Originally Posted by DrFeelGood
I am linking a pic from 98se5speed and his take on the modification.
Notice the filter down on the EGR tube, this is to keep the intake from sucking any debris in.
I ran that setup for quite some time, never had any CELs from it. But I don't think my setup or running a hose to the intake is a great solution.
I've been fighting with my car seeming "rich and sluggish" probably since I got it on the road. Worst part is that it's not ALL the time, but often enough that I've tried many many things to fix it. Sure, these engines aren't powerhouses at low RPMs, but mine often seems excessively bogged-down and the exhaust smell is often very rich or smells of raw gasoline.
My setup: 2004 with an 09 Fusion V6, 09 Fusion fuel rail & lower intake, Injen CAI, 3.7 TB + spacer, MSDS headers, downstream O2 sensors in spacers to avoid CELs for no precats.
Things I've replaced on my quest to running cleaner & meaner:
- Ignition coils: OEM Ford coils from 2009 Fusion engine
- Spark plugs: OEM Motorcraft Platinums
- Fuel injectors: Brand new OEM Ford units for 04 Mazda 6 (different part # than Fusion injectors)
- Upstream O2 sensors: Brand new NTK (OEM mfg) Fusion V6 sensors, adapted to Mazda 6 connectors
And overall... my car is still relatively bogged and rich most days.
Getting back to the EGR topic, I kept having a noticeable throttle surge at times. I thought maaaybe something was a little goofy with me running the 3.7 TB so I ignored it for a while. But then I started researching "engine runs rich" and some people spoke of leaky EGRs letting in air that hasn't gone through the MAF, throwing things off.
So I put a monitor on my dash tablet that lit up every time the EGR opened. Wasn't long until I saw that my "throttle surge" happened exactly when the EGR opened up. It was essentially an electronically controlled vacuum leak. Mine was sucking in filtered air from under the hood, if you run a hose to the intake you'll probably suck in less (since there's some vacuum in there) but it would still be adding air to the intake that wasn't metered by the MAF.
Upon reading that, I removed my "filter" (piece of a T-shirt with a zip tie around it) from the EGR inlet and plugged it up to allow zero flow. Of course I now have a P0401 code, but the throttle surge went away. And while I thought I had also solved the bogged/rich situation, it came back not too long after. My car pretty much runs "lean and clean" upon an ECU reset, but once things settle in it goes back to running rich. So that's fun.
About the only thing left for me to do is to work on eliminating some minor exhaust leaks. I definitely get a bit of exhaust smell when I run the HVAC while stopped. Having exhaust around the O2 sensors will skew their readings (they're trying to compare the exhaust to outside air) so perhaps sealing up some minor leaks will get more accurate readings for me.
I also have never changed the downstream O2 sensors, but I'm 99.9% sure that they have no bearing on fuel trim, they are only there to monitor precats for emissions purposes. I thought about taking out the spacers just for shits (knowing I'd get CELs for it), which I might do if I ever get real bored.
Alright, long story/rant/contribution done. On a good note, it was 44 degrees here in MI yesterday so I got a chance to get all the salt off my baby. Win.