Timing

[Dylan88]

Truck runs great no issues. Just noticed when its warmed up and accelerate it makes a "dieseling" noise then goes away. Usually just happens when you tap the gas. Im going to check and set timing , could be advanced to much?

 

[Schurkey]

WHAT VEHICLE?

The knock sensor should signal the computer, the computer should retard the timing.

Any audible knocking should be of extreme short duration. Realistically, you shouldn't hear it at all.

You can and should check the initial timing if this is a TBI. If it's a Vortec, timing is not adjustable. While you have the hood up, take a small hammer and TAP the cylinder head or intake manifold. You are not beating it senseless. You tap the metal, you should hear the idle slow for a moment and then recover. If you're using the timing light, you'd see the timing retard when you pop the hammer on the metal. Either way, the engine should recover after a second or three.

If the timing does not retard, you'd better investigate the knock sensor, wire harness, computer, and ignition module looking for the problem. A scan tool will make this go much easier, quicker, and more-efficiently.

 

[Dylan88]

88 silverado 350 tbi

 

[Erik the Awful]

As Schurkey hinted at, it's not dieseling, it's knocking. What's your timing set at?

 

[Dylan88]

Checking the timing this week. Is that knocking have a sensor

 

[Dylan88]

I was told it was too advanced had few people listen to it.

 

[someotherguy]

Multiple possible causes for it to knock/ping when accelerating, but base timing too far advanced is the most likely cause.

Other causes can be bad EGR valve, excessive carbon buildup in the combustion chambers, overheating, and more, and more..

But start with the base timing. Zero degrees BTDC with engine warmed up and the tan/black bypass wire disconnected. Snug distributor down, re-check, then plug the bypass wire back in.

Always helps if you clean the timing indicator tab off on the cover so you can read the #'s, but it's also easy if you notice the slightly wider "tooth" in the indicator is zero. Marking the line on the balancer with a paint marker, piece of chalk, etc. helps you see it with the timing light.

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Tan/black wire location on most 88-93 trucks -

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And for others searching, typical bypass wire location on most 94-95 models -

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And where I found one hiding in a 1994 model that didn't have it further down, had to pull the glovebox insert to find it:

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Richard

 

[thinger2]

I was told it was too advanced had few people listen to it.

Do not listen the those people.
And do not let them anywhere near your engine.
The random distributer twisting tuners have always been a problem.
Even back in the old points carb days.
They show up, turn every friggen available screw, turn the distributor all over the place and make it pop and fart and after they are done screwing the entire system way out of parameters they come up with some ******** story that involves them bringing all of their knowledge and ******** experiance .
And it always ends with those dopes going home amd leaving you with a friggen mess.
That they will deny any responsibillty for even though they ****** it up
And the end result is always this pack of random screw turning wire breaking no clue farts telling you that the engine is smoked.
Every time.
They show up, give some idiotic diagnosis based on nothing.
And leave you a friggen mess.
You cant just listen to it and call a Rod knock.
You cant listen to it and decide on the advance.
Tell those clowns to buzz off.
If they have ears that sharp tell em to go tune a friggen violin
Start at square one.
Base timing with the est wire disconnect.
Set it a zero while it is hot.
Base timing, distributor stabbed correctly.
Start with that.

 

[Dylan88]

It worked timing fixed the noise runs good

 

[Schurkey]

Great.

Did you ever verify the knock sensor/timing retard system?