Spark plug issue

[VBlue]

Situation:

I have a '90 Corolla CS Limited SECA, with a 4A-FC engine. I only bought it recently and noticed that when I was driving there was far too much vibration at idle and going uphill, also the car would just surge forward sometimes and lose power simultaneously at random moments. My friends just suggested that it was normal for old manual transmissions to have nasty vibrations because the idle speed is lower, so I didn't think much of it, there was a significant loss of power that I noticed as well and just wrote it off as being an old engine. When I went to get my clutch height adjusted, the mechanic there told me that one of the cylinders in the engine was misfiring and that the car was running on 3 cylinders not 4.

I decided to take a look at the spark plugs and saw that the spark plug in cylinder 3 was a different model to the rest, the recommended part for my car is BCRE527Y with a gap of 1.1mm, but cylinder 3 had a BPR6EFS part with a gap of 1.5mm which appears to be common in Commodores, all the others looked a decent tannish/greyish colour, but this other part looked exactly like a plug with wet fouling as per:

http://www.spark-plugs.co.uk/pages/technical/diagnosis.htm

Question:

I remember before I removed the plug I blew air in to the top, and noticed some oil splashing out of the sides of cylinder 3 only, I checked the oil level immediately and noticed that it was noticeably lower than a few weeks ago, so I suspect there was oil being burnt. Is this only because the spark plug was incorrect, or is a symptom of further possible problems? What should I check for, and investigate?

I changed all the plugs to the recommended parts and set the gap as best as I could to the recommended length, and the car immediately had a significant improvement in power, it no longer decided to do little bunny-hops between shifts, and almost seemed like a new engine was put in, with much better acceleration.

Any help and information would be great.

Thanks!

[01 VEY]

The first thing I would have done is a basic compression test to check if there is any difference between the cylinders. If #3 is much more than 10-15 psi lower than the others I feel there may be need for further investigation.

I tried to search on Google but I could not find any pictures of the exact plugs listed here. All I got was confused.

Any chance of some pics of the two different plugs from your car together.

[VBlue]

Here are the pictures, sorry I couldn't get them more detailed because the camera just blurs the picture if I try to take too close a picture.

The incorrect spark plug is on the right of the first image, and also has the part no. written in blue, as you can see it's significantly smaller than the other one.

How exactly do I carry out a compression test, what tools are needed, and is it easy enough for an average person with little mechanical know-how to do?

[CHA54]

plugs wouldn't be the cause of the oil, more likely worn rings or valve stem seals in that cylinder. Gap the plugs down and put them back in, or put in some standard plugs.

You need a compression tester to do a compression test. Remove all spark plugs from the engine, screw compression tester into 1 cylinder, crank engine with the throttle held wide open, check gauge reading. Repeat on all cylinders.

[01 VEY]

Here are the pictures, sorry I couldn't get them more detailed because the camera just blurs the picture if I try to take too close a picture.

The incorrect spark plug is on the right of the first image, and also has the part no. written in blue, as you can see it's significantly smaller than the other one.

How exactly do I carry out a compression test, what tools are needed, and is it easy enough for an average person with little mechanical know-how to do?

I was originally concerned that the plug may have been too long and hit the top of the piston. I hope this is not the case but if the 'wrong' plug is the long one you may need to get a good look inside to check the top of the piston.

[CHA54]

it would be quite obvious if the plug had hit the piston, the electrode etc would be mashed.