Hello on my 1990 HONDA ACCORD EX automatic I am getting horrible gas mileage about 250 miles per tank I used to get at-least 350 more per tank I noticed I was using more gas but didn't realize it was this bad. The only recent change to the engine is the EGR block off plate I put on to give me some time til I have to take the intake manifold off and clean everything. So do you think the EGR block off plate is the cause of horrible MPG?
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Yes.
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Probably the main reason you're getting shit mileage, the other being the quality of fuel used during winter.
Clean that intake and put the egr back on, your car will thank you for it.Comment
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Not probably. It is.
Winter fuel has nothing to do with it. And I don't know what your saying about it's quality. It's different fuel. Same quality.
Kev1990 put the EGR valve back on the car with a new gasket.
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You are correct, same fuel, with additives that cause you to get worse fuel economy in order to protect the engine. I don't need those additives where I live but get them any how, so winter fuel serves no purpose for me. I get less mileage for the same money and fuel consumed, perhaps I should have said something more specific to that effect.
Regardless, we agree, the EGR is beneficial when it is functioning properly (or in this case installed altogether) it should be put back on.Comment
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Hmm I actually put the block off plate on so I wouldn't get the misfire I really don't like dealing with the misfire but won't be able to deal with it for a while but then again you know that's a big difference in MPG. I've never had to take the intake manifold off of these cars are there any fully detailed DIY'S? I really can't have a lot of down time on this car and could probably use some help doing it lol.Last edited by Kev1990; 03-29-2015, 01:11 PM.Comment
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It's not an additive. It's simply butane. Summer blend has it as well, just less of it.Originally posted by CB7NWDD View Post
The blends are not changed to hinder or help fuel economy. It's done to change the Reid Vapor Pressure. To put it simply, how much fuel evaporates. You do have "these additives" in your area. If the RVP were not kept in check the fuel in your tank could reach an RVP above 1 BAR, (14.7psi, also known as normal atmospheric pressure) thus build up excessive pressure, boil and evaporate.
The blend changes fuel economy but it's normal. It's not an issue or a problem and there's nothing you can do about it. It also won't decrease the OP's fuel economy to around 17 mpg. My point in addressing it, that's all.
Didn't removing the EGR valve turn your CEL on?Originally posted by Kev1990 View Post
If you have a misfire and it's EGR related then check for a vacuum leak in the hose, clean/test the EGR valve. Removing it is not going to work well, as you have noticed.
The EGR valve can be removed and a block off plate installed. But it requires a tune. Which is much move involved and expensive than fixing the issue.
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Actually i'm pretty sure the misfire is due to my EGR ports being clogged. But what's odd is it happens upon take off and steady light throttle cruising. What I did was to block it off. Bought a OEM CIVIC block off plate tightened it down real well put the EGR valve on top of the plate bolted that down left the vacuum connected and the plug no CEL and the misfire went away. So what should you say my next step is Josh?
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I figured you left it plugged in somehow to keep the CEL from coming on.
I know the proper way to test the EGR valve is to disconnect the vacuum line, plug the vacuum line to prevent vacuum leak then go for a drive. If it doesn't miss then your EGR ports need cleaned.
I would say you need to clean the EGR ports/valve. You can get replacement aluminum plugs from Honda. That's what I did.
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