NEED A PROFESSIONAL DIAGNOSIS (SOLVED!)

[^^!SPAWN!^^]

No connections broken on my sensor , it's just failing ...

[ryansouthman]

u try cleaning trottle body??

fuh real

[Rodn3y]

yup qg naturally lazy between 40 to 90 kmph... like it jus hits a low spot right at that speed and then you feel the power again. well daiz my qg16de nyways..

so turbohead.... 20W50 is the oil i should use in my QG. i recently changed to 10W30 and i find the car not performing and using a lot of gas (extra) plugs are denso IK16. injectors were serviced and i got good mileage for that tank but now it back to bad consumption.

i used chevron tranny oil - could your tranny oil affect gas consumption is is it my engine oil?

[^^!SPAWN!^^]

Well guys here's the lastest update :-
The mech who scanned my vehicle told me the air flow sensor is failing and to replace it . I went out and got one , had it replaced this morning , getting the SAME problem (Holding back , I always have to mash right down to get a kick to keep going) , now he telling me to check the brain box because that failing also , WTF ? Is he a quack or what ? Can anyone really telling me what's going on ?

[^^!SPAWN!^^]

Well guys here's the latest update :-
The mech who scanned my vehicle told me the air flow sensor is failing and to replace it . I went out and got one , had it replaced this morning , getting the SAME problem (Holding back , I always have to mash right down to get a kick to keep going) , now he telling me to check the brain box because that failing also , WTF ? Is he a quack or what ? Can anyone really tell me what's going on ?

[eitech]

lawd have mercy....

[^^!SPAWN!^^]

Yeah that's what I said , and I looked like this also >

[Hook]

well when u check diagnosis charts in engine tech manuals once u change a supposed trouble component and the problem still exists then it's the ECU at fault

BUT...first some questions

did u reset the ECU after changing the unit? or did u just change it and expect the ECU to automatically adjust to the new unit?
cuz resetting is a vital part of the repair procedure

also, (provided u reset the thing after changing the AFM and thus cleared the old error codes) when u said u got he same problem even after changing the AFM, did u get a CEL warning this time as well? and if you did, was the error code pulled the second time around?

[^^!SPAWN!^^]

Well the ECU was reset after the part was changed but not immediately after , did not get a CEL warning ..

[eitech]

ok, so i jus re read da ched. tell me this: did these symptoms jus happen overnight or did you do sumtin and then this happened.. and d rims u have, are they d bsa 15s?

[^^!SPAWN!^^]

No didn't happen overnight , was happening before but not so bad , now it getting worse , the rims are 15's Ziglas , what rim size have to do with it ? It was working normal when I change the rims , the recent thing I did was an all around service , and I even changed the air filter (don't know the brand it's a bright red one ).

[eitech]

diagnosin these newer engines can be real expensive...ah dunno how tuh advise yuh again

[^^!SPAWN!^^]

Thanks bro for the support , I wish I knew what I can do , I wasted 500 dollars buying a sensor and that's not even the problem .

[korolla]

Just a thought, did you check the catalyst in your exhaust to see if it clogging?

[^^!SPAWN!^^]

^^ There is no catalyst , it was removed a while back . The cat convertor right ?

[Hook]

Well the ECU was reset after the part was changed but not immediately after , did not get a CEL warning ..

well boi, I dunno what to tell u again...if the AFM was the problem as shown by the error code and u replaced that and have no more error lights, then the problem should be solved...u sure you reset it properly?

disconnect the negative battery pole and press the brake pedal and hold (this gets residual electricity out of the system)...leave the pole off for abt 15mins then reconnect and start the car and let it idle for about 2-3 fan cycles

[^^!SPAWN!^^]

Hook , when the mech told me to change the Air Flow Sensor , the check light was not on , he did a scan and told me that everything leads back to the air flow , he said when you mash the x pedal it suppose to climb but instead it's dropping , don't know what he talkin about .
By the way is there a difference in disconnecting the negative and the positive battery poles ? Jus asking .

