Stutters and backfires - clogged cats?

[RockGlock86]

So I recently replaced 4 lifters after replacing all lifters with AFM delete. All was well for a few days. Yesterday I got a bank 1 lean code and after looking I had a big crack in the rubber boot for the pcv hose where the hard line meets the valve cover. When I had the head off last week I cracked the plastic on the bank 1 intake manifold gasket aswell. I replaced the little rubber boot yesterday and got another lean code within 15 minutes. So assuming it was the intake manifold gasket, I pulled the intake off this morning, and put down Fel-pro metal gaskets instead of the plastic ones. That went normal. When I had the intake off it had oil dripping out of it, seeing as I had just cleaned it a few days ago when it was off the last time I figured it would be a great time to replace the driver side valve cover with the new style that is supposed to cut down on oil consumption. Replace valve cover, replace intake, hook it all back up and fires right up. Idles fine, revs fine. I leave and make it about 2 miles from my house fine and then it starts backfiring hard and stumbling. no power, wont really make it over 2k. I get a P0355 code, and limp back home. I switched the coils with No. 3 and fire it up and check codes and now I have P0353 and P0355, I cleared the codes in case of some ghost in the system, scan again and and now have P0351, P0353 and P0355. seeing as these are all driverside coils I switched the whole coil plate from side to side, thinking it would follow it. Run it clear faults and scan again and still all driver side faults. So I am thinking that either the large grey plug for the coil harness has malfunctioned or maybe there is something else I am missing?

 

[thompsoj22]

injector harness? are you sure it is ignition and not fuel related? although backfiring defines timing not necessarily no spark, no shop rags/paper towels left behind in the intake or head ports? if i read the post correctly, you initially replaced all lifters with AFM delete, than had to go back in and replace 4 of those? did you plug/cap the fuel rail during the R&R? If there were only 4 lifters replaced and they were on the drivers side i would guess lifter compatibility problem or debris in the valve port. ie valves staying open, this will backfire like a mother f'er do a compression test on the affected cyls and verify valves seated? im just guessing! hang in there!

 

[RockGlock86]

No shop rags left in or anything like that I double checked all that before reinstalling everythign and my wife held the wiring harness up while I slide it in place and set it down. I will go out and double check injector harness right now and see if thats all good, I guess I could have a couple injectors plugs switched maybe? could something like that cause this type of behavior? And yes on replacing all 16 lifters, and then going back and replacing 4 of them again. I had another thread about it, I think basically it was crap lifters from a budget kit. But it could have been something I did wrong too.

 

[89Suburban]

Sucks bro. Yep check, check and recheck. I found a few things wrong from installation when I had mine apart. Did you snug up the valley pan bolts? If you have oil coming out of the intake you need a catch can. Check the coil wiring harnesses real good, I nicked one and caught it when installing the intake.

 

[thompsoj22]

No shop rags left in or anything like that I double checked all that before reinstalling everythign and my wife held the wiring harness up while I slide it in place and set it down. I will go out and double check injector harness right now and see if thats all good, I guess I could have a couple injectors plugs switched maybe? could something like that cause this type of behavior? And yes on replacing all 16 lifters, and then going back and replacing 4 of them again. I had another thread about it, I think basically it was crap lifters from a budget kit. But it could have been something I did wrong too.

do a compression test on the effected cyl's and verify valves are sealing, the injector harness probably laid in place perfectly and im not sure that you could miswire one injector to the next? the fact that it started, idled and than drove for a couple miles til it fubar'ed basically rules out any connector mixup?

 

[RockGlock86]

I just checked all my injectors against the wiring diagram and everything is in place, its only the driver side that is effected no matter what parts I swap, and a couple times I have gotten an actual misfire code, P0301, but other than those one or two times it has been coil primary/secondary code, P0351/3/5. Never a P0357 though not sure if that matters. I checked all my connections and plugs and everything is in place. Something I just noticed, as I was laying under the truck while it was running, it sounds like there is one or maybe two small metal objects inside the exhaust where the banks come together. After the cats and before the muffler the Y there. Not sure if it is relevant either but my cats are 150-200 hotter on the passenger side vs the driver side, consistently. Also in laying under the truck I noticed the downstream driver side O2 sensor wire was rubbing against the front driveshaft and one of the browns in there had a rub through the jacket to the copper, only one wire tho. I just repaired that aswell.

 

[Foggy]

Just a thought: I wonder if your injectors themselves are bad OR your fuel
pump is weak... that will certainly cause a backfire AND that driver side Cat
to not heat up.. the pcm may be cutting spark due to no fuel... food for thought

 

[OR VietVet]

A compression test and fuel pressure test is needed to help eliminate the basics. How old are the plugs and what do they look like. The compression test should be done with all plugs removed.

 

[Fless]

A compression test and fuel pressure test is needed to help eliminate the basics. How old are the plugs and what do they look like. The compression test should be done with all plugs removed.

Does "all" include #8? It's sooo haaard! LOL

 

[OR VietVet]

That's a big WAAAAAAHHHHH!!! Suck it up.