I made a run stand to mess around with Ls engines and get familiar with tuning. I have run two engines on the stand and both were throwing p300 code. Could the engine being mounted to the metal engine stand solid with no rubber isolation be causing the random misfire. 22-05-05 20-10-02.hpl
The metal stand will affect the knock sensors, as will the exhaust system or lack thereof.Originally Posted by Brand New Classics
I do have a nice exhaust setup on there. Using factory Tahoe flanges and 02 sensor locations. One big muffler with two inlets and two outlets. One flex joint for easy removal when pulling an engine. I guess I'll rework the engine mounts with some rubber isolation and see if it goes away.
So today I bought some small block chevy rubber motor mounts and bolted them to an Ls adapter plate. Modified my engine supports with a tube on the end so they bolt in rubber isolated from the engine stand. I have a bellhousing from a 4l60e solid mounted to the run stand. While doing the motor mounts I threw in some poly sway bar biscuits on top and bottom to isolate the bellhousing mount. It is now 100% isolated from the run stand and it still has a bad miss fire on # 7 and half as bad on #4. I have several sets of coils in the shop. Used and new and neither make a difference. Swap plugs and wires and it stays in the same hole. I guess Monday ill start with a compression test and maybe throw a new crank sensor at it.
Would not having a torque converter attached to the flex plate cause a random miss fire? No load on the crank so the sensor is thinking its misfiring? OR could it be a sloppy timing chain? Or could it be a random MAF sensor I am using. I grabbed the cleanest MAF sensor I had in the shop. Not sure if 5.3 and 6.0 MAFs are the same or different.
Today I bought a new crank sensor and tried to do a crank learn a few times. Still misfires. did a compression test and im at 160 in all cylinders. I hate these jobs where I get a bunch of random parts or parts missing with no money to purchase correct parts so I use what's laying around sometimes.
SMH could be the 5.3 spark plugs in a 6.0. They are brand new for a 2001 suburban. I wouldnt think spark plugs would cause this big of a problem.
Im using the computer that came on the 6.0 denali and have removed the vats. it runs great but throws the random misfire code.
vince86elcofactory2002denalituneflybywire.hpt The computer im using
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