Compression check question

TitaniumVtec · 5 June 2005

I am going to change my plugs today and decided to check the compression while I'm at it. My question is, do I need to cut the fuel to the injectors during this test?? Other EFI cars I've compression tested, would tell you to pull a relay/fuse to the fuel pump, so to keep the fuel from entering the cylinders during cranking/testing. I did a search but did not find too much on this topic

Any help would be greatly appreciated.

VBNSX · 5 June 2005

yes you need to cut the fuel that goes into cylinders.

Also when you try to crank the engine make sure you step on the pedal to let air get in also.

x

1BADNSX · 5 June 2005

I haven't done it on an NSX, but you usually pull the fuel pump fuse to cut pressure to all the injectors.

Bob

TitaniumVtec · 5 June 2005

Thanks. I will try and locate the fuel pump fuse/relay prior to testing.

Larry Bastanza · 5 June 2005

Easier then that is to unplug the fuel injector resistor pack located in the engine bay by the alternator

.

HTH,
LarryB

Briank · 5 June 2005

I believe the fuel pump resistor is bypassed during cranking. :wink:

Larry Bastanza · 5 June 2005

Briank,

I agree, I meant the FUEL INJECTOR resistor pack

. This is a package of 6 terminating resistors for each fuel injector. If you unplug it, no voltage is fed to the injectors. aka no fuel

HTH,
LarryB

Briank · 5 June 2005

Larry

I miss read that, must have got fooled by the "by the altenator" part into thinking you were talking about the fuel pump resistor. :biggrin:

TitaniumVtec · 8 June 2005

I finally got around to testing my compression and my numbers were 230 across the board. Does that sound correct, or do they appear to be too high? I checked the manual and it says that 199 is 'nominal' and that the 'minimum' is 142, but it doesn't state a max range value.

I'm happy that the numbers are consistent more than anything, but I'm not sure if these numbers are too high and its time for a new tester. I have tested other vehicles before with this tester and the numbers were acceptable for those cars.

Thanks in advance.

Larry Bastanza · 8 June 2005

Even is what counts

. I have seen many at 210-230 across the board.

HTH,
LarryB

TitaniumVtec · 8 June 2005

Larry Bastanza said:
Even is what counts. I have seen many at 210-230 across the board.

HTH,
LarryB

That is great news!!! Thanks Larry.

James

RacerX-21 · 9 June 2005

230 is the exact number I get when I use the improved 3.2 head gaskets on a 3.0 engine. It brings the compression up from 199 to 230. People do this A) for more compression, and B) because Honda had problems with the 3.0 gasket design.

In the future un-plug the ignition module on top of the intake manifold so you don’t get spark. The test is supposed to be done with a warm engine, unfortunately it’s more of a pain to work on… and the plug torques that the manufacturers quote are for cold conditions.

TitaniumVtec said:
I finally got around to testing my compression and my numbers were 230 across the board. Does that sound correct, or do they appear to be too high?
Thanks in advance.

VBNSX · 9 June 2005

RacerX-21 said:
230 is the exact number I get when I use the improved 3.2 head gaskets on a 3.0 engine. It brings the compression up from 199 to 230. People do this A) for more compression, and B) because Honda had problems with the 3.0 gasket design.

In the future un-plug the ignition module on top of the intake manifold so you don’t get spark. The test is supposed to be done with a warm engine, unfortunately it’s more of a pain to work on… and the plug torques that the manufacturers quote are for cold conditions.

Just curious:

How would you get spark if there are no plugs? Although the car would try to pulse the plug, there'd still be nothing there.

x

Compression check question

Similar threads