3RZ Compression Check

Did a compression check in my wife's Honda Civic Si with 222,000 mi to try to identify a power problem. With that problem identified and fixed in short order I decided to pull the plugs on my '02 3RZ Tacoma with 150k just to see the numbers.

Pulled all plugs with the engine cooling down from operating temp. Pulled the EFI fuse so the pump wouldn't run (just like I did with the Honda) and turned over cyl 1 for a few seconds. Psi came up to 162. Cool. Now to cyl 2. Psi much lower, around 150. Hmm. Ok, Cyl 3, even lower around 140. Cyl 4 was even lower than that, around 125. WTF!?

So, I go back to Cyl 1 and it was even lower that 4 this time: 120.

What am I doing wrong here?

 

It's sometimes nesscary to supliment the battery with a charger in order to keep the voltage up while you test each cylinder. The average starter pulls like 300 amps so it doesn't take long to run down a marginal battery. Unless you have the throttle blade closed in which case you're running out of plenum volume.

 

how would you go about supplying additional power?

 

A large (think roll around)battery charger will have a quick charge setting 30-40 amps or also a 200 amp + engine start. If the battery is just marginal I would leave it on the 30-40 amp setting while changing the probe. If it is really bad then use the engine start.

 

Thanks Fordless, I have plenty of juice under the hood and had solid cranking power (big Optima Red top). Plenum volume, though? Yes, that could be it as I never did crack the throttle.