Posted: 3/16/2010 5:07:43 PM EDT
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My 98 Rav4 is acting up. It's missing at low idle (700 rpm) and the exhaust system is running hotter then normal. I can smell the undercoating. I pulled the codes. P0303 P0300 P0302 x 2 P0401 The 30 codes are misfires. 300 is random. 302 is #2 cyl. 303 is #3 cyl. The P0401 code is for exhaust gas recirculation flow insufficient detected. Is that a defective egr valve? Would that cause the misfires? It doesn't do this constantly..it's intermittent. |
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George, the P0401 code on Toyota Rav-4is rarely a bad EGR Valve. It's more often a bad EGR VSV (vacum switching valve), followed by the EGR Vacum Modulator -or in ARFCOM tradition- BOTH. The last P0401 I did had a bad VSV and a bad Modulator. In any case, check all the vacum lines first, at all three components...EGR, EGR VSV, and EGR Vacum Modulator(AKA backpressure transducer). A simple broken or cracked hose will also cause a P0401.
LMK if you need specifics on testing the EGR VSV and Modulator. The P030x codes shouldn't be caused by a P0401, if EGR's not flowing it shouldn't interfere with the engine firing steady. If EGR is stuck OPEN and flowing at idle then you can get P030x codes. For the P030x codes as a group and especially on cylinders #2and #3, I would look into ignition problems, SPECIFICALLY the ignition coils.Cylinders #2 and #3 SHARE an ignition coil so that's most likely your problem for P0302 and 303. More info on missfires...If the ignition is not firing on one or two cylinders..it's a very big deal on a 4 cylinder motor...even if it's intermittent. Losing good spark at the rate of 25-50% (of total) will cause serious heat in your exhaust system, in many cases the Catalytic will turn RED HOT from the raw unburnt fuel that's still being introduced into the cylinders. That's when you smell the exhaust burning. Catalytic should be fine if it hasn't been running like this for a very long time. |
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Quoted:
George, the P0401 code on Toyota Rav-4is rarely a bad EGR Valve. It's more often a bad EGR VSV (vacum switching valve), followed by the EGR Vacum Modulator -or in ARFCOM tradition- BOTH. The last P0401 I did had a bad VSV and a bad Modulator. In any case, check all the vacum lines first, at all three components...EGR, EGR VSV, and EGR Vacum Modulator(AKA backpressure transducer). A simple broken or cracked hose will also cause a P0401. LMK if you need specifics on testing the EGR VSV and Modulator. The P030x codes shouldn't be caused by a P0401, if EGR's not flowing it shouldn't interfere with the engine firing steady. If EGR is stuck OPEN and flowing at idle then you can get P030x codes. For the P030x codes as a group and especially on cylinders #2and #3, I would look into ignition problems, SPECIFICALLY the ignition coils.Cylinders #2 and #3 SHARE an ignition coil so that's most likely your problem for P0302 and 303. More info on missfires...If the ignition is not firing on one or two cylinders..it's a very big deal on a 4 cylinder motor...even if it's intermittent. Losing good spark at the rate of 25-50% (of total) will cause serious heat in your exhaust system, in many cases the Catalytic will turn RED HOT from the raw unburnt fuel that's still being introduced into the cylinders. That's when you smell the exhaust burning. Catalytic should be fine if it hasn't been running like this for a very long time. How do people know this stuff???? I couldn't make this up, even if I had to. 
vmax84 |
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George, the P0401 code on Toyota Rav-4is rarely a bad EGR Valve. It's more often a bad EGR VSV (vacum switching valve), followed by the EGR Vacum Modulator -or in ARFCOM tradition- BOTH. The last P0401 I did had a bad VSV and a bad Modulator. In any case, check all the vacum lines first, at all three components...EGR, EGR VSV, and EGR Vacum Modulator(AKA backpressure transducer). A simple broken or cracked hose will also cause a P0401. LMK if you need specifics on testing the EGR VSV and Modulator. The P030x codes shouldn't be caused by a P0401, if EGR's not flowing it shouldn't interfere with the engine firing steady. If EGR is stuck OPEN and flowing at idle then you can get P030x codes. For the P030x codes as a group and especially on cylinders #2and #3, I would look into ignition problems, SPECIFICALLY the ignition coils.Cylinders #2 and #3 SHARE an ignition coil so that's most likely your problem for P0302 and 303. More info on missfires...If the ignition is not firing on one or two cylinders..it's a very big deal on a 4 cylinder motor...even if it's intermittent. Losing good spark at the rate of 25-50% (of total) will cause serious heat in your exhaust system, in many cases the Catalytic will turn RED HOT from the raw unburnt fuel that's still being introduced into the cylinders. That's when you smell the exhaust burning. Catalytic should be fine if it hasn't been running like this for a very long time. How do people know this stuff???? I couldn't make this up, even if I had to.
