Cel On, Random Misfires, P0300/p0303/p0304, P1130, P0172

[Mike in PDX 00 RX300]

2000 RX300

150k miles

Car ran perfect until one day when I started it it barely ran. It shakes like a V8 muscle car at idle.

Initial codes were P0303 & P0304

Replaced:

3 ignition coils

spark plugs

MAF sensor

Rebuilt ALL injectors

Still getting P0300/P0303/P0304 AND occasionallty P1130 &P1172 or P1171.

IF I pull the ECU fuse before I start the car all gears work until I turn the car off. I can really feel the misfire around 2200 rpm in overdrive on the freeway.

THEN when I RESTART it goes into safe mode and only gears 1-3 work. Sometimes in safe mode the car will run even worse and BARELY run, feeling like it's gasping??? (major backfiring etc) until I hit 3800 rpm and then it catches and goes like a powerband is kicking in???

My thoughts are:

Vacuum leak?

O2 Sensors?

Knock sensor inside engine?

Something else going on inside the motor???

Also:

1. My ABS light was on when I got the car back after the transmission was rebuilt and is not working but the car ran fine so I suspect that is unrelated.

2. There are 2 ground wires near the drivers side strut tower. behind the airbox under the brake fluid resivor. One of them was dangling and I could not find out where to connect it so I just attached it to the block???

Any suggestions would be greatly appreciated!!!

Thank you.

[tmastres]

This may seem like a silly question but when you say you replaced 3 coils , did you replace the #3 and #4 coils?

I assume you know the cylinder arrangement/order

135

246

|

v

front of vehicle

The #3 coil is the most difficult one to reach and since you said you replaced 3 coils when there were only codes for two cylinder specific misfires, P0303/P0304 (the P0300 indicates multiple random misfires) I was just wondering if simply replaced the 3 easy ones in the front and still have a bad one in the back?

[Mike in PDX 00 RX300]

This may seem like a silly question but when you say you replaced 3 coils , did you replace the #3 and #4 coils?

I assume you know the cylinder arrangement/order

135

246

|

v

front of vehicle

The #3 coil is the most difficult one to reach and since you said you replaced 3 coils when there were only codes for two cylinder specific misfires, P0303/P0304 (the P0300 indicates multiple random misfires) I was just wondering if simply replaced the 3 easy ones in the front and still have a bad one in the back?

I replaced 3, 4 and 5 but I didn't really notice an improvement.

[tmastres]

You've probably seen these posts already but in case you hadn't.

http://us.lexusownersclub.com/forums/index...=P0304&st=0

This one is long but the answer comes in post #32

http://us.lexusownersclub.com/forums/index...st&p=346857

Please let us know if you get this solved. Too many people don't follow up and we never know how they solved the problems.

[Mike in PDX 00 RX300]

You've probably seen these posts already but in case you hadn't.

http://us.lexusownersclub.com/forums/index...=P0304&st=0

This one is long but the answer comes in post #32

http://us.lexusownersclub.com/forums/index...st&p=346857

Please let us know if you get this solved. Too many people don't follow up and we never know how they solved the problems.

When my mechanic replaced the injectors, seals etc he mentioned that one of them was physically broken too. The net result was mycar wentfromrunning lean to rich and still getting codes .

the 2 constants in this whole process are p0303 and p0304, with the other codes being often but not always

[Mike in PDX 00 RX300]

You've probably seen these posts already but in case you hadn't.

http://us.lexusownersclub.com/forums/index...=P0304&st=0

This one is long but the answer comes in post #32

http://us.lexusownersclub.com/forums/index...st&p=346857

Please let us know if you get this solved. Too many people don't follow up and we never know how they solved the problems.

When my mechanic replaced the injectors, seals etc he mentioned that one of them was physically broken too. The net result was mycar wentfromrunning lean to rich and still getting codes .

the 2 constants in this whole process are p0303 and p0304, with the other codes being often but not always

So today I went and had my codes pulled again:

P0300

P0301

P0303

P0304

P1130 bank 1 sensor 1

I disconnected the o2 sensor on the manifold behind the radiator...was that the right one? It seems like itmay run a litle better but not a lot. CEL still flashing,rough idle and shakes under load around 2200 rpm in OD

[code58]

You've probably seen these posts already but in case you hadn't.

http://us.lexusownersclub.com/forums/index...=P0304&st=0

This one is long but the answer comes in post #32

http://us.lexusownersclub.com/forums/index...st&p=346857

Please let us know if you get this solved. Too many people don't follow up and we never know how they solved the problems.

When my mechanic replaced the injectors, seals etc he mentioned that one of them was physically broken too. The net result was mycar wentfromrunning lean to rich and still getting codes .

the 2 constants in this whole process are p0303 and p0304, with the other codes being often but not always

So today I went and had my codes pulled again:

P0300

P0301

P0303

P0304

P1130 bank 1 sensor 1

I disconnected the o2 sensor on the manifold behind the radiator...was that the right one? It seems like itmay run a litle better but not a lot. CEL still flashing,rough idle and shakes under load around 2200 rpm in OD

Mike, if you're refering to P1130 bank 1 sensor 1 is the sensor in the rear manifold, at the firewall. The front 1 that you disconnected is refereed to as bank 2 sensor 1.

