Changed exhaust and fuel filter - now hesitation and miss

[TimKonaGT500]

I have searched a lot around hesitations, but mine has a very clear start point, which has me pondering.

I bought my 01 at the end of May. 56K miles, stock drivetrain except for a shifter and K&N. I have driven it close to 1000 miles, no issues.

Last weekend I replaced the factory exhuast with a Magnaflow catted X-pipe with new O2 sensors, and Magnaflow cat back, changed the transmission fluid and aluminum driveshaft. While having it up, and some extra room without the exhaust, I also changed the fuel filter.

Love the sound, but picked up a hesitation/miss. Started noticing at highway speeds, when making small throttle adjustments. Slowly give it more gas, it continues to sputter (feels like hitting rev limiter). Give it a hard stab of the throttle, it gives a little pause and roars back without the miss. Repeated it several times. Just seemed odd that it ran flawlessly before I did that, and after I have the miss.

Since then, I replaced the COP and plugs. I had them already, and just had not gotten around to installing. Old plugs looked fine (Motorcraft platinums). No change after the installation.

My thoughts:
- Did i get something into the fuel line when I changed the filter that is now causing the issue at the FPR or injectors?
- Was going to remove/inspect injectors and FPR and see if I find any debris.

I am hesitant to throw a bunch of fuel injector cleaner or seafoam in as this was such a sudden change, seems like something more than just a gradual build up.

Thanks for the help!!

 

[Roots-type]

What kind of oxygen sensors did you use? These cars should only use Ford.

Are you 100% certain that you put the fuel filter in the correct direction?

If the car ran fine before you did these things, it's most likely something you changed. The odds of it being something else would be very small. I'd start by going over my work, carefully. Congrats on the low mile snake!

 

[TimKonaGT500]

It was a Motorcraft fuel filter and Bosch O2 Sensors. I have my old ones on the stock h-pipe still. Maybe swap those back and see if that helps...

Thanks!

 

[01yellercobra]

My first guess would be the fuel filter might be backwards. I've almost installed it backwards before.

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[TimKonaGT500]

IIRR, the orientation I intended was flat side to the driver's side, curved the passenger side, which was just to do the same as the one that was installed. Seemed to fit tight in the bracket.

Changed the fuel filter on the fox I used to have a couple of times, and seemed identical (other than having the IRS making it a PITA to get to it)

 

[01yellercobra]

I always looked for the arrows.

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[TimKonaGT500]

I always looked for the arrows.

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Yea.... but I didn't notice markings on it.

I think I am going to replace it just to be sure. It's only a $15 part.


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[01yellercobra]

I'd shine a flashlight up there first. You might get lucky and spot the arrows. If it's correct then I'd move on to the O2 sensors as mentioned. These cars can be picky about O2 sensors. I've only used Motorcraft sensors in my Cobras.

Oh, these cars don't have a FPR. They have s Fuel Rail Pressure Sensor. But generally in my experience if they go bad the car runs horrible if it runs at all.

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[DJAMiller]

I've been pulling my hair out trying to figure out a similar problem, just realized it happened about the same time I installed new o2 sensors (also bosch) Odd thing is when I reset the computer it runs great for 10 minutes or so. Maybe these cars don't like the bosch sensors?

 

[TimKonaGT500]

OK... replaced the fuel filter a couple of evenings ago. Seemed to fix it, but not it is creeping back in and check engine light came on. I didn't write down the code but was O2 sensor low heat, or something like that.

I was going to plan to swap out the O2 sensors, or at least the pre-cat ones that this code was on to Motorcraft.... but I can't seem to find anyplace that has them in stock.

Oreillys, Advance, AutoZone, Summit, NAPA, Rock Auto, LMR, American Muscle, etc.... Not have them in stock, or even show they carry them. Are they discontinued? In short supply?

OK.... Back door way though Fordparts.com with cross references... I came up with 4 of the same, Motorcraft DY1401.

They were the cross reference from the 9F472 & DY-834 for the pre cats and 9G44A & 9G44B to DY1104 for the rear ones.

Am I missing something?

Thanks!

 

[omj]

Go with the OEM Ford 02 sensor or NTK #22060. I've ran both with no issues. A lot of people have had bad luck with Bosch. I currently use the NTK since it has the length to work in my longtubes with out extenders.

 

[RX1Cobra]

Do you still have the old ones? Why not put them back in and see if it fixed the issue?

 

[TimKonaGT500]

I couldn't install all the factory ones because I had cut the wires of one of them when taking it out because I could not reach the connector well enough when removing to disconnect. yea... I know.

Good news is that I installed the new Motorcraft Oxygen Sensors, and no more miss/hesitation. I have held off putting up a conclusion on the fix until I put a couple hundred miles on the car at lease. So far so good! Thanks for the help