need help with trouble shooting
ok I have a 2003 6L with about 134k on it
for the most part runs great but a few weeks back it start missing a little when cold ( southern AZ so cold isnt that cold ).
Its done this before about once a year I add some techron to the fuel tank and it clears right up, but this time I also changed the oil which sometimes makes it worse for a week intill the oil is broke down a little ( dont know why its just how it is maybe 15-40 is a little thick in the winter here??) anyway well this time it got worse and didnt clear up, so after a week I drained the oil ( keep in mind i just did a oil and filter change ) so I drained oil and put 5-30 in to see if it would help in winter.. man it got way worse , started cold but almost would not restart after it warmed up .. very hard start had to hold the key down, try a few times hold down the gas pedel and it missed , etc but started so i drove it home and drain the 5-30 out and refilled with my 15-40 I took out.
( had put it in a clean container ) anyway, started running pretty good it would now start right back up after it was warmed up. but now it did it again today after i drove it about 5 miles , shut it off and was in a friends house for about 10 to 15 mins went out and it didnt want to start ?
So what would make this truck start fine COLD, ( miss a little till warmed up ) then make it not want to restart with warm engine. ?
also when i left my friends house intill i got about half way home it was still heasting when shifting ( auto trans ) then once warmed back up ran fine ?
should I drain the oil again and refill with new 15-40 to make sure there is no trace amounts of the 5-30 ? sound like a injector to you ?

 

i am not telling you that this will solve it but i switched from 15 40 to 10 30 and i think it helped my starts. i also wait until i hear the vaccumm pump go off before i start(sounds like a small growl from under the hood)or i watch my insight and when it starts showing the engine reading i hit the starter.

 

Sounds more like an ICP or a high pressure oil issue.

Be aware that your oil system holds 18 quarts, so you always have 3-4 quarts of the old oil left in the system.

 

I had a similar problem and I put a BB from a BB gun under the fuel pressure regulator spring (there is plenty discussion here on the forum about that) and it worked. I speculate when the engine gets up to temp the fuel thins down a bit and squeezes by the regulator easier, thus causing a little lower fuel pressure on start-up. I would also be careful, the BB could cause too much fuel pressure and that could damage your injectors. There are people here that know more about that than I do.

 

I did have the ICP replaced when it blew out and all the engigne oil came out when it did , about 35k miles back. is there a way to test the oil presure ? also can you test for fuel presure ?
there also was a clicking noise under the dash a few weeks back i could never find. I cleaned the battery charge line and it pretty much went away.

 

ok new too me , how do you do the BB thing so that would be a good test to see if that would fix it. anyone have pictures ? also is there a way to do a test on the fuel presure regualtor ?

 

i tryed 5-30 and it almost killed my truck it did not like it at all

 

also could a dirtly lower fuel filter cause this ? i just changed the top filter and havent gottin to the lower yet

 

If you do want to change to a new oil, get a 5W-40. I vote for mobil 1.

The only time I will say get a 30W diesel oil is when I use it and do an oil analysis on it from an extended interval. If it is the same or better than other syn 5W-40 oils, then I will be fine with using it.

 

ya but based on what ever my problem is when i went to the liter oil my truck did not want to start after the engine warmed up and i shut it back off had a real hard time getting it to start again

 

How many miles have you gone since last changing the primary filter?

 

not sure about a year and a half ago, just changed it. didn't look that bad, haven't tested yet. but was thinking maybe if the fuel pressure spring is weak. that a clogged filter maybe enough to start show drivable issues

 

A clogged filter will QUICKLY drop the fuel pressure and result in ruined injectors. Many regulator springs are weak (borderline) from the factory.

I am surprised you haven't heard that preaching before ............

 

well changed and will drive it to town tomrrow and that should be a good test to see if anything has changed if not then i guess i will be ordering the spring kit for the fuel pressure
anyone have a link to a good ( but cheap ) fuel pressure gauge ?

 

Its not exactly cheap, but this is the bestway to go IMO:

Quadzilla Performance Recon XZT Digital Gauge - Truck Customizers