7mgte health...

[LordLo]

Why is it that when I disconnect the spark to cylinder 1, the idle doesn't change, but if I disconnect any other cylinders the engine kinda studders?

 

[1988SupraDreams]

1st cyl is misfiring or not firing at all when the spark is plugged in.

 

[LordLo]

1st cyl is misfiring or not firing at all when the spark is plugged in.

Well I guess it is firing, took it out and it arc'ed on my roommates finger. Should be working fine.

 

[Supra87T]

maybe you should check for a clogged injector then...

 

[starscream5000]

Dead spark plug?

 

[1988SupraDreams]

Well I guess it is firing, took it out and it arc'ed on my roommates finger. Should be working fine.

The Coil Pack can still be sending spark, but that doesn't mean the cyl is firing. Check the three things that go into a Cylinder when it fires. Fuel, Air, and Spark. Check the gap on the plug, Check the injector, and if all of your other cylinders are firing odds are your air flow is fine. :biglaugh:

Hope that helps.

 

[LordLo]

Can someone try disconnecting spark plug for cylinder 1 and tell me what happens? My roommate's 300zx seems to do the same thing, but for cylinder 2.

 

[bluepearl]

You might want to do a compression and leak down test just to verify the health.

 

[rumptis]

what made you pull the spark plug wire off of SP 1 in the first place?

you having some other problems?

 

[LordLo]

Compression is 150 all a cross. So anyone pull off spark plug 1 with the same result?

 

[Nick M]

You did what is called a power balance test, and cylinder 1 failed.

 

[1988SupraDreams]

I disconnected my 1st cyl just to humor ya.. and it studders when I do it.

 

[Supracentral]

You did what is called a power balance test, and cylinder 1 failed.

Ding! We have a winner!

Nick has it dead on, you've got a problem in #1.

If a compression test didn't uncover anything different about that cylinder, I'd move on directly to a leak down test. Compression tests don't always tell the full story. Leakdowns usually do.

If that doesn't show anything, then you've got one of three things going on:

• Valvetrain problem (unlikely)
• Injector problem (likely)
• Spark problem (very likely)

 

[arz]

^^^I agree ^^^

I have had several cylinders bad and the compression showed fine (or at least acceptable) and the leak down test showed 93% on 3 cylinders and 80 something on 2 of them and 60 something on the really bad one.

Leak down test is where its at!!!

I used this one, go here http://www.totalseal.com/Tools.aspx and look for the Dual Gauge Leak Down tester

 

[LordLo]

Ding! We have a winner!

• Valvetrain problem (unlikely)
• Injector problem (likely)
• Spark problem (very likely)

Well valves are good, if I still have good compression. The spark plug was working... so it appears I may have a bad injector. :nono:

I guess it's time to put in my 550's. haha.