Odd starting problem...

Opeth

Original poster
Member
Mar 25, 2012
177
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:
 

The_Roadie

Lifetime VIP Donor
Member
Nov 19, 2011
9,957
Portland, OR
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

Original poster
Member
Mar 25, 2012
177
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.
 

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