bryy

Okay so Ive got about 300 miles on a top end rebuild which included all the works. New head/seals/valves everything from engnblder.

The list goes:
Timing chain
all new hoses vacume and coolant.
thermostat
everything was checked for flatness
oem gaskets used everywhere
injectors sent out to witch hunter.
New oem cap and rotor and plugs
Wire are 1 year old oem

everything was oem except the usual from engnblder.

I just noticed a funny sound coming from my exhaust only at idle and cant figure it out

Things I have tried.

Coolant level( im gonna lift up the front in the morning and burp it again.)
Unplugged TPS got way worse. defiantly not the issue.

Checked Idle RPM set at 750 timing, then with terminals jumped is just about at 5 degrees (maybe a hair more like 5.5 or 6 could this be it?)

I have not replaced the o2 sensor since about a year ago, could it of gotten dirty with the initial start up?

The valves are adjusted

The exhaust kind of makes a sucking sound when it misses. check out the video let me know if you have any suggestions.

Its really not a bad idle maybe fluctuates like 50-100 rpm I get a solid 17mpg with 35's and 4.10's reading of the trip meter so its a little off.

Power is good. I just dont understand it.

Gamefreakgc

You could check for a vacuum leaks... that'll cause weird idles.


If you hold a rag/tissue up to the exhaust pipe, does it ever suck it back in? Or just sound like a sucking noise?

the_supernerd

I am not sure what exactly is causing it, but it sounds like a small random misfire. One of my trucks was doing the same thing, but slightly worse than yours, and I discovered it was a vacuum leak at the intake manifold gasket. The wires are probably ok since they are fairly new, but it might be worth checking under the hood with the engine idling in the dark to look for sparks coming from the wires when the misfire occurs. Did you gap the plugs? Does the timing change when the terminals are jumpered or is it the same as when they are not jumpered?

You might also try cleaning the throttle body and checking the intake system for leaks and cracks. Any unmetered air can cause issues. Check the distributor and make sure the air gaps are good, the shaft is tight, and that the gear is not worn.

bryy

update from this morning, problem still not solved.

Changed the o2 sensor, (it was old and needed it anyway)
Burped the cooling system, no air came out
Checked exhaust manifold for leaks
double and triple checked vacuum hoses.
Unplugged the battery for 30 min


My plan is to recheck the TPS tomorrow and start from scratch for adjustment
RE-check valve clearance.
beef up ground connection to block.

This motor runs awesome through the rpm range except at idle as shown in the video
Good gas mileage
and good power for 35's and 4.10's

The intake and everything was cleaned spotless during the top end rebuild.

TNRabbit

Definitely a miss. I'd go through the spark plug wires, distributor & sparks plugs with a fine tooth comb. Check for consistent bright spark at each plug.

YotiBerra

sorry to hijack but not enough posts yet to start a thread...In the middle of a head rebuild...and had a question...Does anyone know what the random threaded hole into the head on exhaust side 22re in between the two egr ports (directly in between spark plugs 2 & 3) is for? The exhaust gasket just covers it up and its all full of carbon...thanks in advance!
-Jon