2008 T&C PO300 code help
 

Hey guys,

Couple of weeks ago, our van service engine light came and was on for about 4 days when I decided to try turning the gas cap 3 clicks to see if it would go away and sure enough, the light went out the next day! I had my shop just take a look to see if any codes had been stored and it gave us a PO 300 (random multiple misfires). The only odd running issues that I'm finding are:

1) sometimes, when starting the engine, it will crank but it will take 2-3 seconds to start vs like 1 second typically and

2) at idle I feel a very, very, very slight roughness in the motor that vibrates the vehicle. I'm the only one who noticed it as it is so slight.

Any thoughts on if there are any issues we need to be aware of? The service engine light has not returned. Do we just wait to see if it happens again or start going crazy.

PS: I turned the gas cap as a solution because about a month ago, my Ford truck had a service engine light appear and my shop read some code (don't remember what) and my shop said to try changing the gas cap (as it was over 8 yrs old) and that solved the problem as it was probably no longer a tight seal. Thought to try tightening the van cap 'cause one of our drivers had filled gas a few days before the van service engine light appeared and thought they may be related. Maybe it was coincidence, but the light hasn't reappeared since I tightened the cap and that's been over a week. Thanks fo any thoughts.

Some recent developments and discoveries. In addition to the sometimes extended starting time from turning key to engine engagement, yesterday we experienced this for the first time during all this. Turned the key, took 2-3 seconds to engage, then the engine died. Repeated this 2 more times until the fourth time when I depressed the accelerator somewhat to give it "gas" and it started but felt like it needed more accelerator, so I pumped at the pedal when I felt it going to die again and it finally stayed running. As I repeated the start procedure several more times during the course of the day while out and about, the process became more fluid and less of an issue until today where it seems to be back to normal. I started it this morning with none of the issues of yesterday.

Would appreciate any input and thoughts as to what may be going on, coming, or gone. Leaving for PA from MA on Thursday so would really like to have some closure on this (as much as possible). Thanks guys.

From your posting, without specific info about mileage and such, it sounds like the longer crank time was caused by an injector leaking gas into a cylinder on shutdown. On startup the fuel system would have to pressurise to proper specs in order for the rest to spray and fire up the motor. This can also trigger the code you got to be set. If at 100k or more you may seriously want to think about a fresh set of spark plugs and run some injector cleaner in with the gas.

Yeah, At 141,000 mi. Changed all plugs at 102,000 but think I will try the fuel injector cleaner and a tankful of Mobil high detergent fuel (someone told me some time ago that Mobil fuel was high detergent and is always more expensive than other fuels in my general area?). Thanks for the thoughts.

Just tried a tankful of Mobil 89 octane and so far it's been like nothing ever happened. Will keep monitoring at this point if it happens again. Odd.