3.4L hesitant start when cold

When the engine is cold it starts hesitantly. It's like it almost chokes for a second before fully starting. When it's warm it cranks up instantly. It has 160k miles. I'll try to get a video of it happening. Any ideas?

 

Mine does this off and on, always has. It'll go several weeks or months starting up just fine and then a few times a week (when cold) it will crank harder/longer than usual and sort of sputter when it fires up. No idea why. Over the years I've replaced just about everything you can think of that might be related (plugs/wires, fuel pump, fuel filter, MAF sensor, O2 sensors, cleaned throttle body, etc.) and it still does it every so often.

It's never failed to start but it will struggle to start on occasion. Honestly from being on this forum for awhile now and reading a lot of 1st gen threads I've seen a lot of others talk about this too. Almost seems like it's just a characteristic of the 3.4l engine (random hesitant starts). I've yet to read of anything that fixes it, assuming we're talking about the same thing.

A video would help though, just to be sure. You can't upload videos to this site though, you have to do it via Youtube and then post the link on here.

 

Yeah, I'll post a video for sure. Thanks for the insight. I've had this truck for two years and put about 30k miles on it. It just started doing this in the past couple months.

 

The only thing I haven't had tested or serviced are my fuel injectors which might be something to consider. Although usually if a fuel injector is leaking it will make it hard to start up when warm, not cold. But I've heard it go both ways.

 

Injectors were the first possibility that came to mind based on some vague recollection of something I read once. I don't know much about them though.

 

Excess fuel will hinder combustion warm or cold. You likely have a leaky injector(s). A few cranks clears the fuel but you may also be soaking your plugs and slowly fouling them out too.

If a sensor were out you’d likely have a code.

 

I am betting it's injector related. I had it happen a few times. Ran some Lucas fuel cleaner through and it hasn't happened since. Who knows. Maybe it worked? Snake oil? I'll wait until one goes out and replace it I suppose.

 

I've tried that myself, picked up a couple of those big Lucas injector cleaner bottles and ran it with every tank for a couple months...didn't seem to help with my occasional rough start. Even tried

$25 BG44k BG 44K Fuel System Cleaner Power Enhancer 11oz.

BG44k which is supposed to be the bee's knees of fuel system cleaners, still does it every once in awhile.

One of these days I'll have my injectors removed and tested/cleaned, hopefully that'll help

 

My '03 3.4L does the exact same thing. It's hit and miss, no rhyme or reason. As stated above it may be several months before it happens again.

 

I've read more than once on this forum that it's just characteristic of the 3.4l...it's a cranky motor sometimes (pun intended?)

 

About two years ago, I had to replace the oem radiator. So, while I was at it, I replaced the hoses, thermostat and the coolant sensor for the ecu that's located behind the top radiator hose housing.
Toyota Part #

$29 89422-35010 Water Temperature Sensor

89422-35010.
I had a '97 Camry that had starting issues due to the coolant sensor, so while I had mine apart I replaced it. Unfortunately it made no difference. Still glad I replaced it since the plastic on the original one broke off when removing due to age/heat cycles.

 

Hmm coolant temp sensor you say? That is probably a good thing to check out. My 3.4 for idk the past 7 years of ownership has always had a little shake in the idle. Still runs perfect though. I only thought V Dubs had issues with the coolant temp sensor But - good thing to replace while you are in there.

 

I was thinking when I tackle the cam cover gaskets and such that I should just get the injectors rebuilt, replaced or (deported) lol Just peace of mind and maybe even run better. who knows.