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Scott W.
Scott W., Ford Technician
Category: Ford
Satisfied Customers: 3288
Experience:  28 yrs. experience as Ford ASE Master Technician. Accolades include being a 2005 Ford PTS Regional Finalist and 2006 ASE Ford National Technician.
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997 powerstroke, replaced an injector because of a rough

Customer Question

997 powerstroke, replaced an injector because of a rough idle, replaced all the O-rings because they weren't the updated ones and were in rough shape. I also replaced the glow plugs. On start up the truck idles very nice after it smooths out but as soon as the temp gauge starts climbing the engine gets a little bit rougher and a bit of a knocking sound appears. I am using an autoenginuity scanner and the injector buzz test is perfect and no injector has a muffled sound or anything. Looking online the noise I hear is commonly referred to as fuel knock but nobody seems to offer a solution all the answers are all over the map. I have more experience working on 6l powerstrokes and semis then these engines.
Submitted: 11 months ago.
Category: Ford
Expert:  Scott W. replied 11 months ago.

Hello my name is Scott

Expert:  Scott W. replied 11 months ago.

The only injector that is different in this engine is the number 8, which one was replaced?

Expert:  Scott W. replied 11 months ago.

How far has it been driven since the repair?

Customer: replied 11 months ago.
2. Truck is in beautiful shape for year and very well maintained
Customer: replied 11 months ago.
Drove truck hard for a bout 20 min
Customer: replied 11 months ago.
valve cover gaskets and wiring looked mint but codes that appear on KOEO are the whole D/S as high to low side open and p0470
Expert:  Scott W. replied 11 months ago.

Ok what is the exact code for the injector faults?

Customer: replied 11 months ago.
p1272,p1274,p1276,p1278
Expert:  Scott W. replied 11 months ago.

Was the valve cover gasket and or harness unerneath the valve cover replaced also? Were these codes there before the repair also?

Customer: replied 11 months ago.
no they weren't but p0470 was. Injectors all buzz very good though
Customer: replied 11 months ago.
wiring connections all seemed good no melting etc
Expert:  Scott W. replied 11 months ago.

Ok, the P0470 is most likely the EBP sensor mounted by the water pump. The injectors codes are most likely a open high side cicuit to all of them. When the vehicle is running and the problem present, wiggle the large connector at the left hand, drivers side valve cover and see if the engine smooths oiut or runs worse while wiggling it, if it does remove the valve cover and inspect the wiring connector, they were known for coming disconnected under then valve cover. They would pass the injector buzz test, but then when started and having a electrical load on the circuit they would go open circuit. If this doesn't show anything, check the wiring where it drapes over the LH valve cover and inspect the wiring for chafing here. If ok, then a continuity test of all injector wiring from the LH plug to the IDM, injector driver module would be next. It could be a IDM, but I have seen more wiring issues than anything else.

Customer: replied 11 months ago.
Would the engine run smooth when the engine is cold and then start knocking when it gets hotter?
Expert:  Scott W. replied 11 months ago.

It could be the wiring is making connection when cold, then as vehicle warms and vibrations occur, the connection opens and cause the engine to run on 4 cylinders causing the loud knocking, the PCM will keep fueling the engine to hit that idle rpm number reguardless of how many injectors are not firing.

Customer: replied 11 months ago.
could chunks of the old O-rings in the fuel system cause any problems?
Expert:  Scott W. replied 11 months ago.

I haven't seen this before, usually the old orings fall apart under pressure and we swapped them out with no problems. I have never had this happen or heard of orings causing any concerns with these engines as far as plugging a fuel system. Since you have electrical codes, I would look there first.

Expert:  Scott W. replied 11 months ago.

If you have any more quetions just ask, also I am not a employee of just answer, the only way I receive any compensation is when you rate the service I have given, thank you for your business!

Customer: replied 10 months ago.
Ok, I changed the LH valve cover gasket, still had same codes, changed the injector wiring for that side and still same codes. Harness doesn't look rubbed through anywhere. Where in the electrical system would cause these codes on only one side of the engine? I don't believe the IDM could be at fault so what do I check now?
Expert:  Scott W. replied 10 months ago.

I would check the resistance of the 4 fuel injectors, compare all 4 of them when the problem is occurring when hot, shut it down then test them. If they all check the same, remove the left valve cover and run the engine until it misfires, then unplug one injector at a time, see if the engine smooths out, if it does replace the injecgor that is causing the misfiring.

Customer: replied 10 months ago.
The code says an open in all 4 though and now the engine feels like it has a miss all the time. Do I check the resistance to ground? My strengths are definitely not electrical. Hard to believe that all 4 of the injectors are bad especially when 1 is new
Expert:  Scott W. replied 10 months ago.

Not saying all 4 are bad, the resistance needs to be checked while the concern is present. The resistance may be fine, then unplugging the injecgtors will help isolate the misfire, the IDM will cut out the other injectors if there is a possible short circuit.

