I buy gasoline that contains ethanol however, I add Gum Out All In One system cleaner at every fill-up. This car came with no service records so I am thinking of doing a compression check, replacing the spark plugs and doing an oil change. I may check the cylinder temperatures using a temp gun. any other ideas as to why the engine is running rough and/or missing?


It seems when I accelerate fairly rapidly up to 40 miles per hour, the engine stops missing at speed above 40 miles per hour but that may be my imagination.....

Check for trouble codes first, there may be a pending code indicating a coil failure. Plugs and coils are the likely causes of misfires.

Fuel treatment at every fill up isn't necessary if using a Top tier brand fuel. Using a cleaner every time can dilute the engine oil. I use TopTier fuel and fuel treatment with PEA such as Techron before an oil change.

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OK, I will check the plugs and coils. I was thinking of trying ethanol free gas as well.

it is good stuff!

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

It looks like I will pay more for ethanol free gas. Of course, I am hoping for reduced engine problems so perhaps ethanol free gas is worth the extra coin?

Ethanol is a bit of a disaster when used in engines that are not run for extended periods (think lawn mowers, snowblowers and other seasonal equipment), but I've run my daily drivers on E10 for years with no issues. With your regular use of Gumout, I doubt that fuel system deposits are your issue. I believe that your 4.6 uses a coil-on-plug ignition system, giving 8 opportunities for a misfire. If the plugs have never been changed, that would not be a bad idea, just make sure that the engine is ice cold before removing the old plugs, as Ford's 4.6 and 5.4 engines have very few spark plug threads in their cylinder heads, and stripping the threads by removing spark plugs from a warm engine is not unheard of.

thank you for the update, I just bought new bosch iridium spark plugs for this car. I will make sure the engine is ice cold before changing them out. I plan on doing a compression test first.....

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."

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