8 Port 3rz Hot Start Issues

[jmcn]

Hey all,

I'm having some hot start issues with my 1996 4runner 2.7. When cold, the truck starts right up no problem, but if I run it up to operating temperature then shut it off and let it sit for a few minutes it will crank for up to 10 seconds before firing up. After it starts, there will be a brief and minor throttle hesitation then the truck will run fine. No smoke either, no smells and no CEL. If I kill the engine and start it again right away, there's no extra crank time. It only does this on warm days, which makes the problem hard to diagnose.

I initially thought it was some sort of heat soaking, but fuel pressure after the filter is fine.

Oh, and if I unplug the airbox temp sensor, the truck goes in to 'limp home' mode and starts no problem.. Possibly some sort of bank 1 sensor issue?

If anyone has experienced a similar issue, please let me know. It gets pretty annoying on summer days.. Especially when running errands.

Thanks a lot!

 

[jmcn]

Maintenance Completed

Here's what I've had done to the motor recently and some general info:

Motor has 248 500 kilometers,

Head gasket done about a year ago @215 000km which included
- resurfaced head
- new valves
- new timing chain/guides
- new spark plugs

**hot start problem existed before the head was done and hasn't worsened or improved since**

Other maintenance:
New radiator
K&N drop in filter
deck plate mod
new radiator and coolant flush

Compression test results:
#1: 175
#2: 170
#3: 175
#4: 170

Motor has been run on full synthetic since new and had full coolant and trans flushes every 40 000km.

 

[flatboy]

timing is too far advanced, see if you can turn the distributor a bit.

 

[jmcn]

Thanks for the response. I guess if the distributor is too far advanced it could cause some sort of pre-ignition that could result in tough hot starts. I've messed with it before and will do so again.
I still feel like it could be a sensor somewhere though.. My exhaust is pretty ratty, so could a front or rear O2 sensor cause something similar?