vmax84 Mechanic. If it wasnt for people who did not know this people like me would be out of a job. Lucky for me I work on big rigs and we dont have as much bs to worry about yet. |
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[span style='font-weight: bold;']Quoted:
How do people know this stuff???? I couldn't make this up, even if I had to.
vmax84 LOL, it's really not as difficult as it seems. After a while you see patterns in certain cars and the next time you get a car with a similar problem you already know what the most common causes are. |
Well I changed the coils (what a #@%&^^%$ job that was). Started the truck and..it was still missing. So..I decided to pull the spark plug wires one at a time and see what happened. When I pulled the #2 wire..no change. So I decided to pull the plug and see what it looked like. That's when I discovered the rubber boot on the end of the plug wire wasn't on the wire.. It stuck to the plug... Anyone ever run into this problem with a rav4 or any other over head cam engine? I frigged around for over an hour trying to get it off the plug and I can't. I can reach it with needle nose plyers but can't open them enough to grab it. My little claw tool isn't strong enough to hold on to the rubber boot.  |
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cool..what is it called? It might work. Here is what I'm talking about. the rubber part on the very end is the part stuck to the plug.. |
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George, the P0401 code on Toyota Rav-4is rarely a bad EGR Valve. It's more often a bad EGR VSV (vacum switching valve), followed by the EGR Vacum Modulator -or in ARFCOM tradition- BOTH. The last P0401 I did had a bad VSV and a bad Modulator. In any case, check all the vacum lines first, at all three components...EGR, EGR VSV, and EGR Vacum Modulator(AKA backpressure transducer). A simple broken or cracked hose will also cause a P0401. LMK if you need specifics on testing the EGR VSV and Modulator. The P030x codes shouldn't be caused by a P0401, if EGR's not flowing it shouldn't interfere with the engine firing steady. If EGR is stuck OPEN and flowing at idle then you can get P030x codes. For the P030x codes as a group and especially on cylinders #2and #3, I would look into ignition problems, SPECIFICALLY the ignition coils.Cylinders #2 and #3 SHARE an ignition coil so that's most likely your problem for P0302 and 303. More info on missfires...If the ignition is not firing on one or two cylinders..it's a very big deal on a 4 cylinder motor...even if it's intermittent. Losing good spark at the rate of 25-50% (of total) will cause serious heat in your exhaust system, in many cases the Catalytic will turn RED HOT from the raw unburnt fuel that's still being introduced into the cylinders. That's when you smell the exhaust burning. Catalytic should be fine if it hasn't been running like this for a very long time. How do people know this stuff???? I couldn't make this up, even if I had to.
