Car Driving Rough (misfiring)

[Sojhinn]

Need help guys.

I was driving for about two hours today all highway. Got off the freeway and about 1/2 mile down at a stop light the car starts shaking pretty badly.

CEL comes on when I pull away and I pull over.

Code p0303. Misfiring cylinder 3.

Thinking my car finally ate it's first coil pack. I swapped it out and I'm still having the same issue.

No codes have come up after restarting the car.

Mods:

Phantom ESC
JDL Header
Oft Flex Fuel
On about an E65 mix right now.

Any thing I should try? Any where I should take it?

At my parents house in Fontana, CA. I can tow up to 100 miles. WORST ISSUE: I'm moving to WA in two weeks. This needs to be fixed ASAP.





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[steve99]

Hopefully you changed correct coil pack


I think misfire CEL is cumulative so it may need to get certain number of misfires over a period of time, so cel may take a while to show up again.


Think oft can log individual cylinder misfires real time


also check afr , LTFT and knock

[Sojhinn]

Originally Posted by steve99

Hopefully you changed correct coil pack


I think misfire CEL is cumulative so it may need to get certain number of misfires over a period of time, so cel may take a while to show up again.


Think oft can log individual cylinder misfires real time


also check afr , LTFT and knock

Just got p0201


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[Sojhinn]

Also no misfires on oft.... Just really bad rough run.


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[Sojhinn]

Now car won't start at all. It runs for a Sec and shuts off.


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[steve99]

Check injector wiring.
check DI computer is securely grounded to chassis via all mounting screws




Car starts on port injection only


does it crank ?


is key symbol on dash green


run for 5 sec happens with key start models if theirs problem with security.


try different key if you have one


Weird you getting different symptoms, sounds suspect, might be electrical issue low batt volts bad earth or similar

[Sojhinn]

Originally Posted by steve99

Check injector wiring.
check DI computer is securely grounded to chassis via all mounting screws




Car starts on port injection only


does it crank ?


is key symbol on dash green

Stupid question where is the di computer.

It cranks for a second , starts and shuts off immediately. Symbol is green.


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[steve99]

Originally Posted by Sojhinn

Stupid question where is the di computer.

It cranks for a second , starts and shuts off immediately. Symbol is green.


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black box under bonnet left side at top bolted to engine looks like an ECU

[steve99]

Also might be loosing fuel pressure if it starts runs then dies


car only logs high pressure fuel pump.


maybe look at AFR and see if it leans out then stalls

[Sojhinn]

Originally Posted by steve99

Check injector wiring.
check DI computer is securely grounded to chassis via all mounting screws




Car starts on port injection only


does it crank ?


is key symbol on dash green


run for 5 sec happens with key start models if theirs problem with security.


try different key if you have one


Weird you getting different symptoms, sounds suspect, might be electrical issue low batt volts bad earth or similar

Figured out di computer wasn't grounded... Because I was checking injectors

It starts but running rough still at idle. Weird thing when I push on the accelerator it get better and doesn't seem to be an issue. Just under idle.

Also I have a solid check engine light but no codes....


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[steve99]

Originally Posted by Sojhinn

Figured out di computer wasn't grounded... Because I was checking injectors

It starts but running rough still at idle. Weird thing when I push on the accelerator it get better and doesn't seem to be an issue. Just under idle.

Also I have a solid check engine light but no codes....


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non grounded DI computer produces all sorts of weird issues.


OFT only reads engine ECU codes, if code is generated by other computer ie auto trans or VSC oft wont read or clear it.


If you have another code scanner or android torque app use that.


you can clear all codes by removing battery for a minute.


remember to let car idle for a minute after reset or cams wont operate


ecu also get reset when you clear codes so rough idle might go away after a few minutes

[Sojhinn]

Also ltft is 0%


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[steve99]

Originally Posted by Sojhinn

Also ltft is 0%


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shiv might disable ltft in flex tunes not sure.


check the afr at idle should be close to 14.7


look at the short term fuel trim see if it large value and consistently positive or negitive

[Sojhinn]

Originally Posted by steve99

shiv might disable ltft in flex tunes not sure.


check the afr at idle should be close to 14.7


look at the short term fuel trim see if it large value and consistently positive or negitive

-3.12 for stft


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