yukon23
TYF Newbie
First I want to say sup to this comunity I been a member in the shadows for a min now, but I find myself ready to collect on the full coverage im paying for my 2002 yukon xl. Hopefully someone here has faced the situation im trying to figure out now.
I have a 2002 yukon xl with the 5.3 flex fuel motor and for the past few months I have had a problem with the kon. It seems everytime I run the ac and come to a light/stop sign its starts to ping/diesel. Now I removed the cats prior because not one but both cats broke up inside and made a very embarrasing rattleing noise and the price was not realistic or feesable at the time. Since my brother is a welder I pulled the exhaust and went with straight pipes and used non spark foulers to move the o2 sensors out the stream the kon ran fine and sounded better more aggressive. I noticed the noise get louder when the warmer weather rolled around, living in florida we have cool winters unlike my winters in the bronx but as soon as the warmer weather came back the noise got progressively more noticeable. Since this started I have changed the knock sensors and harness, the plugs, wires, I even purchased a new fuel pump. I was told fp should be 55-65 and I had 45 at idle and 50 wot. Well actual fuel pressure is suppose to be 48-56 as per gm stealership by the vin. Well now I have new parts all from the dealership to no avail. The only comfert I have is knowing the parts are new
but the problem is still there and I have to put my truck in park or neutral when ever I come to a light or stop sign im affraid engine damage might occure from the detonation. Now I know the motor should have cats for turbalance reasons and emision etc but I dont believe this is the reason cause I have heard this befor the removal of the cats. The ecm use to throw a map code and I purchased the sensor too but still no change. This is not the underload ping everyone has once I hit the gas the noise goes away YOU DO NOT HEAR IT UNLESS YOU ARE IN DRIVE WITH THE AC ON AND MY FOOT ON THE BRAKE. Any help / suggestions would be greatly appreciated. Now I do need to add at this time I am an ase certified tech also and this has bewildered me and some other techs in my area im sure its something simple I have over looked but im two seconds away from lighting the match..........
The only thing I can think of is the timing chain stretching ever so slightly. Ideas ????????
I have a 2002 yukon xl with the 5.3 flex fuel motor and for the past few months I have had a problem with the kon. It seems everytime I run the ac and come to a light/stop sign its starts to ping/diesel. Now I removed the cats prior because not one but both cats broke up inside and made a very embarrasing rattleing noise and the price was not realistic or feesable at the time. Since my brother is a welder I pulled the exhaust and went with straight pipes and used non spark foulers to move the o2 sensors out the stream the kon ran fine and sounded better more aggressive. I noticed the noise get louder when the warmer weather rolled around, living in florida we have cool winters unlike my winters in the bronx but as soon as the warmer weather came back the noise got progressively more noticeable. Since this started I have changed the knock sensors and harness, the plugs, wires, I even purchased a new fuel pump. I was told fp should be 55-65 and I had 45 at idle and 50 wot. Well actual fuel pressure is suppose to be 48-56 as per gm stealership by the vin. Well now I have new parts all from the dealership to no avail. The only comfert I have is knowing the parts are new
but the problem is still there and I have to put my truck in park or neutral when ever I come to a light or stop sign im affraid engine damage might occure from the detonation. Now I know the motor should have cats for turbalance reasons and emision etc but I dont believe this is the reason cause I have heard this befor the removal of the cats. The ecm use to throw a map code and I purchased the sensor too but still no change. This is not the underload ping everyone has once I hit the gas the noise goes away YOU DO NOT HEAR IT UNLESS YOU ARE IN DRIVE WITH THE AC ON AND MY FOOT ON THE BRAKE. Any help / suggestions would be greatly appreciated. Now I do need to add at this time I am an ase certified tech also and this has bewildered me and some other techs in my area im sure its something simple I have over looked but im two seconds away from lighting the match..........
The only thing I can think of is the timing chain stretching ever so slightly. Ideas ????????
