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Engine keeps cutting in and out when wa


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Drive for about 10 minutes, when engine gets hot she starts cutting in and like the ignition is shutting off fir a split second, no warning lights or codes. Switched coil still doing it. Any ideas?

 

Park for a little while and she is fine till shecwarms up again

 

Just did head gsskets and all timimg components.

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No codes don't mean no issues. OBD is not flawless by any means. It just means the issue isn't on a system that is monitored the way the OBD expects to monitor the issue.

 

My car has an intermittent EGR issue that over enriches the fuel mixture when cold, but runs great when warmed up. No thrown codes because the O2 sensors lean out the mixture within spec and the EGR isn't reporting a fault even though my diaphragm is getting weak. Doesn't mean I don't notice it. Usually OBD reports when something has failed, which is why manufactures invented their own CAN systems on newer vehicles that provide the manufacturer with more advanced monitoring of sensors above and beyond OBD.

 

I can pretty much rule out improper timing, since it only happens when warm. My guess is either a vacuum leak or fueling issue. Have you checked your fuel pressure? How old are the injectors? If you have access to a scan tool, you'll want to run diagnostics and capture the condition on a graph of your ignition, fuel trim, and AFR. You need to know what is happening inside the engine when it happens.

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pcv valves do strange things. like little misses without codes,

 

$15 buys a new OEM one, ...sadly subaru does not put them on a maint schedule despite it being a wear part with a spring in it that can get weak over time. (not just gummed up). weak springs in those can react to heat,...and I have seen weird aftermarket pcvs in a few vehicles that don't resemble the OEM type I bought to replace it.

 

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relays also do strange things and change with temperature. might buzz a little if you are lucky to tell you which one is causing the problem. (can touch them in the under the hood fuse box to feel the bad one vibrating/ buzzing) and you can swap the identical ones around to see if the problem changes.

 

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hope you used NGK plugs and wires, (plugs are so small on these, even the double palts are 4 for $18 from rockauto or amazon)

 

and did not throw out the old coil. (aftermarket coils are JUNK on subarus, last a couple thousand and make for odd misfires). my old 2002 has its original on it and it says "subaru" engraved on the front side, I would pick a used OEM one out of a yard before I got a aftermarket one.

 

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did you check your battery and alternator wires. something might be loose / corroded under the sheath, or the alternator is shorting. (I suppose if the alternator were making noise like the belt or the internal bearing whining you would hear that).

 

 

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what did you pick for a timing belt kit? gates started shipping chinese made junk recently like almost everyone else. Aisin being still Japanese made components.

 

I hope it is not a seizing bearing in the timing belt kit. (such would suck after all the work you have done so far).

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