So who wants their ECU's "Chromed"?

[Greg E]

I get better fuel economy with my EGR out...I've always understood EGR was used to reduce Nox emissions, not increase fuel economy. Also EGR at WOT is bad. It will reduce power. I get the same fuel economy now as I did stock.

Any time there is a differentiation in vacuum before and after the throttle plate that's stronger than the spring tension of the EGR it'll be open. So during WOT it'll be closed as there's positive pressure in the throttle body which will keep the valve shut.

The reason you get better fuel mileage with the value (we're not talking more than 1mpg at best) the little bit of exhaust that gets sucked into the plenum takes up a little bit of space. This means less "fresh air" needs to get sucked in to fill in the rest of the space. Less air counted by the MAF = less IPW = better mileage.

In layman's terms, the egr in a sense makes the motor smaller.

[Greg E]

Hm.. Looks like I should just delete it then to be safe. I would love to reduce the clutter, just didn't want to take functionality from the car (some websites said it helps with fuel economy/temps but who knows how accurate that it. Disabling the trims and doing a lean cruise will probably more than make up for EGR anyway, huh?

Also, should I disable the bit that has to do with EVAP? Sorry for all the questions I just want to make sure all the bits do what I'm expecting them to lol

These are good questions. I will add them to the q/a post on the first page when I get a chance.

The evap operates under almost the exact same as the EGR. I noticed on my 98 sometimes there's this odd stumble when I let off the gas cruising down the free way. I think this is because I have the MAP periphery disabled for the EVO MAP sensor. Logging this occurrence shows a rich condition when letting off the throttle. My guess is the EVAP is sucking in fumes from the tank which is causing this. The evap is supposed to be closed but since the ECU doesn't have the stock MAP sensor, it doesn't know what to do with it.

I was going to experiment with putting the stock sensor back on and see if it goes away.

[Jesters Deadd]

These are good questions. I will add them to the q/a post on the first page when I get a chance.

The evap operates under almost the exact same as the EGR. I noticed on my 98 sometimes there's this odd stumble when I let off the gas cruising down the free way. I think this is because I have the MAP periphery disabled for the EVO MAP sensor. Logging this occurrence shows a rich condition when letting off the throttle. My guess is the EVAP is sucking in fumes from the tank which is causing this. The evap is supposed to be closed but since the ECU doesn't have the stock MAP sensor, it doesn't know what to do with it.

I was going to experiment with putting the stock sensor back on and see if it goes away.

Or you could disconnect the evap solenoids and see if it happends again. or just clip the hoses shut.

[Greg E]

Or you could disconnect the evap solenoids and see if it happends again. or just clip the hoses shut.

Unplugging the solenoids does the sane thing as disabling the periphery.

[aaronatstate]

My point is I get BETTER fuel ecomony WITHOUT the EGR.

[Greg E]

My point is I get BETTER fuel ecomony WITHOUT the EGR.

Really? I noticed almost no difference. Slightly worse without it. Haven't blocked it on the 98 yet.

[aaronatstate]

Really? I noticed almost no difference. Slightly worse without it. Haven't blocked it on the 98 yet.

Yes with all of my emissions stuff removed, I saw an increase of about 2mpg total, not changing my driving habits at all.

[HLxDrummer]

I decided to just get rid of it all. I always wanted to clean up that junk... plus I have basically this weekend to install an entire fuel system (getting rid of solenoid rack also makes room for FPR), 98 ECU, LCD boost controller, FMOC, and a few other things then I have no garage for a while so just want to get the thing running right.

Also, any chance of getting a two step to work on these?

[Jesters Deadd]

Yes with all of my emissions stuff removed, I saw an increase of about 2mpg total, not changing my driving habits at all.

I thought that was because of your rear bank always runs lean at idle.

[aaronatstate]

I thought that was because of your rear bank always runs lean at idle.

My idle AFRs are 14.7:1 give or take a bit. I removed all of that stuff way before I rebuilt my engine, and still saw the increase in MPG.