Cylinder balance test ?

[juan89]

How do I do a cylinder balance test on a turbobuick ? When I disconnect a cylinder , the IAC will bring the RPMs back up.
Is there a way to Lock the IAC position ?

Juan

 

[juan89]

I read the factory manual and it said to disconnect the IAC connector after starting the engine.

 

[earlbrown]

What is a "cylinder balance test"?

and why does the enigne have to be running with the IAC killed off?


If you're looking for a dead cylinder, just spritz some water or brake parts cleaner on each header tubes. The one that stays wet longer than the rest is the weak one.

 

[Boost231]

Leak down and compression test would work as well.

Or temp gun them

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[juan89]

Thanks, for the tips.

Juan

 

[cruzn57]

use a lazer temp gun,... much easier.
but... at idle, you will not get accurate readings, do to poor distribution .

 

[Boost231]

use a lazer temp gun,... much easier.
but... at idle, you will not get accurate readings, do to poor distribution .

Believe it or not if you do have a issue with 1 cylinder you can see a difference more at idle then any other spot. Not sure with the temp gun but with egt probes you can see at idle for sure.

When running down the road or at WOT the difference was smaller.

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[No disintegrations]

Juan, what issue are you chasing? Or just want a health check in general?

I worked on a 5.3 L's Tahoe that passed a leak down test and compression test but failed the compression test with the engine actually running. Which I did a comparison between a good cyl and the bad one. The bad one had a pumping up lifter which held a valve open.

 

[juan89]

I did the balance test by disconnecting the IAC. And found a bad cracked spark plug.

Thanks Everyone,
Juan

 

[gunzandgearz]

Another good test for chasing something like that is pull one plug wire at a time with the engine running the one that doesn't make any difference or change in rpm, you just found your dead hole

 

[dank GN]

I did the balance test by disconnecting the IAC. And found a bad cracked spark plug.

Thanks Everyone,
Juan

What is a balance test ? How do you do it ? I’ve never heard of it before . I’ve done plenty of leak down tests and compression tests but never a balance test .

 

[No disintegrations]

What is a balance test ? How do you do it ? I’ve never heard of it before . I’ve done plenty of leak down tests and compression tests but never a balance test .

The IAC is shut off. Each cylinder is killed one at a time and the rpm drop is written down. All cylinders should cause the same rpm loss. Weak cylinders show little or no loss of rpm.

 

[chopped39]

Cotter pins and a test light work great. or a high amp probe and crank trigger for compression test.

 

[dank GN]

The IAC is shut off. Each cylinder is killed one at a time and the rpm drop is written down. All cylinders should cause the same rpm loss. Weak cylinders show little or no loss of rpm.

Okay how are you shutting down each cylinder? Pulling spark plug wires,

 

[No disintegrations]

Okay how are you shutting down each cylinder? Pulling spark plug wires,

I myself try to pull injector plugs, but you can also pull the plug wires. Or You can also short the spark by sliding a test light into the joint where the spark plug boots go in the plug wire. Safer than just pulling the wire.

Some engine designs are harder or easier to get to things. On a coil near plug or coil on plug you can easily unplug each coil one at a time.

Some will ask why mess with this test but its nice to have in the bag of tricks. It really can help focus in on the real problem area and then decide the next step. And typically offers proof of the failure.

 

[Jerryl]

Pulling plug wires is not something I am fond off because I don't get along with electricity. The injectors also keep firing and depending on how long the test lasts, or can wash down the walls and the ECU will over fuel the other 5.

Therefore, my prefered test is by disconnecting the injector(s). It's quick and easy, and I won't get shocked. Lol

I don't have the ECU-GN, but pretty sure from the video it has a build in feature to locate a lower performing cylinder.

 

[gunzandgearz]

Pulling plug wires is not something I am fond off because I don't get along with electricity. The injectors also keep firing and depending on how long the test lasts, or can wash down the walls and the ECU will over fuel the other 5.

Therefore, my prefered test is by disconnecting the injector(s). It's quick and easy, and I won't get shocked. Lol

I don't have the ECU-GN, but pretty sure from the video it has a build in feature to locate a lower performing cylinder.

The test is only going to last about five seconds won't come close to washing the cylinder walls down and they make long plug wire pliers that you can pop them on and off in a matter of seconds so there will be absolutely no chance of washing down the cylinder with fuel

 

[Jerryl]

The test is only going to last about five seconds won't come close to washing the cylinder walls down and they make long plug wire pliers that you can pop them on and off in a matter of seconds so there will be absolutely no chance of washing down the cylinder with fuel

I am confident you have less fear of getting shocked than I do. Lol

I have a set of plug wire pliers and wondering if the ones you use work on #6 with the stock AC box?

 

[gunzandgearz]

They are a pair of knipex pliers and yes I can get to #6 with them they work awesome and the handles are insulated and when I do this I reach down there twist them pull them off far enough just to get it away from the plug and then stick it right back on do you wrench for a living, if you do you try a set I think Snap-on or Matco makes them also or something like it but I will say this I treat every engine and situation differently if something is going to be a pain to get to I might go the other route or vice versa sometimes even the injector wiring is hard to get to on different Vehicles so just depends on the situation

 

[Jerryl]

I agree that there are typically multiple ways, and the real answer is "it depends".

I do not wrench for a living and was merely sharing a few options that weren't mentioned.

I am always willing and open to learn new tricks, but still prefer the injector plug for this situation on my setup.