VINCEA: It can depend on the car and EGR setup. Newer cars have them tied into the car's computer. Who knows what will happen then. In older cars they were connected directly to the intake manifold or the carburetor venturi. In this instance it was a matter of plugging the vacuum hose. EGR's work by using the recycled gas to lower the compustion temperature. I had a 1988 Ford Festiva(MAZDA 323); and once, the egr passage was plugged. the nitrous oxice emission was zero. I had to unplug the passage because the California Eco-wackos had a box they had to check. So it passed emissions but emitted a slight amount of NOx. Having a functioning EGR can also lead to a plugged intake manifold.
yeah, thi is on an 87 celica, i have a leak from a broken egr controller/switch, which seems to be causing a sporatic idle. i think think that if i plug the line on the manifold, the problem will be fixed, i just wanted to be sure that no damage would occur from me doing this
On older cars with early emission systems, (band aid quality) you will probably pick up a bit of power and a bit of fuel economy, depending also on overall condition of the engine, the quality of the design of the emission system and your driving style.
Newer systems which integrate with the electronic engine management system, are much more sophisticated and tampering with them often results in poor results re performance, durability and economy.
I don't know your particular model, but 1986 is probably old enough to fall into the early systems category
Regards
pat pprimmer@acay.com.au
eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
Let me relate how a Ford system works in the 5L, 4.6/5.4L engines and many other models, that may be helpful.
The EGR does not function at idle, under acceleration or at wide open throttle.
During a light load cruise in the highest transmission gear, the ECM looks for a relitive steady throttle position against road speed via a speed sensor indicating the assumption of cruise.
The ECM opens a vacuum path thru a solenoid valve to the EGR valve.
Once the valve opens it reports it's operation back to the ECM via a variable resistance linked to the diaphram movment.
This return signal serves several purposes. To tell the ECM the function completed and not store a fault code, to cut fuel injection back to a lower rate and advance ignition timing. Also it is a time to open the canpurge and vent fumes stores in the charcoal container from the fuel tank.
The benifits are improved fuel milage, reduced nit/ox emmissions and fuel fume consumption.
The process is IMO purely an emmissions driven requirement and has no effect or improvment on emgine performance for the way it is engineered to work, but still a slick operation.
In a 1986 Toyota, the EGR is fairly important.
You may not notice anything for a while if you leave the egr inop. You may get a check engine light. You will spew NOX at a huge rate. You will get less mpg and you may slowly detonate the engine to death.
Ben
VinceA (Civil/Environme) Dec 28, 2004
<<why would it cause detonation?>>
EGR dilutes the air fuel mixture, quieting combustion temps and preventing spark knock, or detonation.
It couldnt cost more than a couple of hundred dollars to fix it right, why not just get it over with, especially if you live in an area where emissions testing is done?
It will only cause detonation if the compression ratio is to high for the fuel being used or if the spark advance is to much. These two conditions might be optimised with EGR, then without it you get detonation, however if you re-tune without EGR you should be able to avoid detonation with suitable fuel and ignition timing.
Regards
pat pprimmer@acay.com.au
eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
<<however if you re-tune without EGR you should be able to avoid detonation with suitable fuel and ignition timing.>>
Yeah....that would stop the engine from detonating... and making power... and getting good economy.. and running cool..
Retune for no egr by retarding the timing and you will spend way more money on fuel than you ever would have on an egr repair.
Is this an 'engineering' forum or a 'how a cheapskate can ghetto rig a car' forum?????
Yeah....that would stop the engine from detonating... and making power... and getting good economy.. and running cool..
Retune for no egr by retarding the timing and you will spend way more money on fuel than you ever would have on an egr repair.
Is this an 'engineering' forum or a 'how a cheapskate can ghetto rig a car' forum?????
Yes, it's an engineering forum. EGR is for NOx control. It decreases both power and fuel economy by displacing useful charge with burned exhaust gases. Of course, people who have actual automotive engineering experience will know that.
Where do you work? And if you know about these things, please elaborate the theory behind your peculiar vision of engine operation.
Aquaduct (Automotive) Dec 29, 2004
Is this an 'engineering' forum or a 'how a cheapskate can ghetto rig a car' forum?????
<<Yes, it's an engineering forum. EGR is for NOx control. It <<decreases both power and fuel economy by displacing useful <<charge with burned exhaust gases.
Does egr decrease power? Maybe a tad under certain circumstances. (The cars of the '70's had terrible power problems related to egr; not modern cars)
Keep in mind that the egr only works on initial throttle transition and part throttle steady state driving where power demands are low anyway. ECU maps advance the timing when the egr opens to keep cylinder pressures up, so power doesnt really suffer appreciably. Besides, no egr system has the valve open under wide open throttle, so max power is unaffected.
Does egr affect economy? Yes!
Most cars since the middle '80's have actually used more egr during cruise to increase mileage. When more egr is pumped into the intake, the throttle has to be opened more to maintain speed, thus decreasing pumping losses and increasing effeciency.
Of course, people who have actual automotive engineering experience will know that.
