slight hesitation cycle at 2100 RPM

[MI2003SilverSVT]

I recently had my fuel pump replaced and since have been experiencing slight hesitation/power drop cycles at 2100 RPM. It only happens when I settle in at 2100, and seems more ****ounced at first and tends to lessen after about a minute. It sometimes feels like a rythmic surge, but could just be the jump up to normal after a drop. Due to troubleshooting steps related to the failed fuel pump, I also recently replaced the plugs, wires, ignition coil (all generic), cleaned the MAF and replaced the fule filter and valve cover gasket. Any ideas? Should I re-install the stock Motorcraft coil, plugs and wires?

[SVTfocusO3]

The re-install of those parts may be a good idea. Motorcraft plugs ESPECIALLY!!! maybe not, try it.

Other than that I think you should reset the memory by disconnecting the battery for about an hour or so.

[MI2003SilverSVT]

That's a good idea. I think I'll disconnect the battery first and see if the ECU reset makes a difference. Whether it works or not, I'll swap the parts afterward anyway. BTW, the problem is getting worse now; I'm noticing it at higher revs. It's more ****ounced when I let off the gas, right after an upshift - as soon as the engine settles in after accelerating, the hesitation starts.

[4rd Toys]

You aren't the only one.... Mine has always done the rythymic "rocking back & forth slightly" at the 2100 RPM regardless of speed.
This to me seems normal because it has been like this since the first month of driving.... usually if I set the cruise control at that engine speed.
I changed my fuel filter with a new one (motorcraft) @ 14,000 miles. No change, so I just run my motor a bit higher or lower than 2100 RPM. The car runs fine @ any other RPM speed.
I wonder if there is a balance issue at this rpm or a by-product from the motor assembly plant testing the motor thru their QC program. I even broke it in properly- I accelerated slowly & smoothly never passing 50 m.p.h and varying my speeds to prevent the motor from settling at on set RPM point for 600 miles. I even did the first oil change @ 1000 miles.
If you take in to the dealership, let me know what they say.... :confused:

[4rd Toys]

I just use conventional 5W30 (changing it every 2500 or 3500 miles depending if I have been doing either a lot of Highway driving or short trips locally) & the only mod installed is a K&N Air Filter.

[GapBoyPCS]

Definitely go back to stock setup i.e. using Motorcraft parts.

The Focus appears to only like Motorcraft plugs now. There are a lot of posts on other forums with the same conclusion. Motorcraft parts now aren't that far off in price, compared to aftermarket competitors (considering I believe Autolite still makes Motorcraft plugs).

Also, when you do disconnect the battery, make sure you follow the relearning procedures for the ECU outlined in the owner's manual. Otherwise, the computer is going to be confused and it will take a lot longer for it to relearn "normal" conditions.