PeachParts Mercedes-Benz Forum - View Single Post - 2003 Lincoln Town Car: engine missing, running rough

Diesel911 · #8 06-03-2026, 11:35 PM

In the old days it was typical for an engine to run rough at the low end due to issues with the hydraulic valve lifters. As you increased engine speed the oil pressure would rise and the hydraulic lifer would start working.

This is on a 2012 chevy equinox. I had some rough running issues and pulled the code. It led me to diagnosing that the 2 camshaft timing devices where the issue and it was. Newer vehicles have parts that did not exist on older vehicles.

Also, one would think that if there was a issue with coils that would show up more at higher speeds and eigne loads.

Electrical. Sensors need the proper voltages. Bad grounds and charging system affect them.

Disconnecting the battery and reconnecting it causes your car to have to go back and reprogram itself. If you are going to clean your battery terminals unless you provide a backup battery that is going to happen anyway.

The voltage ripple test, it is called by other names determines if you are getting too much AC voltage from your charging system indicating there is a diode issue inside of your battery. You might be able to get that test done at say Autozone for free.

"AI overview

The automotive voltage ripple test is a diagnostic procedure used to check the health of an alternator. It measures the small amount of leftover Alternating Current (AC) "noise" riding on top of the vehicle's Direct Current (DC) charging system.Why It's DoneYour vehicle's alternator generates AC power, which internal components called rectifier diodes then convert into usable DC power. If one or more of these diodes fail, or if there is stator damage, AC "ripple" leaks into the car's 12V electrical system.This is highly problematic for modern, computer-heavy vehicles because:Sensor Interference: AC noise can disrupt the 5V communication signals between control modules, causing erratic drivability or mysterious system faults.Electrical Damage: High ripple voltage can strain computers and lead to flickering lights or premature battery drainage."