Dealer checked everything and my lopey idle wont duplicate.

He gave me these balance numbers.


Are they good?

Done hot in drive......

1) .53ms
2).53ms
3).55ms
4).60ms
5).55ms
6).55ms
7).55ms
8).58ms

Don't you just love it you take it to the dealer and it won't do it but once you get home it'll start.
Has it happened again since you got it back?
I hope you get it figured out.These kind of random occurences are frustrating to say the least!:confused:

Blake

I believe those are really good consistent numbers.

Those are not the balance rates. The they look more like injection pulse length timing. Balance rates do not have units of "ms" (which I assume means milliseconds).

I wish my #'s where that good...

pc - I wonder if your reluctor wheel has come loose...I have seen a few of these cause a lousy idle...when rev the truck, the centrifical (sp) force straightens it out....just an idea...........

Here are the balance rates for my truck in drive:

Allan, what do those tell you about the condition of the fuel system? Looks like quite a spread. Later! Frank

I wish my #'s where that good...I wish mine looked as good as yours:eek: .

I wish mine looked as good as yours:eek: .You can't get much worse than mine... and not get them replaced. What I don't like is that 5 & 7 are so far apart +5 and -5.

Since getting the predator for diagnosis purposes I have been obessed checking my balance rates.

I can tell you--that at least for mine--they vary--a lot. I have two injectors that read -3 and then as high as -6...

They also vary with driving condition--a lot of stop and go driving seem to drive the balance rates higher--not sure why.

After 2 to 4 hr highway trips--the balance rates always look better..not sure why.

I seem to have two injectors that are my bad ones--but I have seen others that normally read +/- 1 go as high as +/-4 in hot stop and go traffic.

I also noticed that all my rates went high when I got some Diesel at shell without additives and my lopey idle came back.

When I use additives and B20 lopey idle is gone and balance rates settle down.

But I will say this--if you believe that some injectors have more "gain" than others--and yet basically nothing is wrong--it is possible to have a variance in the amount of fuel being put in under a baseline Pulse width variable timing command from the ECM.

The gain could also be influenced by temperature and lubricity--ie driving conditions and fuel type.

Then the ECM has to turn down the timing--shown as a negative number--or turn up the timing--shown as a positive number to adjust for gain variance from injector to injector to achieve some type of idle setting. I am thinking out loud here.

I guess the key thing is that rates do not change from some baseline number--because that could indicate wear and erosion. But we all know the injectors will eventually wear out--and this could be a good way to see it coming--assuming you are checking them regularly.

Unfortunately I already have 30k miles and not sure what my rates looked like new.

Oh yea--truck runs great--quiet idle--no smoke at start or idle--easy start--great MPG.

I am happy.

Don't forget, balance rates are intended to average out the power produced by each cylinder at idle. The purpose of this function in the engine ECM is to make each cylinder look the same at idle and thus smooth the engine idle. If each of the injectors were exactly the same (an ideal injector), the balance rates would still not be the same. There are other mechanical factors that make each cylinder unique.

What is the difference in units "ms" vs "mm"?
I thought someone (a mech tech?) on the forum said that +/-6.0 (mm?) was within reasonable (spec?) limits?
Also it was stated that you can still have injector problems and have good balance numbers. Although bad balance numbers are a sign of injectors with a problem.

Interesting point Alan--but it would stand to reason that you could have a good injector with not so good balance rates.

So now if you add in other variables that are going to be taken into account to smooth the idle--it would stand to reason that there is going to be variances that the ECM will try to even out by changing the amount fuel each injector puts in.

I still think it is the change from baseline/new that counts--assuming the truck is running good--ie none of the tell tale signs of injectors going bad.


BlueDMax--I think that ms is a unit of time (maybe milliseconds) and mm is a unit of volume(milliliters)? I need to order the Helm books.

My point being, that there are many variables that contribute to the injector balance rate number. Not just good or bad injectors. There will be a variance to deal with. As time goes on and things wear (including injectors), I would expect the variance to increase. At idle, GM say +/- 3.0 are the numbers we are shooting for.