Hesitation only when Cold

2000 Toyota Tacoma 2.4L
80000k miles
Received the truck with an occasional slight hesitation while cold and shifting from 1st to 2nd usually, I think I really notice it because I have steep incline out of driveway. If I start the truck cold and don’t let it heat up turn it off and restart it the idle starts real low and builds up to normal.

Changed ignition coil, wires, and spark plugs
New PCV
New MAF
New EGR and EGR Temp sensor
New VSV (under intake manifold)
New vacuum lines
Cleaned throttle body and IAC and new gaskets
Coolant system flush
(All changed in the past year)

Hesistation while cold almost seems more prominent now.
Here are some of my ideas let me know what you guys think!

maybe O2 sensors need to warm up before reading accurately.

maybe Coolant temp sensor or sensors are going bad (more likely the one on the back of engine block if this is the case)

air trapped in coolant hose at the back of throttle body causing miss reading of coolant temp somehow (read someone suggesting this elsewhere)

or maybe one of you guys got a better idea! Would love to hear them. Thanks

 

Your best course of action is to get a scan tool that shows live data… BlueDriver is a good choice, others like ScanGauge. The key to this is knowing what is normal and what isnt. I would start with engine coolant temp. If the truck is sitting outside and it is 60* F and the scan tool show 90* F there is something wrong. As a quick test, pull the EGRvalve vacuum line and plug it and see if that solves the hesitation… IIRC, there should be no EGR flow cold.

 

Thanks for the tips. Ended up hooking it up to a scan device and ECT read 115 degrees while cold. Now we’re on to something.

 

daaamn never mind that wasn’t my problem.. still getting hesitation while cold.

 

Let your truck warm up. Your main and rod bearings will thank you for doing so. Toyota was smart by putting certain "restrictions" in place to protect the engine from people just jumping in with a cold engine a romping on the gas pedal. My truck won't shift gears normally until the ETS reaches the ECM preprogrammed temp threshold. Also the truck is in open loop flooding the engine with fuel to heat up the cat converter to reduce evil green house gas until the ETS threshold is met is also adding to the "problem" The fix, let your engine warm up.

 

Anyone know if a bad purge valve VSV could cause this problem? Measured a resistance of only .32

 

Daamn I like this answer! And I’ve heard it from a few Toyota owners now just kinda refused to believe it cause I’m anal about how my vehicles run but maybe I just have to trust and either wait for a code and or drive it till it dies lol

 

That will be a long, long, looonnnngggg time from now.