how to replace an egr valve on a 93' z32 N/A?
02-12-2007 | 04:20 PM
#2
caught the z fever
Joined: Jun 2004
Posts: 2,518
From: Lafayette, IN
run an ecu diagnostic first to see if it is the egr causing problems
http://www.ttzd.com/izcctech.html
and also do this...
To test the EGR valve operation, start the engine and then disconnect the control hose (light blue dot in 2.). The EGR valve should open and engine should slow or hesitate. If disconnecting the hose makes no difference, either the hose is leaky/ blocked or the EGR exhaust gas pipes are blocked.
heres a write up for replacing the egr yourself.
http://www.ttzd.com/tech/engine/egr.html
it is a lot more difficult with the engine in the car. i believe you have to remove the tranny, both plenums, and raise the rear of the engine to get it out the back. 91zxtt can comment more on this when he gets here
http://www.ttzd.com/izcctech.html
and also do this...
To test the EGR valve operation, start the engine and then disconnect the control hose (light blue dot in 2.). The EGR valve should open and engine should slow or hesitate. If disconnecting the hose makes no difference, either the hose is leaky/ blocked or the EGR exhaust gas pipes are blocked.
heres a write up for replacing the egr yourself.
http://www.ttzd.com/tech/engine/egr.html
it is a lot more difficult with the engine in the car. i believe you have to remove the tranny, both plenums, and raise the rear of the engine to get it out the back. 91zxtt can comment more on this when he gets here
02-12-2007 | 10:46 PM
#3
Registered User
Joined: Nov 2003
Posts: 3,672
From: Gerber, CA
Yes, I can comment on it...It's a bitch. A major bitch. It's bolted to the back of the lower plenum and is very difficult to get to. There is a coolant line that is right in the way, so be prepared. I have a ratchet shaped hole in the sheet rock in my garage thanks to that stupid *** little thing. The easiest way is going to be to lower the cross member far enough so that the firewall isn't in your way. You don't need to remove the tranny though. It's almost easier to remove the whole damn engine.
02-13-2007 | 12:02 AM
#4
Encyclopedic Knowledge
Joined: Aug 2005
Posts: 3,316
From: Naperville, IL
Remove it. It won't hurt the car or emissions if it's removed, but if it's installed incorrectly or malfunctioning, it can cause some serious damage. (If you don't believe me, I'll dig up the post that Ash Power made about it... but I'm too lazy to do it unless you want proof.)
02-14-2007 | 01:33 PM
#7
caught the z fever
Joined: Jun 2004
Posts: 2,518
From: Lafayette, IN
http://www.twinturbo.net/net/viewmsg...cal&dtSearch=0
if the egr is installed correctly, ive only been able to find that theres a possibility that detonation could occur while cruising. but that would be very unlikely since there isnt much of a load on the engine during a normal cruise. i thought there was more to it than that tho.
if the egr is installed correctly, ive only been able to find that theres a possibility that detonation could occur while cruising. but that would be very unlikely since there isnt much of a load on the engine during a normal cruise. i thought there was more to it than that tho.
02-15-2007 | 12:02 AM
#8
Encyclopedic Knowledge
Joined: Aug 2005
Posts: 3,316
From: Naperville, IL
Originally Posted by b300z
Originally Posted by Ash
If the EGR is not properly connected (or it is defective) and allows exhaust gas to make its way into the intake manifold, this creates a couple of serious problems.
1) The ECU relies heavily on accurate mass-airflow-sensor information in order to determine fuel delivery and ignition timing (along with a slew of other control sequences). The typical trend is that as airflow increases, the fuel delivery increases and the ignition timing decreases. In the event that the EGR valve is allowing exhaust gases to enter the intake manifold, this recirculation of air reduces the amount of air drawn through the mass airflow sensor. This will cause the fuel delivery to drop, and the timing to advance.
