1996 LT4 - Intermittent Low Power - Ignition Timing
Thread Starter
Instructor
Joined: Aug 2024
Posts: 108
Likes: 71
1996 LT4 - Intermittent Low Power - Ignition Timing
Car is a 1996 LT4. Just finished a boat load of work (new LS7 lifters, timing chain, rebuilt Opti by Brad, new water pump, radiator, engine completely resealed [timing cover, intake manifold, oil pan]).
I did not put many miles on the car after buying and before tearing it down. I have noticed that sometimes the car will surge above 5k RPM and ignition timing is only 28* advanced. Other times, the car pulls smooth and hits 38* timing. Timing advance at idle is 13-14* as it should be. On the pulls when it does hit full timing advance, the car barely hits 220g/s through the MAF - seems low for an LTx, especially an LT4.
The way I've been able to watch ignition advance is with a cheap OBD2 reader. I will be getting a real logging setup and will work with Solomon on the tuning. Before we start tuning, I want to be sure the car is in good working order. The intermittent surging above 5k and reduced timing advance has me concerned.
Here's a video when the car seems to run right:
My plan is:
Pull all 8 plugs
Perform compression test
Install new NGK TR55 plugs
Install new "OEM" plug wires
Not sure what else to look into before we start trying to tune the car. Any suggestions?
I did not put many miles on the car after buying and before tearing it down. I have noticed that sometimes the car will surge above 5k RPM and ignition timing is only 28* advanced. Other times, the car pulls smooth and hits 38* timing. Timing advance at idle is 13-14* as it should be. On the pulls when it does hit full timing advance, the car barely hits 220g/s through the MAF - seems low for an LTx, especially an LT4.
The way I've been able to watch ignition advance is with a cheap OBD2 reader. I will be getting a real logging setup and will work with Solomon on the tuning. Before we start tuning, I want to be sure the car is in good working order. The intermittent surging above 5k and reduced timing advance has me concerned.
Here's a video when the car seems to run right:
My plan is:
Pull all 8 plugs
Perform compression test
Install new NGK TR55 plugs
Install new "OEM" plug wires
Not sure what else to look into before we start trying to tune the car. Any suggestions?
