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2007 SUBURBAN 4WD LTZ

The location of the fuel pump causes it to rust out the mounting flange. I had to have it replaced a few months ago. I have since parted company with it at the time I bought the 2013 Duramax
 
Understood, went out to try to trouble shoot it. Started right up, so drove 12 miles home. Have an appointment for the tune on Tuesday. I spoke to him and he said it could.jist be related to that and was suprised it was as drivable as it was. So hopefully will know more next week.
 
Update been tuned its not right, but he is stumped as to why we have the hard start after it warm. However the saga continues, espn version i had to pull passenger head due to bent intake valve. Pryor to that it had developed a miss on cylinder 4 , so back together now and still getting 0304 code and a miss. Moved coil,sparkplug, plug wire . Compression is 150is same as cylinder 2 any ideas ??
 
Possible the fuel injector for that cylinder is stuck open, shut, or other problem where it's not working correctly. I have told the story of the TBI new injectors that dribbled fuel only when the throttle was snapped opened seen under a timing light.

Did you check the pushrod? Aka make sure the valves are moving. Damaged lifter or flat cam lobe is always possible.

How did the valve get bent? Is the tune raising the RPM limiter or the shift RPM's? And why is there only one valve bent (Sarcasm) You checked all 8 holes for more bent valves?

Start-stall at idle... What is the idle RPM after an event like this? I have seen older engines with the idle air control valves not getting enough air - thus the tune may need to open the throttle vane more. The 650 idle RPM was showing up low like 500 RPM when the IAC was dirt covered.
 
Ok time for truth! LOL I had young help but when it was time to install the intake we were missing two intake bolts and sleeves. Which was very odd. Was very careful to put all removed hardware in containers. When I tore it down due to a obvious cylinder issue that sounded like a dropped valve to me. (been there) I found both missing intake bolts one under intake and one stuck in the intake valve. Very minor marks on piston or in the head. I did notice the face of the injector on that cylinder looked very "clean" I need to check for voltage at injector at this stage I guess. Compression test was 150 on #2 and #4 didn't do more since there were almost exactly the same.
 
Yeah, you get compression, but are both valves opening all the way? Say if the exhaust valve got bent- you’ll still get full compression and can pass a leak down test just fine. Air and fuel come in, boom goes the fuel and the when it cannot get rid of exhaust, the proper amount of new oxygen cant come in, fuel wont burn. Eventually you would notice wet spark plug, but it takes a long time.
 
When the intake got bent it was stuck open about a 1/4in. When I re- torqued the rockers they all visually opened and closed fine. But I did not put my dial indicator on it the see what the travel was.
 
:facepalm: You officially get the Warwagon award!

I bet you have more than one bent valve.

screwed.jpg


Sadly the debris in the intake doesn't stay in one hole: it bounces around in the intake and can bend several valves. I swapped both heads, and new slugs with gapless rings, after loosing a worm clamp during an IP swap. It took a week to fall apart and "show up". I had intake valves bent on both heads.
 
Fortunately on the LS it wasn't in the intake, it was on the valley cover and fell in the intake runner on the head. So kept the parts in one cylinder at any rate.
1604602227181.png
 
Drove it in to work today, 50 miles ran great no codes, Stopped and filled it up was gas, and had a rough idle on restart. About a mile later set a pending P0304 code. Pulled in work and had rough idle.
Vacuum seems low @ 15in
 
One of the few things I learned in an automotive class by an old GM mechanic who was teaching it: Debris in the intake doesn't follow airflow. The valves and pistons are moving very fast. This speed can smack the debris and bounce it out of the head port (even clean out of the cylinder) into the intake or another head intake port. Vibration and airflow can move it into another intake port from the intake.

This is especially weird with debris in the exhaust getting into the engine. Best example is a manifold cat failure (Nissan V6) getting debris back into the cylinder, scoring it up bad enough to lock the piston up, popping a rod, and hot oil hitting that failing cat burns the car to the ground.

In diesel engines turbo failure on the exhaust wheel only can get into the engine... Don't get us started on glow plug failures becoming debris...

The picture above with the worm clamp screw: the clamp itself was in another intake port.

The above said the minimum needed is to do a compression check on the other head that wasn't removed. Maybe you got lucky: Vegas Odds say you didn't.
 
WarWagon said:
One of the few things I learned in an automotive class by an old GM mechanic who was teaching it: Debris in the intake doesn't follow airflow. The valves and pistons are moving very fast. This speed can smack the debris and bounce it out of the head port (even clean out of the cylinder) into the intake or another head intake port. Vibration and airflow can move it into another intake port from the intake.

This is especially weird with debris in the exhaust getting into the engine. Best example is a manifold cat failure (Nissan V6) getting debris back into the cylinder, scoring it up bad enough to lock the piston up, popping a rod, and hot oil hitting that failing cat burns the car to the ground.

In diesel engines turbo failure on the exhaust wheel only can get into the engine... Don't get us started on glow plug failures becoming debris...

The picture above with the worm clamp screw: the clamp itself was in another intake port.

The above said the minimum needed is to do a compression check on the other head that wasn't removed. Maybe you got lucky: Vegas Odds say you didn't.
Click to expand...
I didn't get to work on this weekend and all "missing" parts accounted for, However you are right I do need to do the compression test at the stage. Idle seems to be the the wild card, going down the road it runs good and is not throwing any codes till you get in to stop and go traffic.
 
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