Stalling on startup and at idle in gear

[maxx4wd]

Is the fill cap for the oil reservoir tight?

yes fill cap tight and sealing as far as I can tell.

 

[maxx4wd]

So I messed around with the vehicle a little this weekend...not as much as I would have liked to - removed and checked all vacuum lines, pcv valves - cleaned the TB again just in case - Everything seals fine but one thing I noticed when I had the valve cover the intake vacuum line off I plugged the hole on the valve cover and immediately the motor ran perfectly smooth - no issue idling etc. as soon as I put the vacuum line back on runs rough as can be.

checked the actual vacuum hose and it seems fine - might replace anyhow but I'm wondering if I shouldn't just try to reset the ECM learning and see if the motor resets the adaptive fuel trims if that doesn't solve the issue....not sure why it would act up now as I haven't really changed anything unless the newish MAF is starting to give up the ghost...just hasn't started throwing codes yet...

if the adaptive reset doesn't work - I'll report back tomorrow then I'm thinking swap all the orings on the injectors and then start systematically replacing vacuum hoses and maybe even the TB.

 

[jeffery borel]

It sounds like it may have a large vacuum leak, which usually doesn't throw a check engine light right away. Lean codes take a bit of driving to flag the check engine light. Can you get access to a smoke machine? two common culprit for vacuum leaks is the main intake hose between the air box and throttle. and sometimes the crankcase vent valve.

 

[maxx4wd]

It sounds like it may have a large vacuum leak, which usually doesn't throw a check engine light right away. Lean codes take a bit of driving to flag the check engine light. Can you get access to a smoke machine? two common culprit for vacuum leaks is the main intake hose between the air box and throttle. and sometimes the crankcase vent valve.

I don't have a smoke machine but I bet I could get a cigar and pull the air filter and try it that way. I think I might have found a good lead last night. turns out the throttle body motor is humming like crazy when the motor is off and the key is on - I posted it on instagram and have gotten a lot of feedback (much of what's been posted here as well) still not ruling out vacuum leak as you say that is the most likely culprit.

 

[DPetty2994]

Possible fuel pump... Have you checked Fuel pressure?

 

[DPetty2994]

Someone said possible injector O-ring...

Could be--normally that would cause flooding, and will cause the engine bay to smell of fuel. Can you smell fuel in the engine bay?

 

[DPetty2994]

Also--could be a clogged fuel filter.

When was it last changed?

 

[DPetty2994]

Also--if it's happening when cold--could be the temp sensor.

It will have the engine run rich while warming up to speed up warming process.

If it's not working properly--it can cause malfunctions.

 

[DPetty2994]

Same with Fuel temperature sensor...

I'd check all of those.

I hear you about no codes--but I've had sensor fail and not throw a code...

 

[maxx4wd]

Possible fuel pump... Have you checked Fuel pressure?

yes I've checked the fuel pressure and all the o-rings for the injectors...pressure is fine and no smell or vacuum leak from the fuel rail or manifold sides - still could be some debris in them but since it's intermittent I'm guessing that's probably not the case (still not ruling it out though).