[eitech]

For the MAF, If the ECM detects a malfunction, it could be fuh 1 of 2 reasons..1)An excessively high voltage from the sensor is sent to ECM when engine is not running.
(Harness or connectors
(The sensor circuit is open or shorted.),
Mass air flow sensor.

2)An excessively low voltage from the sensor is sent to ECM* when engine is running. (Harness or connectors
(The sensor circuit is open or shorted.)
+ Intake air leaks
+ Mass air flow sensor

In the second case, my manual says that the ECM, enters fail safe mode and the check light lights up..

all dis info is from my qg15 manual..i guess he was checkin d sensor signal voltage

[^^!SPAWN!^^]

^^ Hmmmm (Strokes beard and thinks about eitech's theory)

Yes it does make sense .

[^^!SPAWN!^^]

Another thing I just noticed , I started the car , when it reached it's normal operating temp , i depressed the x pedal and released it , did it a couple of times and I getting a flat spot in between .... Could that be throttle body or injectors ? Because they both were serviced recenly .

[eitech]

ah never understood dat term "flat spot"

[^^!SPAWN!^^]

ah never understood dat term "flat spot"

Flat spot is basically another word for sputtering , what I'm getting is a slight "sputter" when I depress the pedal right down and release a couple times to see if it would rev smooth .

[eitech]

ok. while d car is idling, can ur rev to bout 3000rpm? i jus checkin a trouble guide chart here

[eitech]

i have a chart here but dunno how to post it

[eitech]

ok, it's like this...for hesitatio/surging/flatspot.in order of inspection:
These are the 1st set of things to check

.Incorrect ignition timing adjustment
. Incorrect throttle position sensor adjustment
. battery/Alternator circuit

These are the 2nd set of things to check
. fuel pump circuit
. injector circuit
. IACV-AAC valve circuit
.Ignition circuit
. EGR volume control valve circuit
. egr system
. Mass air flow sensor circuit
. Heated oxygen sensor 1 circuit(front)
. Engine coolant temperature sensor circuit
. Throttle position sensor circuit
.Knock sensor circuit

These are the 3rd set of things to check
. Main power supply and ground circuit
. Air conditioner circuit
.ECM
.PNP switch circuit


These are the 4th set of things to check
.Fuel pressure regulator system
.Evaporative emission system
.Positive crankcase ventilation system


These are the 5th set of things to check
.fuel pipin
.poor fuel
.Air duct
Air cleaner
Air leakage from air duct (Mass air flow sensor throttle body)
Throttle body, Throttle wire
Air leakage from intake manifold/Collector/Gasket
Cylinder head/ cylinder gasket
Timing chain
Camshaft
Intake valve
Exhaust valve
Exhaust manifold/Tube/Muffler/Gasket
Three way catalyst
Oil pan/Oil strainer/Oil
pump/Oil filter/Oil gallery
Oil level (Low)/Filthy oil
Radiator/Hose/Radiator filler cap
Thermostat
Water pump
Water gallery
Cooling fan Coolant level (low)/
Contaminated coolant

These are the 6th set of stuff to check
Cylinder block
Piston
Piston ring
Connecting rod
Bearing
Crankshaft

I know it look real overwhelmin but the chart did a lot bettr job and made it look easier. of course the 5h and 6th group are very far down d chart..dats why dey have dat order of checkin...

[Hook]

wow...good stuff, eitech

since you two are QG guys, and u seem to have a good idea of what the engine is about, why don't u guys link so you could him troubleshoot it?

[eitech]

it's no prob but most of the stuff has been mentioned here already...i know the basics. one can only do so much with a fluke..sometimes u really need a scanner to PROPERLY analyze a situation...

[Hook]

true...but a lot of problems can be solved with a VOM and a tech manual that lists the error codes and tolerances for sensor specs and voltages...I would like to know what ^^!SPAWN!^^'s problem really is

[eitech]

yea, mite tek a lil time though. i now readin a part here and they show u every sensor description and what readins to expect under certain conditons...

[^^!SPAWN!^^]

ok. while d car is idling, can ur rev to bout 3000rpm? i jus checkin a trouble guide chart here

Uh my wagon doesn't have the RPM gauge so I doh really know .