Truck dies but revs and accelerates

Common answers from previous forums say it should be either the IAC or a fuel issue. I have no CEL so that's kind of sad.

With the truck being able to rev and accelerate, that should rule out a fuel issue, right? It turns on, goes to 300 rpms or so, runs a bit rough, and then dies.

It's not an issue with the MAF sensor, I've tried OEM, and 2 cheapo sensors that work in another truck flawlessly.

I'm thinking it's an IAC due to having a similar issue on the 4th of July. Truck is doing the same thing but once revved, it would stay on.

I'm at 165k so maybe it's time for a new IAC?


https://imgur.com/a/7beUFZu

 

The IAC would cause a high or rough idle- not for the engine to die.

Someone like @TnShooter might be able to give better trouble shooting steps, but it'd be looking at the open circuit relay or maybe a crank sensor.

 

It could be the IAC.
This video has everything you want to know about it, and how to test and/or replace.

https://youtu.be/agIRNNA-6cs?si=3ltzTwNjVxQfDlZL

 

Need a year and motor size... later tacomas have a drive by wire throttle and if she is of that vintage usually a cleaning of the throttle body cures that. Looking at the throttle for a build up of gunk couldnt hurt either. The Idle air control valve just bypasses the throttle plate with metered air. As a test you could adjust your throttle cable, if so equiped, to just crack the throttle and see is she starts and runs normally but at a higher idle.

 

I would look at the fuel pump and filter. Iac gives you erratic idling.

 

I've had erratic idle for a little. Changed maf sensor and it helped but my idle when cold is 1000 to about 500 and then it warms up to 1000 rpms. It then while driving will fluctuate all over the place

 

2002 3.4 so i do have an iac. I have a IAC gasket and throttle body gasket on the way, was planning to clean it this weekend but truck wont start even

 

Yepp I watched this video fully, was planning to check it out this weekend but ig I was too late

 

Impressive Cluster!

this was my IAC 212k before I took advice here to clean

 

Damn that's gross.

I'm finally going to work on my truck tomorrow. Thankfully I have a friend with the same exact truck so I can pretty much change every part that could be the failure. I'm hoping it's the Throttle positioning sensor because it's easy to fix. Most likely maybe an IAC or a fuel issue, I hope.

 

I’m not sure about 3.4L IAC
But
The 4 Phillips head screws that mount the IAC are known to strip when trying to take off
Once TB off
-use a HIGH quality screwdriver
Or
-manual hand impact



Makes life easier!!!

 

The reason they strip out is because theyre not philips. They're JIS screws or japanese industry standard screws. Another location is on the MAF sensor. I know this because I had to drill them out. I've considered buying a set but I'd rather drill out and replace rather than deal with those gimmicky screws

Thanks for the comment tho. What'd you clean the whole process with, just throttle body cleaner and Q tips?

 

i bought 2 cans brake clean
needed 3.5 cans
(i later learned that $17 gallon of Acetone(another member here told me) from home depot/lowes works the same....just not pressurized

old tooth brush(s) and awl (for the gasket ridge)

 

How would you apply the acetone? Just a paint brush and time or like a spray bottle? Also for the throttle body, i just use throttle body cleaner, right?

 

I just used BC

stiff brush for Acetone

my 96 TB is only mechanical (springs on outside of the TB)
No encapsulated gears in TB like newer 1st gen’s


Hope helps despite being a 2rz

https://www.tacomaworld.com/threads/throttle-body-iac-cleaning.819537/

 

Fuel pressure regulator
Vacuum leak

 

I might make a new thread about this for more publicity but my truck is back to normal, ish? I was talking about how my truck wasn't running at all but now it is.

All I did was unplug some sensors, the airbox system, fuck with the IAC a little bit, park on a hill, and now it's back to good. I'm going to replace the fuel filter and see if that changes anything. If not I'm going to swap the whole throttle body and iac into my truck and see if anything changes

 

Went to go out and see if my truck would start, it didn't. Goes to 300 rpms or so, stays alive for a little bit, and then dies. I'm going to replace the fuel filter. I have no clue why parking it on a hill would have any affect. Also it only seems to act up when the truck is cold. I've parked it on flat ground but the engine stayed warm so it started fine.

Maybe a temperature sensor went bad? I don't have any CEL so I'm confused.

Time to replace and put on two throttle bodies today...

 

Hmmmm

can you look at any data with a scanner?

I replaced my CTS
Then 3 months later taco wouldn’t start
At the time I just had small OBD2 reader, no realtime data.
But
Glamisman asked if my cheap reader would say CTS reading
I went through screens…found reading -40
Without a code popping, that temp reading pointed to bad CTS
Replaced for 2nd time…..Golden

 

I'm able to look at live data but I haven't been able to find any actual readings. From my very limited knowledge, everything looks decent. Do you know what the CTS is supposed to be at? Also it's somewhat hard to get readings when the truck won't stay on. I'll replace the fuel filter and put it on the hill, and then hopefully i can get some readings