TBI rebuild

[tsr2185]

Well, got my new ac delco cap, rotor, and pickup coil installed and still same rough idle. Almost more of a rpm surge/ low idle than a miss now. It idles real low and doesnt shake as much but something for sure isnt right. Still gotta confirm 0deg after dizzy reinstall. Gonna do the shurkey trick with the nails and vac guage, then go through the whole IAC and base idle reset after. Then off to work for 28 days.

 

[tsr2185]

Fix the wiring and the grounds before you pay for a leakdown test.
Too me this sounds more and more like an electrical or maybe vacuum problem as opposed to an internal mechanical problem.
Another test you can do, reset the base idle to 0 degrees with the distributor wire disconnected.
Do this with it warmed up so it is in closed loop.
Does it misfire?
Dont grab an HEI wire when it is running.
That was the part about being carefull.
I should have explained that a little better.
Sorry bud.
The first time I did that I was standing in a puddle of water in a piss down rain storm.
Had a wrench in my hand and set my hand on some bare metal when I pulled a plug.
Blue sparks shot out of my fingertips.
It was really wierd but my friends enjoyed it.

It still idled like crap and misfired with the esc wire disconnected. It was up to temp at the time aswell. Still need to go over and do this with the rebuild dizzy.

The new pickup coil had 845ohm across. And the old one had 1050ohms. Sure it was fine but the windings in the old one was a LOT less than the new one.

My base idle can also be real low from tinkering with tge idle screw. Do I set base IDLE when in park, or in drive? I seen instructions for both.

 

[thinger2]

I always set base idle in park then I look to hit the in gear idle. That is really what you are after and if you are working on your own it is the only safe way to do it.
Never ever tune or adjust any running vehicle that is in gear by yourself.
Never.
One of the problems ive run into over the years is attempting to make too many adjustments at the same time.
Im sure their is an official gm flow chart.
If I attempted to reset base timing and adjust base idle while resetting the idle air control and just put a new temp sensor in.
Its just a bit more than TBI can chuck down at one time.
The TBI system and its diagnosis is based on "Flow Chart" logic.
If, then, yes, no.
it looks to me that you have determined that the basic mechanical functions of the engine are correct.
Everything in the rotating mass appears to be right.
So im pretty confident that you can check that off of the list.
A compression test and a leakdown test will confirm that but I suspect that is not really the problem.
You should certainly do those tests eventually.
Just to get or maybe loose the confidence in that engine.
Once you establish that the basic engine is good or bad,
All else is bolt on ****.
It is either worth the effort or it aint worth a ****.
I think you have some pretty cureable normal TBI troubles.

 

[tsr2185]

I always set base idle in park then I look to hit the in gear idle. That is really what you are after and if you are working on your own it is the only safe way to do it.
Never ever tune or adjust any running vehicle that is in gear by yourself.
Never.
One of the problems ive run into over the years is attempting to make too many adjustments at the same time.
Im sure their is an official gm flow chart.
If I attempted to reset base timing and adjust base idle while resetting the idle air control and just put a new temp sensor in.
Its just a bit more than TBI can chuck down at one time.
The TBI system and its diagnosis is based on "Flow Chart" logic.
If, then, yes, no.
it looks to me that you have determined that the basic mechanical functions of the engine are correct.
Everything in the rotating mass appears to be right.
So im pretty confident that you can check that off of the list.
A compression test and a leakdown test will confirm that but I suspect that is not really the problem.
You should certainly do those tests eventually.
Just to get or maybe loose the confidence in that engine.
Once you establish that the basic engine is good or bad,
All else is bolt on ****.
It is either worth the effort or it aint worth a ****.
I think you have some pretty cureable normal TBI troubles.

I sure hope so. Its definately tolerable, but I dont drive it everyday to get used to it. I just want to make sure its corrected in case it leaves me stranded when I rely on it on my 1.5 hr commute every 28 days, of which it has done no problem so far (knock on wood).

Its GOT to be (hopefully) a bad wire/cable, fuel pump, or ecm.

My local mechanic called back and said he will not do a leakdown test, and pretty much wont be able to find anyone that is old fashioned enough to do so lmao. He says people rely solely on data to troubleshoot this type of issue.

