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?
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
  1. Home
  2. Questions
  3. Poor idling, hesitation on acceleration, and oil on spark plugs.

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: ran out of oil and wont start

Hello. If the oil was completely empty, then you may have a serious engine failure. I would first add oil to it and then try starting it. If it still does not start and makes a lot of noise when...

Q: The vehicle is 4wd drive and wont shift back to 2wd.

Hello there. You have one of a few possible things going on with your 1992 Mitsubishi Montero. If the gearshift shows 2WD and the vehicle is in 4 high, the most likely fault is either the transfer case shift linkage...

Q: Have oil on one of my spark plug wires in the spark plug well the test are fine. What should I do.

Hi there. The issue that you are having is a small o-ring seal on your valve cover is either split or damaged. The valve cover should have a seal all the way around it and 4 o-rings in the middle...

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...
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...
P2103 OBD-II Trouble Code: Throttle Actuator Control Motor Circuit High
P2103 means there is a fault with the throttle actuator control motor circuit, likely due to a defective electrical component or part.