2.3 Egr?.........

[adsm08]

Disabling the egr system will not harm the cats. In general no combustion should happen inside the converters but if raw fuel makes it down there it will ignite because vats normally operate above the flash point of gasoline. This is especially true if you have a dead miss that is throwing Oxygen down there as well.

Look at the 2.9 and 4.0. Both engines were run if factory configurations for years with and without egr systems and no real changes to the cats. Both work fine.
Postin' from teh Galaxy

 

[Wicked_Sludge]

It sounds like you should skim the wikipedia article on cat. converters to give yourself a quick refresher. In particular this part:

Any condition that causes abnormally high levels of unburned hydrocarbons—raw or partially burnt fuel—to reach the converter will tend to significantly elevate its temperature, bringing the risk of a meltdown of the substrate and resultant catalytic deactivation and severe exhaust restriction.

Normal EGTs from a properly running engine will never reach a sustained temperature high enough to damage a cat. converter. It's the heat created by the cat. converter from the oxidation (a chemical processes that takes a fuel and an oxidant and produces, among other things, heat is generally known as "combustion") of unburnt hydrocarbons that can cause a cat. converter to over heat.

It's the reason most OBDII vehicles will flash the CEL and sometimes sound a chime when a misfire is detected; to indicate to the driver to stop the vehicle before the (sometimes very expensive) cat. converters are damaged.

Secondly, 1 PSI of back pressure at idle is considered excessive and is enough to cause drivability problems. Around 10 PSI is enough to cause severe drivability and/or stalling conditions. If a 10 PSI increase in cylinder pressure is enough to blow out a piston than you should probably just sell your vehicle for scrap because it's not worth rebuilding

Did your instructor consider that maybe there was an underlying cause to the piston blowing out and the cat. clogging? My immediate thought would be detonation. If the vehicle had been detonating in one or more cylinders it's going to send a lot of unburnt fuel into the exhaust stream, causing the cat. to melt down. Continued driving with the engine detonating would have blown through a piston.

 

[twistedcomic]

Enjoying the love

Hello to all. I am a brand new member, and I have been a Ranger owner since 2009. I just found this site because I am having some trouble passing the California smog test for my renewal. I read that someone called it Komi-fornia, but the Govt of CA is not commie, they are Facist, you know, like Hitler. Facists want the Govt. to control everything, just like Obama, his socialist leanings are a coverup for the belief that only the privileged are smart enough to run the show. I'm betting that his parents were richer than yours and mine. Oh well, enough of my political views, on with the good stuff. I was just enjoying the back and forth, the to and fro, the zig and zag, the punch and jab, the in and out: Wait a minute I think that I got this site confused with some porn that I was watching earlier. Whatever the case,I was riveted by this discussion/argument, then it just stopped. BS I say. Part of the fun of life is in the opportunity to educate and be educated, no matter the form or subject. So, to all of you involved, get back to the argument, er, discussion. And, while we are at it, how about helping me out with my little problem of a too high reading in the NOx in both the 15mph and the 25mph smog test? Thanks for the fun! Jim

 

[Mark_88]

This thread lives yet again...

High NOx can mean a number of things...like EGR malfunction...over advanced timing...lean air/fuel mixture...defective cat...

I guess if you want to proceed you need to check for codes and other obvious problems like missing or broken EGR tube or fittings...check the timing...pull the cat's tail to see if it screeches...

A 94 shouldn't have a defective cat, but could...and I'm not sure if kookie-Fornication has what we have in Canada...a repair cost limit and a conditional pass...those would get you through the test after having a diagnostic done by a mechanic...

