My 454 Rebuild

[Spareparts]

Man i aint got enough energy for all that! Hats off to you!
I may not be to bright or methodical but i am tenacious.

 

[Road Trip]

Man i aint got enough energy for all that! Hats off to you!

No worries. I used to do stuff like this in a previous life.
And just like always, I always get as much out of something
as I put into it. It's all good!

I may not be to bright or methodical but i am tenacious.

That makes 2 of us! :0)

I read that you have already spread the wires for
tomorrow's travel. Happy Hunting!

 

[Spareparts]

Driving to work today spreading the wires apart made no differance unfortunately.

 

[Road Trip]

Until i get this problem ironed out tuning is little help. I have the stock tune loaded back up now until this problem is finally solved and tuning can do some actual good.

We're in agreement on your debug methodology -- minimize the variables, keep it all as
close to the factory setup (simple as possible) until it runs right...and *then*
finesse/mod/upgrade it as you see fit. (!)

As a matter of fact, in my own budget resto thread I documented sorting
out the rough idle on the 220K mile L29 that followed me home last year.

It took me awhile (over 4 separate passes) to get the engine to idle
smoothly. (Back in the day, I would have ignored any rough running and
just started right in with upgrading the motor, and I'd end up with a bigger
mess than what I started with!)

Now? I'm with you. I won't allow myself to start tweaking/upgrading
an engine *before* I first get it running right as originally built. Without
a solid performance baseline, your project has no foundation to build upon.
(Of course if the machine is a trailered toy, then this level of caution is
laughable.) But when it comes to a DD/work vehicle, IMHO this is the best
approach.

****

You might have already seen this, but just in case, here's a link to where
I work my way through my own rough idle. (LINK) Nothing earth-shattering:

Pass 1: worn plugs.
Pass 2: 1 spark plug wire shorting due to routing.
Pass 3: worn O-ring on oil filler cap
Pass 4: Discovering 'bad coolant temp gauge' was really failed-open thermostat.

I'm 99% sure that 3 of the 4 above don't apply to your situation. And I might
have missed it in the previous 800+ replies, but have you checked the o-ring
shown in the attached photo? Sure, it's a reach, but it made a difference in
my back yard?

 

[Road Trip]

Driving to work today spreading the wires apart made no differance unfortunately.

OK. As discussed previously, instead of hanging everything on this one theory
(ie: spark plug wires affecting each other) now we simply put this theory on the
'parts/subsystem proven-good' pile as we continue to perform the troubleshooting
Process of Elimination.

And from my perspective until we can either eliminate or explain the excess flashing
observed on your timing light, (which varies according to what wire you are clamped to)
we're still on Plan A (chasing ignition anomaly) vs. Plan B. (valve springs?)

Since we're using Symptom Directed Diagnosis, the observed behavior about the ability
to rev without valve float doesn't support the weak spring(s) hypothesis -- which moves it from
probability to simply a theoretical possibility that doesn't apply under your hood.

More in a bit, I gotta go pull some stuff together...

 

[Road Trip]

What would happen if you clipped the timing light on the coil wire? It should flash every 90 deg on the damper, but also let you know that the coil is firing every time.

Hey Scottm, in order to prove/disprove a possible intermittency with the
Crank Position Sensor > ECM path, what if we first took your suggestion
and added the following to the harmonic balancer?

1st, measure/mark the balancer in 4 places, every 90°, indexed of
course off of the factory timing mark. Second, rotate the timing mark
to wherever you can best get to it with a sharpie, and write a '1' where it's visible.

BUT before you do that, plan out the number position so that there's
also room to write '2', '3', and '4', incrementing the number every 90° in
such a way that they are all visible when illuminated (strobed) by a timing light.

Maybe:

1 2
---------- < timing mark
3 4

EDIT: The above is what you would see after the fact with
the timing light strobing properly. In order to implement this
physically, at the timing mark, we would have this:

1
---------- < timing mark


Then Rotate balancer 90°, sharpie this to the right of the 1 position: 2

Then Rotate balancer 90°, sharpie this underneath the 1 position: 3

Then Rotate balancer 90°, sharpie this underneath the 2 position: 4

****

This way, if all 4 numbers show equally brightly (thanks to
a steady strobe from the timing light) then we can safely
assume that we are working with steady sparking every 90 degrees.

On the other hand, imagine only seeing 1, 2, & 4?
And 3 is either missing/dimmer? With our firing order (1-8-4-3-6-5-7-2)
we would have narrowed it down to either #4, or #7,
(dimmer) or *both* (dark/missing) as the victim cylinder(s) of a
flaky/intermittent/missing ignition spark?

