My daughter's 2004 Neon has developed a nasty shudder at about 2000 RPM, and I'm looking for some help diagnosing the problem.

A little background..

A few weeks ago, the transmission cooler line inside the radiator let go. Both the coolant and the transmission fluid were ruined.

I've replaced the radiator, thermostat and hoses. I've also completely flushed the cooling system.

I drained the transmission and replaced the solenoid pack and both speed sensors. I then had the car towed to a local dealership and had the transmission completely flushed using one of those machines that keep the good and bad fluid separate.

The shudder started a few days after the transmission flush. For a few days, the car was fine. It still shifts fine, but at 2K RPM, it shudders pretty violently. It's like driving over the rumble strips they put on highways. If I accelerate or come off the gas, the shudder seems to go away.

The car also has a misfire on cylinder 2 (code P0302). I do not believe it's related to the shudder, as it existed before the shudder started. See my othe r thread for details.

I'm looking for any ideas on what would cause the shudder, and what I can do to fix the problem.

Thanks in advance for the help!

Ron

 

How long was the car driven with the ATF/Coolant mixture?

 

We're not entirely sure if there was a small leak that slowly developed into a complete failure, or if the cooler line failed catastrophically.

If the cooler line leaked slowly, we have no clue how long it was leaking. If it failed catastrophically, then it was driven no more than two miles afterwards.

The mechanic who looked at it initially felt it was a catastrophic failure. His reasoning was that not only would the transmission slip, but the coolant would fail to protect the vehicle from overheating. Since the transmission slipped but vehicle did not overheat, he reasoned the line must have failed catastrophically.

However, I did not take the old radiator apart to see if I could determine how badly the cooler line failed.

 

Determined that the shudder is from Torque Converter lockup.

Next question, does that mean I need a new torque converter?

 

The reason I ask is an ATF/coolant mixture will destroy the...clutch plates is it? The line doesn't fail; it's really the transmission cooler fittings coming apart causing the ATF and coolant to mix. If it is caught quick enough, usually a good flush (the correct way, i.e.- not using a machine) of all the fluid is the best. Is there a stored code for the T/C?

Causes of P0302 could be:
INTERMITTENT MISFIRE
VISUAL AND PHYSICAL INSPECTION
IGNITION WIRE
ASD RELAY OUPUT CIRCUIT (COIL)
ENGINE MECHANICAL PROBLEM
IGNITION COIL
COIL CONTROL CIRCUIT
SPARK PLUG
CHECKING FUEL PRESSURE
FUEL PUMP INLET STRAINER PLUGGED
RESTRICTED FUEL SUPPLY LINE
FUEL PUMP MODULE
CHECKING FUEL LEAK DOWN
FUEL INJECTOR OPERATION
ASD RELAY OUTPUT CIRCUIT (INJECTOR)
FUEL INJECTOR
INJECTOR CONTROL CIRCUIT
PCM (IGNITION SYSTEM)
PCM

 

You need to fix the misfire first and ck to see if the shudder is gone. If the shudder is still there,then as darthroush had said the coolant/atf may have contaminated the clutch disc.Also ck for any stored codes in the tcm too.

 

Being a 2003+ Neon, the TCM is integrated into the PCM. "One-stop-shopping" for codes.
Agree about fixing the misfire first though.

 

Thanks for all the replies and information. Waiting to see how my daughter wants to proceed. Based on everything said here, we'll look into the misfire before we deal with the shudder.

 

fix the shudder

check to see if its just a faulty plug/wire by swapping other plugs and wires around and see if misfire code moves to other cylinders

then check the TC lockup solenoid for proper operation. TC's are pretty basic there is only a couple of things that an fail in them.

I'd bet that its something electric not mechanical

 

Plugs, wires and coils were all replaced. Still got the misfire.

Is the TC lockup solenoid part of the solenoid pack that sits at the bottom drivers side of the transmission, or is it something else? The solenoid pack was replaced at the same time the plugs, etc., were replaced.

Thanks for the tips!

Ron