Hello from blistering SE Missouri, Thank you for your postings re: 04 Freestar Limited--I find your posts informing and I generally trust opinions from the "been there done that" group - and thus seek your advise for my 04 Limited. We bought this van used and do not know a history. It has been giving a P0401 code and lately has started stumbling under light acceleration-and this is getting progressively worse. I now have codes P0316 and P0305 as well. So I checked the online search returns and that is how I came upon this forum. Since the DPFE/EGR unit is expensive I am hesitant to replace it without confirming it to be at fault. The troubleshooting information I find online is for engines with a separate DPFE and EGR device. I keep running across references to blocked passages and carbon deposits without clues as to where to look for this. The two vacuum lines connected to the DPFE/EGR ***'y seem to have about equal vacuum when the engine is running so I am assuming the blockage is not where these are connected to the engine. The spark plug cables are Belden Premium 8mm and bright blue in color--would these be original? I see your Freestar has been well tweaked. What mpg did you have before and after the mods? Do you think iridium plugs make a substantial difference? You are appreciated here, Larry J btw: 45 years in industrial electronics, r&d, environmental testing, power conversion, and rf.

 

Just read this and it's 4:30 in the morning as I'm looking at this. I'll try to give you some info when I get the cob webs are cleared out, but for now I can tell you that the plug wires are NON Stock wires. The OEM wires are grey and numbered 1,2,3,4,5 & 6.

 

You might want to check the ignition coil pack. It goes bad on these cars after awhile. It usually causes the engine to stumble or miss under a load such as going uphill with the AC on when it's hot out and the engine is up to operating temperature. Don't know if that's exactly what you are experiencing but it sounds possible. Autozone, etc have them for something like $80. It's on top of the back valve cover so it's kind of tough to get to, but you can do it yourself. While you're at it perhaps you should do the plugs and wires depending on how many miles are on it.

 

Larry...Hope some of the following rambling makes sense...

I live out in the country, so my mileage is base on my daily commute of a 9 mile trip one way trip to work zig-zagging and up and down hills to complete a 550 foot climb from 1439 to 1989 feet above sea level. I replaced the original Goodyear Integrity tires at 3,000 miles because they just plain sucked as a tire (no dry or wet traction). I replaced them with 4 Hankook HPW401 (P235/70R16) snow tires. I ran them at 42 PSI in the fronts and 40 PSI in the rear. Rotated every 5,000 miles and put 67,000 miles on them. These were then replaced, not for being worm out, but not being flexible anymore (loosing winter traction). They were replaced with Hercules (Cooper) Avalanche X-Treme (SUV P235/70R16) snow tires as Hankook didn’t make my tire size/tread any more. The Hercules is the same basic tread design. Presently have about 40,000 miles on these. I run the same air pressure as I did with the Hankook tires. On my Freestar, this make the tread wear flat across the tread surface.

Anyways, my mileage after the tire change to and from work was averaging 14.7 – 15.1 MPG and on the Highway/Interstate, I was averaging 19.3-20.2 MPG. I then installed an AquaTune passive water injection system and iridium spark plugs and my mileage went up to about 2-3 MPG back and forth to work and 3-7 MPG on the Highway/Interstate depending on my MPG and terrain.

My fuel mileage is currently down about 10+% due to almost every fuel I find in my area has that crappy 10% ethanol in it. I also need to replace my fuel filter. A dirty fuel filter normally nets me about a 2 MPG loss.

The use of iridium plugs has a two-fold factor for me. 1st being that an iridium plug requires less voltage to jump a gap under compression, thus it’s easier on the vehicles ignition system. 2nd, with the water injection, I would need to use a copper plug as they burn hotter (hotter spark) than a platinum plug. So without a hotter spark, the water injection would cause the engine to miss. Doesn’t happen with the copper or iridium plugs. The copper plug wears from spar, while the iridium doesn’t, thus a longer life. Also, an iridium plug can withstand a hotter environment than a platinum plug can.

I replaced my wires when I replace my coil. I replaced my coil as I was experiencing an occasional transmission type jolt only while the engine was under load. The new coil resolved that issue.

Since I run water injection, I don’t have any type of carbon build up, thus have never experienced an EGR problem or any EGR related codes.

I can go on and on but, some folks might get tired…