I need some help diagnosing an engine with fuel issues. It is a 2002 Sunfire with the 2.2l EcoTec, and it has about 35k miles on it. I will provide some background info that may help in diagnosing the issue.
I bought the car used a couple months ago from someone I know very well. The previous owner installed a GM supercharger on it, and he had the installation certified and warrantied by GM. When I bought it, the car had been sitting for about 2 years and had about a 1/4 tank of gas in it (that was probably just as old). We filled it up with 93 octane gas, and of course it ran like crap for a while and would stall occasionally.
After several tanks of gas, the car seemed to run ok, and it no longer stalls. However, there appears to be an issue with it even after about 10 tanks of gas. Engine light will come on and will not go off unless I disconnect the battery. Once the battery is reconnected, it doesn't take long for the engine light to come back on.
Here are the symptoms. I think they are all caused by the same issue, but I don't know for sure:
p0420 - Catalyst System Efficiency Below Threshold (Bank 1)
Vehicle takes longer to crank than it should to start up. Sometimes you can even hear some of the cylinders firing while cranking, but it isn't enough to stay running. Keep cranking and it eventually starts
Vehicle appears to be running lean. There is an aftermarket A/F gauge hooked up. Even with 12 psi of boost, the gauge rarely reads below 13 while at full throttle, and it seems to want to creep up higher as the RPMs increase.
This next symptom is intermittent, but happens almost daily. Sometimes, it appears that the fuel system is delayed. Let me explain. I'll be cruising just fine (minus the slight lean A/F), but when I give it throttle to accelerate, there is almost no response and the A/F gauge reads an even higher A/F (around 18). After a few seconds, the A/F will drop back down and the car will begin accelerating. In addition, if I am accelerating and let completely off the throttle, the A/F gauge goes extremely rich (around 10) for a few seconds before going back to "normal."
The car seems to behave exactly as the gauge is reading. For example, if I give it enough gas to generate boost, instead of speeding up, the car slows down. I can only assume that due to the delay in fuel that the supercharger is robbing power from the engine to create boost without creating any extra power due to lack of fuel.
Again, that last symptom is intermittent. Even on my roughly 20 minute drive to work, I can experience this symptom for a part of the drive, and another part of the drive, the car will seem to run just fine.
I apologize for the lost post, but I feel like all of this info is necessary to properly diagnose the issue. If anyone can point me in the right direction, or at least give me tips on how to eliminate possible causes, I would greatly appreciate it. Note that I have already replaced the fuel filter, but that didn't help.
I bought the car used a couple months ago from someone I know very well. The previous owner installed a GM supercharger on it, and he had the installation certified and warrantied by GM. When I bought it, the car had been sitting for about 2 years and had about a 1/4 tank of gas in it (that was probably just as old). We filled it up with 93 octane gas, and of course it ran like crap for a while and would stall occasionally.
After several tanks of gas, the car seemed to run ok, and it no longer stalls. However, there appears to be an issue with it even after about 10 tanks of gas. Engine light will come on and will not go off unless I disconnect the battery. Once the battery is reconnected, it doesn't take long for the engine light to come back on.
Here are the symptoms. I think they are all caused by the same issue, but I don't know for sure:
p0420 - Catalyst System Efficiency Below Threshold (Bank 1)
Vehicle takes longer to crank than it should to start up. Sometimes you can even hear some of the cylinders firing while cranking, but it isn't enough to stay running. Keep cranking and it eventually starts
Vehicle appears to be running lean. There is an aftermarket A/F gauge hooked up. Even with 12 psi of boost, the gauge rarely reads below 13 while at full throttle, and it seems to want to creep up higher as the RPMs increase.
This next symptom is intermittent, but happens almost daily. Sometimes, it appears that the fuel system is delayed. Let me explain. I'll be cruising just fine (minus the slight lean A/F), but when I give it throttle to accelerate, there is almost no response and the A/F gauge reads an even higher A/F (around 18). After a few seconds, the A/F will drop back down and the car will begin accelerating. In addition, if I am accelerating and let completely off the throttle, the A/F gauge goes extremely rich (around 10) for a few seconds before going back to "normal."
The car seems to behave exactly as the gauge is reading. For example, if I give it enough gas to generate boost, instead of speeding up, the car slows down. I can only assume that due to the delay in fuel that the supercharger is robbing power from the engine to create boost without creating any extra power due to lack of fuel.
Again, that last symptom is intermittent. Even on my roughly 20 minute drive to work, I can experience this symptom for a part of the drive, and another part of the drive, the car will seem to run just fine.
I apologize for the lost post, but I feel like all of this info is necessary to properly diagnose the issue. If anyone can point me in the right direction, or at least give me tips on how to eliminate possible causes, I would greatly appreciate it. Note that I have already replaced the fuel filter, but that didn't help.
