2002 XK8. Last few cold starts rough idle. P301, P302, P303, P304, P308 and P1316 (injector circuit/DM codes detected). After 30 seconds, misfires stop. While running, if I clear the codes they don't reappear including no pending codes. Does not happen on warm start. Two weeks ago I changed the valve cover gaskets but don't think that is connected as I'd driven multiple times since then without codes.

 

Watched live data on startup. Both banks went from Open Loop to Open Loop fault to Closed Loop. Codes today P300 random/ multiple misfires and P1316.

 

Clearing them & not recurring while running is normal as they are 2-trip codes (as Jag DTC doc show), so proves car obeys the law but not much else.

Probably air leak or coils or both. Do the usual checks for those.

 

Started simple. MAF cleaned. No change.

 

Smoke test yesterday. Leak in accordion of intake tub. Taped. No misfires on cold start this morning.

 

I had very similar issues and codes. Replaced the air tube which did have some leaks, but the main culprit turned out to be the rubber gasket that goes between the snorkel and MAF housing was missing.