I usually dont ask questions, but this has me stumped. 2004 ford explorer (no wise comments i love fords) replaced fuel injection pressure sensor, manifold gaskes (cause we had to take top manifold off to get to sensor. Driving down road as i press gas it seems like a shutter/hesitation. But idles fine in park and in drive without pushing gas. For some reason it seemed it wasnt getting good gas flow. So just put new fuel filter on and still same thing. But did notice if i go over 60mph check engine light flashes. I slow down it stops. Not over heating and transmission seems to be shifting fine. Just cant figure out the shuttering like laging gas. Has lots of power. Sitting at idle cant hear anything. Very quiet. Any ideas? It is 4.0 sohc 4×4 2004 ford explorer with 203000 miles.

Troy Mahan: Catalytic converter plugged Seen all the same symptoms on a 2007. Just a guess. Should throw a code.

Christene Deason: Check engine wont stay on for us to get codes.

Greg Massey: Need a better scanner. It should have stored a history code.Orielys mode6 to monitor misfires.

Christene Deason: One of my spark plugs was cracked. But replaced all i bought anyway. Plugs, wires and coil pack. Runds great but check engine light is on all the time.

Jay Smith: A flashing check engine light indicates a type A misfire (catalytic converter damaging), should have a code for the offending cylinder(s). Check plugs, wires and coil.

Christene Deason: But the cel only comes on and flashes at speeds over 60 once i slow down or keep under 60 it does not come on. Example i drove on cruise at 55mph 60 mile round trip. No engine light. Daughter drives same route at 60mph light flashes. Drove today no light till i got over 60 then went off when i went slower. Pulled in drive still off, cut it off and start back up idles fine no cel still.

Jay Smith: Have you had the codes read? there can be stored codes without light being on, if not an advanced scan tool can read mode6 data that will store misfires per cylinder.

Christene Deason: So your saying take to shop to read invisible codes bacause the light is never on when i go to a parts store. But the one time it did light up it gave orileys no codes.

Greg Massey: Parts stores scanners arent worth a crap. They wont pick up codes in a lot of situations, and dont give any kind of diagnostic data or tests.

Josh Marxen: I was thinking cat too based on over 60mph but a vacuum leak possibility at the new manifold gaskets comes to mind. Your 04 has the big aluminum intake manifold with a gasket for each side right? I dont remember if its 180 off, side to side or up and down but (correct me if Im wrong) theres a way they will bolt in but not seal right, or maybe you got a bad one, but its sucking a tiny bit of air directly into your fuel air mix so the computer is not happy. Seen it happen on a truck where guy had overtightened one side first and seem to be warned about the gaskets by a Ford tech.

Christene Deason: We had to replace this cause the sensor was under it that went bad and a piece was broke on old one per inspection. So it called for new gaskets and we did that. All is hooked up fine. Now ponder me this if its a vacuum leak wouldnt it have a shutter at idle to?

Christene Deason:

Josh Marxen: The stutter at take off is what makes me think vacuum leak, just the engine light at over 60 the cat starting to clog or a weak link in the spark system makes the most sense, but the stumble at take off you mentioned is when the computer is trying to a…See more

Christene Deason: One of my spark plugs was cracked. But replaced all i bought anyway. Plugs, wires and coil pack. Runds great but check engine light is on all the time.

Josh Marxen: On wifes truck its the EGR now. Same thing no longer flashes or bogs, but CEL stays on. The fact that it runs good eliminates vacuum leaks, ect, but Id bet money that your emissions system is the cause of the code. Luckily in Iowa we dont have the inspections and a new EGR may raise her mileage but up to 1mpg but just havent worried about it. Think the part is $300 for the Hemi, truck has 280K.

Christene Deason: Josh Marxen did you not read my updated comment? All is fine and back to normal. Just cel light stays on. Im not too worried about that it runs good and gets 26mpg.

Josh Marxen: Sorry I worded it wrong, just the cel bugs some people, and illegal in some states is why I brought it up. Ive had customers get mad at me when they are told their $500 car needs $600 in emissions work or a peice of black tape over the light. They dont understand that just shutting it off will only last for a few miles.

Christene Deason: It never stayed on till we replaced everything and didnt come on till i went over 60mph. I aint worried too much motor is quiet, shifting fine, runing great again. But will get it check just to be sure but its probly something useless all car makers have. Thanks

Josh Marxen: Ive seen them shut themselves off after the computer resets itself, gets used to running right, however you want to say it. The newer stuff has a limited ability to learn driving style. The newest stuff gets worse.

Bryan Ruigrok: So since it is a ford, I would suggest coil issue. Typically converters that are plugged dont rev up. So at idle it should struggle to get above 2500-3000rpm. The flashing light is Infact a misfire. Could be plug coil or wire. I have seen coil packs crack between the E-Cores. This is caused by heat and corrosion.

Christene Deason: But if its a miss why would it idle perfect?

Bryan Ruigrok: As engine load increases so does the resistance in the air gap inside cylinder if resistance is greater in cylinder than internal or external short of coil it will take path of least resistance

Greg Massey: You can get misfires only at idle, only at certain rpms, or various other conditions.

Ronald Johnson Sr: No , you can have a miss at hi rpms, sounds like a possibility of a bad wire connection at injector , it can idle just fine but as you climb into higher speeds resistance will build up causing a miss

Christene Deason: One of my spark plugs was cracked. But replaced all i bought anyway. Plugs, wires and coil pack. Runds great but check engine light is on all the time.

Ronald Johnson Sr: Disconnect neg battery cable for 10 min. Reconnect ,code should be gone

Greg Massey: Pull the codes for the check engine light if it doesnt go off or comes back on

Christene Deason: Went and bought coil pack, spark plugs and wires. 🍻 heres to hoping it works! Will update tomorrow. Thanks guys!

Christene Deason: One of my spark plugs was cracked. But replaced all i bought anyway. Plugs, wires and coil pack. Runds great but check engine light is on all the time.