Charge relief valve
08-01-2007, 11:59 PM
#1
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Join Date: Jan 2006
Location: Arlington WA
Posts: 14
Tired of getting minimal, if any, help on RX7 club site, so I'm trying here. Hopefully somebody out there knows how the charge relief works? I've done a bit of reading, but I have conflicting information.
Basically what I conclude is that if one of two conditions is not met the charge relief solenoid is de-energized, allowing vacuum to reach the charge relief valve. This "engages" the charge relief valve and vents the charge from turbo #2 back to the airbox. At this time the charge control valve is closed as well.
Then, when one of two conditions are encountered the ecu tells the charge relief solenoid to energize, which blocks the vaccuum to the charge relief valve, causing it to close. At the same time the charge control valve opens and the charge from turbo #2 is routed to the engine.
The two conditions mentioned above are...1) when the engine rpms reach a predetermined point for even an instant and 2) when the engine rpms continuously exceed another lower predetermined point. The exact points in the rpm range are where I've found differing information.
Am I interpretting my readings correctly or am I totally out in left field here?
The reason I'm asking about this is because my CEL comes on after say 10 minutes of driving. When I check the code it tells me the charge relief valve is the cause. I've done everything the FSM recommends, except replace the ecu, but I've been told by a VERY reliable source that the ecu will not normally fail in this manner. As a matter of fact he says in his considerable experience he has never seen an ecu fail in such a way as to produce just one fault code. Therefore I'm trying to determine if the charge relief valve is actually working. Is there any way to tell if the valve is actually opening/closing? How will low-end performance be effected if the charge relief is not opening? I'm pretty sure it is not stuck open because around 3000 rpm it's like someone lit a rocket under my ***. That could be from the charge control valve opening, but only if the charge relief valve is closed.
Another thing I don't understand is how the ecu knows if the charge relief valve actually opened or closed. There's no connection between the ecu and the charge relief valve, only the solenoid. If you put a meter on 4S of the ecu and drive the car the voltage should go low at some point. Theoretically that would indicate the charge relief valve is good. In actuality that will only tell if the ecu is sending a signal to the solenoid, not whether the valve is functioning.
Note - I do not have a boost gauge yet. Actually I've got one,but it's not installed yet. Can't decide what to use for my 3rd gauge. I've got a boost gauge and an air/fuel mixture gauge. Thinking about oil temp for the 3rd. Any recommendations?
Sure hope someone can help me out with this. I'm tired of looking at that damn light.
Basically what I conclude is that if one of two conditions is not met the charge relief solenoid is de-energized, allowing vacuum to reach the charge relief valve. This "engages" the charge relief valve and vents the charge from turbo #2 back to the airbox. At this time the charge control valve is closed as well.
Then, when one of two conditions are encountered the ecu tells the charge relief solenoid to energize, which blocks the vaccuum to the charge relief valve, causing it to close. At the same time the charge control valve opens and the charge from turbo #2 is routed to the engine.
The two conditions mentioned above are...1) when the engine rpms reach a predetermined point for even an instant and 2) when the engine rpms continuously exceed another lower predetermined point. The exact points in the rpm range are where I've found differing information.
Am I interpretting my readings correctly or am I totally out in left field here?
The reason I'm asking about this is because my CEL comes on after say 10 minutes of driving. When I check the code it tells me the charge relief valve is the cause. I've done everything the FSM recommends, except replace the ecu, but I've been told by a VERY reliable source that the ecu will not normally fail in this manner. As a matter of fact he says in his considerable experience he has never seen an ecu fail in such a way as to produce just one fault code. Therefore I'm trying to determine if the charge relief valve is actually working. Is there any way to tell if the valve is actually opening/closing? How will low-end performance be effected if the charge relief is not opening? I'm pretty sure it is not stuck open because around 3000 rpm it's like someone lit a rocket under my ***. That could be from the charge control valve opening, but only if the charge relief valve is closed.
