I just had one of mine changed last month at our local dealership. It was covered under the 5 year warranty. My truck was purchased in March 2005. What is the date of your trucks purchase? Could be covered under the warranty.

 

It may correct those but after replacing them others that show good may now be out of tolerance for test of injectors at idle and in park. But being an LLY the work is easier since they are externally accessible compared to the LB7 set up. This post may give you an idea to buy direct from GM parts which I say be about a 1/3 of the price of the $600. Or possible where else to try. Might try search tool for like ' buy injector where '. Might give some links to places reselling remanufactored injectors.
http://www.dieselplace.com/forum/showthread.php?t=356185&highlight=where+buy+injectors

Brian

 

Have you tried running any type of injector cleaner? I've had great results from a TCW3 2-stroke oil. 1 oz/gal for 2 tankfuls and the balance rates are much better.

 

No warranty left on this puppy now.
I always run either Stanadyne or Power service. Also ran a couple good
doses of two stroke oil to see if that would quiet it down so it wouldn't
sound like a powerstroke anymore. No dice though.

Talked to a guy this morning from a turbo/injector shop for big rigs,has
Bosch remans,and my cost would be $498 each.Better than GM's price.

Tech says #3 & #7 aren't giving enough fuel,possibly clogged or dirty tips.
Should i just bite the bullet and replace these as well?

 

No warranty left on this puppy now.
I always run either Stanadyne or Power service. Also ran a couple good
doses of two stroke oil to see if that would quiet it down so it wouldn't
sound like a powerstroke anymore. No dice though.

Talked to a guy this morning from a turbo/injector shop for big rigs,has
Bosch remans,and my cost would be $498 each.Better than GM's price.

Tech says #3 & #7 aren't giving enough fuel,possibly clogged or dirty tips.
Should i just bite the bullet and replace these as well?

It's easy enough to pull them and clean the tips, but not likely your problem IMHO..

 

Don't think it would be just 2 dirty tips.
Guess i will be picking up 3 new injectors.

 

Give me a call. I can't quote prices in the forum, but
I'm sure I can help you out.

Guy

 

What symptoms are you having? I would be slow to condemn the injectors based solely on those balance rates. When were those taken? Park or in gear?

 

Had the balances rates checked yesterday at GM.
Tech said those were at idle in park.
Truck seems as though it is down a hair on power,but the biggest concern
is it sounds like a powerstroke.Fuel knock is apparent.

The tech was really only worried about #5 until he called their techline
which in turn said that 3 and 7 values were off and probably plugged.

Was able to quiet the fuel knock down with the tech 2.

Are my balances rates bad or still half ass?

 

Its possible that there is some trouble there, but a few things you can try first to possibly save a few bucks.

Change the fuel filter, if its restricted, it can make the truck act as if its low on power.

Change your fuel source. Its possible for a load of bad fuel or sub par fuel to give some problems. Run a good additive consistanly as well.


Any smoke? An injector on the fritz can cause a fuel knock, sometimes it will quite down with a lubricity additive.

 

Fuel filter is new,and previous filter had about 8,000km on it.
Always run either stanadyne or power service.Have also tried some
two stroke oil.

Will try changing fuel stations again.
Try to fuel up at the truck stop as they tend to go through more fuel.

Truck seems to have a light blue/grayish smoke when cold and on high idle.
Not much for smole once warmed right up.Is some black soot on the box side
and the bumper,but don't normaly see any black clouds under normal driving.

Been about -20c here,so it takes a while for this beast to warm up.

 

Any smoke once its warmed up?

 

Smokes a bit if i snap the throttle.
I just towed my empty car hauler home on friday,and didn't notice any
smoke on the highway.

 

I have smelt raw fuel walking past the front of the truck after driving,
but have searched all over and can't see anything.
Fuel mileage has been down,but just figured it was the winter fuel.

Forgot to mention that the exhaust will burn your eyes just walking by.
Was never that bad before.

 

Now I'm agreeing more with the bad injector theory. Balance rates will not tell the whole story though. Need to find out what the individual injector pulse is. Its listed just after the balance rates on the scanner

 

ok.
I will have to stop by the shop tommorow and see if he marked down
any other info.The Balances rates were all they gave me.

I can get away with just changing #s 3,5,7?

Thanks for your help.

 

Look for numbers that are lower then the average of the group. For instance, you may see most of them running around the .40 microsecond range. One of them may be at .20 microseconds, this would be the suspect injector.

In laymens terms, the ECM can detect the speed of the crankshaft speeding up everytime an injector fires and if a particular injector fires and the crankshaft speeds up to much, it pulls some pulse from that cylinder to make the engine run even. An injector that has a leaking tip will deposit fuel into the cylinder when its not ready for it, the unburnt fuel exists the exhaust as white smoke and will burn your eyes., the fuel that is injected at the proper time combined with whats leaking in is too much at that point.

Hope this helps

 

That's a great help.

Thanks again.

 

Cyl # 3 balance rate is 3.9,is that to close to spec,or can i get
away without having to change it for a while.

Is it common for the injectors to plug up?

 

+/- 4 mm3 at idle in park, +/- 6 mm3 at idle in drive, with "stock" injectors. I have let mine out to about +/- 6.5 before changing, each to their own.

LLY's typically don't have injector issues,

 

So i changed out the #5 injector,fresh fuel filter,oil change,added
some power service and filled up at a different spot again.
Truck ran great for 2 days after all this.Now when started cold,this thing
hammers bad and runs a little rough.Once the engine warms up the hammering goes away.
Back to GM to check the balance rates again,#'s 3 & 7 have come down from where they were,but # 5 is -2.8 to -3.0. What gives,brand new injector?

This hammering when it is cold sounds like a wicked fuel knock,but unsure
why it would show up all of a sudden.
Anyone have any other ideas before i loose my marbles?

Thanks

 

No one has any ideas?

 

There is nothing wrong with that balance rate

 

I just thought the # would have been a bit lower on a new injector.
Any ideas what would cause a heavy knock only when cold?
The tech says he couldn't find anything out of spec,and it runs nice once
warmed up.
This thing is normaly loud in the mornings,but never like this.

 

My truck always knocks hard when its cold...I just ignore it because it goes away after its warmed up.

 

Just found it odd that this hard knock showed up a few days after
the injector being done.
Guess i will run it for a while,see if there is any change.