf 100.0
ba 100.3 bp -3.8 to -4.5 dc 129.8 afl 12-16 ve 64-65 fi 0 fo 38-40 tm 0 rs 0
 
at part throttle, the O2 is supposed to move around, to tell if you are rich or lean you look at the BLM.

your BLM is lower than 128, so the ECM is removing fuel (because things are rich).

this is a separate issue from the bogging when you try to give it throttle.

Bob

I understand that O2 moves at part throttle, but the last test I did
(above: [ "shut off car (key off), plug cam sensor back in, reset computer, start back up: O2 starts at 230 goes up to 600 then runs sporadic 100-600 (never more than 600) int back to 128 bl 128" ] )
the O2 was moving like that while the car was idling & me giving it no throttle at all.
I could understand it varying a little, but all the way from 100 up to 600?

blm, yes, shows rich, even tho o2 says lean :confused:
 
FP/driving it will be next. here's some PL files:

1) startup. cold engine, I have to keep giving it gas or it dies.
2) 2k revs, on cold engine.
3) idling only, engine warm.
4) engine warm 2k revs.
5) brake torque, to 2k rpm. I'm trying to get up to 2k rpm, but had to keep letting off throttle else it wants to die. stutters, rpm & o2s drop while I'm giving it gas.

yes, I realize the O2 drops (going lean) when I rev it up, but cant figure out why?

after #5, idling in park, SM says:
O2 098 af 5 l8 38-53 int 128 bl 119 iac 175 cc 162 (steady)
 

Attachments

  • startup.dat
    51 KB · Views: 82
  • cold2krevs.dat
    139.1 KB · Views: 52
  • idling only.dat
    58.3 KB · Views: 46
  • engine-warm-2k-revs.dat
    114.9 KB · Views: 64
  • brake-torque.dat
    119.8 KB · Views: 62
Have you checked the fuel pressure yet?

not while driving it yet, but I set the new AFPR to 43 line off, 38 line on, and it does go up when revving it.
In the PL file, it shows a little lower, perhaps its not quite in sync, or because the transducer is at the very end of a hose mounted on dr fender, while the gauge is on the rail.
(38 on rail mounted gauge, about 36 on PL).
 
well, that software is ANCIENT....... so the first thing we need to do is update the unit. Do you have the communication cable for it?

The new manual seems to be too big to attach. Go hunt around on fullthrottletech for it, its posted there.

Bob
 

Attachments

  • TPCU with 5.27.zip
    430.3 KB · Views: 96
well, that software is ANCIENT....... so the first thing we need to do is update the unit. Do you have the communication cable for it?
The new manual seems to be too big to attach. Go hunt around on fullthrottletech for it, its posted there.
Bob

I found the manual.
I didn't have the original cable, so I bought a 9pin serial to usb cable.
I open up TPCU & the window comes up (with update button, a blank box next to it, then under those upload/download BIN buttons).
I hit update, select the 527 file, & the black box pops up very briefly (1/4 of a second or less), I can't even read it its so fast, then it closes!?
(I've tried starting with car off, then turning on {powering up maftpro}, and also with maftpro already started then running the TPCU, no difference).
won't update. Do I need the original cable for it to work?

On a side note, I taped the fuel gauge on windshield, sped up the driveway & the pressure does go up. I can't drive the car further than this, as the stutter is still there.

Also, I had a (caspers) volt booster on it, & removed it, and the car does run a bit better (??), but still stutters...
 
well, that software is ANCIENT....... so the first thing we need to do is update the unit. Do you have the communication cable for it? The new manual seems to be too big to attach. Go hunt around on fullthrottletech for it, its posted there. Bob

I got the correct cable and updated the MAFTPRO using the zipfile you attached.
I updated to the TPRO503.s19 file. Now the MAFTPRO doesn't seem like its working correctly!

The first screen upon power-up shows this:
Cfg: FlowErr Mde
SD / MAF

I can change those settings by simply using the up/down set buttons,
Whereas previously, you had to hold the PG button, etc. to get to config page / change settings.
(holding it down does nothing now, even while pressing range buttons).

Reading the new instruction manual, I am not able to get to any of the other pages for settings, etc.
Perhaps I need to update ads & xdf file? If so, HOW do I do that??
(I have the new files, [TPRO520.ads & TPro500Vehicle0.xdf] just can't figure out how to upload them to Maftpro).
the tpcu program &/or the "update" app/programs don't allow this.

Thank you for your continued support!
 
heated o2 will not affect the Pro at all. the issue guys have is connecting a wideband, the plug-and-play harness cross connects the stock O2 and wideband, so that just needs to be fixed.

What exactly is THE FIX?
I just installed a wideband in hopes it will help diagnose the other problems I have going on.
(but I want to fix the maftpro issue first).

