I now have about 2000 miles on my JWT install and the only problem I'm having (besides paying for it) is the P0300 code. Every time I fill the tank I get one thrown in about 30 seconds, not one sputter from the engine. After I clear it I don't see it until the next fill up 2 days later.

 

Random misfire learn to live with it...

 

I under stand it a random misfire code but only for the first 30 seconds on a fresh filled tank everytime is not what I'd consider very random. I'm thinking it has something to do with fuel pressure. wierd...

 

A/F doesn't change? Do you have a fuel pressure gauge? Any difference in any gauges / logs after fill up?

 

i get it too, i also get 175, which is too rich, which i really dont understand since i am monitoring a/f

 

The A/F is bouncing between 14 - 15, this happens at idle right after starting at the gas station, one time it did it as I was pulling out of the station. at 12 mph. Next time I fill up I'll check the fp gage. At idle fp is around 65 - 67 psi when I filled it up today I saw 70 I think when I started it up. The engine is running great and the CEL is no big deal, I clear it right away it just bugs me this is the only thing that keeps it from being perfect, well that and not having the bb 700 turbos, 650 injectors, return fuel system and FCON V PRO and a few other things.

 

If you are going strictly by when the CEL comes on you are not getting a true indication, that might be the final time the event happened and caused the light to come on. Some of the CEL codes do not come on after one event but rather wait for a few events, I think 3, before the light comes on.

 

Nope, I've been checking that. Today before I got fuel I hooked up the scanner, no pending faults all tests completed.

 

if it only happens at fill up and a rich code may be involved disconnect your purge solinoid and fill up ,no misfire code after might mean you charcoal cannister is bad/getting flooded with fuel at top ups,do you fill past the first auto shut off?

 

What happens if you only add a half a tank of gas?

(Don't fill up.)

 

Yep

that's exactly right. Learn to live with it.

Actually, the description of "random misfire" is almost a misnomer.

P0300 causes are:
- Incorrect PCV hose connection

Once, I did swap out the o2 sensors, and it did fix it. Other times, swapping out the spark plugs imporved the situation considerably, delaying hte intervals in between the 0300 code, but didn't eliminate it.

In your case, I'd bet it's the overly rich condition. Havign a cipher cable/software is invaluable to FI guys like us. I'd check the fuel pressure and make sure it's consistent at all times relative to how much gas you have in the tank. And of course, look at hte short term and long term fuel trims, and see what happens with them.. if they ever peg out (either one) at +/- 20% , then that's gonna be another cause of the issue. This is possible to fix by carefully and deffectively fine tuning the injector scaling (in the SS box) to make sure that at any RPM/load point, the fuel trim never get near the 20% mark, and ideally stay under 6-8%.

Otherwise, the ECU always monitors the periods between each of the teeth on the flywheel, detecting any anomalies (like incosistent period) tha may occur due to poor compression one one cylinder, and throwing the code. That's another cause.

Hope this helps.

 

good info Gurgen, but I don't understand what filling up the tank has got to do with it? weird.

 

I know that's a weird one for me too.

That's why I talked about fuel pressure monitoring at different tank levels. I heard (and never really researched since I don't have this setup) that JWT has an in-tank FPR setup (at least it did originally as described in Sport Z Mag turbo shootout)...i guess there is a chance that such setup maybe affected. Who knows. I'd need to now more about hte actual setup to say for sure. In all cases, that's why I said to make sure just monitpr the FP at all tank levels to see if it's the same, so you can rule that in/out as part of the cause.

 

Ok, so I fill it up last night, before starting it I just turned the ignition on and watched fuel pressure it only got up to 38 psi. I cycled the ignition switch on and off 3 or 4 times just to check starting fuel pressure, highest it went was 40 psi. Started it up and it went straight to 70 PSI, let it idle 30 seconds and I did not get the check engine light this time so I'm sure it's a fuel pressure related issue.

 

There you go...your FP regulation problem. That's the only thing that would explain the full tank P0300 issue. Talk to JWT see what they say about it, as I said I am not familiar with the JWT TT so can't offer any more advice.

 

i am almost 3/4 of a tank gone without throwing the 300 code (AAM fuel return).