Compression test and bad spark plug

[tekno9000]

How do u check the compression in the cylinders and how do u find which spark plug is not having a spark? Checked the wiki's but could not find them.

Thanks in advance.

1995 Camry LE 139K miles.

[Jimnist]

Check compression by screwing out spark plug and putting the compression tester in place. Crank it over a few times, don't try to or let it run. Turn off and repeat one or 2 more times. Check compression readings and compare to what it should be, also check for discrepancy. You can also squirt a bit of oil in there to help seal it. I don't remember, but using the oil can give you an indication as to whether the rings are worn or not; whether the pressure stays the same or increases a bit/

(To see if car is running on all cylinders) With the engine running, take out each lead one at a time for a few seconds and replace. Do this with all leads, whichever lead you take out that doesn't affect the engine(sound and smoothness) is the cylinder that is not firing.

[ShawnM]

When you do check compression its a good idea to disable the fuel system. All you really need is for the engine to crank. If the fuel injectors are constantly trying to spray fuel in while your cranking its going to wash down the cylinders and give you a false low compression reading. The easiest way to check for a lack of spark is to get an inline spark tester or to just let the engine idle then pull off one spark plug wire end at a time. The idle will drop and the engine will run worse if the spark is good at that particular cylinder. If theres no change then youve found the problem cylinder. By the way when pulling wires with the engine running be sure to use a set or plastic pliers or something thats well insulated. If you dont you'll get a decent shock.

[tekno9000]

thankx to u both.......... now time to do the things.........

[tekno9000]

I just checked my spark plug cable resistance (Wanted to test my new multimeter) and these were my readings :

Cable 1 : 11.9 K ohm
Cable 2 : Greater than 2000 K ohm ----> seems the cable is bad
Cable 3 : 8.94 K ohm
Cable 4 : 6.73 k ohm

I believe root cause of my misery is cable no 2 and not spark plug. Will change this cable first and then do compression test.


Question : Should i change all cables or only the bad one?


My old cables are SUMITOMO brand. What is the OEM brand?

[flyeri]

Probably be hard to find just the one wire. How old are they? I would replace all four if it were mine but I tend to do way more than really needed.

[tekno9000]

Originally Posted by flyeri

Probably be hard to find just the one wire. How old are they? I would replace all four if it were mine but I tend to do way more than really needed.

Has 1994 printed on all of them. I never changed them since i bought this Camry 6 yrs back.

[JohnGD]

Unless you go to the dealer I doubt you can buy just one. But after all these years, I'd just do the entire set.

You posted resistance values for 4 wires. Do you have a 4-cyl or 6-cyl? Sumitomo was probably the OEM back then. I would get NGK iginition parts. However, rockauto shows only Delco or Powermax for 1MZ, surely reboxed wires for ~$11+shipping.

5SFE:
NGK Part # 8762 {#TE62} California $35.79
NGK Part # 8130 {#TE43} NON-CALIFORNIA $38.79

Originally Posted by tekno9000

Has 1994 printed on all of them. I never changed them since i bought this Camry 6 yrs back.

[tekno9000]

Originally Posted by JohnGD

Unless you go to the dealer I doubt you can buy just one. But after all these years, I'd just do the entire set.

You posted resistance values for 4 wires. Do you have a 4-cyl or 6-cyl? Sumitomo was probably the OEM back then. I would get NGK iginition parts. However, rockauto shows only Delco or Powermax for 1MZ, surely reboxed wires for ~$11+shipping.

5SFE:
NGK Part # 8762 {#TE62} California $35.79
NGK Part # 8130 {#TE43} NON-CALIFORNIA $38.79

Mine is a 4 cyl. I have installed Denso spark plugs.

[tekno9000]

Originally Posted by ShawnM

When you do check compression its a good idea to disable the fuel system. All you really need is for the engine to crank. If the fuel injectors are constantly trying to spray fuel in while your cranking its going to wash down the cylinders and give you a false low compression reading. The easiest way to check for a lack of spark is to get an inline spark tester or to just let the engine idle then pull off one spark plug wire end at a time. The idle will drop and the engine will run worse if the spark is good at that particular cylinder. If theres no change then youve found the problem cylinder. By the way when pulling wires with the engine running be sure to use a set or plastic pliers or something thats well insulated. If you dont you'll get a decent shock.

stumped !!! I pulled the spark plugs while running the engine. For all plugs, the engine had a bad run when the wire was pulled out. even for plug # 2.

I dont know what to do plz help.