It's not exactly using a full-on Pico scope setup,
but if we use your idea to put the timing light on
the coil wire feeding the cap and then mark the damper every
90 degrees with numbers to differentiate the 4
quadrants...then with an old school timing light
we can either assign more or less credence to
whatever the scan tool is reporting for misfires.
(correlation)

And we're talking a zero dollar expense to try this out!

Q: Does this explanation make sense? It's really
a lot easier to share some of these troubleshooting
ideas via the spoken word + whiteboard vs. typing
it in & hoping for the best...

Thanks for sharing, Scottm - I like!

PS/EDIT: All of the above may seem just way out there,
but when you read about CKP signal amplitude variations
due to runout as well as signal integrity (signal/noise)
being adversely affected by bad diodes in the alternator
or spark plug wires? In electricity/electronics, I am rarely
surprised anymore when all the tolerances stack up against
me on an older piece of machinery.

Check out this informative article for more: (LINK)

 

[BeXtreme]

I could have gotten a cap but not from my favorite parts store. I would rather wait for one from Orilley's then buy one from Autozone. Road construction between me and Napa and i did not want to deal with it waiting in traffic.

Everyone has their own preference, but I have found both Autozone and NAPA parts to be far more reliable than things I've gotten from Oreilly... just in general. I went through 4 alternators before getting one that wasn't bad right out of the box from them. The first one I thought was maybe my bad... so I took it right back off and took it in and had them test it. Nope.. tested bad. So they pulled another one off the shelf and I made them test it before I took it out of the store... BAD. So then they didn't have another one in the store and ordered more in. Came in the next day to pick it up and THAT one tested bad. Thankfully they had ordered three of them into the store instead of just one, so the second one tested fine. I took it home and installed it and it worked fine, except it would sometimes read a bit low charge when at idle and the electric fans kicked on.. I figured it was just a high draw. Nope, after about 3 months THAT one failed. Still under warranty, so I pulled it and took it in for yet another exchange. They pulled one off the shelf and tested it... tested fine. So I took it home and installed it and now my voltage is rock steady all the time and hasn't had an issue for about a year now.

Also, their order tracking for warranty parts is hot garbage. Their computer system sucks and doesn't properly track any of my parts and you can't look up items ordered for a specific vehicle like you can at Autozone or Napa. The autozone one is an AC Delco part... so not sure why you wouldn't want to do that.

Like I said though, if it is suspected that you might have a bad BRAND NEW part, you probably shouldn't try to replace it with the same part from the same supplier, unless it is free under warranty. If you are getting it free under warranty, then sure... but it still doesn't rule out that you might have gotten a bad part. Maybe the caps were manufactured at the same plant, in the same batch, with the same defect.

 

[454cid]

This thread makes me want to check my wires. I've always had what feels like a slight miss. I changed my wires last year, and struggled with the routing, trying to make it just right, but didn't know the importance of 5 and 7 specifically. I will definetly check this, and see if I can find an official routing in the manual, too.

 

[Spareparts]

The one I have now is AcDelco.
Looks feels cheap compared to the summit blue cap but the new one is gm so it will go in this weekend
Also: this will be new cap #4

 

[Road Trip]

This thread makes me want to check my wires. I've always had what feels like a slight miss. I changed my wires last year, and struggled with the routing, trying to make it just right, but didn't know the importance of 5 and 7 specifically. I will definetly check this, and see if I can find an official routing in the manual, too.

454cid, while you are at it, if you can find out what aftermarket spark plug
wire loom L31MaxExpress installed, I'd highly recommend it for the following
reason. There's something called the 'Inverse-Squared Law' in electricity that
we can take advantage of.

For example, if we double the distance between 2 wires, instead of 1/2 the coupling
like you would assume, it's actually results in only 1/4 of the coupling! (induced voltage)

NOTE: With the 5/7 layout, there will always be an inevitable degree of coupling
among wires running alongside each other, but the *key* is that the
resulting induced voltage stays *below* what it takes to fire the spark plug gap
on the 'too early' plug.

No doubt using the new wire-wound wires in accordance with the factory guidance
will get the job done, but if I can then add a little insurance policy by doubling the
'good enuf' distance and ending up with 1/4 of the induced voltage, I think that's a good deal.

I'm hoping that L31MaxExpress can share what he's using -- heck, I'll buy a set!
And take pics of it & share that as well. :0)

I mentioned that to him on a post he has in HP Tuners forum. The GM service manual has a diagram of the wire routing and it needs to be followed. The aftermarket wire looms I just put on the van have the wires routed correctly and they have 2x the spacing of stock. It definitely runs more smoothly between that and the shimmed up distributor.