Skip the auto shop - Our mechanics make house calls

Q: I missed a shift from 3d to 4th and over-revved the engine. There is now a misfire in every cylinder.

asked by on

Missed gear going into 3d and over revved engine and misfire every cylinder

My car has 157000 miles.
My car has a manual transmission.

A: Unfortunately, this could mean you have ben...

Unfortunately, this could mean you have bent some valves. The best test for this is to put air pressure into each cylinder and see where it leaks from. You can utilize an expensive leak down tester or simply modify a compression tester to put around 50 psi of compressed air into each cylinder, one at a time. You will want to do either one with the the piston at top dead center. Sometimes you will need to hold the crankshaft by the crankshaft bolt to keep the piston from moving from TDC (Top Dead Center). TDC is important to make sure the valves are in their closed position. With the piston at TDC, compressed air in the cylinder, listen at the tail pipe, the intake manifold through the throttle body and remove the oil filler cap and listen in the crank case. You are listening for a significant rushing sound of air. If you here this at the exhaust, you have a bent exhaust valve, if you hear it at the intake, you have a bent intake valve, if you hear it from the crank case, you have a piston problem.

Most likely you will not have a piston problem. If you do, there will a lot of other problems besides a misfire. It is also possible the timing belt has slipped a tooth or two. While your checking for cylinder leakage, you can do a compression check in each cylinder. If you find some cylinders have very different results and the valves in the suspect cylinder are not leaking, it is likely the timing belt has skipped a tooth or two. The only other way to check the timing belt timing is to disassemble the front of the motor as you would in preparation to replace the timing belt.

It sounds like you were driving quite hard when this occurred. Somehow you have determined all the cylinders are missing as a result of the over revving, and if they are all missing, the most likely cause would be bent valves or camshaft timing. Hard driving can foul and damage spark plugs. So when you are doing compression and leak down tests, I would definitely take note of the condition of the spark plugs.

If you should need further assistance, I recommend having one of our mobile technicians come to your home to perform a misfire inspection and help you make the necessary repairs to your vehicle.

Good luck!

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: Hesitating and missing in drive or park, fine over 45 mph

Hello. Quite a few different items can cause an erratic idle as well as an engine that misses. The spark plugs and wires are a great place to start. Other possible causes of this fault include: low fuel pressure, vacuum...

Q: AC not blowing cold air

Hi. There are many different possibilities here. Most A/C systems stop working due to switches in the system failing or a bad clutch on the compressor. You may have also just overcharged you’re A/C system or have a Freon leak....

Q: Flames coming from the tailpipe and rough idle

Hello there, many common faults will cause your 1984 Dodge D250 to have a rough engine idle and have flames coming from the exhaust. When flames are seen coming form the exhaust it is most often due to unburnt fuel...

Related articles

How Do Power Car Windows Increase Passenger Safety?
Power windows are responsible for approximately 2,000 emergency room visits every year. When a power window closes, it exerts enough force to bruise or break bones, crush fingers, or restrict an airway. Though...
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...
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...