 

[tomw]

You will get high NOx output if the 1)peak combustion temperature is too high, generally caused by a non-functional EGR, high coolant temp can contribute, I suppose, or 2) a converter that does not do the reduction needed. Reduction is the opposite of oxidation, and converters do that to make NOx back into N and XOx, likely COx something and H2O.
Check the EGR by opening the EGR valve at idle. If EGR can flow, it will mess up the idle, or cause the engine to stall. Your EGR valve should have an electrical connector that connects a position sensor to the ECM. The sensor tells the ECM how far open the EGR is in its stroke, as was most likely commanded by the ECM. If the EGR doesn't report, or reports bum info, the ECM will light a light or store a code, depending on frequency of this particular condition, and whatever other params the maker desired.
I would check that the EGR will and can flow exhaust as noted, and if not, take it apart and clean the pipe, the valve and the inlet on the intake to make sure it was not plugged. Oh, and don't take it for the '20 mile high speed warm up clean up run before SMOG test', just drive it normal to keep the temps down. A weak converter may be coaxed to pass the test if it is not run hot from highway miles. At least I had one that was CLoooose on NOx, and I was doing the 20-mile run prior. Next year, just drove over and parked in line, tested, and passed without any other action on my part. {'87 Vulcan 3.0 without EGR}
tom

 

[Clumzi]

I just read this post front to back and - wow. I really wanna drive to Westport and shake someone's hand .

I was planning on trying to fabricate a little block off plate a la this website

http://www.route66hotrodhigh.com/EGR.html

But now I really don't think I will.

ZOMBIE THREAD!!!!!!!!!!!!!!!!!!!!!!!!!!!

 

[Sidewalk]

Good news is, some people know how to use the search function.

 

[ancient]

Hey Wicked! Thanks for the EGR info. I've contemplated removal of the one on a Turbo Coupe engine I'm about to tear down. I appreciate the reasons a component is useful and why. I hear of and see numerous mods but don't always hear the reason.

 

[NIPs]

up here in michigan no EGR is not illegal, because here in michigan we dont have that shitty emmissions shit

 

[NIPs]

exhuast gases are not entirely inert, no engine will ever obtain 100% burn, gasoline engines only burn 75%-85% of the gas in the combustion chamber, diesel burn about 90%-95%, so when ur exhuast exits (even if u have the dual plug system on 2.3 or 2.5) there is still a small amount of Hydrocarbons in the exhuast, yes the EGR does keep ur engine from burning the important shit up, but it does play a big factor in mpg

 

[Austin S]

if you dont understand how a system functions for yourself, you really shouldnt mislead others by trying to explain it.

the EGR system has nothing to do with burning unburnt hydrocarbons...the converter will take care of that (and has been since the 1970's).

the EGR system is designed to reduce the production of a pollutant called nitrogen oxide (NOX), which only forms in combustion chambers over a certain temperature. the EGR system prevents their formation by lowering combustion chamber temperatures.

exhaust gases are inert, meaning they do not add any fuel or air to the combustion chambers, all they do is take up room. since they are cooler than the combusting a/f mixture, they provide a lower combustion chamber temperature.

i can hear it now: "but mr sludge, doesnt the exhaust gas taking up room mean i have less room for air and fuel, and thus, less power from my motor?" no. the lower combustion chamber temperatures mean that the ignition timing can be advanced further than on a non-EGR engine, thus making up for any power lost due to exhaust gas presence in the chambers.

furthermore, all EGR operation is shut off during wide-open throttle...meaning even if the EGR system did cost you power, it wouldnt effect peak power.

as was mentioned, your computer is programmed to account for the EGR systems presence (primarily in the form of advanced engine timing). disabling the EGR on an engine programmed to run with it will cause a number of drivability concerns including, but not limited to:

-knocking/detonation - this can be fatal for a motor, leading to broken pistons, rings, and connecting rod bearings.
-lower fuel economy.
-rough running during cruise speeds
-check engine light
-failed emissions testing
-decreased power output

as was also mentioned, removing the EGR system is highly illegal. in fact, its against FEDERAL law to tamper with or disable any factory equipped emissions devices, regardless of wether or not you have emissions testing and/or inspections in your area. if your within the borders of the united states, your in violation of the law and the fine is heafty.

I hate to bump a 15 year old post but-

The EGR system was implemented to lower the combustion temperature because catalytic converters were getting too hot and creating NOX, not to reduce NOX in the combustion chamber. Reducing NOX was a byproduct of reducing combustion temperatures AND catalytic converter technology improving to accommodate higher temperatures. And now you have variable timing valvetrain that makes EGR systems obsolete for the most part.

And... not only was this reply snobbish, it was wrong. And it being wrong means you were a hypocrite. And only fools are hypocrites. Kudos.