3RZ Misfire after head replacement.

I'll have time in the morning to pull the valve cover off and check timing again

 

This should be correct timing? Yes? Engine is set to what I believe is top dead center.


Blue shows the marks at the 12' clock position


Exhaust and Intake cam dots are lined up.



You can see through the exhaust cam gear and sub gear, I believe that means the sub gear is lined up, ( the service bolt can go through it)



And i'm 90% certain the harmonic balancer is in the correct spot.. The harmonic balancer has two v notches.. One notch is lined up with the zero gauge above, the other notch is lined up with the zero gauge on the oil pump cover.

 

Tried my old pcv valve, no change.

tested the three grounds, all have zero ohms, or when connected to battery they have the correct voltage.

If I pull any single fuel injector connector, the motor still runs just as crappy

 

What did a spark plug look like when you pulled it out?

i can only imagine your frustration...

 

They looked fine, given I haven't ran the motor long enough to make a mess, maybe a total time of 10 min, she don't sound happy.

 

Maybe found my first weird issue...

I unplugged my IAC connector, the truck ran quite a bit better, but not perfect.. I unbolted from throttle body and performed the test:

Connect IAC to plug
Desconnect the ECT sensor ( i'm assuming that's the one on the back of the block)
Turn ignition switch on
check IAC valve moves.

The IAC valve sometimes moves, sometimes it just moans and buzzes.... Who the hell knows... Expensive part to just throw at it, but i'm at my witts end, this sucks.

 

(130) IAC Valve Testing and Cleaning - YouTube

 

https://youtube.com/shorts/nlp2nM-7wjE?si=ofBZswTTmEUmbZsL

Here is the surge of the idle. If I hold it at 1500 it idles great.

 

My bet is the IAC sticking. My first attempt to clean the throttle body (didn't remove it) only succeeded in flooding the IAC. So I took the throttle body off and half assed cleaned the IAC. Guess what? It still had enough gunk in it so that it was sticking at times and ran just like your vid. Cold cranking it would stumble and stall at idle. I figured the IAC was kaput so I put in an aftermarket IAC (doesn't have the thermo spring thingy inside) and the truck runs fine but won't idle below 900RPM. I've since disassembled the original OEM IAC, cleaned it all up and the barrel inside, tested with wires to terminals to a 12v battery and it appears to function flawlessly. Am planning to reinstall it sometime soon, get the aftermarket IAC off and hopefully gain the normal 750-800RPM again. As I understand it, the IAC should be open when cold cranking and close at operating temp. Also operates to open for accessories running/more engine load, like when running AC etc. If your IAC is sticking closed it could cause a low idle on a cold crank and do like mine did.

 

Interesting!! That sounds promising, I tried to undo the bolts in the back of the IAC but out of the 10,000 bits I have in my garage none of them fix that funky screw. I ended up just buying a new IAC from the dealership, should be here in a week. I pray thats all it is.. I guess I can't figure out why It would stop working after taking my cylinder head off.

 

Can you idle the truck and then unplug the iac.....and it still idle...

According to that timmy vid....is the default setting on the iac is for it to slightly open....
takes power to open all the way....and to close.....
never realized that until that video......

maybe even try choking the iac air supply and see what happens....

 

That's a great idea. I should have done that before buying one. I'm at work for the next 48 hours so I'm done tinkering for awhile haha

 

Having an extra iac is not a bad thing.....I kept my old one and cleaned it up...
for a rainy day......

especially if they discontinue them in a few years.....


there's a video of someone comparing the guts of oem to non oem...
and that tension spring is substituted with a cheap plastic bushing instead....

 

Did you see anything that raised your eye brows with my timing picture?

My mind keeps going back to timing, but I swear I got it right.

Beside the IAC valve

I think the next 3 things i'm gonna look at are:

Injectors
vacuum lines
(leak down test, hoping i didnt screw up the head gasket again)

 

(132) How to test a rotary type Idle Speed Control Valve #1211 - YouTube

 

Found the issue!!! The injector o ring kit I purchased had the wrong o-ring for the base of the fuel injector cup... I used a home made smoke machine, put a baby oil soaked sock in a glass jar with a electric solder iron on top heating it up. Made a ton of smoke, charged it with a bike fuel pump and tested ports...



Smoke poured out of my fuel injector area.


The truck runs near perfect now! I'm guessing I pinched a o ring somewhere... I'm getting extended crank times after truck is sitting.

 

No....the o-ring is different....there are three different tips on the injector ends...

and each oring is just a little different....sad but true...

I've got a bucket of old 3rz/2rz injectors......brown ones, blue ones, pinky's......

 

Now I know!

Hopefully it's not a leaky injector, if it is, do you trust a aftermarket brand? Or nut up $800 bones

 

Most here will recommend these guys...

late 90's denso started suppling oem injectors to toyota.....

Toyota Tacoma 2.4 2RZ, 2.7 3RZ, 4-Runner (CA Only) OE Replacement Fuel Injectors (fiveomotorsport.com)