Car hesitating
04-06-2014, 04:57 PM
#1
Car hesitating
Hello.
I've got a 2000 I30 that's been behaving oddly for the last few weeks. I've got hesitation at throttle tip-in (off idle) and at 3500-4000 RPM in 1st and 2nd gear; feels like I'm letting off the gas when I'm not. The car doesn't have any mods (unless you count 259k miles as a mod) and has been receiving Shell V-power premium unleaded for the last few months. There are 4 DTCs present right now:
P0400 EGR Flow
P0420 Catalyst Efficiency B1
P0158 O2 Sensor Circuit High Voltage (B2S2)
P0159 O2 Sensor Circuit Slow Response (B2S2)
I have an OBD-II app on my phone and have confirmed that the B2S2 sensor is dead, but since the ECU doesn't use it for engine control, I'm not too worried about it at this point. The other thing that is odd is that B1S1 O2 sensor reads low at idle (barely gets past 0.5V), yet reads normal with the car at speed (in contrast, B2S1 reads normal all the time). I've been told I might have an exhaust leak near that sensor (and given the car's age, that's possible) but there is no audible evidence of it, and when I tried stuffing shop rags up the exhaust, there was no change in engine sound.
My gut is telling me its the TPS, but I've also been told that the EGR and an exhaust leak will produce these issues. Any input would be appreciated.
I've got a 2000 I30 that's been behaving oddly for the last few weeks. I've got hesitation at throttle tip-in (off idle) and at 3500-4000 RPM in 1st and 2nd gear; feels like I'm letting off the gas when I'm not. The car doesn't have any mods (unless you count 259k miles as a mod) and has been receiving Shell V-power premium unleaded for the last few months. There are 4 DTCs present right now:
P0400 EGR Flow
P0420 Catalyst Efficiency B1
P0158 O2 Sensor Circuit High Voltage (B2S2)
P0159 O2 Sensor Circuit Slow Response (B2S2)
I have an OBD-II app on my phone and have confirmed that the B2S2 sensor is dead, but since the ECU doesn't use it for engine control, I'm not too worried about it at this point. The other thing that is odd is that B1S1 O2 sensor reads low at idle (barely gets past 0.5V), yet reads normal with the car at speed (in contrast, B2S1 reads normal all the time). I've been told I might have an exhaust leak near that sensor (and given the car's age, that's possible) but there is no audible evidence of it, and when I tried stuffing shop rags up the exhaust, there was no change in engine sound.
My gut is telling me its the TPS, but I've also been told that the EGR and an exhaust leak will produce these issues. Any input would be appreciated.
Last edited by carguy1701; 04-12-2014 at 04:29 PM. Reason: Knock sensor code isn't present
04-06-2014, 06:00 PM
#2
The P0400 usually does not affect the engine performance. You might want to check if the metal tube between the EGR valve and the engine is plugged. This happens a lot. But there are other causes besides the tube being plugged.
The O2 sensor code for sensor 2 usually doesn't cause performance problems either.
The P0325 pretty much always tags along whenever you have another code. If you read enough here, you will see it referred to as a ghost code. Fix the other codes and there is a good chance that it will go away.
The P0420 is the one I would focus on. That code says the pre-cat is plugging up. This would cause restriction/back pressure on the 3 cylinders in that bank. That could be your hesitation.
The bank 1 pre-cat is built into the y-pipe that connects the 2 banks of the engine. So you have to replace the y-pipe. You could consider a y-pipe that eliminates the pre-cats such as Warpspeed. If you do, the exhaust will be a little louder because the pre-cats do a little bit of muffling. But it won't be much.
If you are going to eliminate the pre-cat with a Warpspeed pipe, a question is does the car have Cali emissions or federal emissions? If the car is Cali spec, any brand of pipe like the Warpspeed will only eliminate the bank 1 pre-cat. It is highly advisable to remove the bank 2 pre-cat, gut the innards out and re-install it. This gives the 2 banks of the engine balanced back pressure. If the car is federal emissions, the y-pipe will eliminate both pre-cats.