[Mike in PDX 00 RX300]

You've probably seen these posts already but in case you hadn't.

http://us.lexusownersclub.com/forums/index...=P0304&st=0

This one is long but the answer comes in post #32

http://us.lexusownersclub.com/forums/index...st&p=346857

Please let us know if you get this solved. Too many people don't follow up and we never know how they solved the problems.

When my mechanic replaced the injectors, seals etc he mentioned that one of them was physically broken too. The net result was mycar wentfromrunning lean to rich and still getting codes .

the 2 constants in this whole process are p0303 and p0304, with the other codes being often but not always

So today I went and had my codes pulled again:

P0300

P0301

P0303

P0304

P1130 bank 1 sensor 1

I disconnected the o2 sensor on the manifold behind the radiator...was that the right one? It seems like itmay run a litle better but not a lot. CEL still flashing,rough idle and shakes under load around 2200 rpm in OD

Mike, if you're refering to P1130 bank 1 sensor 1 is the sensor in the rear manifold, at the firewall. The front 1 that you disconnected is refereed to as bank 2 sensor 1.

HMM...I was wondering that. It's funny because while it isn't running perfect it DOES run a little better. I'm getting an extra 1 MPG I think.

I'll try disconnecting the other one too and see what happens. Is that one really hard to get to?

Is it possible BOTH sensors failed near the same time?

[code58]

I disconnected the o2 sensor on the manifold behind the radiator...was that the right one? It seems like itmay run a litle better but not a lot. CEL still flashing,rough idle and shakes under load around 2200 rpm in OD

Mike, if you're refering to P1130 bank 1 sensor 1 is the sensor in the rear manifold, at the firewall. The front 1 that you disconnected is refereed to as bank 2 sensor 1.

HMM...I was wondering that. It's funny because while it isn't running perfect it DOES run a little better. I'm getting an extra 1 MPG I think.

I'll try disconnecting the other one too and see what happens. Is that one really hard to get to?

Is it possible BOTH sensors failed near the same time?

Mike, that is always a possibility. There is a way to test the A/F ratio sensors. Unfortunately the rear sensor plug is difficult to get released because of where it is. I actually think it's worse to disconnect it than it is to remove it. It's up behind the engine and you pretty much have to do it from underneath. The problem is it takes 2 hands to hold the plug and release it and it's virtually impossible to get 2 hands up there. Now if you had the intake manifold off, that would definitely be the time to change the plugs, A/F sensor and a few other things that are BURIED back there.

[artbuc]

I disconnected the o2 sensor on the manifold behind the radiator...was that the right one? It seems like itmay run a litle better but not a lot. CEL still flashing,rough idle and shakes under load around 2200 rpm in OD

Mike, if you're refering to P1130 bank 1 sensor 1 is the sensor in the rear manifold, at the firewall. The front 1 that you disconnected is refereed to as bank 2 sensor 1.

HMM...I was wondering that. It's funny because while it isn't running perfect it DOES run a little better. I'm getting an extra 1 MPG I think.

I'll try disconnecting the other one too and see what happens. Is that one really hard to get to?

Is it possible BOTH sensors failed near the same time?

Mike, that is always a possibility. There is a way to test the A/F ratio sensors. Unfortunately the rear sensor plug is difficult to get released because of where it is. I actually think it's worse to disconnect it than it is to remove it. It's up behind the engine and you pretty much have to do it from underneath. The problem is it takes 2 hands to hold the plug and release it and it's virtually impossible to get 2 hands up there. Now if you had the intake manifold off, that would definitely be the time to change the plugs, A/F sensor and a few other things that are BURIED back there.

If/when my O2 sensor fails, I plan on cutting/splicing the wires instead of removing the seat to get to the connector.

[smooth1]

I disconnected the o2 sensor on the manifold behind the radiator...was that the right one? It seems like itmay run a litle better but not a lot. CEL still flashing,rough idle and shakes under load around 2200 rpm in OD

Mike, if you're refering to P1130 bank 1 sensor 1 is the sensor in the rear manifold, at the firewall. The front 1 that you disconnected is refereed to as bank 2 sensor 1.

HMM...I was wondering that. It's funny because while it isn't running perfect it DOES run a little better. I'm getting an extra 1 MPG I think.

I'll try disconnecting the other one too and see what happens. Is that one really hard to get to?

Is it possible BOTH sensors failed near the same time?

Mike, that is always a possibility. There is a way to test the A/F ratio sensors. Unfortunately the rear sensor plug is difficult to get released because of where it is. I actually think it's worse to disconnect it than it is to remove it. It's up behind the engine and you pretty much have to do it from underneath. The problem is it takes 2 hands to hold the plug and release it and it's virtually impossible to get 2 hands up there. Now if you had the intake manifold off, that would definitely be the time to change the plugs, A/F sensor and a few other things that are BURIED back there.

