Q: Cylinder 1 misfire

asked by on November 20, 2016

Truck is new to me. It has a misfire on cyl 1. I decided to change plugs and noticed a plug wire was off. I replaced all plugs and made sure all my wires were on & it started real hard & idled worse. If I pull the wire that had previously been off it starts easy & idles like it used too. I don't know how long it had been driven with the wire off. Truck had been sitting awhile before I got it because of a knock which was a cracked flywheel. Please help

My car has 170000 miles.
My car has an automatic transmission.

Engine is misfiring Inspection $94.99 - $114.99 Get a Quote

Hi there. From the description you have provided, two things come to mind. One, a blown head gasket between cylinders #1 and #3. Two, an intake valve not sealing ie; broken valve spring, burnt valve. Providing spark to the number one cylinder, allows the combustion process to take place, which is affecting other cylinder performance. A compression test and cylinder leakage test would confirm this possibility. Proper diagnoses should be performed. I recommend having your vehicle’s #1 cylinder misfire be diagnosed and repaired by a certified technician, such as one from YourMechanic.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing


Experienced Mechanic?

Earn up to $70/hr

What others are asking

Just bought my car not to long ago with a decent amount of mods done, I cleaned the cold air intake filter and now it makes a pop.
When it comes to these cold air intakes and K&N type filters, the engine air flow is different than the original and your engine control module may not be able to correctly read the amount of air that the engine...
Soft breaks
When you say (and now my brakes are still soft) this means you had soft brakes before and after the master cylinder was replaced. If you have soft brakes, it is caused by air in the brakes, problems with flexible...
install ac in a no ac car
To convert a vehicle that did not originally come with air conditioning to a vehicle that does have air conditioning can be VERY difficult. I would only recommend doing this on maybe an older classic car. Starting at the heart...
Won't shift out of second gear - 2000 GMC Sierra 2500
Hello. This definitely sounds like an electronic transmission control issue. It could be something as simple as a transmission range selection switch (https://www.yourmechanic.com/services/transmission-position-sensor-switch-replacement) or something as serious as a transmission valve body. You may want to consult with a transmission...
Odd marks on rotors
Hello. This can happen for any number of reasons such as a small burr in the pad material or even a small piece of dirt or debris lodged in one of the rotors. If you are starting to notice changes...
I own a 2000 mercury sable LS DOHC and yesterday I changed my cyclinder 3 coil and my car ran better then ever but I went to start
Hello. There are 2 likely sources of the white smoke - which is engine coolant getting into the exhaust system. The lower intake manifold gasket can leak coolant into the air intake and a blown headgasket - common on these...
DTC Code interpretation
It looks like you're using the Star Diagnostic system. So you are getting Mercedes Proprietary codes. The codes may not be published in a place where you can access them without going through Mercedes. They guard a lot of their...
ABS light is on
Your car is equipped with wheel speed sensors at each of the four wheels which monitor wheel speed while relaying this information simultaneously to the ABS and traction control system which are controlled by the car's ECU. When the ECU...
I have a 93 chevy astro and im not getting spark to from my ignition coil
There is a problem on the primary side of the ignition circuit. If your distributor was not replaced and contains a Hall effect pick-up assembly that can be tested using a self powered “indicator light” that is made for this...

Related articles

A Buyer's Guide to the 2012 GMC Yukon XL
When When you want a huge vehicle with plenty of luxury inside, you’re probably going to be happiest with the 2012 GMC Yukon XL. Key Features The 5.3-liter V8 engine on this full-size SUV isn’t surprising, but its fuel economy...
The Best Used Cars to Buy If You’re Over Six Feet Tall
While While shorter than average drivers can have a tough time finding the right car, it’s equally hard for taller drivers, perhaps more so. If you’re feeling squished, or have to hunch over the wheel to drive, then you’re not...
How Long Does an Oil Cooler Last?
The The heat that the engine produces can produce a lot of damage in the right situation. Making sure that all of the systems on a car that reduce the heat of the engine are working properly is important. The...