Car (engine?) trouble question...

Sometimes when I start my car, *especially* in cold weather, the "check engine" light comes on and it rides a little rough, especially when stopped and idling.

When it warms up after a few minutes of driving or later in the day, though, I never get that again.

Since the light goes away the auto shop can't reproduce it or find the exact code.

It's a 94 Chrysler T&C V6. Anyone have any idea?

Thanks.

I'd bet its a worn out oxygen sensor. Especially if your van has 100K to 120K miles and it's never been replaced. The car's computer is supposed to store fault codes in memory for a certain number of ignition cycles after the Check Engine Light (CEL) is triggered. You need to get the code read within probably 20 or so trips of when the CEL was triggered, or the fault memory will be cleared until it is triggered again.

Speaking from 13 years of Mopar minivan ownership experience. A couple suggestions:

1) Your 1994 is "pre-OBD II" standard, so you should be able to read the codes yourself, with what Mopar guys call the "key dance". Basically you cycle the key on and off 5 times in quick succession (without starting the car) and the CEL will flash out a series of pulses that you can translate into what CEL code is set. Here's the specifics of doing the key dance and interpreting the codes.

2) www.allpar.com is the "CPF" of Mopar. Go there and browse the tech help section and search the archives of the message forums. I am positive you'll find a wealth of information that's worth spending the time to look thru. You'll also find all the eccentricities, common problems, and solutions pertaining to these hearty vehicles.

2) Alternatively, go to one of the chain store (Pep Boys / Precision Tune / etc) and they will hook it up to their diagnostic machine for free. They should be able to read the code for you and give you an estimate on the spot.

3) While you're there, pick up a Haynes repair manual and you can read up on all the codes and what they mean. The book is pretty well done and is definitely worth the $15 investment.

Good luck,

Dave

Hmm ok, thanks. I got 12, 27, 55. Which means battery recently disconnected, problem with fuel injection driver(?), and end.

I searched the forums and didn't see anything jump out at me, but I'll continue digging. Not sure why it's temperature related.

Thanks, though. Appreciate the info.

Dig here.
Scroll down and find what your driving.

What's the condition of your battery? I'm beginning to think a low voltage condition may be causing my CEL to occasionally come on. A bad battery caused an airbag light to come on in my wife's Honda. Apparently enough voltage is more critical than it used to be.

Geoff

dirty battery cables caused my mom's crysler minivan to turn on the air bag warning light and set a low voltage code.

my grand am has a better code readout system-very easy and simple. Each code is repeated 3 times and there is long pauses between codes. to read the codes you use a paper clip. all cars should be this easy.

I was fixing a friends 89 bronco 302 v8 it's code readout system really sucked

Have your idle air control valve checked out.

most engines run open loop untill the exaust and oxygen sensor are up to operating temp.
some oxygen sensors are heated electrically so that the engine spends less time in open loop mode.
an open heater circuit could cause your engine to run bad untill the oxy sensor heats up.

[ QUOTE ]
Frangible said:
Hmm ok, thanks. I got 12, 27, 55. Which means battery recently disconnected, problem with fuel injection driver(?), and end.I searched the forums and didn't see anything jump out at me, but I'll continue digging. Not sure why it's temperature related.Thanks, though. Appreciate the info.

[/ QUOTE ]
check the connections at each injector.the driver can still be bad but a bad connection/intermittant open coil in an injector will cause the same code.i would unplug all and let it get overnight cold and do a resistance check in the morning when its cold enough to have this issue on startup.you are looking for one that reads significantly different from the rest. all the other advice is good for pm but lets focus on the injector issue first.

I tried poking around under the hood, but to be honest I only have a theoretical grasp of how car engines work, not much practical knowledge.

I scheduled an inspection at a Chrysler ceritifed place (V-Tech failed twice to fix it, tho it cost me a few hundred bucks). Hopefully that will help, and they'll be able to discover the problem.

I think the o2 sensor sounds like a good spot to start. Just unplug it and see if it changes behavior. If the o2 sensor is bad the car resorts to a default value for the richness of the fuel mixture to make the car run. The o2 sensor helps to regulate this to make it burn clean-er.

you could have an injector that the solenoid coil is starting to go bad.(impedance too high or low)
I was getting quad driver error code which is the fuel injector driver error code on my car.
The impedance of the solenoid coil(in the injector) was too low and the driver circuit was sensing the excess current draw.
my car ran rough in open loop mode(cold) then the oxygen sensor compensated and maybe the impedance of the injector increased when it warmed up-then the warm engine ran fine.(not as good as it does now)
finally the injector shorted out.
I should complain to bosch their cheap injector only lasted 168,000 miles-ha ha
this made it easy to find the bad one.(try this on your car before it warms up-while it idles rough)
If you can reach the electrical connector on each injector
simply unplug them one at a time with the engine running.
the good ones will affect the idle of the engine the most.
the bad injector will not affect(much or at all-it depends) the idle when it is unplugged because it is spraying little or no fuel.
Does your van have the 3.0 ohc v6 mitsubishi engine ?
if it does the injectors are on the underside of the intake manifold under the intake plenum.(hard or impossible to reach)

I think all of the other engines Chrysler put in the tc mini-van are ohv v6 engines.

Also all of the engines except the 3.0 v6 are distributor less ignition system-3 coils using the waste spark system.
you need to be careful because you can damage the coils if the secondary does not have a return path to ground that is below the break down voltage of the insulation material of the coil.(actually even if your engine has a distributor
you may still damage an epoxy potted coil if you unplug a cylinder with out terminating it with a grounded spark plug)
My moms Chrysler van has the smallest(cheapest)ignition coil I have ever seen on a car.
So there is another way to find the possible bad injector with out unplugging it.(I hate cars-I really hate working on them)
mount a spark plug so that its base is grounded to the engine.
Stop engine.
unplug one spark plug cable at a time and plug it in to the external grounded spark plug.
then start the engine.
the bad cylinder will affect the idle the least(or the most if it is a paired injector and you unplug the bad one) and if your external spark plug is sparking away you will know that it is a fuel problem.

Some engines run the injectors in pairs-the injector pairs are in parallel driven by one driver circit.
so a failing injector can adversely affect the one that it is paired with.

So your idle may improve when you unplug the bad injector
or you may have 2 sorta dead cylinders(one more dead than the other-maybe)(do all of this when engine is cold-injector impedance goes up-improves with heat in this situation)

So when you find the dead or near dead cylinder/cylinders
and it is not spark start ripping it apart.
if you have paired injectors replace the injector with the inconsistent-too low or too high as compared to known good injector too low-nearly shorted is most likely.(hope you have a good meter)depressurize the fuel system before removing fuel lines or injectors(disconnect positive battery cable-yada yada yada)
Replace all the o rings on any injector you remove from the engine-any o ring that comes out of its bore gets replaced-they are cheap just replace them all-the orings will have swollen up with gas so the replacement ones will be a little smaller.
I think her van used the same bosch injectors as my car.
o ring size width 3/32" I.D. 5/16" O.D. !/2"
My mom's haynes repair manual is around here some where.
I have trouble shot quite a few injected cars I have not seen a bad injector driver yet. (ingnition coils and modules that is a different story)

does the injector driver trouble code indicate a specific injector driver circuit ?
A scan tool may tell you more but that is cheating.
you could have a bad cable harness plug or ground connection or a bad or corroded connector on one of your fuel injectors. I hope this helps

Probably something ultra simple and you found it all ready.