 

[tsr2185]

I always set base idle in park then I look to hit the in gear idle. That is really what you are after and if you are working on your own it is the only safe way to do it.
Never ever tune or adjust any running vehicle that is in gear by yourself.
Never.
One of the problems ive run into over the years is attempting to make too many adjustments at the same time.
Im sure their is an official gm flow chart.
If I attempted to reset base timing and adjust base idle while resetting the idle air control and just put a new temp sensor in.
Its just a bit more than TBI can chuck down at one time.
The TBI system and its diagnosis is based on "Flow Chart" logic.
If, then, yes, no.
it looks to me that you have determined that the basic mechanical functions of the engine are correct.
Everything in the rotating mass appears to be right.
So im pretty confident that you can check that off of the list.
A compression test and a leakdown test will confirm that but I suspect that is not really the problem.
You should certainly do those tests eventually.
Just to get or maybe loose the confidence in that engine.
Once you establish that the basic engine is good or bad,
All else is bolt on ****.
It is either worth the effort or it aint worth a ****.
I think you have some pretty cureable normal TBI troubles.

All that being said, I am starting to understand the hatred some people have for TBIs.... I myself love it cause it's easy to understand and see how everything works. Pop the hood on my 2016 pwoerstroke and I pray to god I dont have to mess in there too much (other than my emissions bye bye I did for 650+ hp) ((that truck brings much more smiles per gallon that this k1500 so far lmao))

 

[thinger2]

It still idled like crap and misfired with the esc wire disconnected. It was up to temp at the time aswell. Still need to go over and do this with the rebuild dizzy.

The new pickup coil had 845ohm across. And the old one had 1050ohms. Sure it was fine but the windings in the old one was a LOT less than the new one.

My base idle can also be real low from tinkering with tge idle screw. Do I set base IDLE when in park, or in drive? I seen instructions for both.

Does it seem to have a repeating kind of a surge in rpm?
In other words its like a pulse or it seems to repeat over and over?
That could be a bad sensor and the ecm is stuck in a data loop or the ecm loosing input from a bad ground or a bad sensor and the ecm cant resolve it .
Grounds my friends.
Fix yer friggen grounds.

 

[tsr2185]

Does it seem to have a repeating kind of a surge in rpm?
In other words its like a pulse or it seems to repeat over and over?
That could be a bad sensor and the ecm is stuck in a data loop or the ecm loosing input from a bad ground or a bad sensor and the ecm cant resolve it .
Grounds my friends.
Fix yer friggen grounds.

I have no codes, and all the sensors checked out fine in the data log. Unless the frequency of the data log isnt enough to catch the drop out, but I should at least catch it eventually...

Still have to take care of the head to firewall ground. And my thermostat housing grounds are reterminated, but there is exposed copper 3-4 inches up the wire....

 

[thinger2]

I have no codes, and all the sensors checked out fine.

Still have to take care of the head to firewall ground. And my thermostat housing grounds are reterminated, but there is exposed copper 3-4 inches up the wire....

Yep. Bad grounds from the head to the firewall will foul out your plugs.
Can also cause instrument cluster problems.
The grounds at the manifold can cause problems with the temp sensor loosing contact with the ecm and causing it to constantly trying to close loop.
Intermittants or bad grounds make the ecm repetively recycle over and over.
But it as as slow as mud.
So any time you **** with that reset outside of its parrameters,
You are starting again from scratch.

 

[tsr2185]

Question. I just noticed the little filter on the injectors....

I didn't change them nor even notice them when rebuilding TBI. What do they do and how critical are they? Could this still be my issue??? I still have the box but I planned to send injectors off to Mr injectors when I come back from offshore in 3 weeks. Scrolling though the pictures and just noticed it.

You must be registered for see images attach

 

[PlayingWithTBI]

What do they do and how critical are they? Could this still be my issue???

That screen is for bleeding trapped air and balancing pressure in the injector. It gets its fuel mainly through the bottom screen. Unless it's totally plugged, no it won't cause much if any issues. It's just there to keep the inside of the injector clean.