Engine issue(s)

chas0218 · September 16, 2013

Thought this might be a better place to ask.

Ok so my wife and I were bringing home our 6800lbs. camper it's about 180 miles total. Half way thru our trip the truck began shaking violently in 4th gear my immediate thoughts were crap I just burned up 4th gear. So I shift into 3rd and start looking for a spot to pull over but the shaking goes away. About 15 miles later the truck starts to do the same in 3rd gear but not as bad. Thank god I got to somewhere with a large enough shoulder I could pull off. When I come to a stop the truck is barely idling and chugging BAD. So I shut it off get out and start to look at stuff. First thing is tranny fluid it is bright red and smells like the brand new stuff in the truck. Oil was the typical color and just changed in July. Replaced plugs 1 year ago (about 6k miles), and wires 3 months ago.

Now onto the truck. It is a 2003 5.3L 80k miles. I have had a random miss fire for almost 3 years along with a slight manifold exhaust leak (broken bolts). Until lately the exhaust leak would seal itself back up now but now it is leaking badly (for about 1 month) and the truck has no power and just shakes and chugs at lower rpms. Higher you go the more it cleans up but gives an random misfire almost constant in the higher rpms.

Are my cats clogged? Cam position sensor? I am at a loss and all of this would have been fixed in a timely manner if my daily driver commuter car would have just cost me $1000 in struts, tires and ball joints.

I'm just wondering where I should start looking for the problem and where to go from there.

kstruckcountry · September 16, 2013

Have you had it scanned with an actual scanner? Yeah it may be cats backing up your exhaust causing the leak and chugging. But sounds like there's a deeper issue if you've had a code that long?

chas0218 · September 16, 2013

Well the light would come on and flash then go back off. This generally only happened when the motor was held constant at 3k rpm or higher (while towing or hauling) the truck seldom goes above 2500 rpms during normal driving. It hasn't stayed on constant until yesterday. The truck barely runs so I am really hesitant to take it anywhere in fear of being stranded. My neighbor might have a scan tool so I will see about getting some codes read. Otherwise the only code I know of is random misfire.

kstruckcountry · September 16, 2013

It's common for the cats to plug after running with a light for an extended period because of the engine not running clean. So maybe that's it, if you can scan it, it will tell you if the cats are plugged. Knowing which codes will definitely help. Rob should chime in soon, he will know!

chas0218 · September 16, 2013

Sweet thanks, I appreciate the help!

gmtech4 · September 17, 2013

i would have a shop put an exhaust back pressure gauge in the 02 sensors before any more cat talk

all i got ,,,,

scan it first

chas0218 · September 18, 2013

Got it scanned and got some interesting codes. One was for my crank position sensor, unable to communicate with obd2, random misfire, and some 4wd codes (guessing because I spin the 4wd shaft by hand to check the ball joints), wheel speed sensor codes (I think these might be related to my speedos servo motors going bad).

That's all I have for ya guys. I put my hand over the exhaust and there was a good amount of pressure pushing back.

chas0218 · September 20, 2013

Ok so I replaced the crank shaft sensor now the truck won't come above 2k rpm. Will the truck eventually start to run a little better if I let it keep running? I know I need to have the PCM relearn done but am hesitant because I am not sure it will make it to the dealership only pulling 2k rpm. I am looking at a $100 for the relearn and $75 for the tow to the dealership. At this point I might as well had the dealership do it. O forgot the $55 for the sensor.

chas0218 · September 20, 2013

Would this work for re-learn?

1. Turn off all of the accessories. With the Air temperature sensor and Coolant temperature within 5 degrees (Centigrade) of each other, start the engine and let it idle in Park or Neutral for two minutes.

2. Accelerate the vehicle to 55 mph at part throttle. Cruise at 55 mph for 8- 10 minutes until the engine reaches operating temperature.

3. Cruise at 55 mph for another 5-6 minutes.

4. Decelerate to 45 mph without using the brakes, and maintain 45 mph for 1 minute.

5. Perform 4 deceleration cycles, without using the brakes, of 25 seconds each where no specific speed is necessary. Returning to 45 mph for 15 seconds in between deceleration cycles.

6. Accelerate to 55 mph and cruise for 2 minutes.

7. Stop the vehicle and idle for 2 minutes with the brake applied and the transmission in Drive (automatic trans.) or Neutral (manual trans.) with the clutch depressed. Refer to diagram A on page 8.

nickvrebel · September 20, 2013

I don't think it's possible to relearn it with a drive cycle.

I do know that a Tech II (or whatever the current GM scan tool is), Snap On scan tools, HP Tuners and a few others can run the procedure.

gmtech4 · September 20, 2013

ya dont get 4wd codes from turning a driveshaft

chas0218 · September 23, 2013

I put it in 4wd over that weekend but it went in and out no problem. I don't know what the issue could have been there. But the engine is actually running worse after I replaced the CKS.

The check engine light is no longer flashing at me when it is running but the rear of the Catalytic converters turned cherry red after running it for 10 minutes at 1000 rpm.

On a side note would a wheel speed sensor code left and right have anything to do with my speedo reading incorrect? I saw these trucks had a gage cluster problem but I just had the front wheel bearings replaced 2.5 yrs ago and barely have any miles on them.

chas0218 · October 21, 2013

Update:

So I have an update, the truck seems to start and idle fine for a little while. Once I let it idle or drive it a mile it will start to run rougher and rougher until it dies and won't start back up. Once it sits for a couple hours it will start back up and allow me to drive/run for a short distance.

Any other ideas? I will be checking fuel pressure tonight. I haven't been able to get the exhaust flange nuts off so it looks like I will be cutting them off.