If/when my O2 sensor fails, I plan on cutting/splicing the wires instead of removing the seat to get to the connector.

I would really advise against doing it this way. The wires and the sensor are matched to carry the correct ohms and impedence. Cutting and splicing can change the impedence of the wire. You may start throwing cels later just because of the splice.

[artbuc]

I disconnected the o2 sensor on the manifold behind the radiator...was that the right one? It seems like itmay run a litle better but not a lot. CEL still flashing,rough idle and shakes under load around 2200 rpm in OD

Mike, if you're refering to P1130 bank 1 sensor 1 is the sensor in the rear manifold, at the firewall. The front 1 that you disconnected is refereed to as bank 2 sensor 1.

HMM...I was wondering that. It's funny because while it isn't running perfect it DOES run a little better. I'm getting an extra 1 MPG I think.

I'll try disconnecting the other one too and see what happens. Is that one really hard to get to?

Is it possible BOTH sensors failed near the same time?

Mike, that is always a possibility. There is a way to test the A/F ratio sensors. Unfortunately the rear sensor plug is difficult to get released because of where it is. I actually think it's worse to disconnect it than it is to remove it. It's up behind the engine and you pretty much have to do it from underneath. The problem is it takes 2 hands to hold the plug and release it and it's virtually impossible to get 2 hands up there. Now if you had the intake manifold off, that would definitely be the time to change the plugs, A/F sensor and a few other things that are BURIED back there.

If/when my O2 sensor fails, I plan on cutting/splicing the wires instead of removing the seat to get to the connector.

I would really advise against doing it this way. The wires and the sensor are matched to carry the correct ohms and impedence. Cutting and splicing can change the impedence of the wire. You may start throwing cels later just because of the splice.

Good point. Does make me wonder about the two A/F sensors. Bank 1 and Bank 2 originally had different wiring harness lengths and, up until the last 6 months or so, there were two different replacement A/F sensors to match factory installed. Now, there is only one replacement A/F sensor with a common wiring harness length. Sort of suggests resistance of the wire itself is not important.

[smooth1]

I disconnected the o2 sensor on the manifold behind the radiator...was that the right one? It seems like itmay run a litle better but not a lot. CEL still flashing,rough idle and shakes under load around 2200 rpm in OD

Mike, if you're refering to P1130 bank 1 sensor 1 is the sensor in the rear manifold, at the firewall. The front 1 that you disconnected is refereed to as bank 2 sensor 1.

HMM...I was wondering that. It's funny because while it isn't running perfect it DOES run a little better. I'm getting an extra 1 MPG I think.

I'll try disconnecting the other one too and see what happens. Is that one really hard to get to?

Is it possible BOTH sensors failed near the same time?

Mike, that is always a possibility. There is a way to test the A/F ratio sensors. Unfortunately the rear sensor plug is difficult to get released because of where it is. I actually think it's worse to disconnect it than it is to remove it. It's up behind the engine and you pretty much have to do it from underneath. The problem is it takes 2 hands to hold the plug and release it and it's virtually impossible to get 2 hands up there. Now if you had the intake manifold off, that would definitely be the time to change the plugs, A/F sensor and a few other things that are BURIED back there.

If/when my O2 sensor fails, I plan on cutting/splicing the wires instead of removing the seat to get to the connector.

I would really advise against doing it this way. The wires and the sensor are matched to carry the correct ohms and impedence. Cutting and splicing can change the impedence of the wire. You may start throwing cels later just because of the splice.

Good point. Does make me wonder about the two A/F sensors. Bank 1 and Bank 2 originally had different wiring harness lengths and, up until the last 6 months or so, there were two different replacement A/F sensors to match factory installed. Now, there is only one replacement A/F sensor with a common wiring harness length. Sort of suggests resistance of the wire itself is not important.

I've actually run into this before with some customers that came in who had done some header and exhaust work and went to an 02 sim. Later they went back to stock and just spliced in the 02 sensors and kept throwing cels afterwards. I just replaced the 02's and the wire harnesses and everything was roses. So I'm sure there may be a window of acceptability for the 02, and there is even a good chance that the splice may fall right back into that, but that would just be a guessing game there.

[artbuc]

smooth 1 wrote:

"I've actually run into this before with some customers that came in who had done some header and exhaust work and went to an 02 sim. Later they went back to stock and just spliced in the 02 sensors and kept throwing cels afterwards. I just replaced the 02's and the wire harnesses and everything was roses. So I'm sure there may be a window of acceptability for the 02, and there is even a good chance that the splice may fall right back into that, but that would just be a guessing game there."

Gotcha...thanks for the info.

[Mike in PDX 00 RX300]

UPDATE...I disconnected the front sensor, wrong one I know and my MPG Increased by 0.5. Today I disconnected the rear sensor, by firewall and my MPG Decreased by 1.

I can still feel the car misfiring...that has remained a constant. Perhaps it's time to dig in & check compression, etc?