Skip the auto shop - Our mechanics make house calls

Q: cylinder 3 and 4 misfire

asked by on

It all started with overheating, then we discovered the cat behind the turbo on the drivers side is blocked. We solved that, it wasn't still working well then I opened it to check for timming issues and I noticed the passenger side bank exuast and intake was off a bit, I then set it back cos am also a mechanic. From time to time I do hear the cam adjusters hitting the cylinder head covers but didn't want to think it could be the cause. Now it's worse, the engine is no longer working fine and cylinder 3 and 4 are not firing at all, even swapped the ignition coils but still the same. Now am guessing the igniters on the air box or cam adjusters making the engine timing shift. Secondly, if the notch and arrow pointing the direction of timing on the cams are slightly off, can it cause a big drop in power to the extent of not firing plugs 3 and 4. Thank you, Martin. My email -martospliff@gmail.com, Audi 2.7t 2000 model year

Hi there. Check the spark plugs to see if they have burn spots on them. Switch them out with cylinders that are firing. If the other cylinders do not fire now, then the spark plugs need replaced. If the same cylinders 3 and 4 are still misfiring, then there could be a burned valve. Check the compression on the two cylinders and compare them to the other cylinders. If they are both low, then you will need to perform a leak down test (which requires a source of compressed air like an air compressor or something). If the compression on the cylinders is good and a leak down test passes, then there could be an issue with the fuel injectors not firing on those cylinders. If you need further assistance with your engine misfiring, then seek out a professional, such as one from Your Mechanic, to help you.

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: Can a bad alignment cause a loud noise when driving and stop when turning wheel ?

If the noise did not start until after the alignment was done then you need to return to see if they left something loose or have an explanation for the noise. If you had a tire rotation then a tire...

Q: Limp mode on audi a4 quattro 2003

Hi There, A number of things may cause your vehicle to go into limp mode such as engine overheating, low oil pressure and many other things that may potentially cause severe engine damage. The purpose of the limp mode feature...

Q: Electrode tip broke off

One way to try and get it out would be to blow air into the cylinder, to try and dislodge the piece. The other way is to use a specialist tool with a bore scope and grab tool, to try...

Related articles

What Causes Hoses to Leak?
While the largest part of your engine is mechanical, hydraulics plays a significant role. You’ll find fluids at work in a number of different areas. Your car's fluids include: Engine oil Transmission...
How Long Does a Distributor O Ring Last?
The distributor is part of the ignition system in your vehicle and its purpose is to route high voltage from the ignition coil to the spark plug. The spark plug then...
What are the Car Pool Rules in Hawaii?
Hawaii is widely regarded as a land of vacation and relaxation, and as such, its scenic roads and routes are far better known than the state’s freeways. But, as with all...