I have had my car over 10 years and back when I first bought it I made some "modifications" as per the resident LT1 expert. I removed my AIR injection, TB bypass, etc. This brings me to my query...

The charcoal canister/vapor system remains despite the removal of my AIR injection. I have given myself a headache trying to understand the correlation between the two, and recently after I replaced my charcoal canister, purge valve and solenoid due to a code 26, I had an epiphany. Am I right to assume the AIR injection dilutes the EGR hydrocarbons? If so, does this mean that I could be doing engine damage by injecting straight EGR emissions into the engine? And further, is this effecting my air/fuel combustion? I had the EGR tuned out of the computer, but for some reason it still throws a 26 when the vapor system is not functioning properly.

Thanks in advance,

Charlie

 

The two are not related in function.

A code 26 is for the electrical circuit to the EVAP solenoid, which would include the wiring and solenoid.

 

I see, what are your thoughts on maintaining the EVAP system despite having the AIR injection removed? As my engine nears the 180,000 mark I am trying to take precautionary measures to help facilitate another 180,000.

Thank You!

Charlie

 

You still seem to think one has something to do with the other. It doesn't.

The EVAP is beneficial for dealing with any fumes from the tank. The system has no effect on performance. I don't see any benefit to removing it. MHO.

 

Ahhh I see. That is the info I was looking for, thanks again!

Charlie

 

AIR, EGR and EVAP are three TOTALLY different systems, each aimed at a particular form of emissions reduction.

AIR - injects filtered air into the exhaust manifolds for the first 2 or 3 minutes from startup, then shuts off. It's only purpose is to put the air into the exhaust to help burn up the excess hydrocarbons that come out in the exhaust, due to the very rich mixture used to start the engine. In burning the HC's in the exhaust manifold, the heat generated helps the cat heat up faster. The cat won't work until it reaches 600*F.

EGR - Dumps exhaust products back into the intake manifold, to help reduce the formation of oxides of nitrogen (NOx). The EGR only flows under engine operating conditions that cause high combustion chamber temperatures. That's when the normally inert nitrogen in the incoming air starts to combine with the oxygen and form the polutant NOx. Does not operate at idle, does not operate at WOT. Does not operate above 3,500RPM. In addition to reducing the formation of NOx, it also helps minimize detonation (knock) when the engine it being lugged at low RPM in the wrong gear.

EVAP - Collects the hydrocarbon vapor being vented from the fuel tank, by adsorbing the HC's on the charcoal. Periodically, the EVAP purge solenoid opens, and allows engine vacuum to pull fresh air through the charcoal canister to strip the HC's from the charcoal, and allow them to be pulled into the intake manifold, and burned in the combustion chambers.

In a practical sense, NONE of these hurts your engine performance. EGR offers the advantages of reduced knock,. EVAP collects the fuel vapor, preventing a gas smell at the rear of your car, and gaining some tiny amount of improved fuel mileage.

In fact, there is really no good reason to delete them. I built an 800HP nitrous 381, and kept all three system totally intact and functional (at least until it became a "track only" car).

 

Excellent info, thank you. It is amazing how my approach to the car has changed during the course of ownership (10 years). I used to be concerned with the "go" and blindly cut wires, deleted this or that, spray painted things, etc. Now I strive to return the car to stock appearance and functionality and I find myself questioning my practices of old. Thanks again for your help.

Charlie

 

i noticed on my lt1 when troubleshooting the running problem, the owner before me had removed the EGR vacuum hose and plugged it, will this mess an engine up

 

"mess the engine up"..... depends.

It will prevent the EGR system from operating. EGR is used only when cruising below 3,500RPM, and typically when lugging the engine in the wrong gear. That causes high combustion chamber temps, which causes the formation of oxides of nitrogen (NOx) in the exhaust. The PCM opens the EGR valve, using the vauum solenoid, to dump exhaust gas into the combustion chamber and reduce the temperature. Without the EGR, when lugging the engine, you may encounter detonation (spark knock). The PCM will pick that up via the knock sensor, and pull ignition timing to prevent the detonation.

If you frequently lug the engine, and run low octane (regular grade) fuel, you may encounter more detonation than the PCM can prevent, and then you could "mess up the engine". The knock would be audible at that point.

Depending on the year of your car (which you have not indicated), you may or may not get a code/SES light for the non-functional EGR system.

You need to add a "Signature" with basic info about your car - year, model, engine, trans and any major modifications. There are subtle difference from year to year, type of trans, etc. that may affect the answers to your questions.