ChinoHillian Posted June 10, 2011 Report Share Posted June 10, 2011 (edited) Truck is throwing this code after putting on hi flow cats with my long tubes. I do have a ticking sound from front driver side of the engine so I don't think this could be a plugged cat. Any help or suggestions on what this is? When I go WOT on the truck, she starts to shake back and forth around 3000 rpm so I back off. Other than that, drivability has remained the same. I just read that an exhaust manifold leak could cause this so I believe that is where the ticking sound is coming from. Should i buy OEM exhaust gaskets and check my spark plug torquing? Edited June 10, 2011 by ChinoHillian (see edit history) Quote Link to comment Share on other sites More sharing options...
tonycillo Posted June 10, 2011 Report Share Posted June 10, 2011 yes i would start there. i reused my stock oem gaskets with zero problems. Quote Link to comment Share on other sites More sharing options...
desrtrat Posted June 10, 2011 Report Share Posted June 10, 2011 oem gaskets work real good. did you remove the plugs when you installed the headers? had the same bucking when i did mine, and found i damaged a plug some how.. good luck Quote Link to comment Share on other sites More sharing options...
Cramer Posted June 10, 2011 Report Share Posted June 10, 2011 The p0420 is from the high flow cats. The sample between front and rear sensors are too close. The ticking can be hard to pinpoint. The sound can be magnified and travel to the opposite place it actually is. Use the stock MLS gaskets and make sure the bolts are correctly torqued. Use anti-seize on the bolts too. Run the truck normal for a few heat cycles and recheck the bolts torque. Quote Link to comment Share on other sites More sharing options...
ChinoHillian Posted June 11, 2011 Author Report Share Posted June 11, 2011 well i crawled under the truck and banged on the driver side cat and it sounded fine. could there be anything else besides an exhaust leak that would cause the code to be thrown? maybe my tune? Quote Link to comment Share on other sites More sharing options...
Cramer Posted June 11, 2011 Report Share Posted June 11, 2011 (edited) The p0420 is from the high flow cats. The sample between front and rear sensors are too close. The ticking can be hard to pinpoint. The sound can be magnified and travel to the opposite place it actually is. Use the stock MLS gaskets and make sure the bolts are correctly torqued. Use anti-seize on the bolts too. Run the truck normal for a few heat cycles and recheck the bolts torque. As stated above....... Soooooo have your tuner tune out the rear O2 sensors. If the truck isn't tuned it needs to be, and if not the high flow cats will be melted and you'll need new ones. Search P0420 in the search tab, and you will see how common this is with LT headers and hi flow cats. BTW what headers did you put on? Edited June 11, 2011 by sinr98 (see edit history) Quote Link to comment Share on other sites More sharing options...
ChinoHillian Posted June 11, 2011 Author Report Share Posted June 11, 2011 i put on dynatechs and had my tuner tune out the rear o2 sensors. Quote Link to comment Share on other sites More sharing options...
ChinoHillian Posted June 14, 2011 Author Report Share Posted June 14, 2011 Took the SSS to a shop today and found out that a cylinder wasnt firing because one of the spark plug wires was leaning on the header. So the high rpm shuddering is fixed. Came to find that there is an exhaust leak in the hi flow cat! Still working on P0420 Quote Link to comment Share on other sites More sharing options...
Fireman31 Posted June 14, 2011 Report Share Posted June 14, 2011 Took the SSS to a shop today and found out that a cylinder wasnt firing because one of the spark plug wires was leaning on the header. So the high rpm shuddering is fixed. Came to find that there is an exhaust leak in the hi flow cat! Still working on P0420 The driver's cat is leaking? Is one of the 02 sensor bung plugs missing? A leaky cat would definitely cause a P0420(driver's side cat low efficiency)..... Quote Link to comment Share on other sites More sharing options...
ChinoHillian Posted June 14, 2011 Author Report Share Posted June 14, 2011 Its the driver side cat but the bungs are fine. It's under the heat shield and I was going to find a place that can take the heat shield off and take a look at it to see if its crack or hole or whatever the case may be Quote Link to comment Share on other sites More sharing options...
Fireman31 Posted June 14, 2011 Report Share Posted June 14, 2011 Was the Dynatech kit new? Quote Link to comment Share on other sites More sharing options...
ChinoHillian Posted June 15, 2011 Author Report Share Posted June 15, 2011 used from kcsilveradoss. Good dude to do business with Quote Link to comment Share on other sites More sharing options...
kcsilveradoss Posted June 15, 2011 Report Share Posted June 15, 2011 Was the Dynatech kit new? It was MY dynatech kit. with less than 5k miles on it. Like I told Nathan, I would be contacting Dynatech or having a shop weld the leak. I stilll do not think it is plausible that they are leaking, nor can I understand how they decided there was a leak "under the heat shield"...I think the shop is trying to sell him a bill of goods. Quote Link to comment Share on other sites More sharing options...
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