2003 ford focus missing at 50mph - Ford Forums - Mustang Forum, Ford Trucks, Ford Focus and Ford Cars

cstn2007 · 06-02-2009, 06:39

i have a serious engine miss at 50mph.. had coil pack replaced.. still misses. what else can i do?

**360ci** · 06-02-2009, 18:55

If you haven't had a tune up done in a while (air filter, plugs, etc) it's time to do so. I'd do this every 40K for best performance.

If the vehicle has any engine codes (light on), get them scanned to help narrow down the problem. It could even be related to a clogged injector. However, you first have to test that it's RPM, not speed related.

To do that, keep the transmission in a lower gear (2nd for example) and drive 30-35mph. RPM will be in the 2500-3500 range. If the 'miss' occurs around a certain engine speed (not road speed) then it may be a bad/faulty injector.

cstn2007 · 06-07-2009, 12:27

Quote:

Originally Posted by 360ci

If you haven't had a tune up done in a while (air filter, plugs, etc) it's time to do so. I'd do this every 40K for best performance.

If the vehicle has any engine codes (light on), get them scanned to help narrow down the problem. It could even be related to a clogged injector. However, you first have to test that it's RPM, not speed related.

To do that, keep the transmission in a lower gear (2nd for example) and drive 30-35mph. RPM will be in the 2500-3500 range. If the 'miss' occurs around a certain engine speed (not road speed) then it may be a bad/faulty injector.

did the tune up new plugs wires air filter,,, no mising at 50... but when i am in reverse.. its very sluggish.. i had tune up done by professionals

Matt Cramer · 06-10-2009, 10:07

Is it a manual or automatic?

**360ci** · 06-14-2009, 07:51

Have you replaced the transmission fluid at all?

Wobbie · 11-16-2009, 09:57

I have a similar issue - have changed plugs, checked air intake and EGR. Some speeds and part throttle give a slight surging. I've decided it's the nature of the beast. Not about to spend too much time/money troubleshooting.

for 360ci - yes I have changed my ATF and the filter.

**Bert** · 11-16-2009, 12:10

Try cleaning the MAF with the special MAF cleaner.

Fordtech. · 11-27-2009, 08:29

Most times on Focus petrol a misfire is down to the leads, which then take down the plugs and then coil pack, possibly ECU and oh also the cat as well if left long enough :-(

gtuplin · 11-30-2009, 22:26

Check the brand of wires. Had very bad luck with cheap wire sets and the same symptoms were produced, seemed worse in cool damp weather.