Cold start rough idle and sometimes 303 code

[Hoist]

Cold start sitting for maybe 4 hrs or longer, has rough idle, no knock, ESS inop regardless of 303 Cade or not. Engine smooths out fairly quickly and I can clear the misfire code. I did change the spark plug and coil but it didn’t solve the problem.
wouldn’t think it was the cam or head gasket as I wouldn’t think either would go away after running maybe 5 minutes.
Yes I’ve read the threads but I’m not seeing what causes the cold start misfire.

Sponsored

 

[Hoist]

I should mention 70k on the miles.

 

[Lost1wing]

Cylinder nbr 3 is a smoking gun. Swapping coil packs and replacing sparkplugs would be a start. You could check the connections of the fuel injector for nbr 3.

 

[Hoist]

I still have to check the injector connection but wouldn’t think it would fix itself after a few minutes running. Having said that, the A light never goes away so there’s something somewhere.

 

[Lost1wing]

Could be an EGR issue. Cylinder 3 may
The one showing the issue. How are you clearing the codes? Do you have a way to do a misfire count? Still could be a fuel injector. Bad spray pattern? I bet that you have a misfire even when warmed up, you just don't see it.

 

[Hootbro]

Bad fuel injector is possible but swapping that is going to mean removing the upper intake, fuel rail assembly to do any swaptronics.

How is your coolant level? Another possible issue is a slight leaking of coolant into the cylinder as it cools down and pools. Any white exhaust smoke on cold start? Even if no white smoke, it could still be small enough of leakage to cause a misfire. Bore Scoping the cylinder and if the piston head looks steam cleaned and no carbon, that is a sign.

Like what @Lost1wing alluded to, need a scan tool like Jscan or others that can monitor misfires.

 

[Lost1wing]

Bad fuel injector is possible but swapping that is going to mean removing the upper intake, fuel rail assembly to do any swaptronics.

How is your coolant level? Another possible issue is a slight leaking of coolant into the cylinder as it cools down and pools. Any white exhaust smoke on cold start? Even if no white smoke, it could still be small enough of leakage to cause a misfire. Bore Scoping the cylinder and if the head looks steam cleaned and no carbon, that is a sign.

Like what @Lost1wing alluded to, need a scan tool like Jscan or others that can monitor misfires.

I should have mentioned a coolant leak. Maybe he still has that sparkplug to peek at!

 

[Hoist]

Could be an EGR issue. Cylinder 3 may
The one showing the issue. How are you clearing the codes? Do you have a way to do a misfire count? Still could be a fuel injector. Bad spray pattern? I bet that you have a misfire even when warmed up, you just don't see it.

I broke down and ordered a dongle so I can read a Jscan display for individual ignition.
I have an innova 5610 that reads codes and some other info and will also clear codes but not show individual misfires Which is why I want the Jscan.
haven't ruled out an injector yet.

 

[Hoist]

Bad fuel injector is possible but swapping that is going to mean removing the upper intake, fuel rail assembly to do any swaptronics.

How is your coolant level? Another possible issue is a slight leaking of coolant into the cylinder as it cools down and pools. Any white exhaust smoke on cold start? Even if no white smoke, it could still be small enough of leakage to cause a misfire. Bore Scoping the cylinder and if the piston head looks steam cleaned and no carbon, that is a sign.

Like what @Lost1wing alluded to, need a scan tool like Jscan or others that can monitor misfires.

Haven’t seen any white smoke after start but i need to check coolant. Unfortunately no borescope but I might be able to borrow one from our A&P mechanic.

 

[Hoist]

 

[Hoist]

Doesn’t look that bad to me, maybe a little lean? Never could read a plug except for obvious oil or wet with gas.

 

[Hoist]

Should have my OBD plug in for Jscan by this evening if Amazon isnt lying. In the mean time I though i'd try some things to see when it actually happens.
Started this morning, still had code, waited a few minutes to warm up and smooth out and drove 25minutes to work. Shut down, cleared the 303 code.
This time, I went to accy first, turned off the ESS then started normally and no codes or A warning. Hmmm. Let it run for a bit turned off and tried again, first ESS off then do a start and good to go.
Wait an hour then try it using same technique and no lights runs fine.
Waited two hours same same and so far so good. I'm going to wait three hours before I try again.
Don't know if turning the ESS interrupt switch off first is relevant but this is the first I havent gotten the A light when starting. I am mostly trying to see how "cold" it has to be before the misfire triggers the engine light.
There is another odd BCM code that shows stored and wont clear-U1514-87. Says EC secret code-missing message. Not a clue what that is but haven't searched yet.

 

[Hootbro]

There is another odd BCM code that shows stored and wont clear-U1514-87. Says EC secret code-missing message. Not a clue what that is but haven't searched yet.

I get that a lot too. Comes and goes. Seems to be a code stored if you try to start the vehicle and it has not yet picked up the RFID data from the FOB.

 

[Hoist]

I get that a lot too. Comes and goes. Seems to be a code stored if you try to start the vehicle and it has not yet picked up the RFID data from the FOB.

Doesn't sound like a problem then. Good to know.

 

[Hoist]

After 3 hrs, ESS disable then start no codes runs smooth. No ESS light fault either.

Ambient temp has been showing 72deg.

Sponsored