AlanTLS

I was just wondering if this was an issue or maybe part of my cold start misfire issue Iv been having. I removed my egr valve to clean it. After I put it back on and while engine was running I unplugged the egr connector just to see if there was any change by unplugging it and nothing happened not that I expected it to but my ? is...should the engine light go on by unplugging that connector or is this normal. Should I have noticed any change when unplugging the egr? ty 08 type s 172k

losiglow

iTrader: (1)

I removed my EGR altogether on my 3G and never noticed any change. And yes, the light will come on if you remove/disconnect the EGR. It may take a little while however. It may not be immediate.

Removal or bypassing the EGR is a bit of a debated topic. Some say it helps performance because there's no exhaust gasses being routed back into the cylinders. Or that it helps keep the intake manifold and intake valves a bit cleaner since exhaust gas obviously contains residue and particles that can result in some buildup. However, after doing a good deal of research on the topic, and testing EGR vs. No EGR, I no longer bypass it (I have a 4G TL but it's essentially the same) because I don't believe either of those are real benefits.

First, I've never noticed a difference - with the 3G or 4G. Which makes sense considering that the EGR is not active when at full throttle. When you're at WOT, the EGR closes, allowing only fresh air into the engine for maximum power. About the only performance increase would come from that first fraction of a second when you hit full throttle but some exhaust gas may still be present in the intake manifold. The EGR is only active when you're at partial throttle when you're not using peak power anyways. So the power arguement is largely moot. Also, unless you have direct injection (which the 3G does not), the fuel from port injection is going to keep your intake valves sparkly clean, even if there's exhaust gas being run past them. You're going to be hard pressed to find any buildup on your intake valves on a 3G or 4G TL.

Also, as silly as it sounds (considering that exhaust gas is hot), routing exhaust gas into the cylinders during partial throttle actually decreases the combustion temperature by absorbing some of the heat. Obviously excess heat is bad and can result in knock which will pull timing. So in essence, removing the EGR could actually decrease power since the ECU pulling timing is going to result in less power, especially during VTEC. The EGR also increases fuel mileage slightly since exhaust gasses routed back into the cylinders reduces parasitic pumping losses that would otherwise exist from drawing in fresh air, as well as burning that little bit of fuel that might be present in the exhaust gas.

So yeah, that my on that. But experiment with it if you'd like. Like I said, you're not likely to see much of a difference either way.

Edit: Sorry, I didn't really address your cold-start misfire issue. I doubt it's likely to make a difference there since the EGR is not active until the engine warms up. The ECU restricts any use of the EGR until the engine reaches operating temperature. Exhaust gasses introduced into the cylinders when the engine is cold results in the exact opposite of when the engine is hot - rough idle, difficulty starting, poor fuel economy, etc. So if you're getting misfires when cold, the EGR wouldn't make any difference - removed or not.

If the EGR is at fault, the only reason I can think of would be because it's staying open during startup, which would cause all the aforementioned issues. However, if that were the case, the ECU would immediately sense it and throw a check engine light. So unless you're getting a CEL for EGR (without disconnecting or removing it), then it's very unlikely to be the cause.

AlanTLS

Thank you very much for your time Sir.