Does not start when cold and back fires in the motor

you meant CARAVAN? or grand caravan with
no engine told. size , 4 engines, 2.4 to 3.8L v6
so does not START and run
or does start and runs and stalls. (or runs for 3 seconds and stalls)
or stalls driving random. hot or cold engine,?
the starter motor always works perfect, spins GRRRRRRR and engine spins crank shaft fast or now, or starter is some times silent or just clicks.???????????
back fires to where? the rear car tail pipe end?
or to intake manifold (air cleaner side)>>>>>??????????
back firing to air cleaner , hits of gross timing of cam , burned intake valves.

tail pipe backfire can be what is called muffler explosions super load POP sounds, and is engine gross raw fuel lander there, mostly from leaking injector(s)
check engine lamp never glows, running or just before stall.
scan the PCM yet see stored DTC errors. (like CKP fails)

no engine told so hard to be more exact. above is generic.
ASE generic , gas engines,
if stalls driving can a fast right foot save the stall and if yes, do you still have full engine power.?

the 3.0L has a 2 cam timing belt(plus pump)
that fails easy, it slips and timing is lost !
and backfires every which way .
it is a 60k mile service point.
this 3.0L same belt runs water pump and you never want it to slip.bad belt too.
V6, 1 cam per head free running engine. (no bent valves) like the DOHC will do. 12v 6x2 heads no 24valve .

but no VIN or engine told.

is your electric fans running constantly. and most times then not you`ll need a water temp sensor or water temp relay. usually the temp sensor on that model comes usually next to the thermostat with a little wired plug on top. or on the radiator. either way pull the plug while the motor is cold. unscrew the sensor and screw the new one in and replace the electric plug back on top of the sensor. 2 things: Cold motor, have every thing set up and ready because when you take out the sensor the coolant will start to come out. you will not loose much if you work quick. keep rags or paper towels below the sensor to keep coolant off the motor and smelling when it gets hot. you have also pour or hose off coolant after your done installing the new coolant temp sensor.

hello Dennis. (no miles stated)
what engine, 4.0L I6 2.5L? I4
ever tuned it up? all spark and filters, the 60k mile, ever?
this post is random engine stalls?
so does it stall hot or cold or both
does it stall moving, right foot planted, cruisng
or only parked, or only as you come to a stop
do dash lamps/gauges or? go out before the stall? (look)
CEL off running.. ok, no DTCs stored if USA car. is it?

my guess is this stall can happen hot or cold engine.
location not in klondike (location not stated, so wild guess.)
hot stalls, ?
1 lets say coming to a stop. is very common EGR sticking open
2 never tuned up, ever or even the last decade?
3: ISC/iIAC sticking closed, jeeps love to do that any I4 , its a big issue. the idle stepper motor cone gets gummed up, clean it.
i clean both my jeeps, I4 ISC like 100 times since 1988.
4: bad TPS. but usually it throws DTC'S for this. if driven hard)

some I6' have no EGR valve. PCM has no EGR pins.!
you can monitor DC power at the CIG lighter, to see if power drops
at stall, easy, 13.3v to 15v is normal or ALT system is dead..

make sure the Automatic shut down relay is not being shut down
by PCM (DB/YL wire) goes to 12v is shut down, 0v is not.
the PCM can cut the ASDR for may reasons, oil pressure or battery overheat,? many, best it to find out of this RELAY is dropping EFI
off LINE. IT can .

lets do stalls.
i see tachometer drop below 800 RPM hot .
i try to save the stall, ISC stuck closed, and my right foot
opens throttle instictively and i save the stall.
easy, that is loss of air. see why?
on mine the stupid, ISC/.IAC works like this
the PCM remembers to ISC positions (stepper)
one cold start and one hot start (a secret i learned)
it then looks at water temps and guess (math) at a best start position.
if it used hot ISC for a COLD start the engine will want to flood due
to valve mostly closed, from last hot shut down,.
so floods, use right foot 10% ,

so i cant comment on what it might be until you state (displacement)
the engine temps. at fail
the operational mode, parked, stopping or between 5speed mt shifts.
or what?
if it fails parked in drive way.
or only moving or only coasting.
stalls on the fly?

im online at alldata.com and there are 16pages for PCM only.

this car the PCM controls the Alternator, (a software reg)

now another tack.
the car in usa, as OBD2, i connect my scan tool
and log, i drive and log. car stalls
i drive home ,play back my logs, and bingo
i see what happens at the stall, all sitting at my desk.
warm and dry.
lost comms,?. is DC power lost.
Pending DTCS
real live DTCS
some DTCS auto clear, at die.
some PCMs will reset the CKP or CMP sensor or spark failures.
so can only be seen live. (watching, 1 more secret)

now Bar stool answsers (any EFI car)
ever tune it up, ever do the 60K>? if not why not now?
lost spark, see if spark is being lost at stall, (at all plugs)
bad fueling, (too high or low fuel pressure at stall)
loss of air (ISC/IAC failed)
EGR (if there) stuck wide open,


if the engine runs perfect at most times, its probably ok
so is bad spark or fuel
spark is first. but not if never tuned up.
fueling is last to check , as PCM cuts fuel with spark failure sensed.
bad fueling can be bad injection or total loss of air supple , at idle.

Your vehicle uses the coolant temp sensor and the intake air temp sensor to determine the engines temperature on a cold start. If one of them is dramatically different than the other it will flag a code.

Is the check engine light on?

When was the last time you had a tune-up? if recently what brand of plugs where used?

Have you noticed any hard start issues after a hot soak? A hot soak would be driving the car until fully warmed up, shutting of the engine for approximately 15 to 20 minutes, and then starting the engine again.

I’m happy to assist further over the phone at https://www.6ya.com/expert/jeremy_d728a59f986299fa

PUT A SCANNER ON IT AND CHECK THE TEMP READING FOR THE COMPUTER IT IS MORE THAN LIKLY BAD LIKE IF ITS 40 OUTSIDE THE SENSOR IS READING 90 SO IT DOESNT GIVE IT THE EXTRA FUEL IT WOULD NEED WHEN COLD

Sounds like the coil has gone bad. This is usually the syptoms of this. When it is in the non crand status cool the coil down quickly with ice and see if it doesnt crank.

Let your engine warm up with the rad. cap off and see if the coolant level drops. and make sure your overflow is full. It blows cold air because there is no water getting to the heater core. And it shows a normal(ish) temp because the water needs to be touching the temp. sensor. I really do think there is air in the system and there is not enough coolant but hard to tell from here. Also as with overheating any time make sure to check your oil and look for any coolant as the head gasket seldomly holds together if the motor overheats.

cold start device ?? need changing

Naaaa.Old wives tales.I grew up in northern NY and back in the day,30 years ago,the climate was much more severe than today.I have seen -40 below up there.Block heaters back then were necessary for especially diesel trucks,as they do NOT like to start in those temps.Gasoline engines with today's fuel injection and computerized engine controls have no need for a block heater as they will fire at the hit of the switch immediately in those temps.Old carbureted cars from 30 years ago normally would NOT fire right up at -40 below WITHOUT a block heater.The only reason i can think to install a block heater is that you will have instant heat when you get in the car.If you are worried about accelerated engine wear because of extreme temps,then by all means install one,or just have a remote start installed,fire the car in the morning and let it warm up 10 minutes at idle before you drive it off.I have a certain relative in N.C. that does this in the summer time.Start the car out in the driveway from inside the house via the remote start,let it run for 10 minutes with the A/C on high to COOL it DOWN,lol.

your battery is about to die....