Fun on a budget- My 96 Sierra 2500 454

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454C2500Longbed

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454C2500Longbed,

Thanks for the photos. I looked closely at the underneath of your distributor cap, and it looks
like it is just starting to show the discoloration that was evident in the cap below, which also
was causing a no-start situation:

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As for your new injectors, I want to be clear about the correct terminology.

When you engine is first started, and as long as your O2 sensors are below ~600°F, the
computer will be making all fueling and timing calculations based *only* on the stored
(default) tables in memory. This is referred to as Open Loop.

Once the O2 sensors are up to temp & the engine coolant is above a certain threshold, the
computer goes Closed Loop, and the fueling is now driven by feedback signals from the
operational O2 sensors.

In English, the tables in your VCM are tailored to the original injectors, so whatever net difference
there is between your new injectors versus the factory ones will be the error during Open Loop
operation. Once the system goes Closed Loop, then assuming the difference is within the limits
that the computer is allowed to deviate from the default, then your system will 'tune' around
this difference. Given this, I would expect that your truck won't drive quite right when cold,
but once it goes Closed Loop it may run just fine.

Definitely get your tuning setup operational, and once you figure this out, then all future tuning
down the road will actually be fun. Just that steep learning curve in the beginning.

Fingers crossed that you get this all sorted out sooner rather than later.

Best of luck --
Of course, thanks for taking the time to inspect and for all the information and advice you have to offer.

Oh, sorry, I'm an idiot, I had those two switched around. From reading a bunch of other threads in the past, I was able to learn and understand all of that, but it certainly doesn't help when I'm using the wrong terminology! LOL! So what I meant to say was, once it entered Closed loop, it idled just fine and ran much better, but was still getting too much fuel, so it must be maxing out the fuel trims. I really do enjoy the way that you explain things and make it so easy to comprehend.

Computer things. Heck. I'm not good at those. I'll have to dig into it more and if I can't figure it out on my own I will definitely be surfing the forum for threads on it. I do look forward to that fun tuning where it'll be send it as hard as possible and then figure out how to get more out of it!

Thank you, I appreciate the kind words and support!
 

454C2500Longbed

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Well, took it out again yesterday and no good news. The temps were way up and the oil pressure was down. Temp was holding constant at 215, dropped a little once I got some more air hitting the radiator. Coolant appears to be the stock crap that it came from the factory with, so it needs drained and flushed, a lot of flushing. Might just replace the thermostat while I'm at it, can't hurt. Oil pressure will fix itself once the temps are down. Still not running great, but better than Friday.
 

Sean Buick 76

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A proper tune will effect both the oil pressure and the temperature of the engine. If the engine isn’t getting the right fuel and timing it will run poorly with low oil pressure and overheat. What’s the plan for getting it tuned?
 

454C2500Longbed

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A proper tune will effect both the oil pressure and the temperature of the engine. If the engine isn’t getting the right fuel and timing it will run poorly with low oil pressure and overheat. What’s the plan for getting it tuned?
Running rich should mean running cooler, as I understand it. It also had a history code for the coolant temp sensor when I looked last. I need to play around with settings for the JET software on my computer, I can't get it to open files. Once the computer plays nice I will get into the tune.
 

454C2500Longbed

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How’s this thing running? Any better?
It is running a little better, I've taken it for a little drive here and there with no real problems. Still dumps too much fuel when starting warm, but at least I can get it to start now. I haven't touched the truck much in the last week, my attention has been tied up in my new dirtbike- a YZ426F!
 

454C2500Longbed

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Well I just had a smack me in the head with a 2x4 duh moment. I put the scanner on to see the live stream data, and wouldn't you know it, the coolant temp sensor is reading -40 degrees. :doh2:
You'd think with all the time I spend on here and all the threads I read that would be the first thing I check, but nope. :nono:
Anyway, I gotta thank my grandpa for reminding me to check that. Man do I do dumb stuff.
 
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