When does the distributor need replacement?

[fixkick]

just to show odd things happen. (random)
my 96 had an  induction air leak , the top rear huge aluminum air pipe (maf to TB) had a rear left (right facing it) mount snapped off, it as just dangling on the head mount it fits to.
this was sucking air like mad causes MAF to read wrong, causes what is called UN METERED AIR. (and power loss and surge as engine shacks and crack size varied, yah nuts.)
wild effects it caused,
so finding problems can be very hard.\

OXYGEN (B1S1) Front)
o2 (front) pulled forces righter mix, fuel. and runs better , so that big  hint says engine fueling is (was) lean.
ever run the 02 sensor in the full O2 meter mode, plotted, and drive. like below.



this happens hot idle or light flat cruising at 45mph or near.

the front 02 swings, that swing is a loop, (firmware ECU ) that adjust fuel mix 6 times a second about. the ECU hugs for perfect fuel mix this fast,  see it below.
note the center point too, not offset. it swings near 0.45vdc. center point, O2 goes off line WOT normal, so only do idle and easy steady cruise , right foot steady./


and exhaust manifold crack or gasketi bad sucking ear wrecks the front 02 horrible. or just enough,  air is 20% O2 so slams the sensor to death 20 times to much 02.
the bottom header end DONUT  ring gasket bad, or loose or clamp bad too , same thing. bad.

any good scan too can plot any sensors an for sure 02. and do and X/Y plot. live in real time (near enough)

Unfortunately the tracker computer does not seem like it wants to set codes or even put things in pending.
I can unplug a spark plug briefly and no pending codes get set unless I leave it disconnected for a few seconds like >5.
spark plug  #1 shows P0301 if pulled. ?
The engine needs to be warm, not dead cold. and 5 seconds is not a long time. (the ECU busy doing  all spark and all 4 injectors , so Dtc can roll out sllow )

Unplugging the OBD sensor took several minutes to set a code and turn on the check engine light. I use a portable engine monitor and a wifi obd adapter to phone and neither sees any pending codes.

Misfire/or whatever it is maybe every 2-3 seconds. I can hear it and feel it by putting my hand on the engine during fast idle. Engine stays still visually. I will try doing some type of logging using the OBD phone app.
I have an entire tracker for spare parts at the moment so I could try swapping things and seeing what it is. (spare parts GREAT)
i did. check fuel pressure last year and it passed the tests you put on your website.

odd that is,,  does the car have a  good working dome fuse , this  fuse powers the ECU DTC memory,bank inside,  if fuse blows the ECU can not store DTC  errors at all.
a real scan tool can do pendings, some cheap ones  are just cheap code readers.
a scan tool real  can do all that and plot live sensor data.
 

the 4 chapters  on topic , FSM factory service manual are (but the maker lost these (no me ,him)  these cover fully how all DTC test are done and rules for easy, for sure driving cycle rules.
Volume 2, Section 6e3-A Part 1    Fuel Injection VIN 6
Volume 2, Section 6e3-A Part 2    Fuel Injection VIN 6
Volume 2, Section 6e3-A Part 3    Fuel Injection VIN 6
Volume 2, Section 6e3-A Part 4    Fuel Injection VIN 6


part 3 covers misfire.   (hidden here) page 11 part 3

  https://web.archive.org/web/20101119080203/http://acksfaq.com/96-FSM-v2-6E3-A-part3-pdf.htm


case in point fuel tank must  be greater than 15% or P0300 or these monitors are dead (off line) not sure why but is.  my guess is the pump sucks are and causes false DTC P0300
a steady throttle or idle, NOT accelerating

a good scan tool can see pendings and also freeze frame, if a DTC sets and clears fast,  (say CKP sensor is flakey) the freeze frames shows it DID and conditions at failure. (RPM etc)

is your gas tank near empty?

same page 11 says,  DTC will not show up until 5 seconds from engine startup
and P030x  errors DTC as they set, make the CEL blink like mad,  the blinking means CAT damage is happening soon. (over heated cat) from super rich fueling (no spark X)

is #4 exhuast header tube cracked? making 02 top (B1S1) go NUTS?  S1 is top,  S2 is behind cat.

the only way I know to test for DRIVE_ability  problem (misfiring , spark, for injection, or intermittent sensors) is to use scan tools that log any data you want.
not all problems can be found parked in a drive way some need driving to find them or up hills. flogged.
seeing DTC come and go, finds  a problem.
seeing sensors going dead driving.

all comments by me assume , fuel NOT bad, compression good.,  spark parts tuned up. injectors cleaned. 16v. fuel pressure is good at keyon, and it IDLE BOTH (16V rule !!!)
the scan for errors, scan for intermittent sensor (NO BLOWN or missing DOME FUSE !)
scan for hot 180f, engine DTC parked idle and gunning throttle, and driving.
Thermostat factory temp,180F and not 150f allowed, ever, up to 195F thermostat are sold and work great and is a valid temp in this case.



see what a real scan tool can do, for sensors scans.  the bottom blue is 02 S1 swings like mad (good) VSS is vehicle SPEED. I can watch 12 sensors or parameters at once. driving./parked
 

I can drive and log raw data too, to CVS fails for EXEL plots

this is my bad THERMOSTAT 1996 takes for ever to warm up. and lands on 160f, wrong that TOO !  and perfect MAF readings here, VSS is speed, TP is TPS throttle angle.
this is a 20 mile on road test, and spikes are me doing WOT (wide open throttle to see if MAF really does work) and does. (Excel graph data)


in a nut shelll
good engine good compression 180psi is good.  1996 Geo Tracker 1.6Liter 16valve. , pulls 183-185 PSI on all 4 cylinders. (warm )
good spark, mag wires work best on this weak spark system !
fuel pressure Static test:  1.6L KEYON-nostart ---Suz 35.6–42.7 psi     ( this is same as WOT at no/low vacuum present)
at idle is 6 psi less, must be,   so if above  is 36 (mine is) it drops to 30 PSI at idle. (19" of idle vacuum is that)
if the drop test fails the FPR IS TOASTED.(bad)
no exhaust crack near 02 top for sure #4 exh. man. tube not cracked as most are, from  limphome mode tortured.
FPR vac tube  not leaking fuel (drips) is bad.
DTC not set driving or parked,
pendings show none
CEL OUT DRIVING. ALL THE TIME OUT. AND NEVER FLASHING.

Surging while driving is EFI going lean and rich over and over (02 front is bad or being clobber with crack leaking air )



here is why folks do not understand why the exhaust is not just ONLY pressure
this is the PUTT effect,  see POINT B, this is how any exhaust crack newer the 02 ,top, will suck in 20% AIR (atmospheric air is that)
IF O2 top signals look wrong , find cracks.(near)







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