Customer: replied 10 months ago.
All the engine codes are gone except p0470. Engine still run a little rough when warm. Can this code be causing this? The other codes disappeared on their own after I removed the edge programming. I didn't know about the tuning before. Also, engine smooths out when in gear and foot on the brake.
Expert:  Scott W. replied 10 months ago.

Has the EBP sensor been replaced? This sensor usually causes the 470 code.

Expert:  Scott W. replied 10 months ago.

I have only seen the EBP set the 470 code, and I have never seen one cause a rough idle concern.

Customer: replied 10 months ago.
I don't know if it was ever replaced. Customer bought this truck brand new in 1998. Have you ever heard of # ***** injector not being right? How do I tell if it is right? This is Canadian truck if that makes a difference. What about it smoothing out in gear? It is an automatic
Expert:  Scott W. replied 10 months ago.

Number 8 injector is different, they used a different fuel injector for #8 cylinder to help with engine noise called fuel injector cackle. I am not sure what would happen if the wrong injector was installed in the number 8 position. They are usually marked or a different color sometimes. I am not sure if the canadian engines used a different injector or not, I am pretty sure they probably did though. The rough running in gear we use a fuel injector cancel tool to figure out which cylinder is causing the rough idle, when we find the one that is causing the problem, we do a compression test and if ok, we replace that injector. You could do the same thing by removing the valve covers and disconnecting each injector one at a time to see if there is a weak contributing cylinder.

Customer: replied 10 months ago.
I am gonna pull the valve covers and check each injector while engine is warm because this is when it happens. Is there anything in the fuel pressure regulator then can plug up? I pulled it away from the fuel cannister and the little screen was partially plugged so I cleaned that. Made no difference
Expert:  Scott W. replied 10 months ago.

Have you checked for codes yet? Have you looked at the wiring where it drapes over the LH valve cover, I had one shorted here on friday.

Customer: replied 10 months ago.
I mentioned earlier that I removed the edge programming that I had no idea was on and all the codes disappeared except the p0470 code. The edge programmer left codes for the L/H bank having codes for an open on the high side which led me to change the valve cover gasket and injector wiring for that side for no reason. Codes still remained until I removed the programming. Just the one code and still the same problem
Customer: replied 10 months ago.
Haven't changed the ebp sensor yet but I don't like wasting the customers' money on things that might not be related to the problem
Expert:  Scott W. replied 10 months ago.

I haven't seen a EBP sensor give a problem, but if there is moisture in there, it could short out VREF causing a stall. Now as far as this rough idle, how rough is it? Does it pass cylinder contribution test with the scan tool? These engines never idled completely smooth anyway, just asking.

Customer: replied 10 months ago.
Using autoenginuity so not as good as an ID but shows no codes for injectors. Engine shudders a bit when temp climbs. And there is still the fuel knock sound when temp climbs off of cold. When engine first starts it is very smooth and the idle is smooth. As it warms up there is a slight knocking sound and the idle stumbles a bit. When reved up or driven everything is smooth until it idles again. Customer has 2 other 7.3 engines same year and says they are all smooth
Expert:  Scott W. replied 10 months ago.

Were the injectors properly torqed down? Is there any smoke while knocking? If you disable cylinders does the knock go away on one cylinder?

Customer: replied 10 months ago.
After my day job today I'm gonna pull the valve covers and start disabling injectors. They were torqued down properly
Expert:  Scott W. replied 10 months ago.

Ok, let me know what happens

Customer: replied 10 months ago.
Today I got the engine to operating temperature and the miss and knock started again. I removed the valve covers and started disabling the injectors one by one. There was a clear miss when each injector was disabled. The oil spill on each injector looked good. I'm running out of options. #8 injector # ***** ***** and the other # ***** it is *********** Can you confirm that number is ***** for #8? The first number is ***** same as the other 2 on that side. The other injector is an Alliant power injector that I put in and has a different #.
Expert:  Scott W. replied 10 months ago.

Did the sound change when one of the injectors was disconnected? I have no way of confirming the numbers, but I am sure the parts guys could. I just know #8 usually has a AE letters and 1-7 have AD, as far as your numbers I don't know for sure.

Customer: replied 10 months ago.
Hard to tell if knocking noise disappeared the engine started missing hard whenever an injector was unplugged. # ***** looks exactly the same as the other injectors
Expert:  Scott W. replied 10 months ago.

I have a feeling that alliant one is wrong or bad. I would call ford parts and ask them about the numbers on #8 also.

Customer: replied 10 months ago.
Why do you say that about the Alliant one? When unplugged it misses just like the other ones.
Expert:  Scott W. replied 10 months ago.

Just from past experience, the aftermarket ones always fail before the Ford injectors.

Customer: replied 10 months ago.
That's a new one so it's not likely bad.
Expert:  Scott W. replied 10 months ago.

Have you tried a cylinder contribution test with the scan tool?

Expert:  Scott W. replied 10 months ago.

Can you post a video of the rough idle and knocking noise?