Also, considering I am MAFless, trying to use the MAFTPRO in SD mode, is it necessary to have a "Tuner Pro" chip?
I'm willing to acquire one if need be, right now have a TT 5.7 chip.
 
you can run the TT chip, some of the stuff the pro can do doesn't work without the matching chip (spark advance control and WOT A/F ratio control)

update to 5.27 (attached) then do a memory reset (hold the left 2 buttons when powering up, and keep them held until the display says that the memory has been reset.)

(it might be the right 2 buttons, its been a while)

then go thru the config and settings menu and adjust to match your setup (use GN stock for the F Out mode). the car should start and run then, and you can work on tuning.

leave the wideband unhooked from the Pro until the basics are working.

Bob
 

Attachments

  • TPRO527.zip
    42.6 KB · Views: 50
Update:
I have replaced the spark plug wires & updated the MAFTRPRO to the latest version (5.27 using above attached files).

After doing the above, and using just the factory settings for Maftpro:
For whatever reason, the stumbling issue is now gone.
The car is running rich at idle & whenever I give it gas (puffs black).

I made a few adjustments inside Maftpro, which helped a little, but now still blows grayish smoke when I give it gas.
If I just let the car idle, it does not smoke at all.

I have not made any adjustments on the TT chip yet (for fueling, so the settings are whatever came as default).

the attached log for PL:
the CEL is not on when I start the car (and doesn't come on when car is cold)
{The code thrown is 23; IAT sensor (low temp)}, it only triggers after the car is warmed up to temp. (WHY?)
I have just replaced the IAT (yesterday), plug & wiring looks good, but it still throws the code. Any ideas?

start temp was 158 when I started the log, so CEL comes on soon after log starts.

Theres a few revs in park (up to 3k on tach, but PL shows its more?)

about frame 4500, I stick it in drive & do a brake torque, once, then shut car off.

Car still feels lacking in power, no tire spin (whereas it use to at about 2200 rpm), and still running rich (exhaust smoking while doing brake torque).

Can you see anything wrong here with the PL file?

Car has Alky setup, but is off for now. Wideband also not connected yet.

MAFTPRO Settings: (note, I am still learning to tune with this)

config setup
cfg: flowerror mode: sd/maf
aux1 mode off
f-in none
afr srce none
vout2 set max setting
vout1 spark control
fout mode gn stock maf
baro mode sealevel
load source use map
map source gm 3 bar
airfl mode speed density
displ 3.8
#cyl 6
veh sel 0

system setup
spkbase 15
ve table #1
fe smooth 30
iat airflow 15
tm correct 1.23
tm base 0.0
f out max 0
hi load pt 143.0
mi load pt 100.1
lo load pt 48.1
afterstart 0.0
vout2 max 4.000
vout1 max 2.560
main scale 0.0

boost control (not using yet, but plan to once issues are resolved):
tps spool 2.000
rpm spool 3040
tps start 3.700
psi start 10.0
dc% start 22.0
psi set 20.0
psi aux 20.0
gain 4.0
dc% st aux 22.0
max rpm 5024

afr tracking
min tps 3.000
min rpm 2592
min load 166.4
lean lim% 10.0
rich lim% 20.0
gain 4.0
afr2000 12.0
afr3000r (to 8000r) 11.5
aux % 0.0
af trdecay 0.0

airtemp, all 0
tune hi load, all 0

tune mid load, @3400 (&lower) -1.0% - @4000 (&higher) 0.0%
tune low load, @2200 (&lower) -1.0% - @2800 (&higher) 0.0%

tune response
tps enrich 0.10
tps decay 0.80
tb size 7
tps mapmax 85.8
map enrich 0.10
bst enrich 0.10
map tpsmin 0.600
map rpmmin 2560
maflim tps 0.600
maf limit 0.0
maf /krpm 2.5
lim minrpm 1504
lim time 2.0
offidle% 0.0

spark wot all rpms = 15.0
spark aux/mid same as above

pt tracking idle tps 0.540
idle rpm 1280
idle a/f 13.5
cruise tps 1.300
cruise rpm 3008
cruise load 91.0
cruise a/f 14.5
lean load 84.5
lean delay 10.0
lean a/f 16.0
gain 15.0
enabl dly 90

(i dont know what this ETPS is/does):
etps rpm 4800
etps load 166.4
etps gain 12.8

thanks for the continued help!
 

Attachments

  • idle 2500 revs brake torque.dat
    623.1 KB · Views: 57
sounds like a bad connection at the pcm harness connector , same prob here ,wont read o2 properly o2 is around .355 pcm reads .255 ,car wont charge under 1200 rpm , scan tool sees 7-15 volt fluctuation at pcm , is the grey smoke blow by or rich fuel setting ?If your engine coolant sensor isnt getting the right voltage and returning it to the pcm it can cause all sorts of headaches ,timing , fueling ect . your getting a good o2 signal right up to your pcm connector i bet and nothing on the side that attaches to the pcm . Ground strap from engine to firewall clean and tight . If you figure out how to clean the pcm harness contacts effectively let me know how plz
 
Top