2) Exhaust gas is hot, REALLY hot. The more boost you are making, the hotter the exhaust gases are. Typical exhaust temps on a twinturbo are from around 1100F up to 1550F (max safe). 93 octane fuel has an auto-ignition temperature of around 850F - this is the temperature at which it will spontaneously ignite, even without a spark or flame. There aren't really any concerns with blowing up the intake manifold since there is a large quantity of cooler air coming through the throttlebodies, not to mention, the injectors are waaay down at the intake valves. However, when amounts of super-hot exhaust gases are making their way into the intake manifold and on into the combustion chamber, you are significantly increasing the chances of detonation. Mix this with the fact that a leaky EGR is going to cause a leaner mixture and more timing advance, and you have a mix for catastrophe on your hands.
1) The ECU relies heavily on accurate mass-airflow-sensor information in order to determine fuel delivery and ignition timing (along with a slew of other control sequences). The typical trend is that as airflow increases, the fuel delivery increases and the ignition timing decreases. In the event that the EGR valve is allowing exhaust gases to enter the intake manifold, this recirculation of air reduces the amount of air drawn through the mass airflow sensor. This will cause the fuel delivery to drop, and the timing to advance.
2) Exhaust gas is hot, REALLY hot. The more boost you are making, the hotter the exhaust gases are. Typical exhaust temps on a twinturbo are from around 1100F up to 1550F (max safe). 93 octane fuel has an auto-ignition temperature of around 850F - this is the temperature at which it will spontaneously ignite, even without a spark or flame. There aren't really any concerns with blowing up the intake manifold since there is a large quantity of cooler air coming through the throttlebodies, not to mention, the injectors are waaay down at the intake valves. However, when amounts of super-hot exhaust gases are making their way into the intake manifold and on into the combustion chamber, you are significantly increasing the chances of detonation. Mix this with the fact that a leaky EGR is going to cause a leaner mixture and more timing advance, and you have a mix for catastrophe on your hands.
02-18-2007 | 11:48 AM
#9
Registered User
Joined: Nov 2003
Posts: 3,672
From: Gerber, CA
Interesting. I thought the EGR valve (when working properly) was to help keep the combustion temperatures down. and in doing so, it keeps the carbon monoxide numbers down. With no egr valve, isn't the likelihood of detonation greater than it would be with an EGR valve installed and properly working?
Last edited by 91zxtt; 02-18-2007 at 11:52 AM.
02-18-2007 | 12:26 PM
#10
Banned
Joined: Feb 2007
Posts: 92
Originally Posted by 91zxtt
Interesting. I thought the EGR valve (when working properly) was to help keep the combustion temperatures down. and in doing so, it keeps the carbon monoxide numbers down. With no egr valve, isn't the likelihood of detonation greater than it would be with an EGR valve installed and properly working?
02-18-2007 | 07:34 PM
#12
Encyclopedic Knowledge
Joined: Aug 2005
Posts: 3,316
From: Naperville, IL
Originally Posted by 91zxtt
I guess it comes down to if the EGR isn't there, then you know exactly what's going on in the engine. If it's there and it fails, then you may not catch it in time.
And to be 100% honest, the effects that the EGR valve has on cooling the combustion chamber is minimal at best. Removing it will have such a minute effect that it's really nothing to worry about.
02-18-2007 | 10:42 PM
#13
caught the z fever
Joined: Jun 2004
Posts: 2,518
From: Lafayette, IN
Originally Posted by ZLover4Life
And to be 100% honest, the effects that the EGR valve has on cooling the combustion chamber is minimal at best. Removing it will have such a minute effect that it's really nothing to worry about.
02-19-2007 | 12:25 AM
#14
Encyclopedic Knowledge
Joined: Aug 2005
Posts: 3,316
From: Naperville, IL
It's also important to note that the EGR valve only operates at a constant engine speed... and since detonation is very rare at a constant engine speed, it should not be a concern with the EGR valve removed.
Most detonation occurs at WOT, when the EGR valve is functionless anyway.
Most detonation occurs at WOT, when the EGR valve is functionless anyway.
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