I'm planning a tune-up of the LG4 this weekend. I plan to do the plugs, the wires, check the timing, change the oil, and change the air filter. I'm looking for advice on what else to do / check.

The car's performance ranges from bad to terrible. It's got poor throttle response, and seems to miss between 1000-3000 RPM. I also get some backfire (or engine cut-out) during heavy acceleration. The gas mileage is poor as well.

Here are some specifics:

LG4 with cc Quadrajet
headman headers w/air
stock cat and muffler
automatic transmission

Here are some observations:

code 32 on deceleration.

I'm reasonably confident that I'm not running in closed loop mode, because I've disconnected the ECM to carb and noticed a distinct change in idle.

I'm not sure about the O2 sensor, but I understand that a bad one can cause a mixture problem.

I'm fairly certain that the EGR is bad (code 32). I think I'll inspect and clean its components.

I've got some fuel build-up in the charcoal canister.

I've got a recurring problem with the header bolts backing out. I'll be switching to some with a hex face so as to get a little more torque on them. Could the loss of seal affect engine performance?

I'm not sure that the spring on the quadrajet secondaries is loose enough. But there doesn't seem to be an objective way to measure this. I might adjust this a bit once the other work is done.

I'm also wondering if I should take a quick look under the valve covers. I don't plan on keeping the LG4 indefinitely, or even doing any major work on it, but knowing for a fact that the valve train has problems might help to accelerate engine replacement.


thanks

 

cap/rotor
coil
pvc
o2 sensor
fuel filter(s)

 

you should check TomP's tune-up post. It will tell you exactly what to do.

 

Take the carb off and spray it down completely. The fuel filter is probably done.

If a tune-up doesn't help, check your fuel pressure , as the pump may be dead/dying.

You sound like a problem I had for a while, which ended up being a plugged catalytic convertor. Might want to check that out too if all else fails.

 

My car ran much better after I replace the original cat.I got a 3" catco one from summit at the same time i got my cat back exhaust.
Definately check your o2 sensor also,if its bad the car will run in open loop hurting your performance and gas milage.
I just did a major tune up to my car cause its mostly been sitting in the garage the last year and a half. I sprayed out the carb real good as previously mentioned,changed the cap ,rotor,plugs,went with MSD wires,replaced the fuel filter,pcv valve,o2 sensor,canister filter,re-oiled the K&N filter,changed the oil and filter and checked the timing. It runs great now.
Good luck with your car.