Trlrider
OBS Enthusiast
Simple thing to do to eliminate the cats being the problem, loosen the exhaust at the manifolds and see if the issue goes away or is less."
Had a customer a few years back with the same issue. He threw several hundred dollars in parts at the truck including a starter, battery, tuneup, etc and did not fix it.
Brought it to us and the first thing I did was loosen the exhaust at the manifolds.
Truck would start, idle and go down the road without coughing.
Sadly, he had screwed with it to long and the backpressure from the bad cats caused damage to the cylinders and the engine was down like 50% or worse on compression.
This fuel we have today destroys the mid to late 90's VORTEC cats.
Had a customer a few years back with the same issue. He threw several hundred dollars in parts at the truck including a starter, battery, tuneup, etc and did not fix it.
Brought it to us and the first thing I did was loosen the exhaust at the manifolds.
Truck would start, idle and go down the road without coughing.
Sadly, he had screwed with it to long and the backpressure from the bad cats caused damage to the cylinders and the engine was down like 50% or worse on compression.
This fuel we have today destroys the mid to late 90's VORTEC cats.