Yup. You got a lot more problems. First of all, you're following a real common misconception, even among some mechanics. The Engine Computer is capable of detecting close to 2,000 different problems. About half of them refer to things that could adversely affect emissions. Those are the codes that turn on the Check Engine light. The light never turns on for the other half of the codes, so saying there's no codes solely because the light is off is totally incorrect.
Chrysler makes reading the codes in Engine Computers much easier than any other manufacturer. Cycle the ignition switch from "off" to "run" three times within five seconds, leave it in "run", then watch the code numbers show up in the odometer display.
The white exhaust smoke does indeed point to a leaking cylinder head gasket. The clue is the level will be dropping in the coolant reservoir. Your mechanic can perform a chemical test at the radiator to verify that. Another test involves adding a small bottle of dark purple dye to the coolant, then you check a day or two later with a black light. The dye will show up as a bright yellow stain that you can follow back to the source. If a head gasket is leaking, the dye will show up inside the tail pipe. Auto parts stores will have the dye, and those that rent or borrow tools should have a black light.
You've created a huge problem by hollowing out the catalytic converter. It is going to have to be replaced. Starting with '96 models, they all have oxygen sensors after the catalytic converters to monitor their efficiency. The front O2 sensors switch between "rich" and "lean" about two times per second. If the converter is doing its job, the rear O2 sensor will switch perhaps once per minute or two. When you remove the catalyst, no change takes place in the exhaust gas, so the rear sensor switches just as fast as the front sensor. That mimics a converter that has totally failed. A fault code will be set and the Check Engine light will turn on.
There's two problems when the Check Engine light turns on. The first is, since it will always be on, how will you know when a different problem is detected? Many of those other problems can be very minor, but will turn into expensive repairs if they're ignored. The second problem is to set any diagnostic fault code, there is always a long list of conditions that must be met, and one of those is that certain other codes can't already be set. When a code is set, the computer knows it can't rely on that circuit to use when making comparisons to other circuits or operating conditions. It will suspend those tests that need the information from the circuit with the defect. With suspended tests, any problems related to them will not be detected, and unless there's a performance problem, you'll never know it. If there is a running problem, you need that fault code to tell you which circuit or system needs further diagnosis. Without that code, you can waste weeks trying to find the cause of the problem.
First you'll need to replace the converter and erase the fault code so the rest of the tests will resume. That is when the other problems will finally be detected and the fault codes will set. When drivers wait to have a problem repaired, it is common for a second problem to develop, but they aren't aware of that. Based on the limited number of fault codes, the mechanic provides an estimate for repair for only what he knows needs to be diagnosed. It isn't until that problem is repaired and the tests resume that the next problem is detected and the Check Engine light turns right back on again. Of course the car owner assumes the mechanic didn't diagnose the problem correctly, or didn't fix it properly, but that is not true.
Monday, July 6th, 2020 AT 12:10 PM
