I have the dreaded idle problem that you see all over the web CAN NOT find the answer.
NO CEL
iac removed cleaned
it happens cold open loop when op temp smooths out
all those web topics replace various items with no results I want my truck back and fixed!
so please ideas?
new exhaust manifolds back
170k
recent tune

What problem is it having? Too fast? Too slow? Rough?

https://youtu.be/mfgmGZ3qR0I
NOT MY TRUCK same condition
but i have seen and read others that replaced iac tps map with no results
1000's of topics/post no real answer..

I see some replace upstream o2, I am going to test it this weekend,saw a test online I know a bad o2 will trip CEL,but will a underperforming o2 trip CEL?





p.s. REALLY WANT A NON COMPUTER D SERIES

Hard to tell anything from that video but things to check are of course the pan on the bottom of the intake manifold. The other thing I've found is the wires for the coolant temp sensor behind the thermostat housing will get dry, brittle and flake the insulation off and the wires will short together. When that happens the PCM will see the coolant temp as -40* so it richens the fuel mixture a bunch. This and also a thermostat that is stuck partially open will run the adaptive fuel mixture way rich. So even after you fix these problems you need to clear the adaptive memory by removing the positive battery cable from the battery. Touch the removed cable to the battery negative terminal and hold it for 30 seconds. This does a cap discharge and the learning process will start over so it may not idle well at first. Cycle the engine on and off a few times then drive it for awhile so it can relearn.

you are looking for a miracle solution, it's not that simple. proper diagnosing needs to be done.

did you clean the throttle body also? need to get the crude out of the throttle body butterfly. air needs to pass through them cleanly.

need a scan tool to read the air temp sensor (in intake plenum), MAP sensor, injector time and the coolant temp sensor. sensor can be within it's parameters and NOT set a code. could be reading wrong, computer only knows extreme high or low or open or closed circuit for the codes.,
A scan tool will also read the oxygen sensors, and see what they are doing. again they can be within it's parameters but read wrong for what i is actually doing or needed and NOT set a code.

I have seen the ground wire corroded and give goofy readings to the 02 sensors. it also operates the heater circuit of the sensor ( ground wire is at the driver front cylinder head area)

weak ignition system will show up more during cold / warm up than when at operating temperature. are the cap,wires, spark plugs good? ignition coils go bad all the time.if you have a special spark plug in it, then change them to the normal champion. these hate those bosch platinum especially.

bad intake plenum can be checked by pulling the pcv valve and breather hose out of the valve cover, cover 1 hole and check for vacuum at the other hole. if vacuum present, then plenum is sucking from underneath. any other vacuum leak can cause problems. you will usually see that at the MAP sensor reading.

low fuel pressure can cause problems, low pressure will be more troublesome cold than at operating temperature. (eg) if spec is 37-45 and it is at 30, you will have cold running problems. but probably run ok, maybe a touch low on power. if a fuel injector isn't spraying correctly, it will cause more problems cold than warm.

1 other thing and I don't remember what years have and not have.(brain fart) is the egr valve can be stuck slightly open. Thinking you do not have 1, but just putting it out there, since some years do and some don't. (causes and internal vacuum leak)

you say you here a loud sucking noise, my first thought is fuel issue
somehow, low pressure or computer is closing / opening injector because of some false reading.
alot of these sensors can be monitored with a volt/ohm meter, but you need there specific chart as the reading change with temperature, they are not all the same.

make sure the connectors do NOT any corrosion in them, this causes resistance in the reading and the sensor output signal to be wrong.

Awesome responses you Guys.


Fluctuating idle/die-sometimes-at-a-stop was a pooched plastic distributor rotor in my 01' 360. Easy fix, but of course had to go through the whole thing to figure it out.

Crankcase position sensor?

Above advice is reasonable.

1998 Magnum V8s have computer systems that are OBD-II
Friends that had post 1996 OBD-II systems seem to be very sensitive to battery health. Batteries that were old and still able to start the truck would cause very "squirrelly" problems including an intermittent rough idle.

While troubleshooting make sure you have a good battery and clean ground connections.

On my 1995 OBD-I system the most challenging intermittent problems occurred around 180,000 miles.

I had come and then go warmed up rough idle at first.
Then the truck would suddenly die on the highway, refuse to restart for 10 to 30 minutes, then start back and run fine for hours before having the same problems again.

In the end this turned out to be a plugged up "sock filter" at the bottom of the in tank fuel pump/pressure regulator/ double fuel filter assembly.

The lowermost sock filter was causing the fuel pump suction to "cavitate" when the fuel got hot, which causes very sudden fuel flow loss,

Fuel pump, pressure regulator, and high pressure fuel filter were still good at 180,000 miles,
but the sock filter designed to protect the pump from wear was causing odd and intermittent behavior.

If the o2 sensor is suspect (and it is) try un plugging it. You will need to wipe the computer memory either with a scanner or un hook the battery for 10 minutes or so. Leave the sensor un plugged and drive it. I have seen them cause it, that reminds me, my wife's van has the sensor unplugged for that very reason and I need to pick up a sensor.

Thanks for the replies you are all awesome!
have not been able to test o2 or do anything,am in severe pain
no egr
mopar cap rotor wires
o.e. champions
throttle body spotless
plenum gasket ok
new battery no corrosion anywhere
o2 does not operate in open loop
poor can not afford a scanner or a place that has one unless someone near kingsport ,tn can come help with one
i belive it to be something electrical because when cold it does it shut off still cold starts fine then minute or two back to doing it, if it was mechanical or vacuum leak would always be present not stop and do it on restart.
just dont understand when i try to drive to store mile or so it is popping thru tb how can that not set CEL?
sorry that i am wanting a miracle with no money
are you sure touching battery terms together will not fry the PCM?
once again everone here THANK YOU!!

http://www.gofundme.com/p523e8

You carefully remove the positive cable end from the battery. Touch the positive cable end (NOT the battery terminal) to the ground. The battery is taken out of the system at this point. If it makes you feel better remove the battery completely, touch the two cable ends together, this will drain the capacitors in the PCM and start the learning process over. We do it all the time.

You have no tools to properly diagnose the issue and you won't take it to a mechanic with the correct tools and training to diagnose your issue. You will be simply throwing parts at the truck praying that the next part you install will magically fix the problem. All I can tell you is good luck, say some prayers and maybe sacrifice a chicken or two.

This winter my truck was experiencing some issues including popping. Turned out to be a poorly working coil with weak spark.