I'm working on a 04 X350 supercharged. When you start it cold it will miss on 1,3 and 7. No detectable intake leaks. Coils are all new.

Anyone run into this before?

 

Probobly injectors, send them out and have them cleaned i use these guys
WWW.injectorrx.com
the 10% methanol creates deposits and cold start issue. Ive even tested and foubnd gas that contains alot more than 10%. But you have no idea of whats going on with injectors without having them tested, cleaned and screens replaced. And @ $18/injector its cheap diag, elliminates guessing, and thinking your gonna do much with tank or on board cleaners is a big waste when you have problems that you suspect might be injectors

 

Interesting. Injectors wouldn't be my first guess with no complaints of top end performance or acceleration. I have never seen a fuel injector so bad that it will cause a bad misfire at start up then just go away. I could be wrong.

Also its about a 9 hour job to remove a fuel injector in SC 4.2 so unless I know for sure I cant really say its a cheap diag.

I am leaning towards the upstream fuel/ratio sensor on that bank.

 

How about plugs?

 

Plugs on that bank came out clean and proper gap. I would be looking at three plugs failing at one time with out an outside cause.

 

SORRY I JUST MISSED THE SC, YES ITS ALITTLE HARDER THAN A NA MOTOR BUT i HAVE SEEN THIS AND OTHER ISSUES LIKE DEAD MISSES IN THE MID RANGE AND BOTH WERE FROM INJECTORS. ON COLD STARTS WE DO HAE ALOT OF ISSUES WITH INJECTOR SPRAY PATTERNS. ITS MORE AN ISSUE AT IDLE SINCE A MISFIRE IS DEFINITLY MORE PRONOUCED AT IDLE AT NOTICABLE. AND WHY UPSTREAM 02, ON COLD STARTS ITS NOT IN CLOSED LOOP YET AND USES ADAPTIVE FUELING(ECU PROGRAMMING AND LEARNING) AN DOESNT READ 02 ON STARTUP. THEY DO COMEUP QUICK, BUT HOW SOON ARE YOU TALKING DOES IT MISFIRE. THERE ARE OTHER ISSUE WITH COLD STARTS WITH AIR FILTERS TOO, BUT THEN THERE IS A WHOLE DIAG PROCEEDURE TO DEAL WITH TO ISOLATE ISSUES WITH 02, FUELING, MASS AIR FLOW SENSOR ETC.....GOOD LUCK

 

I had an X300 with a no load idle misfire, as soon as the car was put into gear or had any load applied, the misfire would stop. Tough one, but I finally determined that one injector had a no load pulse width failure, and sure enough, I had them tested and this was the problem. When the injector was getting a 3ms pulse signal, it would not open, when it got a 6ms one, it started working! The injector company thought I was crazy but did the test and confirmed my guess.

 

You might try a can of BG-44K in the fuel system. It solved my misfire problems. I run a can of it once a year and have had no more injector problems.

 

Did a leak down test. Coolant in bank 1 cylinders.

Broken head gasket. Customer came clean and told me about how 2 months ago it blew a hose on the freeway and he extremely overheated it.

Thanks for all the advise, just another case of not getting the whole story