How long would you run these injectors?

fl0w3n

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Jan 8, 2015
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Truck idled, ran and drove great. No indication of bad injectors other than checking balance rates. This is in park only. Forgot to do drive. They’re 55-60k miles on a dealer install.

I’m wondering if I can get by with 2-3000 miles before putting SAC00s in and not risk any more damage that hasn’t already been done to bearings and cylinders. Or should I be worried about the 200 mile drive home after buying it?
Bone stock truck

 

DAVe3283

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The damage comes from diluting the oil. If you keep an eye on it, and change the oil when it starts to get diluted, you can go a long time. Might get expensive if you end up having to change the oil every couple hundred miles or something.
 

Chevy1925

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Please explain the column headings @5mm3 and @6mm3. I have never seen these used in connection with balance rates.
Without it, balance rates won’t give you accurate info. It’s the main injection rate over all the computer is calculating.



I’d drive them 2-3k. Change the oil now and just check rates every 500-1000 miles to make sure that 6 don’t turn to a 15
 

fl0w3n

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Please explain the column headings @5mm3 and @6mm3. I have never seen these used in connection with balance rates.
Like James said, my main injection rate was already pulling 2-3mm3 (5-6mm3 main rate) of fuel out so I ran the numbers at those two. Search for “proper way to check balance rates” and I think it was Thermarator who did a solid write up explaining it.


Okay, that makes me feel way better. I’ve got a move coming up into a new house and juggling some other things, I don’t want to buy a new truck and then have to park it for a couple months because it needs injectors.
 

2004LB7

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I wouldn't sweat those numbers too much but I would keep an eye on it. Have you tried a heavy dose of injector cleaner yet?
 

fl0w3n

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I wouldn't sweat those numbers too much but I would keep an eye on it. Have you tried a heavy dose of injector cleaner yet?
Good call I forgot about that. I’ll definitely give it a try, can’t hurt.
I actually haven’t bought the truck yet, I was hoping to meet the guy this weekend to pick it up but he’s out of town. I should get it sometime next week. Which is why I asked the question, I’d be more hesitant to buy the truck and have to park it for a month or two right now with everything going on before I can do an injector job.

Bad injectors can also burn up a cylinder if they get stuck open too long right? Contaminated oil isn’t the only concern?
 

2004LB7

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if stuck open, it will probably smoke (likely white smoke) and/or knock pretty bad. don't drive it anymore if it does.
 

slowlml

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Feb 6, 2015
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If they stick open youll know it. It will smoke heavy white and rattle or knock bad. If you can find the gm injector cleaner that goes through the lines not the tank that may buy ya some time.
 

fl0w3n

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Well hopefully it doesn’t come to that.

I Pretty easily found a few bottles At my local dealer of the injector cleaner a year or so ago for my current LB7, is it getting hard to find?
 

fl0w3n

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Holy crap... I must have really lucked out a year and a half ago on that upper injector cleaner. I just walked into my local dealership and got a couple bottles off the shelf. Now they're running $95+ on Amazon and eBay?!

Well, I made some calls and I found 5 bottles of old stock sitting on a shelf... so I've got that paid for and on the way.
 

2004LB7

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I use whatever I find on the shelf at the local auto parts store. I've even used E85 and it worked great but would not recommend anyone else try it. the GM stuff was just too much m
for my appetite. but if you can get at a reasonable price, go for it. supposed to be about as good as it comes
 

fl0w3n

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I use whatever I find on the shelf at the local auto parts store. I've even used E85 and it worked great but would not recommend anyone else try it. the GM stuff was just too much m
for my appetite. but if you can get at a reasonable price, go for it. supposed to be about as good as it comes
Got it for $20/bottle

I'll probably just save the other bottles for maybe running a second one through this truck or I'm sure the future Duramax's I'll own lol
 

fl0w3n

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Picked up the truck last night. Pretty stoked on it.

04 LB7 w/ 147k on it. Bone stock other than a stereo system. Got it for $13,800
It's pretty damn clean, but that still doesn't mean I have a big list for what I'm going to do to it. I'll probably leave it stock tuning wise for the next year or two.

New.jpg
 

fl0w3n

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Weird, I drove the truck 150 or so miles home last night and just now today I was checking rates again. Looks like they got worse.

In park, my main rate was dropping all the way to steady 4mm3 but the balance rates were about the same I posted before. With AC on the main rate kicked up to 7-9mm3

In drive foot on brake, main rate went up to 9mm3 and all rates looked a lot better except #3, it hung around the -3

Very very slight haze at idle now, reminds my of my LBZ at idle.

Hopefully that injector cleaner shows up this weekend and it actually helps.
 

fl0w3n

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Holy crap this is progressing at an alarming rate.
It’s gone from very slight haze to beekeeper status smoking out stop lights
 

fl0w3n

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Maybe. Guy seemed real stand up, but was also more of a take-it-to-dealer kinda guy not a DIY'er so not sure how he would have accomplished that. Also coincidental that AC checked out perfect (I specifically checked that there was no blown blower motor resistors) and then started kicking the bucket 15 minutes from his house.

I'm thinking he's probably had it sitting or just local town trips recently, and my couple hundred mile return trip dislodged something. Also really hoping the injector cleaner buys me some more time.

I did buy it knowing I'd be doing injectors, I was just hoping it wasn't immediately lol
 

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