The O2 sensor code for sensor 2 usually doesn't cause performance problems either.
The P0325 pretty much always tags along whenever you have another code. If you read enough here, you will see it referred to as a ghost code. Fix the other codes and there is a good chance that it will go away.
The P0420 is the one I would focus on. That code says the pre-cat is plugging up. This would cause restriction/back pressure on the 3 cylinders in that bank. That could be your hesitation.
The bank 1 pre-cat is built into the y-pipe that connects the 2 banks of the engine. So you have to replace the y-pipe. You could consider a y-pipe that eliminates the pre-cats such as Warpspeed. If you do, the exhaust will be a little louder because the pre-cats do a little bit of muffling. But it won't be much.
If you are going to eliminate the pre-cat with a Warpspeed pipe, a question is does the car have Cali emissions or federal emissions? If the car is Cali spec, any brand of pipe like the Warpspeed will only eliminate the bank 1 pre-cat. It is highly advisable to remove the bank 2 pre-cat, gut the innards out and re-install it. This gives the 2 banks of the engine balanced back pressure. If the car is federal emissions, the y-pipe will eliminate both pre-cats.
04-09-2014, 01:02 PM
#3
The P0400 usually does not affect the engine performance. You might want to check if the metal tube between the EGR valve and the engine is plugged. This happens a lot. But there are other causes besides the tube being plugged.
The O2 sensor code for sensor 2 usually doesn't cause performance problems either.
The P0325 pretty much always tags along whenever you have another code. If you read enough here, you will see it referred to as a ghost code. Fix the other codes and there is a good chance that it will go away.
The P0420 is the one I would focus on. That code says the pre-cat is plugging up. This would cause restriction/back pressure on the 3 cylinders in that bank. That could be your hesitation.
The bank 1 pre-cat is built into the y-pipe that connects the 2 banks of the engine. So you have to replace the y-pipe. You could consider a y-pipe that eliminates the pre-cats such as Warpspeed. If you do, the exhaust will be a little louder because the pre-cats do a little bit of muffling. But it won't be much.
If you are going to eliminate the pre-cat with a Warpspeed pipe, a question is does the car have Cali emissions or federal emissions? If the car is Cali spec, any brand of pipe like the Warpspeed will only eliminate the bank 1 pre-cat. It is highly advisable to remove the bank 2 pre-cat, gut the innards out and re-install it. This gives the 2 banks of the engine balanced back pressure. If the car is federal emissions, the y-pipe will eliminate both pre-cats.
The O2 sensor code for sensor 2 usually doesn't cause performance problems either.
The P0325 pretty much always tags along whenever you have another code. If you read enough here, you will see it referred to as a ghost code. Fix the other codes and there is a good chance that it will go away.
The P0420 is the one I would focus on. That code says the pre-cat is plugging up. This would cause restriction/back pressure on the 3 cylinders in that bank. That could be your hesitation.
The bank 1 pre-cat is built into the y-pipe that connects the 2 banks of the engine. So you have to replace the y-pipe. You could consider a y-pipe that eliminates the pre-cats such as Warpspeed. If you do, the exhaust will be a little louder because the pre-cats do a little bit of muffling. But it won't be much.
If you are going to eliminate the pre-cat with a Warpspeed pipe, a question is does the car have Cali emissions or federal emissions? If the car is Cali spec, any brand of pipe like the Warpspeed will only eliminate the bank 1 pre-cat. It is highly advisable to remove the bank 2 pre-cat, gut the innards out and re-install it. This gives the 2 banks of the engine balanced back pressure. If the car is federal emissions, the y-pipe will eliminate both pre-cats.
04-10-2014, 02:02 AM
#4
If you went to a website such as infinitipartszone.com and entered your vin, it will tell you something like: 200004 S VQ30DE FED BASE AT EV0 P where you can see the label FED in there as opposed to CAL.
