Cant you test the injectors with Tech II??

[Alli-max]

dealer says nope, but I thought you could. Wont it tell you exactly which one is acting up?

If so, does anybody know how to check?

[thechevyhdman]

You can check the balancing and flow rates to determine if one or more injectors are bad. I was told that the tech should check both balancing and flow rates from start-up to operating temperature to determine which need replacing. At least thats what I told my service manager and they replaced the two I found out of spec with the TII. Bill

[dmaxalliTech]

[QUOTE]Originally posted by thechevyhdman:
You can check the balancing and flow rates to determine if one or more injectors are bad. I was told that the tech should check both balancing and flow rates from start-up to operating temperature to determine which need replacing. At least thats what I told my service manager and they replaced the two I found out of spec with the TII. Bill [/Qoute]

accuracy is not there until vehicle is warmed up

[hoot]

What is being monitored that allows balancing levels and leakage to be detected. e.g sensors of some sort?

How do it know?

[mackin]

My under standing is it is all about voltage monitering .....

The balance rate is the opening and closing of the injector .....


The Pulse rate is how many times it opens ,varies by rpm of course .....


Pulse width is the duration the injector is open ......


I could tell you the ranges ,but I'm at work .....

How far of am I tech'ies ?? Seems this info is hard to get to the bottom of ,has been asked a few times,so I'll stir the pot ...... :rolleyes:


Mac :D :D :D

[Kennedy]

It is an inexact science, but can provide a general indication of condition of the injectors AND mechanical components.

What we are looking at is how much pulse is required to deliver the correct shot of fuel. If an injector is needing a large positive correction, it could be either returning a bunch of excess, possibly leaking or has a plugged discharge hole.

If an injector is balancing hard to the negative side, it coul be either leaking at the tip, or delivering stronger than all of the rest. This is where the big picture comes into play.

Once we see a pattern or standout, it should really be bench checked to verify and remove any variables...

[hoot]

How does it know how much fuel was injected?

[Alli-max]

Once we see a pattern or standout, it should really be bench checked to verify and remove any variables...
Easier said than done. It's a little hard to even find an injector tester that has pumps to obtain these kind of psi levels.

[Kennedy]

Originally posted by hoot:
How does it know how much fuel was injected? This has to be done by mathematics and relies on injector condition.

Basically, they know what pulse duration @ say 10,000 psi delivers "X" amount of fuel. From there they obtain calculated fuel rate per 1000 strokes. This is why the MPG computers get skewed when boxes are added...

[Kennedy]

Originally posted by Alli-max:
</font><blockquote>quote:</font><hr />
Easier said than done. It's a little hard to even find an injector tester that has pumps to obtain these kind of psi levels. </font>[/QUOTE]I have had a few sets tested, but now my local guys are getting the equipment so it wil be easier. The proprietary nature of the system details requires a lot of "reverse engineering" to establish procedures etc...

[hoot]

In that case, it looks pretty useless to me. If the nozzle is bad, or something mechanical is wrong, that doesn't change the computer input to the injector for duration.

In the same cycle time a bad injector could shoot more or less fuel than a good one even though the "prescribed" cycle time is the same.

Only the computer changes cycle time, correct? It knows how long it wants the injector open. Is it getting feedback somehow on how long the solenoid is physically open, maybe by resistance readings?

[ 07-09-2003, 11:54 AM: Message edited by: hoot ]

[SoCalDMAX]

I may be completely wrong here, please correct me if so.

I got the impression somehow that the Dmax has multiple position sensors (2 or 4??) that the computer can thus correlate relative position in 1/2 or 1/4 revolution increments to acceleration rate based on the last cylinder to fire. It can then compare power delivered by that one cylinder and calculate actual fuel delivered compared to other injectors and then calculates balancing rate ( a "correction factor") for each injector to get the smoothest and equal power from each cylinder.

Whew! Or, I might be hallucinating and this is how I would have done it if I were an engineer. I honestly don't know how accurate the above paragraph is.

Regards, Steve

[hoot]

Now that makes sense and shows how "balancing rate" could be an indication of injector problems. Many other things can effect balancing rate, not just fuel and injection. A bad valve or head gasket leak for instance.

So "balancing rate" is a measure of cylinder power, not injector pulse.

[Kennedy]

You are ALMOST there...

[dmaxalliTech]

Originally posted by SoCalDMAX:
I may be completely wrong here, please correct me if so.

I got the impression somehow that the Dmax has multiple position sensors (2 or 4??) that the computer can thus correlate relative position in 1/2 or 1/4 revolution increments to acceleration rate based on the last cylinder to fire. It can then compare power delivered by that one cylinder and calculate actual fuel delivered compared to other injectors and then calculates balancing rate ( a "correction factor") for each injector to get the smoothest and equal power from each cylinder.

Whew! Or, I might be hallucinating and this is how I would have done it if I were an engineer. I honestly don't know how accurate the above paragraph is.

Regards, Steve I forgot what I was gonna say :(

[Wally]

SoCalDmax,
Except for the multiple sensors, I'm not sure about that, you are right on with your supposition about how the balancing rates are determined.
Very good description of how the system works. :D
It's flippin amazing what fast electronics can do.