WTF? Engine light
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Joined: May 2017
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From: Ohio
So a couple of things.
Whoever set up the catch can ended up jerry rigging the bypass CC vent. Having routed all the way over to the radiator and opened to the atmosphere isn't hurting anything, but if a tech type did an emissions inspection in, lets say, California, and he/she was sharp, they would fail the car. But again, venting to atmosphere is better than plugged. The harm is coming in letting the other side, the rubber inlet tube, open to the atmosphere. With a "hole" in your intake tube, when intake air volume is present, it will create a low pressure point at that opening (like a vacuum) drawing unmetered air into the air inlet stream. That is NOT good. You'd be better just blocking this off while the tube is vented to the atmosphere. Better - is to hook the tube (at the radiator) up to the air inlet opening. That would mimmick the original bypass. But, there is NO vacuum at this line. CC pressures will naturally exit the valve cover making its way into the air inlet stream, but nowhere near the volume of an open port. And. because of the way the valve cover tube is baffled under the valve cover, vapors from thee crankcase will only release in that tube if there is CC pressure. This is not possible if the two lines on the catch can are clear and the CC is functioning.
On to the catch can. I don't know this particular catch can or how it's plumbed. At least, if it is a two port can, those two places, the crankcase outlet and the intake manifold inlet are the two ports connected to a typical two port can. Hopefully they're connected correctly, they could be on backwards. There are so many cans on the market. Some designs are not that good, and again, I don't recognize this one at all. But, at least you have the correct lines terminating at the can.
BTW, check that little plastic "ell" fitting in the rubber inlet. Maybe the previous guy blocked it.
Anxious to hear what the codes are!
Whoever set up the catch can ended up jerry rigging the bypass CC vent. Having routed all the way over to the radiator and opened to the atmosphere isn't hurting anything, but if a tech type did an emissions inspection in, lets say, California, and he/she was sharp, they would fail the car. But again, venting to atmosphere is better than plugged. The harm is coming in letting the other side, the rubber inlet tube, open to the atmosphere. With a "hole" in your intake tube, when intake air volume is present, it will create a low pressure point at that opening (like a vacuum) drawing unmetered air into the air inlet stream. That is NOT good. You'd be better just blocking this off while the tube is vented to the atmosphere. Better - is to hook the tube (at the radiator) up to the air inlet opening. That would mimmick the original bypass. But, there is NO vacuum at this line. CC pressures will naturally exit the valve cover making its way into the air inlet stream, but nowhere near the volume of an open port. And. because of the way the valve cover tube is baffled under the valve cover, vapors from thee crankcase will only release in that tube if there is CC pressure. This is not possible if the two lines on the catch can are clear and the CC is functioning.
On to the catch can. I don't know this particular catch can or how it's plumbed. At least, if it is a two port can, those two places, the crankcase outlet and the intake manifold inlet are the two ports connected to a typical two port can. Hopefully they're connected correctly, they could be on backwards. There are so many cans on the market. Some designs are not that good, and again, I don't recognize this one at all. But, at least you have the correct lines terminating at the can.
BTW, check that little plastic "ell" fitting in the rubber inlet. Maybe the previous guy blocked it.
Anxious to hear what the codes are!
I'm just going to cap the tube. The catch can seems to be working. It did have oil in it that I dumped out. I assume that if it wasn't hooked up correctly there wouldn't be any oil in it.
Le Mans Master
Joined: May 2016
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From: Florida
Yes, I agree. If there is oil in the can probably a good indicator. If the ports are marked at all - Inlet and Outlet. The bottom (lower crankcase port) is the inlet to the can. The upper port (intake port) is the return or outlet out of the can.
So, you're receiving (and have received in the past) an IAT failure. The IAT on an LS3 is built into the MAF. Essentially, the voltage signal getting back to the ECM is out of range and appears to be intermittent. This could be happening for two reasons:
1. The IAT side of the MAF sensor has failed (or is failing intermittently) or
2. The MAF is dirty (look up how to properly clean a MAF).
As a distant possible 3rd, check the harness and connector to the MAF and check the rubber seal around the MAF is in place.
An IAT out of range isn't going to put you in limp mode, but when the ECM cannot reconcile the intake temp, it will default to a safe spark timing. When it pulls ign. timing you'll lose optimal power if P0113 is active at WOT.
Cap the tube, or see if it isn't blocked already.
So, you're receiving (and have received in the past) an IAT failure. The IAT on an LS3 is built into the MAF. Essentially, the voltage signal getting back to the ECM is out of range and appears to be intermittent. This could be happening for two reasons:
1. The IAT side of the MAF sensor has failed (or is failing intermittently) or
2. The MAF is dirty (look up how to properly clean a MAF).
As a distant possible 3rd, check the harness and connector to the MAF and check the rubber seal around the MAF is in place.
