Ranger 2002 v6 3.0l, hard to start engine warm

[carlitos1082]

Hi there
I have a problem and i hope someone can help me out, my ranger edge 2002 V6 3.0L automatic trans 2wd is having a hard start issue when the engine gets warm (driven for a while), when a try to start it, it will take 3 or 4 seconds cranking the key, and when it starts it will throw black smoke, i have no trouble to start it when the engine is cold nor black smoke, recent services are the following.
1.- Spark plugs and cables on July 2015 with 139k miles
2.- Thermostat and coolant on November 2015 with 142k miles
3.- Oil and oil filter on January 2016 with 144k miles
4.- Gasoline filter, ECT Sender and cleaned de MAF past weekend with 147k miles
Read somewhere on the net that this type of problem was because the ECT was going bad, that's why i repleaced it with a Duralast one, but the problem does not go away, got a OBDII scanner but no codes come up on the scan nor de pending ones.
Any advice is appreciate
Than you in advance

 

[RonD]

Could be a couple of things.

2002 will have the Returnless Fuel system, and at the end of the Fuel Rail(supplies fuel injectors with fuel) will be a Pulse Damper, it will have a vacuum hose attached to it.
Remove this hose and check it for fuel, replace damper if fuel is found in there, it is flooding the engine via the vacuum hose.

Leaking fuel injector is more likely if MPG has drastically dropped, (the above would tend to do that).
All fuel injection computer have a "Clear Flooded Engine Routine"
And it is a good way to test for leaking injector.
After truck is warmed up shut it off and then do this test:
Turn key on
Press gas pedal to the floor and hold it down all the way(this tells computer to shut off fuel injectors and enter Clear Flooded Engine Routine)

Now crank engine, leaving gas pedal all the way down
Engine should NOT start, or even fire at all, no fuel should be in the intake.

As soon as gas pedal is released injectors will start again, even while cranking.

If it fires then gas is getting in, and if engine sits for a bit warm it will get flooded, so hard to start and some black smoke when it does.

After sitting overnight, or for a few hours all the leaked in fuel will have evaporated.


IAC valve, you can tell if this is working and a few other things on cold starts.
Just FYI, you should never touch the gas pedal when starting a fuel injected engine, it is simply not needed.

Each time key is turned on the computer opens the IAC Valve all the way for starting, warm or cold.
So engine RPMs should always go high, 1,500+, when engine starts and then drop to approx, 1,100rpm cold, or 750 warm.
RPM are based on ECT(engine coolant temp) sensor, the colder the engine the higher the idle will be.
As engine warms up computer closes IAC Valve more and more until warm idle, target idle for that engine and trans, is achieved.
Manuals is around 625rpm, autos 750rpm

If that doesn't happen then could be IAC Valve sticking or ECT sensor is giving computer the wrong info(temp)

When cold an engine needs to be "Choked", rich fuel mix and high idle, on a carb that was done with a Choke plate, on fuel injection it must be done by the computer.
Computer bases Choke Routine on ECT sensor temp.
Warm engine floods out on Rich Mix...............

While it is a long shot, it could be your ECT sensor is telling the computer engine is cold when you first turn on the key, even if engine is warm, so computer is sending a rich mix for starting a cold engine, would be a hard start and black smoke, then ECT sensor comes to it's senses, lol, and sends real temp to computer so all is well.

Use scanner to look at ECT temp(engine temp) just before starting engine warm.

 

[carlitos1082]

Thank you for the time for posting.
I will check your advice.
I am getting around 11 to 13 MPG with this issue, before i was getting 18 to 20 MPG (mostly highway)
I can remember that this hard to start when warm issue started to happend when i mechanic cleaned de injectors a few months ago, meaby one is malfunctioning, but a don't get any codes.
I runned the scanner and the ect temp shows 189 degrees f.
Another thing a saw is that the o2 bank 1 sensor 2 is not getting any voltage, don't know if its normal, bank 1 sensor 1 and bank 2 sensor 1 are gettin around 0.5 to 0.75 v.

 

[RonD]

Bank 1 Sensor 2 is the rear O2 sensor behind the Cat converter its voltage should be low .1 or so

.5-.7 on Sensors 1's means engine is running Rich but it will do that when idling, when driving it should be changing quickly but stay between .3-.6, .45 is the sweet spot for correct air/fuel burn, best fuel economy.

O2 sensor voltage has a range of .1 to .9 volts, .1 is a Lean Burn, .9 is a Rich Burn
Rear O2 sensor(sensor 2) should always show Lean because Cat converter is suppose to "burn up" exhaust emissions, so .5 going into Cat should come out .1 if Cat is working, that O2 sensor is there to "see" if Cat is working

What do the Fuel trims show
LTFT and STFT

If you see "-" numbers like -10 to -20 then you probably do have a leaking injector

 

[carlitos1082]

Don't know if it's the same, but theres a line with "shrtftb1s1" reads -0.8 to 0.8 %, "shrtftb1s2" reads 99.2 %, and "shrtftb2s1" also reads -0.8 to 0.8 %,

 

[monstermazda]

The o2 sensor are not the problem.
The computer goes in a dummy start up mode.
Three things I would check
Fuel pressure
Tank pressure
And egr
Have you been going down the road on the freeway and it start the bog down a little or alot? If so fuel pressure can be the problem. Mine did it like that when warn little hard to start but started after driving by the time I get 25 miles on the freeway it would bog down. I pull over and it sounds like we trying to drag race it lobing so bad.
If the tank isn't pressurized and drawing a vacuum it could do the same starving for fuel the opens up.
Egr if it's open 30% to 60% will have a hard start anything above 60% your not going to be able to start it.


Sent from my SAMSUNG-SM-G870A using Tapatalk

 

[carlitos1082]

HI THERE, THANK YOU FOR POSTING, THE FUEL PRESSURE WAS CHECK A COUPLE OF MONTHS AGO, A THINK IT WAS 60 PSI WHEN TE KEY WAS TURN ON (NOT THE ENGINE).
MEABY THERE IS A PROBLEM WITH THE FUEL TANK, BECAUSE WHEN A FILL IT UP, SOMETIMES IT TROWS BACK THE FUEL THROUGH THE FILLER HOSE.
WHEN I'M ON THE FREEWAY IT RUNS VERY SMOOTHLY, THERE A NO BACKFIRES ON THE ENGINE.
BTW, HERES THE DATA THE SCANNER GAVE ME WHEN THE ENGINE WAS RUNING, HOPE YOU CAN TELL ME WHAT IT MEANS BECAUSE I DON'T UNDERSTANT MOST OF IT
DTC_CNT 0
FUELSYS1 CL
FUELSYS2 --
LOAD_PCT 18.8 %
ECT 189 °F
SHRTFT1 -0.8 %
LONGFT1 3.9 %
SHRTFT2 -0.8 %
LONGFT2 10.2 %
RPM 952 rpm
VSS 0 mph
SPARKADV 12.0 °
IAT 106 °F
MAF 0.01 lb/s
TP 20.8 %
O2SLOC B1S12--B2S1---
O2B1S1 0.595 V
SHRTFTB1S1 -0.8 %
O2B1S2 0.000 V
SHRTFTB1S2 99.2 %
O2B2S1 0.085 V
SHRTFTB2S1 0.0 %
OBDSUP OBDII
MIL_DIST 0 miles