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  #16  
Old 06-06-2006, 09:05 AM
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CDG CDG is offline
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And right you are Earthworm.
the code 34 returned the next day, and always does if I start the car while its still warm, the code will post.
It seams every time I drive the car,
park it for a short while, an hour or less,
I start the car again and the Check Engine comes on solid,
check the code, and its 34.
Seams like the EGR solenoid gets stuck until the car cools down enough or something.
Still no code 37 or 28.
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  #17  
Old 06-06-2006, 01:22 PM
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Most DTCs won't set on the first failure. EGR doesn't work until car is adequately warmed up. That's all. Whatever is not working, is never working.
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  #18  
Old 06-06-2006, 02:28 PM
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DTC's?

So what you are saying is that once I post a code 34, solid: meaning the light came on and stayed on until I turned the car off and on again. Then its no longer checked?
I have always had this problem when I start the car when its already warm. So the EGR is actually defective, but can only tell me when the car is warm, so it posts?

If I have that right?
1)it makes sense for me to review the NEW EGR test proceedure , now that I know where the EGR solenoid is,
2)Diagnose and repair, and
3)that should fix my high NOx reading????
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  #19  
Old 06-06-2006, 07:30 PM
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DTC = Diagnostic Trouble Code. Sorry, an industry acronym I read all day long.

Almost every issue must occur on at least two consecutive drive cycles before the Check Engine light is commanded 'ON'. The parameters for determining a specific issue varies, depending on the device, etc.

Specifcally, EGR systems do not function until the engine has nearly reached full operating temp. A number of other prerequisites must also be met - engine speed, road speed, throttle angle, etc.

So, the prerequisites must first be met before the EGR can operate. The ECU can't check the EGR's operation before that so there is no way it can determine if it is faulty. And then it has to occur on two or more consecutive drive cycles. If the fault occurs on trip one but trip two doesn't actually get to the point of operation it may need to have another full drive cycle or it may erase trip number one's history. In any event the faulty part is still faulty, it just hasn't been recognized yet.

The only purpose for EGR on gasoline engines is for NOx reduction. Period. Detonation/knock can be controlled solely through timing manipulation and fuel quality without resorting to introducing an inert gas.

The NEW procedure is just another way of accomplishing the same thing. The first way was a result of me working from my fractured memory of the SVX's specifics. The second way was a result of me using the diagram. This system is similar to some Nissan, Chrysler & Toyota but not like Ford, GM and others. You gotta cut me some slack. I can look at a car, recognize the system, the technology and know what to do but for me to recall it exactly from memory is a crap shoot.
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  #20  
Old 06-06-2006, 09:08 PM
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Wow, thats awesome Beav.
OK, now that I can figure out how to test it,thanks to you and Trevor, I should run through the EGR testing and find my bad part, but the most logical perception is that it is indeed failing and thats why I have high NOx emmisions.

Question:
So High NOx comes from not reburning enough exhaust gases? i.e. EGR not flowing back to intake? or the other way around?
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  #21  
Old 06-06-2006, 10:29 PM
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Quote:
Originally Posted by Beav
DTC = Diagnostic Trouble Code. Sorry, an industry acronym I read all day long.

Almost every issue must occur on at least two consecutive drive cycles before the Check Engine light is commanded 'ON'. The parameters for determining a specific issue varies, depending on the device, etc.

Specifcally, EGR systems do not function until the engine has nearly reached full operating temp. A number of other prerequisites must also be met - engine speed, road speed, throttle angle, etc.

So, the prerequisites must first be met before the EGR can operate. The ECU can't check the EGR's operation before that so there is no way it can determine if it is faulty. And then it has to occur on two or more consecutive drive cycles. If the fault occurs on trip one but trip two doesn't actually get to the point of operation it may need to have another full drive cycle or it may erase trip number one's history. In any event the faulty part is still faulty, it just hasn't been recognized yet.

The only purpose for EGR on gasoline engines is for NOx reduction. Period. Detonation/knock can be controlled solely through timing manipulation and fuel quality without resorting to introducing an inert gas.

The NEW procedure is just another way of accomplishing the same thing. The first way was a result of me working from my fractured memory of the SVX's specifics. The second way was a result of me using the diagram. This system is similar to some Nissan, Chrysler & Toyota but not like Ford, GM and others. You gotta cut me some slack. I can look at a car, recognize the system, the technology and know what to do but for me to recall it exactly from memory is a crap shoot.
Maybe I'm taking this out of context, but the EGR only reduces NO levels? Would it have any effect on HC levels?
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  #22  
Old 07-08-2006, 08:31 PM
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Was just researching for a different post and saw the last two posts here. For some reason new posts don't always show up in bold.

Anyway.... You can't burn something that is already burnt, can you? Exhaust gas is inert, i.e. has no O2 content. NOx is a result of high combustion temperature. So, in order to lower combustion temp, exhaust gas is introduced into the intake. This keeps combustion chamber pressure up, to keep power up, but the inert gas inhbits combustion just enough to keep the temp under control.

The EGR is only for NOx reduction but if it were allowed to flow at idle it would reduce the O2 level in the chamber. Remember - HC is raw fuel and CO is a product of incomplete combustion from lack of adequate O2. So HC might go up a couple points but CO will climb quite a bit. Then again, if the EGR opens more than just a little bit at idle the engine will usually stall.
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  #23  
Old 07-09-2006, 10:02 AM
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Well after all the palying around I have done I still have the same problem. And that is that once my car is warm, and I restart it within 1 hour of turning it off, it periodically posts a 34.
I still have not done the "Idle Bypass to make it stall" test, but I suspect it will fail, i.e. will not make the car stutter or stall.
I did get it to pass our aircare test buy replacing a bunch of vacuum lines and hoses, and diverting the rocker cover hoses, temporarily of course.

I still need to isolate the issue.

And thx Beav, I was completely wrong on what I thought the EGR did.
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