An IAT out of range isn't going to put you in limp mode, but when the ECM cannot reconcile the intake temp, it will default to a safe spark timing. When it pulls ign. timing you'll lose optimal power if P0113 is active at WOT.
Cap the tube, or see if it isn't blocked already.
Last edited by BlindSpot; Jul 17, 2017 at 04:31 PM.
Le Mans Master
Joined: May 2016
Posts: 6,909
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From: Florida
BTW Hwyknight, I omitted but should have added:
First step, clear the codes active and history, start the car and observe the dash, see if/when a CEL is reset. If it takes some driving to get the CEL to reset, or if it takes a certain speed or certain outside air temp, these all can be valuable observations in diagnosis. These conditions would indicate an IAT sensor that is failing at a given point or temp. Here is where cleaning might help, an intermittent cable failure, or the MAF sensor might need replacement.
If, on the other hand, the CEL sets immediately, then more indicates a hard failure, but cleaning might still work. I like doing observations like these and only want to replace a part as a last resort.
First step, clear the codes active and history, start the car and observe the dash, see if/when a CEL is reset. If it takes some driving to get the CEL to reset, or if it takes a certain speed or certain outside air temp, these all can be valuable observations in diagnosis. These conditions would indicate an IAT sensor that is failing at a given point or temp. Here is where cleaning might help, an intermittent cable failure, or the MAF sensor might need replacement.
If, on the other hand, the CEL sets immediately, then more indicates a hard failure, but cleaning might still work. I like doing observations like these and only want to replace a part as a last resort.
Last edited by BlindSpot; Jul 18, 2017 at 07:21 AM.
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Joined: May 2017
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From: Ohio
BTW Hwyknight, I omitted but should have added:
First step, clear the codes active and history, start the car and observe the dash, see if/when a CEL is reset. If it takes some driving to get the CEL to reset, or if it takes a certain speed or certain outside air temp, these all can be valuable observations in diagnosis. These conditions would indicate an IAT sensor that is failing at a given point or temp. Here is where cleaning might help, an intermittent cable failure, or the MAF sensor might need replacement.
If, on the other hand, the CEL sets immediately, then more indicates a hard failure, but cleaning might still work. I like doing observations like these and only want to replace a part as a last resort.
First step, clear the codes active and history, start the car and observe the dash, see if/when a CEL is reset. If it takes some driving to get the CEL to reset, or if it takes a certain speed or certain outside air temp, these all can be valuable observations in diagnosis. These conditions would indicate an IAT sensor that is failing at a given point or temp. Here is where cleaning might help, an intermittent cable failure, or the MAF sensor might need replacement.
If, on the other hand, the CEL sets immediately, then more indicates a hard failure, but cleaning might still work. I like doing observations like these and only want to replace a part as a last resort.
Interesting note, the VIN returned by my code reader doesn't match the car, so I'm guessing that at some point the cars main computer was replaced. Possibly with a used one........or I need to update the software in my code reader......
Le Mans Master
Joined: May 2016
Posts: 6,909
Likes: 1,546
From: Florida
I'm convinced there may be some ghost in the machine. Cleared th codes, and stared it up; CEL stayed on, and service TC & AH warnings popped up. Drove it a mile or two, pulled over, shutdown, and cleared the codes again. Restart and all warnings gone. I'll just drive it a bit and keep an eye on it.
Interesting note, the VIN returned by my code reader doesn't match the car, so I'm guessing that at some point the cars main computer was replaced. Possibly with a used one........or I need to update the software in my code reader......
Interesting note, the VIN returned by my code reader doesn't match the car, so I'm guessing that at some point the cars main computer was replaced. Possibly with a used one........or I need to update the software in my code reader......
TC and AH are two of the most misunderstood messages and constant threads on CF confirm that. As soon as the CEL issue is fixed and code cleared, TC and AH come back on their own. But, expect to see them every time a new CEL is set.
If the ECM was changed somewhere along the life of this car, whoever installed it would have had to program in the correct VIN to match the EBCM; otherwise, the car wouldn't have started. Probably not that big a concern with a less expensive Scan tool as long as its reading the P-Code faults.
Yes, if you have codes cleared, then as you drive it, note the conditions under which the car is operating if/when it sets again. If P0113 continues to show up, time after time, then you'll likely end up replacing the MAF if you've tried cleaning it already.
Last edited by BlindSpot; Jul 18, 2017 at 01:11 PM.
Le Mans Master
Joined: Oct 2014
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From: Atlanta GA
I thought that hose from the valve cover to the bellows was where the engine drew in clean air for the PVC system ...as it pulls vacuum from the other hose that connects from the valley pan to the port just behind the throttle body
Is that not what it is ?
Dave
