Cold start issue: 2.7L Stumbling/Stalling UPDATE: Fixed

I'm having a weird issue intermitted cold start issue. It's happened twice in the past month, both times it's been sunny and hot (60-70deg) but that could be coincidental. I don't do much driving since I'm working from home but each time it happened the truck had been driven the day or two prior. Truck drives completely fine otherwise.

So here's what happens, it starts right up on the first crank but idles super low and starts stumbling and if I don't give it gas it stalls. Once I give it a rev it idles fine, but a little low. Then I drive to the grocery store about 10 minutes away, park, go shop for about 15 minutes, come back out and the truck will crank and crank and crank and unless I pump the gas a bit it won't start, then it stumbles to life and idles fine. I took out my air filter and cleaned it out, there were some mouse debris in the airbox. I also reset the ECU. Only other work that has been done recently is that the fuel pump was replaced about 8 months ago, less than 10k on it, I used a Bosch and also replaced the strainer and gaskets.

From what I've read on here I'm thinking IAC valve...seems unlikely that it's a fuel issue from what I've read but could be possible. I'm trying to catch it on my datalogger, if I do I'll post it here. Logging spark adv., MAF, Fuel System status, short term fuel trims, long term fuel trims..anything else I should try to capture?

 

Coolant Temp Sensor could be a possible culprit. Add that PiD to your live data list.

 

Have you tried any fuel injector cleaner?

 

I have not, but my MPGs have stayed about the same as they always have been. I have no other stumbling or stalling while driving or at higher RPMs

 

Added intake air and coolant temp

 

I had the same symptoms and P0446.
After replacing the Purge Selnoid the crank no start went away as did the CEL.
Engine was getting flooded with EVAP vapor.

 

Oh right I forgot to mention that...no pending or set codes I just passed state inspection as well

 

I had something similar with my old truck. I never got it solved, but the likely cause was leaky fuel injectors. Mine would stumble and likely stall if conditions were right. Giving it gas would help. I never got it solved because the injectors were such a pain to get to on that engine.

 

Good to know, I’ve only got 156k miles and I’ve had no engine issues since owning it. I guess injectors could get funky from sitting. Truck sat at home a good bit while I was in college and sometimes my dad remembered to put fuel stabilizer in sometimes not

 

Yeah that's a whole crap shoot. For what it is worth, my old truck was a 2008 GMC Canyon. The issue shafted shortly after 100k and I ended up trading it in for my Tacoma at 156k.

 

check for holes or breaks in the plastic intake duct that runs from the air filter canister to intake. I had this issue a few years ago, no codes but the extra air reaching the IAC for the first part of start-up tells your choke to close and injectors to lean out which causes a stall. We taped up mine and have been good to go ever since on that issue.

 

Okay I got a log file...it should be attached. This time it started on the second crank but slowly stumbled to life and almost stalled. For some reason it captured every PID not the ones I told it to...

 

That is REALLY hard to sift through, right off the bat though, fuel trims for bank 3 (2?) seem a bit out of whack. I'll try and get this into an easier-to-read format in a bit and see if I can actually glean anything from it.

 

I just deleted out all the unecessary stuff...let me repost it

 

Let's try this again... @tirediron i deleted the unecessary stuff and froze the top rows so you can see what you're looking at as you scroll..and saved it as an excel file so you can actually format and save it

 

Interesting; your CTS didn't change by even one degree; granted that only shows about 40 seconds, but I would have thought it would have increased a little bit. The other thing is your fuel trims are showing a lean condition which doesn't equate to running cold. Step one, run for >5 minutes and document your CTS over that time, and then check it again after >15 minutes of running and make sure it's 190+.

 

I just reset the ECU a few days ago, still relearning trims?

 

Possible, but I would expect them to be the same on both sides.....

Waitaminnit… I just twigged to the whole "2.7l" in your thread title; why is there anything other than Bank 1?????? WTF is it reporting as "Bank 3"??????

 

Yeah bank 1 was there too but it was empty. My guess is it’s just a quirk with the app I’m using.

 

I think O2 sensor was also reading as bank 3