Odd starting problem...

[Opeth]

I had my head just replaced at the dealership under warranty about two weeks ago due to a burnt valve. My OE battery died shortly after this, and have a brand new one now. The truck cranks just fine, and starts every time but....

.... After it cranks a couple times it's doesn't always smoothly catch and start to run every time. On random cold starts only, it will crank a couple times(3-4 as usual) when it starts to fire, it sounds like its fuel starved and then surges on ( like whoooosh) and begins to run but feels like it has a few random hesitations until the air injection pump kicks on and everything smooths right out. It could be just paranoia on the hesitation feeling since I just went through a head replacement nightmare, cylinder 6 misfire with burnt valves and those misses were obvious at idle.

However, these odd starts did happen a few times randomly before my whole head situation occurred, but they seem to be more frequent now.

Other side notes:

* new battery / new air filter/ cleaned TB.
* truck runs perfect with no problems after cold start ups.
* after air injector kicks on, ghost hesitations seem to disappear on these odd cold starts
* letting truck sit in on position to prime fuel pump doesn't seem to affect this, will start waiting timed increments instead of guessing to see if it's the fuel pump.
* checked intake manifold bolts for tightness, all easily accessible bolts were tight.
* this does not always happen on a cold start, this afternoon it was in the 70's and fired normally after sitting 10 hours, leaving work at 11pm it was 60's and sat for 5 hours and started normally again.
* dealership refilled engine with conventional oil + additives( not happy) after it was ran on synthetic for 20k+ miles when they replaced the head. Havent swapped it out yet since I was advised to wait a few miles for valve train to break in. Almost gone 1k miles, will swap back then

I tried getting a video of the fluke, but both times she started normally .... :scratches head:

 

[Opeth]

No one?

 

[The_Roadie]

Get a scan tool on it that can check for proper operation of the O2 sensor. The SAIS pump just hastens the heat-up of the O2 sensor to get the engine into closed-loop operation, and your issue might be due to wackiness in the open-loop operation. In my experience, the SAIS pump comes on within a second or two of a cold start. Is that the only time you get your intermittent misfire? A good scan tool can also store data to look at other information that might contain a clue in the first few seconds. Guessing is usually not the right way to go - you should be able to find an indenpendent mechanic with a good enough scan tool f you don't want to spend any more $$ at the dealer. But did you give them a call first? You might be able to convince they they're responsible for a diagnosis to prove it wasn't their work that caused this issue.

 

[Opeth]

In the winter, the pump kicks on right away but now that it is in the 70-80's here it has been coming on maybe 5-10 seconds after start up. It hasn't done any of the weird surge starts since I've posted this, but I can still feel the vibrations.

I also don't know if my truck has an exhaust leak either, I get a rattling sound ( similar to a failing ac compressor clutch) when I get on the gas and when truck goes into D. But at idle and start up I can't hear a distink tick tick tick like you would with a normal leak. I asked the tech to check my manifold when they had everything apart for cracks, and he didn't see anything wrong.

Guess I'll see if I can get a sound clip.