Topic: EGR Delete Sensor Problems

[beadle934]

I deleted the EGR system on my 94 EX Cab 22RE and it keeps throwing the egr code (7 blinks _ 1 blink).  I've heard that you can put a resistor in that will keep you for throwing the code and having to reset it all the time or just leave the check engine light on.  Has anyone fixed this problem before? Which resistor do I need (ie: how many ohms, watt, tolerance, etc.)?  Any help with this would be great. I'm tired of seeing the check engine light on. 

[TNRabbit]

10k ohm resistor from Radio Shack for less than $1.  wire to the two terminals.

you are increasing your cylinder temp by deleting the EGR...subjecting yourself to premature head gasket failure.  A PROPERLY FUNCTIONiNG EGR doesn't affect performance.

[beadle934 [OP]]

Ok, thanks. Did not relaize that you increase the cylinder head pressure with egr system removed.  Only have run about 1500 miles without it, mybe I should put the egr back on the truck.

[yotarunner85]

10k ohm resistor from Radio Shack for less than $1.  wire to the two terminals.

you are increasing your cylinder temp by deleting the EGR...subjecting yourself to premature head gasket failure.  A PROPERLY FUNCTIONiNG EGR doesn't affect performance.

Removing the EGR will NOT cause premature head gasket failure, will NOT cause increased engine, cylinder temp. or cylinder head pressure.  Removing the EGR will increase NOX emissions due to increased combustion temp. The EGR only turns on when the vehicle is at a cruising speed. When you step on the gas pedal the EGR turns off, that's why performance is not affected, and that's why it has no effect on the head gasket or engine temp.

[TNRabbit]

I beg to differ with you, yotarunner85:

The main effect of egr is to lower combustion temps to combat nox emissions. Remove egr, and you'll increase combustion temps.

From eHow.com:
Combustion Chamber Temperature
# There are two ways to decrease combustion chamber temperatures. The first is to reduce compression ratio. Compression ratio is the amount of compression provided by the cylinder. But significantly reducing this factor to less than 8:1 or so drastically reduces both performance and efficiency.
Another way to reduce combustion chamber temperature is to add something inert to the air-fuel charge. Something that won't burn. Fortunately every car and truck has a ready made supply of inert gas--the exhaust.
Surprisingly, adding exhaust to the inlet air charge actually decreases maximum combustion chamber temperature. This seems counter-intuitive since the exhaust is hot. However, when it exits the cylinder it is cooler than the maximum combustion chamber temperature. So by pumping it back into the combustion chamber it will not burn again and absorbs heat.

[yotarunner85]

I beg to differ with you, yotarunner85:

The main effect of egr is to lower combustion temps to combat nox emissions. Remove egr, and you'll increase combustion temps.

From eHow.com:
Combustion Chamber Temperature
# There are two ways to decrease combustion chamber temperatures. The first is to reduce compression ratio. Compression ratio is the amount of compression provided by the cylinder. But significantly reducing this factor to less than 8:1 or so drastically reduces both performance and efficiency.
Another way to reduce combustion chamber temperature is to add something inert to the air-fuel charge. Something that won't burn. Fortunately every car and truck has a ready made supply of inert gas--the exhaust.
Surprisingly, adding exhaust to the inlet air charge actually decreases maximum combustion chamber temperature. This seems counter-intuitive since the exhaust is hot. However, when it exits the cylinder it is cooler than the maximum combustion chamber temperature. So by pumping it back into the combustion chamber it will not burn again and absorbs heat.

TNRabbit you mean you agree with me not differ since you posted the same information. I wrote "Removing the EGR will increase NOX emissions due to increased combustion temp." You wrote "Remove egr, and you'll increase combustion temps." Also you wrote "The main effect of egr is to lower combustion temps to combat nox emissions" and I wrote "Removing the EGR will increase NOX emissions" Same thing said differently.

[TNRabbit]

Well, the difference being that EGR DOES lower combustion temps, so removing it would INCREASE combustion temp.

[THK Matt]

doesnt mean youll have a premature HG failure. if you're worried about that.... run a lower thermostat.

[yotarunner85]

Well, the difference being that EGR DOES lower combustion temps, so removing it would INCREASE combustion temp.

That is correct, but combustion temp has nothing to do with cylinder temp, engine temp, or cylinder head pressure. The EGR only turns on when the vehicle is at a steady throttle cruising speed. Full throttle the EGR is turned off and combustion temp increase, also if the EGR was disconnected and the vehicle was at full throttle the combustion temp would increase the same amount. The only things that happen when the EGR is disconnected is NOX emissions go up and the engine light will come on.

[THK Matt]

That is correct, but combustion temp has nothing to do with cylinder temp, engine temp, or cylinder head pressure. The EGR only turns on when the vehicle is at a steady throttle cruising speed. Full throttle the EGR is turned off and combustion temp increase, also if the EGR was disconnected and the vehicle was at full throttle the combustion temp would increase the same amount. The only things that happen when the EGR is disconnected is NOX emissions go up and the engine light will come on.

and thats when you are not accelerating... your at a cruising speed.

[yotarunner85]

and thats when you are not accelerating... your at a cruising speed.

Yes. Thanks.

[TNRabbit]

Gotcha

[THK Matt]

So i when you are accelerating, the EGR isnt on and will not do anything or change anything if its removed or not. only when its at a cruising speed will it make a difference. and what difference is that? I HIGHLY doubt its enough to pop a HG.

[yotarunner85]

So i when you are accelerating, the EGR isnt on and will not do anything or change anything if its removed or not. only when its at a cruising speed will it make a difference. and what difference is that? I HIGHLY doubt its enough to pop a HG.

Thanks, that pretty much sums it up.  So beadle934 if this is a daily driver leave the EGR on so you keep the environmentalist happy. If you are looking for more power there are many other ways to get more power out of that engine.

[beadle934 [OP]]

Thanks for all the info on the EGR system.  I did however talk to the guys at LC (I have a LC built engine in the truck) and they said not to worry about it?  I talked to a few other people about this and will probably put the EGR system  back on the truck.  I am not sure if putting a 16 year old EGR valve (with 200K on it) back on a NEW Motor is a good idea or not? Maybe a new EGR valve is in order?

[yotarunner85]

If the old one still works clean it and put it back on. I have my old EGR (290,000+miles) on my new engine.