Another thing I don't understand is how the ecu knows if the charge relief valve actually opened or closed. There's no connection between the ecu and the charge relief valve, only the solenoid. If you put a meter on 4S of the ecu and drive the car the voltage should go low at some point. Theoretically that would indicate the charge relief valve is good. In actuality that will only tell if the ecu is sending a signal to the solenoid, not whether the valve is functioning.
Note - I do not have a boost gauge yet. Actually I've got one,but it's not installed yet. Can't decide what to use for my 3rd gauge. I've got a boost gauge and an air/fuel mixture gauge. Thinking about oil temp for the 3rd. Any recommendations?
Sure hope someone can help me out with this. I'm tired of looking at that damn light.
08-02-2007, 10:21 AM
#2
Senior Member
Join Date: Dec 2003
Location: Mid-West
Posts: 791
You may have seen this already, but just in case......
http://www.autosportracetech.com/RX-7/Turb...bleshooting.htm
Re: Gauge choices: IMO, boost and Water or Oil temp are the two most important on a relatively stock car/ECU. Water temp is the easiest to install if you still have the throttle body coolant line.
http://www.autosportracetech.com/RX-7/Turb...bleshooting.htm
Re: Gauge choices: IMO, boost and Water or Oil temp are the two most important on a relatively stock car/ECU. Water temp is the easiest to install if you still have the throttle body coolant line.
08-02-2007, 11:24 PM
#3
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Thread Starter
Join Date: Jan 2006
Location: Arlington WA
Posts: 14
Major break-thru today. I figured out a way to measure the voltage at 4S while driving the car, so I connected it up and went for a drive.
According to F-176 in the FSM, the charge relief solenoid should energize, which means 4S should go low, when the engine rpm is 4000 – 5500 for 8 seconds OR if the engine rpm goes over 5500 rpm. In order to get the rpm up to that point I’m driving around 1 gear lower than I normally use and I can see the voltage at 4S go low and then back high. Guess what…no CEL. I figure it must have been a bad connection and head for the house. On the way home I go back to my normal mode of driving and the CEL comes on after about 10 minutes. So I stop, shut the car off, restart it and drive around 1 gear lower than normal for like 40 minutes. The CEL didn’t come on 1 time. That’s not the end of the story though.
Where the FSM says 4000 – 5500 rpm for 8 sec or over 5500 rpm, this is not what I saw. As long as I kept the rpm over about 3000 – 3500 I got no CEL, but the voltage at 4S stayed high. If I accelerated harder than usual at any engine speed, 4S went low and again, no CEL. SO, I’m thinking the ECU has to be monitoring something in addition to engine speed to control the charge relief valve. Anybody know the story with that?
Guess I'll have to quit driving like an old granny huh? Seriously though, anybody else seen anything like this?
According to F-176 in the FSM, the charge relief solenoid should energize, which means 4S should go low, when the engine rpm is 4000 – 5500 for 8 seconds OR if the engine rpm goes over 5500 rpm. In order to get the rpm up to that point I’m driving around 1 gear lower than I normally use and I can see the voltage at 4S go low and then back high. Guess what…no CEL. I figure it must have been a bad connection and head for the house. On the way home I go back to my normal mode of driving and the CEL comes on after about 10 minutes. So I stop, shut the car off, restart it and drive around 1 gear lower than normal for like 40 minutes. The CEL didn’t come on 1 time. That’s not the end of the story though.
Where the FSM says 4000 – 5500 rpm for 8 sec or over 5500 rpm, this is not what I saw. As long as I kept the rpm over about 3000 – 3500 I got no CEL, but the voltage at 4S stayed high. If I accelerated harder than usual at any engine speed, 4S went low and again, no CEL. SO, I’m thinking the ECU has to be monitoring something in addition to engine speed to control the charge relief valve. Anybody know the story with that?
Guess I'll have to quit driving like an old granny huh? Seriously though, anybody else seen anything like this?