vmax84 Mechanic. If it wasnt for people who did not know this people like me would be out of a job. Lucky for me I work on big rigs and we dont have as much bs to worry about yet. Really? Your fleet all pre -.07? EGR SCR ACERT DPF's and Regen (of which I am having ALL KINDS of problems with) Iteris Vorad APU's (also very problematic) I have been pulling Mid's Pid's and Sid's for almost a decade now... No different then an OBD code.... I mean hell..... We even get SPARK PLUGS now for crying out loud I would venture that with the '10 EPA regs truck have made the great leap forward to "just and technology riddled and problematic " as cars Oh yeah ..... forgot my favorite technology that should have been left in cars ..... Automatic Transmissions..... |
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Thanks. I'm going to try my dental pics tomorrow..if that doesn't work I'll order that. |
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Quoted: Happens a lot, especially on old wires. Extended shank Dental picks work great for this, that's what I normally use. Sometimes the boot will only come out in small pieces no matter what you try. Hopefully the metal clip will come off the plug without much struggle.. I can't complain, We've owned it for 6 years and other then the normal tune up stuff I've put an o2 sensor, rad and gas tank fill pipe on it. |
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Thanks for the tip about the dental pick..worked like a charm. After screwing around for about half an hour trying to get the metal clip off the porcelain part of the plug..I discovered the plug was loose. So I put a piece of vacuum hose over it and removed it as I couldn't get a socket on it. I have no idea where the clip went though.. I was very worried the threads were stripped in the head. Good news is..the threads were fine. I put anti-seize compound on them when I changed them the last time. The #2 and #3 plugs were both loose. One was bad enough that the boot on the plug wire was black with soot. I have no idea why or how they loosened up..but I suspect it was due to me being cautious when I changed them the last time and not cranking on them. New plugs and wires and she is running like a swiss watch. I still have to deal with the EGR error code but it isn't an emergency. thanks for all the help guys..  |
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Glad you got it fixed. With NGK and ND plugs that have the crush washer use an approx 8-10" ratchet wrench and a good spark plug socket(SnapOn, MAC, Matco, etc.) of the proper length. A short socket will work but can stay on the plug and require fishing it out with a long needle nose. Carefully start the spark plug threads with a starter tool or a long straight piece of rubber hose. Turn the plug in untill it just stops and you are sure the seal has made contact with the head. Tighten an additional 1/8th or 3/16th turn. It should feel firmly tight. Don't use a long ratchet or overtighten the spark plug. If you have a torque wrench you can use it after you find out what the proper torque is. I have a calibrated elbow from experience so I don't use a torque wrench anymore. 
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Thanks for the tip about the dental pick..worked like a charm. After screwing around for about half an hour trying to get the metal clip off the porcelain part of the plug..I discovered the plug was loose. So I put a piece of vacuum hose over it and removed it as I couldn't get a socket on it. I have no idea where the clip went though..
I was very worried the threads were stripped in the head. Good news is..the threads were fine. I put anti-seize compound on them when I changed them the last time. The #2 and #3 plugs were both loose. One was bad enough that the boot on the plug wire was black with soot. I have no idea why or how they loosened up..but I suspect it was due to me being cautious when I changed them the last time and not cranking on them. New plugs and wires and she is running like a swiss watch. I still have to deal with the EGR error code but it isn't an emergency. thanks for all the help guys.. Probably. To the best of my knowledge, no manufacturers recommend using anti seize on spark plug threads. For that reason. There's some kind of formula, I forget what the exact name of it is, to calculate the new torque value for something with anti seize on the threads. |
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Quoted: Quintin, from reading your posts I realise you don't use anti-seize on spark plug threads.Quoted: Thanks for the tip about the dental pick..worked like a charm. After screwing around for about half an hour trying to get the metal clip off the porcelain part of the plug..I discovered the plug was loose. So I put a piece of vacuum hose over it and removed it as I couldn't get a socket on it. I have no idea where the clip went though.. I was very worried the threads were stripped in the head. Good news is..the threads were fine. I put anti-seize compound on them when I changed them the last time. The #2 and #3 plugs were both loose. One was bad enough that the boot on the plug wire was black with soot. I have no idea why or how they loosened up..but I suspect it was due to me being cautious when I changed them the last time and not cranking on them. New plugs and wires and she is running like a swiss watch. I still have to deal with the EGR error code but it isn't an emergency. thanks for all the help guys.. Probably. To the best of my knowledge, no manufacturers recommend using anti seize on spark plug threads. For that reason. There's