Hey guys I’m lost. I built an 96 lt1 for about two weeks it ran remarkably but one day I got on it pretty hard and during deceleration it started backfiring and again when I pulled out. I noticed immediately that it lost power and a lot of it. Ever since I’ve been putting parts on it to try and cure the issue it’s running a lot better now but it’s power band is nowhere near where it was before. It used to come alive at 2500 rpm and I mean come alive but now it has a smoothe power band until it hits 5600 then it put you back in the seat. Now I’m not saying it didn’t have power until 5600 but it’s nowhere near what it used to have. Is it possible it jumped time could it even happen and would it run if it did. PLEASE HELP here’s a list of parts I built it with and what I’ve changed since it went south.

first built
afr 195 street heads
Howard’s 585 lift 246 duration at .50 113 ls
scorpion full roller rockers
fidanza light weight flywheel
trick flow 58 mm throttle body
stock intake port matched
30 lb per hr fuel injectors
pace setter headers
pcm for less Comp tune
double roller timing set
duralast optispark
mad 6al box wires and coil

parts after power loss
fuel pump
o2 sensors
maf sensor
fuel pressure reg
opti harness

 

Bad "Optispark" ignition module - behind the water pump, I think.

Rick

 

Other than the power loss, does the car run fine and not have any odb codes? I would go back to basics. Put a wideband on it to check the tune. Check compression and maybe leak down.

On a side note...Is this a 350 cubic inch motor? I would expect a 246 duration cam on a 113 to be a little lazy until the 5000-7000 rpm range.

Chad

 

Im curious on the tuning as well. For one, you put all that money and got an AutoZone opti? Shame on you.

Anyways, i just got tuned as well. I was wondering if the pcm still "learns" after tuning? As in adjusting to driving conditions, saving previous logs to adjust to, blah blah. Or is it, when you get tuned, those settings are set, no adjustments made by PCM after?

If there's still "learning", maybe you driving hard for two weeks caused the PCM to tweak itself?

Something I've been brainstorming for myself. I would start with getting a better opti. I never use electrical parts from AutoZone

 

I thought about the control mod but wasn’t sure if it could cause that but I’m on the verge of a new opti

 

Yes it runs good really no codes at all. Sometimes when I start it it acts like it’s locked up for a split second the started bogs to a stop and then immediately takes back off and it starts other than that no problems. It is a 350 but when I first built it it ran like a scalded dog from 2500 rpm and up it felt like nitros kicked in at 3000. But now it didn’t come in till the high 5000. The motor is real lazy in low rpm hind sight I wish I would have went with a little smaller cam

 

Well I did a lot of browsing on here about Optis and almost everyone said it was the best. Was gonna go msd but got a lot of bad reviews so yeah. But as far as I know once it’s tuned it’s tuned. It down not change in any way with the time I have anyway