Hey guys, I have a 396 in my 96. It ran good with the new engine but when it melted the A/C clutch bearings, and the clutch itself, I decided to take it all down to replace the entire A/C system less evaporator and replace the clutch with a centerforce. The engine has JE Pistons, AFR 195 heads, Comp Cam, etc... So after reading in the threads about the opti sparks, I decided to replace my 30k mile opti with a new MSD and wires while the car is down. While down, it also got a new fuel filter, TPS, and O2 sensors in front of the gutted cats. Computer tune is from Ed Wright in Oklahoma for the mods listed. About a year and quarter to a year and a half later, the car is running again. Well, let's say it started right up, but it is popping spitting and sputtering.

The car starts but needs some throttle to stay running initially or it dies. Normal start is no gas needed for anything to start or idle. The injectors were removed and sent to Premium Injector Service to get cleaned and there were some poor ones. They show on his graphs to be back to healthy status again with good spray. The old gas was drained and 100 octane (from local Airport) was added to the car for this last three weeks of troubleshooting and waiting for the cleaned injectors. MAF and throttlebody are stock.

But the car is running POORLY, very poorly. It seems to be missing but doesn't show any misfires on my Autotap. I have collected some logs from it. It shows PO154 "Low O2 activity on Bank 2, sensor 1" the pre cat O2 sensor on the passenger side. This is the 2nd O2 replaced on it so could it be the wiring or something else there? What affects this condition? Where is a good place to see where the vacuum hoses go from the intake manifold? I think they are all right but cannot find a good reference to go by (pics in some docs would be great). It pops out the tailpile (lean I think right?) but it does that from the time it starts. Fuel pressure was in the 40s so it looks fine. Since the O2s do not have any bearing on motor mixture the first 2 minutes (I've read that), then where would one go to find the issue? One thing that caught my eye is that the idle timing is -27* and goes to -43 to -46* when reved. This seems excessive to me, but turning the MSD timing screw makes no difference in the timing at all. Should I yank that MSD and check something else? But you guys may know what a PITA to pull the opti is so I hate to go there if I don't have to. And since its popping out the pipe with that O2 code, I feel it's a fuel issue. It fires right up, but just runs horrible. I have some autotap logs if that's a help at all but I'm not sure how to get them posted on here. I am willing to take the car some distance to get it worked and figured out but I fear for the charges spent per hour to find it.

Since it starts and runs (but pops out the pipes so intermittently and runs so badly) I figure something is basic. if any of you have a LT4, where do the vacuum hoses run from the intake? I see one that appears to go over to the other side of the intake. There is a hose that goes to the distributor too but isn't it for moisture removal? And where is its origination supposed to be from? I'm very old school, and while the computers on these are nice when all is in sync, they can be a PITA when something gets hosed. The engine was dynoed at 525HP and 530 torque but since this replacement of parts, I bet my Honda Accord V6 would give it good run for the money, it's that bad. Thanks for any assistance. Autotap logs available on request. Ken

 

I was looking at the autotap files and there is a HUGE difference in the O2 sensors (Pre cats) readings between the left and right sides. The drivers side is varing greatly as the car runs or on a drive. The passenger side varies very little. However, it does vary more than it did prior to the replacement of each. Still it is so little compared to the drivers side, and along with the PO154 "Ho2s Circuit Insufficient Activity Bank 2 Sensor 1" (Passenger side pre cat), they seem to go hand in hand. The O2s have 4 wires, 2 for the heater and 2 for the computer I think. Could the two wires be hosed to the computer but why would it matter in the first two minutes if they are not used during that time? Still, I think it's leading to the problem area. Just an update. I did some autotap graphing of the O2s and they are drastically different too there. Thx for any assistance. Ken

 

Don't get upset for me suggesting that you may have a couple of plug wires crossed. It will affect the engine in the way you describe.
This happens more that one would think. Check them 2-3 times to make sure they are not crossed. They are hard to see and feel.
Probably on the driver's side that you notice the excessive O2 sensor readings.

Top to bottom - Left side: 5-3-7-1 Right side: 4-6-8-2

The fresh air/vacuum hoses that go to the distributor, the top nipple (metal, fresh air intake) hose goes to the intake tube before the throttle body and the other (vacuum) connects on the bottom nipple (plastic) below the plug wires on the driver's side and goes to the intake manifold by the PCV valve vacuum line. The bottom one will have 1 or 2 check valves on it and is a bigger size than the top one.

Good luck

PS: Set the distributor adjustment back to 2 turns out (factory setting).

 

Ken, I had pretty much the same problems with my engine. Would start right up but only to die on me. The only way to keep it running was, giving it a bit more throttle. Wouldn't idle when warm, and ran very poor. It was my IAC that was bad. After installing a new one, everything is back to normal.

Arnold

 

I appreciate the answers and I understand and am not upset at all on the wires. I know they will be a PITA again but its worth it to get that resolved or eliminated as an issue. I will try these and get back on results later as my car is in my shop several miles away. I hope its something this easy.