Skip the auto shop - Our mechanics make house calls

Q: replaced bad coil pack and new coil not sparking car starts but runs rough engine light on blinks sometimes

asked by on

Car started running rough while driving. tests revealed bad coil pack cyl 1&4. replaced coil still not firing now #6 not firing too. Car starts right up runs rough and even more rough when shift into drive or reverse engine light on and blinks when accellerator is pressed. Car has over 250000 miles but was rebuilt about 10 months ago. Car was operating fine and noticed gas milage began to decrease in last couple weeks this problem started 3days ago. Spark plugs and wires replaced about month ago. Would appreciate some direction to take troubleshooting or a diagnosis. Thank You.

My car has 250000 miles.
My car has an automatic transmission.

A: Hello and thank you for your questions. If...

Hello and thank you for your questions. If your engine was rebuilt about 10 months ago, the question is to determine if the management system has been installed as well. With the symptoms that you are having, it sounds like the coil packs are old and in need of replace. You replaced numbers 1 and 4 and now number 6 is not firing. I recommend replacing number 6, 2, 3, and 5. This will ensure that you have all 6 coil packs that are new.

Just because the coil packs are okay during a test doesn’t mean that they are functioning correctly. Coil packs on Buick vehicles from 1998 - 2005 last between 150,000 to 200,000 miles. I also recommend having your fuel injection system flushed. Unless you have new injectors, the old injectors could cause a cylinder to fail, even though it is working correctly. These symptoms can cause the engine to have a rough idle and rough running during conditions. If you need assistance troubleshooting the rough running condition, I recommend having a professional, like one from YourMechanic, inspect the car and move forward with repairs.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!

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

Get a quote

What others are asking

Q: When I put it into Drive, it won't barely move, but it will reverse.

Hi there. Unfortunately, this sounds like an internal failure of the transmission. One or more of the components inside the transmission that is required to engage the forward gears has failed. The transmission will require replacement or a rebuild. Unfortunately,...

Q: What is causing my warning lights to come on?

Your battery and charging system will need to be tested to see if the alternator is charging correctly. The alternator is most likely the cause of your Charge Light and Battery Light coming on. You should replace the alternator after...

Q: Are the front driver and passenger strut assembly parts the same for the 2008 Buick Enclave?

When I look up the strut assemblies parts on this vehicle the left and right struts use the same part number. They are the same.

Related articles

P0240 OBD-II Trouble Code: Turbocharger Boost Sensor B Circuit Range/Performance
P0240 code definition Turbocharger Boost Sensor B Circuit Range/Performance What the P0240 code means P0240 is an OBD-II generic code triggered when the Engine Control Module (ECM) detects the intake boost...
Rules of the Road For Iowa Drivers
Driving on the roads requires knowledge of the rules, many of which are based on common sense and courtesy. However, even though you know the rules in...
P2428 OBD-II Trouble Code: Exhaust Gas Temperature Too High Bank 1
P2428 code definition A P2428 trouble code signifies that the PCM has detected a problem in the exhaust gas temperature sensor circuit in bank 1, which subsequently contains the number one...