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

Weird, definitely something off with that fuel trim data, but it may just be the way that app is reporting. Start by by checking out the CTS data between start and fully warm just to rule that out.

 

90 deg C after about 10 minutes of driving/idling

 

Okay, that sounds like it's reporting accurately, so the easy answer isn't the right one...

 

Your first guess of IAC may be right; easy enough to check. Get it to the point where it's idling normally and just unplug it. You should notice a significant change in engine tone/note/speed. If nothing at all happens, then it is likely the IAC. The other likely culprit that would explain all of these symptoms is a vacuum leak. If you have the hood up, engine running normally, do you hear any noise like an out-of-place whistle, or air blowing?

 

Yeahhh I’m familiar with how to check for vac leaks...spray starter fluid around any connections or suspect areas along with a visual inspection. I’ll take a look this weekend, gonna be a pain in the ass I guess.

 

Okay these two banks of fuel trims are making no sense now...this is log file from my 10 minute drive yesterday...bank 1 shows rich and bank 3 shows lean. Both change throughout the drive. It's a 4cyl there should only be 1 bank. Bank 1 looks pretty normal but bank 3 is all over

 

Can you get your hands on another scan tool?

 

I'm trying to...my friend who used to be a toyota/lexus/nissan mechanic told me that the old non turbo 2jz had two cats (one for each 3 cyl) and therefore 2 O2 sensors and would read as 2 banks. But that is likely not the case here because I have two cats in series not parallel. He agreed that the numbers were all fucked and if it did have two banks they should be close to one another, not one reading rich and one reading lean...

 

Definitely some fuckulation going on there... happens quite often that one scan tool that works perfectly on Make/Model XYZ will totally s**t the bed when trying to read Make/Model 123.

 

Do all the easy stuff first, but the first gen 2.7 has some known burned valve issues. Usually after 150k miles.
Maybe do a compression test after all the easy stuff is don't

 

Good to know! I would also recommend a leak-down test to confirm what is actually leaking.

 

I don't watch them too much but TFL has a YouTube video on a 2.7 and they had to get some head work. They might have symptoms that could quickly eliminate that idea.

 

I mean I don't wanna get ahead of myself here...seems like a big jump from coldstart issue to valves and head issues. Truck runs perfectly fine otherwise. First step is finding another OBD tool

 

Totally agree, all easy stuff first. Data is the only way to fix cars now days.
Burnt valve can cause that problem though, so wanted to add that since it's not mentioned yet.

 

If we can confirm a consistent lean condition, then I can buy off on a burned valve, especially as the trims don't seem to be wildly out of whack, but right now, they're too crazy to make a good diagnosis.

 

I threw this into datazap cause I was having trouble reading it and sorted out the PIDs that aren't complete trash

https://datazap.me/u/speedytech7/tacoma-3rz?log=0&data=15-17-20-21-22-26

 

Also to me, since I had this happen on my last 3RZ truck, sounds like a cracked head, happens when the exhaust valves tighten up from lack of re-shimming and then you get coolant leakage and it makes starts rough as hell

 

Bank 3 isn't real, bank one is the only real PID, 3 is derived from somewhere by your tool, my guess is a wrongly named PID for something else.

 

Cracked head

I don't think it's consuming coolant though, normal temps, and no white smoke

 

Double check on the coolant consumption, mine had normal temps and a lack of white smoke too though, just looked like normal condensation on startup