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HDGENE, Ford Senior Master/Diesel/Trans
Category: Ford
Satisfied Customers: 5581
Experience:  25 years Auto experience, Ford ,GM, Chrysler, Asian & European
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I have a 01 3.8L first start runs smooth, drive 15 mins

Customer Question

I have a 01 3.8L first start runs smooth, drive for about 15 mins starts to bogs, misfire, pre-ignition rough idle. Replaced 2 injectors 3-4 as per o'reilly codes, changed plugs, coil pack, EGR, Car sat up for awhile 2yrs, had to replace fuel pump, ran great for 40 miles then after that started having all these problems. After changing fuel pump tank drained fuel and started fresh and put in fuel cleaner additives.
Submitted: 1 year ago.
Category: Ford
Expert:  HDGENE replied 1 year ago.

Hello, do you have the same codes now as you originally did when you changed the injectors? Fuel Pressure is good when it looses power and has it ever had any major engine repairs done like a blown headgasket? What model ford is this in?

Customer: replied 1 year ago.
New codes but cyl 4 misfire showed up again and Cyl 5, haven't checked fuel pressure yet had to rent a fuel pressure tester, tried to drive today dies when put in drive if I give it gas, rough idle, also HO2S-11 low signal and HO2S-22 no activity code showed up. DPFE high ckt input is new but I had it disconnected to test voltage coming to sensor while the engine was running.
what should I expect with fuel pressure if the engine runs rough? Should I clear the codes after fuel pressure test? And as far as I know the head gaskets have not been replaced before, we had the car for about 6 years. It ran great until it sat up for 2 years.
Customer: replied 1 year ago.
Its a 2001 base model convertible mustang, but there was some work done on it, shifter kit was placed in tranny.
Expert:  HDGENE replied 1 year ago.

Ok cylinder 4 and 5 are next to each other on the drivers side bank. Head gaskets are popular issues with the 3.8 liter engine. Verify fuel pressure is steady and not leaking down when the loss of power occurs. Inspect the spark plugs on cylinder 4 & 5 for signs of coolant burning on the tip of the plug.

Customer: replied 1 year ago.
what will coolant burn look like
Expert:  HDGENE replied 1 year ago.

it will have a greenish hue on the tip of the spark plug or collection of white ash. Typically green. A compression test will tell more as well, especially if you are running low on coolant

Customer: replied 1 year ago.
OK my pressure test failed 8lbs but I believe it may be due the pressure release valve stem gasket is displaced inside by the stem, I pulled it out and looked at it. I will get another in the am to check fuel pressure accurately. It idles well only. There is no water in the oil but I will pull the plugs and check it out, I may be able to do compression test on 4-5. But I did have misfire on 3 also before changing that injector. So its possible for the head gasket go bad after sitting up for 2 years? Coolant level seems ok but I haven't had much drive time I'll keep an eye on it
Expert:  HDGENE replied 1 year ago.

Well number 3 is on the rear passenger side cylinder head from front to back 1-2-3 and drivers side 4-5-6 so was thinking head gasket issue when you have a misfire with two cylinders next to each other.make sure the fuel pressure is good, may have enough to idle and not enough to run, but should have 30 psi at idle, 40 psi with the fuel pressure regulator vacuum hose disconnected and blocked off. And not leak down while diving or under a heavy load/power braking the vehicle with your foot on the brake and in gear.

Customer: replied 1 year ago.
Ok checked plugs and compression 4-5 cyl, black tips on plugs no white /green residual compression 105-110 max with several turn overs 180 psi. Got a new schrader valve changed fuel filter. 6-8 psi w/engine idle and then the pressure drops off to zero within 1 minute or so. Stop engine restart same results all in park at idle only. Anything else that could be causing drop in pressure once running? What keeps pressure up for a short time when engine is turned off?
Customer: replied 1 year ago.
Also Did block off vacuum line but if I disconnected the electrical connector from the fuel pressure valve engine runs real rough and dies.
Expert:  HDGENE replied 1 year ago.

A pressure relief valve holds pressure in the pump. It should be 30 psi at idle. Its too low. You can disconnect the fuel line at the fuel rail and dead head the pump by hooking a pressure gauge adapter up to the supply line and see if it leaks down, if it does its an issue with the fuel pump. If it holds, its leaking down through a fuel injector

Customer: replied 1 year ago.
Where can I find an adapter and the fuel pressure will be tested without starting the car only activating the pump by cranking the engine ?
Expert:  HDGENE replied 1 year ago.

Most auto parts stores rent tools and may have a quick disconnect adapter to fit the supply line to the rail