Trouble Diagnosing Problem

[H3slate]

I am trying to figure out what is wrong with my truck. At low rpms while in gear my truck is cutting out/surging. It is most noticeable in first gear, I let out the clutch with constant throttle, as the truck accelerates the rpms will rev up (with no increase in vehicle speed and without me applying more pressure on the gas pedal) then cut out (without stalling). It will also happen in other gears at low rpms.

My truck is a manual trans with 83,000 miles. There are no codes stored, I have new spark plugs, new MAF sensor, new throttle body, and a K&N intake. The problem occurred both before and after installation of new parts.

Is this an engine issue? PCM, throttle reponse, vacuum??

Is it an issue with the clutch? It shifts gears just fine with no abnormal noise when shifting. The transmission doesn't slip when going up a hill.

When these symptoms occur I can make them stop by applying more throttle. It occurs most often when starting from a dead stop and in first gear.

Any help troubleshooting this would be appreciated.

 

[06 H3]

sounds like the same thing I had with my 06 auto tranny...low rpms it cut out. It ended up being the head issue

now its fixed and I have no issues

 

[H3slate]

sounds like the same thing I had with my 06 auto tranny...low rpms it cut out. It ended up being the head issue

now its fixed and I have no issues

:gaah:

I hope not. Mine will rev up and cut out and rev up. Almost fluttering but just a couple of times. It it was an engine issue I can't believe I don't have a CEL to go with it. :huh:

 

[erdlen65]

Just as a guess I would check the wiring harness to the pedal assembly if it's intermittent maybe a loose wire or bad connection

 

[alrock]

It seems the head issue manifests itself in a few different ways, including what 06H3 said. While your symptoms are similar I do hope it isn't the same thing.

I had occasional CELs, always P0300 (general misfire) that usually occurred when off road and they would go away within a day. One of my head issue symptoms was that it would drop revs too far and fast, often almost stalling, when slowing down. I actually had the engine stall on me on a hairpin turn coming down a mountain road. Wasn't fun.

One of the common (but broadly defined) symptoms is that the engine runs "oddly" at low revs. That's obviously a very broad definition, and you fall into that, but that of course does not mean it is a head issue. Unfortunately, I think you should confront it and get a leak down test (or whatever it is called) at the dealer.

Along the lines of what erdlen said, it is a drive by wire system so there could be issues there though I think they would manifest themselves at all times, not just low revs.

 

[06 H3]

I would look into a leak down test like Alex said...give it time and see if a cel goes on. Mine normally would go on if it idled for a while. 5 minutes or so...

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[Scarsman]

Time for an Alpha conversion!

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[H3slate]

I think I found my problem!! The intake manifold was loose and leaking oil. Some of the bolts were not even hand tight. :whaa: I have to remove the alternator to get to the last bolt and the rest I could only access through the drivers wheel well.

Hopefully get it all apart tonight and then get new gaskets tomorrow and put it back together.

Can't wait to have my truck running like it is supposed to. :horns:

 

[alrock]

That will be great news if that fixes everything.:woot:

 

[Scarsman]

That could make sense why it did it as you were letting the clutch out to start going. As it startes to engage the motor twists from the torque. That could cause the intake tube, which is fixed to the fenderwell, to make the manifold move a little, opening up the seam causing it suck air through the gasket. That would make it run lean, making it surge. Then once you were rolling it would not be noticable.

 

[H3slate]

Got the truck all back together today with a new intake manifold gasket, new throttle body gasket, properly torqued manifold bolts :roll:, and a properly seated dipstick tube.

Took the truck out for a test drive today and it ran great. No more stutter in first gear, and smooth acceleration even at low rpm in the higher gears. :woot:

Can't wait to drive my truck now, want to get a feel for how the ported throttle body feels with everything else running properly.

 

[alrock]

Excellent!

 

[Bigunit]

Great news!

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[Scarsman]

Sweet!

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