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Old 04-05-2012, 12:31 AM
EcoBrick Bob EcoBrick Bob is offline
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Default Anyone have a bad fuel injector?

All of a sudden, I have a cylinder (#1) that shows a mis-fire. It seems to happen at very low RPM at stoplights etc. with A/C on. Pulled plug and it seems slightly wet with fuel after letting car idle with the miss occurring in driveway. Replaced the plug, but new one also fouled at low RPM. Switched the coil packs with #3 cylinder and it made no difference. Code popped up after about 3 min of rough idling as #1 mis-fire again. When over 3,000 RPM everything is fine. Wondering if anyone has had a similar issue? In reviewing the Ford Shop Manual on injector replacement, one needs to use a Fuel Injector Brush to clean the orifice in the combustion chamber. Thinking I have something partially clogging the orifice, rather than a bad injector, but it could be either or both. Flex has 34,700 mi on it.

Will video scope it out tomorrow before I go further....

Info... or Suggestions?
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Old 04-05-2012, 07:58 AM
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SHOrod SHOrod is offline
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Since it seems to run fine when over 3,000 rpms it sounds consistent with an ignition misfire versus a fuel-related misfire. Since you've swapped plugs and CoPs though, I'm not sure what to suggest next. If you have an oscilloscope you could check the primary signal to the CoP and make sure it looks fine. With an o-scope you could likely identify, based on the primary pulse, if the coil secondary is firing properly. However since swapping the CoP didn't make a difference you may be looking more for evidence of a primary signal of correct amplitude.

-Rod
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Old 04-05-2012, 04:20 PM
EcoBrick Bob EcoBrick Bob is offline
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This is what might be the problem.... That's the coding I am getting... Also... the last mis-fire issue I had about 2 months ago was the plug ceramic broken and dropped that is shown in this TSB.

Anyone else have these issues?

TSB 11-8-19

3.5L GTDI ENGINE RUNS ROUGH, HESITATES,
SHUDDERING WITH MISFIRE DTCS P0300, P0301,
P0302, P0303, P0304, P0305, P0306 OR P0316
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Old 04-05-2012, 05:54 PM
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Just like you did on the CoP, you could always swap the spark plug with a different cylinder and see if it follows it. That would rule out the spark plug itself starting to go bad.
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Old 04-05-2012, 10:24 PM
EcoBrick Bob EcoBrick Bob is offline
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I have plenty of plugs... I switched out twice, once with new, and once with a plug that was a month old.

Not a plug issue.... Not a coil pack issue... May be a bad injector, or bad injector programming that is related to the TSB....

I am going to scope that cylinder and another one and take pix... tomorrow.

Oil looks great ( still clear - just changed), no issues in coolant. Both tailpipes look identical, with typical soot on both.

Frustrating... but a real learning experience on DI engines.
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Old 04-06-2012, 07:59 PM
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Mine did it at about 10,000 miles. Ford replaced the bad injector andreceived 6 new spark plugs and been problem free since.
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Old 04-06-2012, 09:49 PM
EcoBrick Bob EcoBrick Bob is offline
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Quote:
Originally Posted by SHO U UP View Post
Mine did it at about 10,000 miles. Ford replaced the bad injector andreceived 6 new spark plugs and been problem free since.
Today I checked out what would happen if #1 plug was disconnected. The misfire was continuous and noticeable up to 5,000 rpm when I quit. Also got instant code on both misfire and on spark distribution issue. Plugged it back in and no codes, and above 2,500 RPM it runs fine... no miss. If I let it idle for a couple minutes straight, it will code, otherwise no....

Is this how your injector was acting, or had it failed completely? There are now 3 TSB's relating to this problem, which refer to a new PCM strategy. I may have a bad injector, or... the controller for the injector isn't turning it on and off correctly. If the latter is the issue, the new PCM strategy will fix it.
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