1999 Chevy Silverado 4.8L running rough only on one bank of cylinders! other fine!

Hi all,

I have a 1999 Chevy Silverado 4.8L V8 1500 pickup mated with the 4L60E transmission.

It has crank trigger ignition.

Left bank of cylinders runs perfectly fine, exhaust manifold gets up to temp quickly and runs well (dual exhaust modification).

Right bank of cylinders doesn't run well, although, it does run. The exhaust manifold is colder, much more noticeably colder than the left bank. This vehicle is also equipped with headers, so every tube is equal in temp on the right side (using an infra red pyrometer). The plugs get black, AND the engine backfires through the right bank exhaust (out the back, dual non H-pipe exhaust). This vehicle has run perfectly well before.

No codes in memory, checked with OBDII scanner..... nothing. I pulled out the injectors, and they look alright. I am going to have them ultrasonically cleaned.

Has anyone encountered this problem before? The engine harness to coil pack harness connector is in good shape, voltage exists where it should, injectors are getting voltage (they click as well), this is the opposite side to the fuel pressure regulator. Just miffed that one bank is doing this. The O2 sensor doesn't do anything 'till the temp gets high enough, although it is a heated type (both front and rear). It runs open loop while warming up, but the OBD scanner shows that it is rich on that one right side...

Any suggestions would be greatly appreciated.

Thank you.

Reply to
Robert
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"Robert49" wrote: > Hi all, > > I have a 1999 Chevy Silverado 4.8L V8 1500 pickup mated with > the 4L60E > transmission. > > It has crank trigger ignition. > > Left bank of cylinders runs perfectly fine, exhaust manifold > gets up to temp > quickly and runs well (dual exhaust modification). > > Right bank of cylinders doesn't run well, although, it does > run. The > exhaust manifold is colder, much more noticeably colder than > the left bank. > This vehicle is also equipped with headers, so every tube is > equal in temp > on the right side (using an infra red pyrometer). The plugs > get black, AND > the engine backfires through the right bank exhaust (out the > back, dual non > H-pipe exhaust). This vehicle has run perfectly well before. > > No codes in memory, checked with OBDII scanner..... nothing. > I pulled out > the injectors, and they look alright. I am going to have them > ultrasonically cleaned. > > Has anyone encountered this problem before? The engine > harness to coil pack > harness connector is in good shape, voltage exists where it > should, > injectors are getting voltage (they click as well), this is > the opposite > side to the fuel pressure regulator. Just miffed that one > bank is doing > this. The O2 sensor doesn't do anything 'till the temp gets > high enough, > although it is a heated type (both front and rear). It runs > open loop while > warming up, but the OBD scanner shows that it is rich on that > one right > side... > > > Any suggestions would be greatly appreciated. > > Thank you.

my 03 has 3 oxygen sensors one for each bank and one after the cat maybe yours is the same?

Reply to
kenowen

No comment on this problem, but my 97 S-10 has 4 O2 sensors, gm is stupid, why would a V8 have 3 and a V6 have 4, dumb~!

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Reply to
Kiel Uyttenhove

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