Hi there,

Im trouble shooting the MPV milage 143576Km.

first thing engine light is on it was P0300 random miss firing. And I remember fuel too lean bank 1 guess.
doesn't show engine light again after deleted. But still feel miss firing the time.

then I check bank 1 spark plugs, looks like lean condition.

I put OBD2 again and shows P0172 system too rich bank 1. but its only pending, no memory or recorded.

so I check live data on idling after warm it up engine.

FUel sys 1 CL
Fuel sys 2 CL
Calc Load (%) 20.3 to 21.1 moving
ECT(F) 210
STFT B1 (%) -4.6 to 3.7 moving quick
LTFT B1 (%) -25.0 to -20.3 moving once a while
STFT B2(%) -5.4 to 1.5 moving quick
LTFT B2 (%) -17.9 to -12.5 moving once a while
Engine rpm 705 to 679
Veh speed 0
Spark plug adv 9 to 12
IAT(F) 118 to 122
MAF (lb/min) 0.547 to 0.514
TPS(%) 0
O2S B1 S1 (V) 0.860 to 0.060
O2S B1 S2 (V) 0.130 to 0.075
O2S B2 S2 (V) 0.825 to 0.075
O2S B2 S2 (V) 0.140 to 0.065
MIL DIS (mile) 0

actual fuel presser idling or key is on 66psi spec 61 to 66 psi
won't keep fuel presser after 3 hr, went 18psi. Check at least after 5 min off the ignition key. Spec more than 25.5 psi.
this car has only one fuel rail.
but engine start right up.

drive fine after check spark plug and fuel presser but shows the pending error code and the live data.

now I search for it little bit.
the LTFT shouldn't be the number like -25.0. usually stay around 0 +- 10.0?
I think the B1 LTFT show too lean. So gives error code for too rich..

also got some specification
intake MAF(g/s) 3.3 to 4.7 at idle
engine load calculated value(%) 18 to 20 at idle

intake MAF(g/S) 12.1 to 15.0 at idle
engine load calculated value(%) 17 to 19

Live data at around 2500rpm on parking
Fuel sys CL
Calc load 15.2
ECT 212
STFT B1 -4.6 to 0
LTFT B1 -4.6
STFT B2 -2.3 to 0.7
LTFT B2 -0.7

rpm 2463
spark adv 42
IAT (F) 168
MAF (ib/Min) 1.346
TPS (%) 7.0
O2S B1 S1 0.790 to 0.115
O2S B1 S2 0.700 to 0690
O2 S B2 S1 0.810 to 0.095
O2S B2 S2 0.750 to 0.745

I tried remove air filter and check. Nothing change.



now I'm going to check PCV valve, purge valve, EGR valve and rear bank spark plug(B2).

what else should I check?
is there any more information for this problem?

wondering is any possible to happen like this problem when cat converter plug it up?

thank you for read this and thank you for your help and information.

Thoughts:

. Replace the spark plugs with the same NGK plugs that originally came in the vehicle. Gap plugs to spec. Lightly coat the porcelein and top electrode with dielectric grease. Ensure each coil's spring electrode is positioned directly on the plug.

. Examine the wiring going to each fuel injector. Look for anything that's suspicious; e.g. breaks in insulation (due to mice), partially broken wires, or questionable connections. These factors affect the wave forms coming from an injector, if you back-probed the proper ECM pins and you were using a scanner.

. Check engine compression and look for vacuum leaks.

. Replace the coil to any marginal cylinder.

. Check/replace Camshaft Position Sensor.

OK, I did change spark plug and check all vacuum leak.

I check calc load is should go up close to 100% when open wide throttle.
But only went 62%.

I also found people say this engine MAF sensor goes bad a lot.

So looks like cat converter or MAF sensor after read lots of people posts.

Anyway I will wait little bit and if I really need it I will change MAF first and if won't fixed change cat.