Skip the auto shop - Our mechanics make house calls

Q: Poor idling, hesitation on acceleration, and oil on spark plugs.

asked by on

I own a '92 3000GT non-turbo which I have had for 16 years. The engine had been running really bad; low idling, extreme loss of power, knocking noise under hood on acceleration, some times stalling when put in reverse (car is automatic), light smoke coming from exhaust tail pipe, and the car hesitates with acceleration as if it is choking on it's own exhaust. I suspected a spark plug miss fire. I removed the spark plugs to see if they needed replaced and there was oil on the front 3 spark plugs and within the housing where the spark plug sits. This has never happened before. Also, prior to lifting the spark plugs out, I tried disconnecting the battery. When I did the positive side connect just broke off from corrosion so that I will be obviously replacing.

Could the battery connector be the problem with the car running badly if that connector couldn't conduct the electricity from the battery well? What could have caused the oil to get to the front three spark plugs?

My car has 230000 miles.
My car has an automatic transmission.

Hello. From what you describe, it would appear that your vehicle may be experiencing more than one issue. Oil on the spark plugs can be caused by a few different things. If you also found oil in the spark plug tubes, then it may be possible that the valve cover gaskets or spark plug tube seals have begun to leak allowing oil into the tubes.

In some cases, the oil can work its way past the threads into the cylinder. You also mention, however, a loss of performance as well as smoke in the exhaust. This can be caused by oil getting into the cylinder, usually due to engine wear.

If the engine piston rings, or the cylinder head valve stem seals wear out they can allow oil into their respective cylinders. This could explain the oil on the plugs, the smoking, and even the loss in performance, if the issue is related to the piston rings.

A compression test would be the best way to determine if this may be the case. The battery terminal will also need to be taken care of before the engine can be restarted again.

In some cases, a poor battery connection can affect engine performance, however, it will not cause oil on the spark plugs or smoke from the tailpipe. I would also check the opposite terminal, as well as both battery cables to see if they may be corroded or in need of replacement as well. If you would like to have a professional scope this out, a certified technician from YourMechanic, can come to your car’s location to inspect the rough idling, hesitating acceleration, and oil leak to figure out what repairs are needed.

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: Engine overheated maybe, but now it’s broken

Hello, engine failure can be very traumatic. For an engine to run out of oil with no leaks, the engine must be using oil internally. For the vehicle to be covered under warranty, all the oil changes must...

Q: Valve gaskets need replacing.

Hi. Your cooling and oil systems would need to be checked for leaks. These are two separate issues. The cooling system should not be getting low, except for a very small amount over a six to twelve month period. The...

Q: Car idles and multiple trouble codes are triggered

Hi there. If this vehicle is having an idle concern, I have to ask if you may be having a stumble or stall issue when coming to a stop. If so, your vehicle may be covered under a special...

Related articles

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...
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...
How Much Does a Mechanic Make in Vermont?
Automotive technician jobs in Vermont have an average mechanic salary of $37k, with some mechanics earning a salary of $53k.