some kind of formula, I forget what the exact name of it is, to calculate the new torque value for something with anti seize on the threads. I have run into a lot of high mileage "original factory installed" spark plugs that were either very tight and loudly snapped when broke loose. I've had them reverse my Snap-On ratchets because of the backlash vibrations. I've also had some plugs that were so dry that they tried to gall on removal. Even with application of penetrating fluids they squeaked and squawked all the way out. The worst was an Isuzu V6 left rear spark plug. It fought every millimeter. With these experiences I always apply a daub of anti-seize to allow reinstalling the spark plugs without galling. I have found spark plugs that were not fully installed because they were stuck or galled. I properly torque them and have had no problems to date. I believe the anti-seize prevents electrolisis(?) between dissimilar metals resulting in "bound up" spark plugs. Beside that it makes those damn Subaru DOHC spark plugs start and screw in much easier. I always ended up with hand cramp from playing musical sockets! My 2 cents, your experience may vary. |
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George, the P0401 code on Toyota Rav-4is rarely a bad EGR Valve. It's more often a bad EGR VSV (vacum switching valve), followed by the EGR Vacum Modulator -or in ARFCOM tradition- BOTH. The last P0401 I did had a bad VSV and a bad Modulator. In any case, check all the vacum lines first, at all three components...EGR, EGR VSV, and EGR Vacum Modulator(AKA backpressure transducer). A simple broken or cracked hose will also cause a P0401. LMK if you need specifics on testing the EGR VSV and Modulator. The P030x codes shouldn't be caused by a P0401, if EGR's not flowing it shouldn't interfere with the engine firing steady. If EGR is stuck OPEN and flowing at idle then you can get P030x codes. For the P030x codes as a group and especially on cylinders #2and #3, I would look into ignition problems, SPECIFICALLY the ignition coils.Cylinders #2 and #3 SHARE an ignition coil so that's most likely your problem for P0302 and 303. More info on missfires...If the ignition is not firing on one or two cylinders..it's a very big deal on a 4 cylinder motor...even if it's intermittent. Losing good spark at the rate of 25-50% (of total) will cause serious heat in your exhaust system, in many cases the Catalytic will turn RED HOT from the raw unburnt fuel that's still being introduced into the cylinders. That's when you smell the exhaust burning. Catalytic should be fine if it hasn't been running like this for a very long time. How do people know this stuff???? I couldn't make this up, even if I had to.
vmax84 Mechanic. If it wasnt for people who did not know this people like me would be out of a job. Lucky for me I work on big rigs and we dont have as much bs to worry about yet. Really? Your fleet all pre -.07? EGR SCR ACERT DPF's and Regen (of which I am having ALL KINDS of problems with) Iteris Vorad APU's (also very problematic) I have been pulling Mid's Pid's and Sid's for almost a decade now... No different then an OBD code.... I mean hell..... We even get SPARK PLUGS now for crying out loud I would venture that with the '10 EPA regs truck have made the great leap forward to "just and technology riddled and problematic " as cars Oh yeah ..... forgot my favorite technology that should have been left in cars ..... Automatic Transmissions..... I didnt even think about the 07 stuff. We dont see much of that yet. We get one every once in a while. I only work on Detroits and MBEs. More problem with the MBEs then anything. We dont have much problem with the DPF systems. I dont touch auto trans. We sure dont have spark plugs either. |
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Thanks for the tip about the dental pick..worked like a charm. After screwing around for about half an hour trying to get the metal clip off the porcelain part of the plug..I discovered the plug was loose. So I put a piece of vacuum hose over it and removed it as I couldn't get a socket on it. I have no idea where the clip went though..
I was very worried the threads were stripped in the head. Good news is..the threads were fine. I put anti-seize compound on them when I changed them the last time. The #2 and #3 plugs were both loose. One was bad enough that the boot on the plug wire was black with soot. I have no idea why or how they loosened up..but I suspect it was due to me being cautious when I changed them the last time and not cranking on them. New plugs and wires and she is running like a swiss watch. I still have to deal with the EGR error code but it isn't an emergency. thanks for all the help guys.. That's real good to hear, glad you got her running like new again...nice work brother. 
ETA: Let us know when you want to test the EGR system. |
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Will do...what a fun job getting at that switch is going to be..That's real good to hear, glad you got her running like new again...nice work brother.
ETA: Let us know when you want to test the EGR system.
 The engineers never thought it might need checking one day
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Quoted: fixed it for ya! Quoted: Quoted: Will do...what a fun job getting at that switch is going to be..That's real good to hear, glad you got her running like new again...nice work brother. ETA: Let us know when you want to test the EGR system. The engineers that have fingers 12 inches long with an eyeball on the end never thought it might need checking one day |