I just refreshed my ls1, new bearings ect, after about 15miles or so of driving, I decided to give it a little pull. On the decel I developed a backfire coming from what sounds like intake manifold . Cyc 2 was cooler then the rest after drive. Now it doesn't get hot at all. So I checked the coil for spark which it had and i changed it out anyway, I put in new plugs went to a tr5 from tr6s, new wires and new injectors, thinking it was stuck open,, I also checked for exhaust leaks. No new codes or anything. I can't figure this out. https://youtu.be/ZZehKv4OP6U

 

I noticed a bit of smoke upon startup, where was that coming from?

 

Not quite sure, I'll have to check tomorrow. I try not to keep it started for long in case it was something major. Plus it sounds like a shotgun going off in my garage lol

 

1st TR6's are for boosted engines only-----They are way too cold for a daily driver N/A car TR55's are the best all round plug for a LS engine----Also GM used to recommend a .060 gap--But in the last 5 years they now recommend a .040 gap
Backfiring is normally from an engine misfire you need to data log your engine to see where the fault lies
Yes it can cause what seems like backfiring if you have an exhaust leak--But it is more of a popping sound than a backfire--
Did you install LARGER injectors than stock ?????? If so why ??
This also will cause fueling issues
Do you have access to a data logger or a hi end scanner ? This will help isolate the issue
Has your eng ever been tuned ?
What eng mods do you have ?
all this info is needed to help ya

 

It's still na, but I've always heard with at least a cam you can run tr6s. Yes it has been tuned a few times, but my tuner lives an hour away. I literally just got hp tuners to load on my laptop last night i was having a hard time loading the drivers. Im going to swap push rods back to the 7.35s which it was tuned on originally, for some reason I decided to go back to my 7.4s when I put the motor back in. The weird thing was it ran fine and sounded good till I came down off my wot pull and that's when it started popping on the deceleration and at cruising speed. I'll gap the plugs to a .40 when I swap the push rods back and run a scan. Just worried leaving it running for long but at this point worst case the heads have to come off. And its still the same size injectors I bought "new" probably just cleaned, i got 97 injectors because they were 29lb compared to new models at 26lb. Which is what I have also I just figured mine were dirty and clogged or hanging open. When I pulled my plugs to swap to tr5s, the old ones seemed like they rich and they were black with maybe 30 miles on them. I'll try a data log, I wonder if false knock could cause this, i did change to a poly stiff mount.

 

i was finally able to do a log, but im not sure what im looking for