08-03-2007, 04:02 PM
#4
Senior Member
Join Date: May 2002
Location: California
Posts: 22,465
the check engine light will come on for any opens or shorts in the circuit.
therefore, for the cel to come on for the crv SOLENOID. there must be an open or short circuit between the ecu CRV SOLENOID, and or the ecu.
so the solenoid could be bad, ecu could be bad, or the wiring in between.
the ecu can and will only spit out one error code at a time. the ecu will get confused if theres more than about 4-5 codes, it's like the buffer gets full.
are you sure you're reading the code right? ive never seen a crv code, i'd suspect the wiring harness off the top
therefore, for the cel to come on for the crv SOLENOID. there must be an open or short circuit between the ecu CRV SOLENOID, and or the ecu.
so the solenoid could be bad, ecu could be bad, or the wiring in between.
the ecu can and will only spit out one error code at a time. the ecu will get confused if theres more than about 4-5 codes, it's like the buffer gets full.
are you sure you're reading the code right? ive never seen a crv code, i'd suspect the wiring harness off the top
08-03-2007, 09:53 PM
#5
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Thread Starter
Join Date: Jan 2006
Location: Arlington WA
Posts: 14
The solenoid is new. The code is 46....4 long flashes followed by 6 short flashes. I've read it a dozen times to be sure. Read my last post. I'm thinking the ecu is doing what it is programmed to do. I can see the voltage at 4S changing as described in my last post. I don't understand the difference in the rpm's, but it looks frighteningly close to what the ecu for an automatic is suppose to do.
Originally Posted by j9fd3s' post='879423' date='Aug 3 2007, 02:02 PM
the check engine light will come on for any opens or shorts in the circuit.
therefore, for the cel to come on for the crv SOLENOID. there must be an open or short circuit between the ecu CRV SOLENOID, and or the ecu.
so the solenoid could be bad, ecu could be bad, or the wiring in between.
the ecu can and will only spit out one error code at a time. the ecu will get confused if theres more than about 4-5 codes, it's like the buffer gets full.
are you sure you're reading the code right? ive never seen a crv code, i'd suspect the wiring harness off the top
therefore, for the cel to come on for the crv SOLENOID. there must be an open or short circuit between the ecu CRV SOLENOID, and or the ecu.
so the solenoid could be bad, ecu could be bad, or the wiring in between.
the ecu can and will only spit out one error code at a time. the ecu will get confused if theres more than about 4-5 codes, it's like the buffer gets full.
are you sure you're reading the code right? ive never seen a crv code, i'd suspect the wiring harness off the top
08-05-2007, 02:56 AM
#7
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Thread Starter
Join Date: Jan 2006
Location: Arlington WA
Posts: 14
Same thing today. As long as I keep the engine rpm's above about 3000...no CEL. If I go below that the CEL comes on. Any9one else noticed this? Seems the ecu is working, but is it working correctly? I don't know.
08-07-2007, 12:53 AM
#8
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Thread Starter
Join Date: Jan 2006
Location: Arlington WA
Posts: 14
Ever hear of cranial-rectal inversion? It means I had my head in my ***. Today I found out that I actually have 2 fault codes, neither of which is 46. I was mis-reading the code. I have a code 16 (EGR) fault and a code 40 (Purge Control) fault.
What I was saying about the symptoms is correct though, as long as I keep the rpm's above 3000 I get no CEL. Doesn't make sense to me, but I am not sure how either of these codes are detected. Back to the drawing board.
What I was saying about the symptoms is correct though, as long as I keep the rpm's above 3000 I get no CEL. Doesn't make sense to me, but I am not sure how either of these codes are detected. Back to the drawing board.
08-07-2007, 10:25 AM
#9
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Join Date: May 2002
Location: California
Posts: 22,465
16 is easy, check the wiring really quick to make sure its not melted, and if its not replace the egr, n3a3-20-300... or change the ecu to a non ca 93 or a 95 ecu, something that doesnt have the egr sensor
40 ive never seen, but it should be the same as 46, just a different solenoid. you also might want to check the purge valves, and check valves in the system, they fail sometimes too, and hey you needed to spend more money on this thing
40 ive never seen, but it should be the same as 46, just a different solenoid. you also might want to check the purge valves, and check valves in the system, they fail sometimes too, and hey you needed to spend more money on this thing
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