Intermittent Stalling at Low Speeds/Braking/Deceleration

[beefsix]

** Fixed by replacing IAC and TPS.

Howdy partners,

My 1998 4runner 5VZ-FE 3.4L (257k miles) has been cutting out intermittently at low speeds or when decelerating and braking, or when in parking lots and driving r e a l s l o w ... It's getting quite annoying when I'm in the stop-and-go traffic and need to keep slapping it in neutral and starting it back up -- which it has done flawlessly each time. I fear for my transmission, however, so this needs to be fixed ASAP. Enough of the story, here's the quick rundown of the symptoms and fixes I've done:

=== Symptoms
* Intermittent stalling at low speeds
* Intermittent stalling at braking
* Intermittent stalling at deceleration
* All dash lights come on
* Starts up like a charm each time
* Sometimes hestitant at throttle from stop for a jiffy
* NO CODES!

=== Fixes
* New fuel injectors
* New fuel filter
* Cleaned IAC valve (I had suspected it was this prior, but I don't believe it is)
* Cleaned throttle body
* Talked nice to it repeatedly

Now, I'm wondering if it's the VSV or EVAP (Vapor) Canister as referenced by this lengthy thread: HELP! Intermittent Stalling, tried everything. (I have brought you to the final fix for the sake of brevity). I am also willing to try the crankshaft position sensor as indicated in that thread. Two questions, then:

1. How do I diagnose my VSV/EVAP canister as faulty?
2. How do I diagnose my crankshaft position sensor as faulty?

I can't seem to find these answers from a google search or my Chilton manual. Any help is very much appreciated, and I owe you a beer.

 

[heat]

Get the factory service manual. Chilton's won't cut it (obviously).

Crank sensor: [deleted] What I posted was incomplete. It requires
a scope and meter.

VSV:

 

[rexassian]

Also check the TPS - throttle position sensor. FSM has the procedure and expected resistance values. I'll add that it's way easier to remove the whole throttle body along with the TPS as those little philips screws are easy to strip trying to take it off from the backside.

 

[brillo_76]

The reason the Philip screws strip so easily is the are JIS Phillips. Not standard Philips. So if you get Japense Industrial Standard Philips kit in various sizes. The issue goes away unless they are really rusty...

Sent from my SM-A505U using Tapatalk

 

[repo]

I just fixed mine of something similar with a new TPS.

 

[brillo_76]

When my tps started to go it threw the CEL light. I replaced it a few days later. I had no symptoms though. I verified it was bad via the fsm tests and that was that.

Sent from my SM-A505U using Tapatalk

 

[cahilc]

Thinking differently...

Any weird transmission noises?

A flex plate going bad will give you a lot of those exact symptoms with no codes.

Just a thought.

HTH

 

[superhomunculus]

My first thought was the IAC, but you said you cleaned it. Could just need a new one though. I didn't see it mentioned, did you check for vacuum leaks? Also, check your fuel pressure.

 

[spartacus]

I would clean the maf test it also the tps.

 

[beefsix]

Thinking differently...

Any weird transmission noises?

A flex plate going bad will give you a lot of those exact symptoms with no codes.

Just a thought.

HTH

No, I don't hear any strange transmission sounds.

I just tested my VSV and I get an ohm reading of ~40.4 after the unit has been sitting in my house for a few days to get to roughly 68F. I'd say that's quite out of spec! I'll be getting a new one of those and reporting back to ya'll to see whats up. I'll probably grab a TPS too.

 

[beefsix]

I've been super busy and have fixed the stalling issue. I put in a new EVAP/VSV and that did not fix the stalling. Then I put in a new IAC and TPS and that fixed the stalling. I'd reckon that the IAC was the culprit, but I did not test it.