There are 2 "features" you can look at on the exhaust to determine the emissions level and the heat shields are not in the way.
Here is a diagram of a FED exhaust system
here is a diagram of a Cali exhaust system:
The easiest way to look and see is to look beneath the car at the main catalytic converter. Look from the driver's side. If you see a wire going to an O2 sensor right behind the main cat, you have a Federal emissions car. The California emissions car won't have this.
As far as emissions tests go, eliminating the pre-cats won't cause you to fail the test. Pre-cats only work for a few seconds when you start a cold engine. They were added because the main cat needs to warm up before it works. So if you drive the car and make sure it is at operating temperature, you'll pass an emissions test.
There are 2 "features" you can look at on the exhaust to determine the emissions level and the heat shields are not in the way.
Here is a diagram of a FED exhaust system
here is a diagram of a Cali exhaust system:
The easiest way to look and see is to look beneath the car at the main catalytic converter. Look from the driver's side. If you see a wire going to an O2 sensor right behind the main cat, you have a Federal emissions car. The California emissions car won't have this.
As far as emissions tests go, eliminating the pre-cats won't cause you to fail the test. Pre-cats only work for a few seconds when you start a cold engine. They were added because the main cat needs to warm up before it works. So if you drive the car and make sure it is at operating temperature, you'll pass an emissions test.
04-11-2014, 08:22 PM
#5
If you went to a website such as infinitipartszone.com and entered your vin, it will tell you something like: 200004 S VQ30DE FED BASE AT EV0 P where you can see the label FED in there as opposed to CAL.
There are 2 "features" you can look at on the exhaust to determine the emissions level and the heat shields are not in the way.
Here is a diagram of a FED exhaust system
here is a diagram of a Cali exhaust system:
The easiest way to look and see is to look beneath the car at the main catalytic converter. Look from the driver's side. If you see a wire going to an O2 sensor right behind the main cat, you have a Federal emissions car. The California emissions car won't have this.
As far as emissions tests go, eliminating the pre-cats won't cause you to fail the test. Pre-cats only work for a few seconds when you start a cold engine. They were added because the main cat needs to warm up before it works. So if you drive the car and make sure it is at operating temperature, you'll pass an emissions test.
There are 2 "features" you can look at on the exhaust to determine the emissions level and the heat shields are not in the way.
Here is a diagram of a FED exhaust system
here is a diagram of a Cali exhaust system:
The easiest way to look and see is to look beneath the car at the main catalytic converter. Look from the driver's side. If you see a wire going to an O2 sensor right behind the main cat, you have a Federal emissions car. The California emissions car won't have this.
As far as emissions tests go, eliminating the pre-cats won't cause you to fail the test. Pre-cats only work for a few seconds when you start a cold engine. They were added because the main cat needs to warm up before it works. So if you drive the car and make sure it is at operating temperature, you'll pass an emissions test.
04-12-2014, 09:49 AM
#6
That would definitely be strange, I haven't seen anyone post that before. But anything is possible. You were looking at the main or rear cat under the passenger seat, right?
Since the parts are not the same between the 2 types of emission designs, you have to know what you have before you go buy anything.
So have you made any decision as to what you are going to work on?
Since the parts are not the same between the 2 types of emission designs, you have to know what you have before you go buy anything.
So have you made any decision as to what you are going to work on?
04-12-2014, 04:22 PM
#7
That would definitely be strange, I haven't seen anyone post that before. But anything is possible. You were looking at the main or rear cat under the passenger seat, right?
Since the parts are not the same between the 2 types of emission designs, you have to know what you have before you go buy anything.
So have you made any decision as to what you are going to work on?
Since the parts are not the same between the 2 types of emission designs, you have to know what you have before you go buy anything.
So have you made any decision as to what you are going to work on?
Last edited by carguy1701; 04-12-2014 at 11:12 PM.
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