Bad Idle & Stalling

gamefreakgc

gamefreakgc

Elite Member
I'm looking for suggestions on what to look at next. My 4Runner stalled on me in the middle of the Nevada desert two weeks ago and has been stalling fairly consistently since. The roads were were on were graded and I didn't take them fast so I don't think anything is damaged from vibration. We did maybe 5 miles off-road, the rest was highway driving.

I've done the following since then:

  • Replaced IAC valve with brand new Toyota unit
  • Swapped MAF sensors
  • Checked all wires, hoses, grounds
  • Fuel trims are normal (high trims would indicate a vacuum leak)
  • No CEL, not even a pending code. I think this rules out injectors or plugs.

Nothing on my OBD-II reader is out of place except for idle speed. In drive it idles around 500-550 and then will stall, especially when first coming to a stop. In park it idles at 550, before this is would idle at 750. Has a slight lope/misfire when it idles near 500.

I did top of the coolant reservoir tank recently after doing some work on the cooling system (e-fan broke) but I did spill some coolant so that could be all it was. No smoke or smells that are out of place either. Really, really stumped on this one.
 
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T4topher said:
Throttle position sensor maybe or bad gas?
Click to expand...

You know I did think about gas. I filled up in Nevada but I've run a full tank since then, unless there's some left still. I would imagine that running most of it out would be ok though. I do plan on picking up some injector cleaner just in case.

Throttle position sensor may be a contributor. I'll get this thing home and unplug the sensor and see if that changes the idle speed.
 
gamefreakgc said:
You know I did think about gas. I filled up in Nevada but I've run a full tank since then, unless there's some left still. I would imagine that running most of it out would be ok though. I do plan on picking up some injector cleaner just in case.

Throttle position sensor may be a contributor. I'll get this thing home and unplug the sensor and see if that changes the idle speed.
Click to expand...

Might want to also check the evap canister/solenoids on the canister, there is a testing procedure with a vacuum pump that is in the service manual.
 
Can anyone with access to OBD data post up what you see the Throttle Position % when at idle and post what that percentage is and what the idle RPM was when the data was taken? I don't know what normal is so the data I have doesn't help without a baseline.
 
gamefreakgc said:
Can anyone with access to OBD data post up what you see the Throttle Position % when at idle and post what that percentage is and what the idle RPM was when the data was taken? I don't know what normal is so the data I have doesn't help without a baseline.
Click to expand...

I tested both my 3rd Gens, my 1998 and 2000

My 98 gave a value of 11.37% and that value didn't change once the engine got warmer and reached operating temp. I did give some throttle response and the value would climb and then go back down to 11.37%. The cold idle was around 1150 rpms and the warm idle was around 700 rpms.

My 2000 gave a value of 8.63%. The 8.63% value also did not change as the engine heated up and the rpms dropped. My cold idle and warm idle were pretty much the same as my 2000, 1150 rpms cold and 700 rpms warm.


Below is a page out of my 2000 FSM regarding testing the TPS.

TPS.jpg
 

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When you get injector cleaner get two bottles of dry gas also. Or put around 6oz of acetone in the tank.

Both 97’s are 11% at closed throttle.

Your LTFT was normal?


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19963.4lsr5 said:
When you get injector cleaner get two bottles of dry gas also. Or put around 6oz of acetone in the tank.

Both 97’s are 11% at closed throttle.

Your LTFT was normal?


Sent from my iPhone using Tapatalk
Click to expand...

Will do. The wife always keeps a supply of acetone in the bathroom, also known as "nail polish remover".

I got a reading of 11% at closed throttle as well, so TPS looks good. I think my throttle valve is sticking though. Going to give it some R&R and noticed the vacuum hose on the throttle body is cracked as well, that most definitely could throw it off.
 
gamefreakgc said:
Will do. The wife always keeps a supply of acetone in the bathroom, also known as "nail polish remover".

I got a reading of 11% at closed throttle as well, so TPS looks good. I think my throttle valve is sticking though. Going to give it some R&R and noticed the vacuum hose on the throttle body is cracked as well, that most definitely could throw it off.
Click to expand...


What’s your MAF at a hot idle?


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mtbtim said:
I tested both my 3rd Gens, my 1998 and 2000

My 98 gave a value of 11.37% and that value didn't change once the engine got warmer and reached operating temp. I did give some throttle response and the value would climb and then go back down to 11.37%. The cold idle was around 1150 rpms and the warm idle was around 700 rpms.

My 2000 gave a value of 8.63%. The 8.63% value also did not change as the engine heated up and the rpms dropped. My cold idle and warm idle were pretty much the same as my 2000, 1150 rpms cold and 700 rpms warm.


Below is a page out of my 2000 FSM regarding testing the TPS.
Click to expand...

Thank you once again Tim! I only have the free online one for the 2002 so it didn't have the full testing procedure since the TPS changed. Turns out VC-E2 is out of spec under vacuum and has a reading of 7.9K ohms. Max is 5.9K ohms. New TPS it is.
 
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gamefreakgc said:
Thank you once again Tim! I only have the free online one for the 2002 so it didn't have the full testing procedure since the TPS changed. Turns out VC-E2 is out of spec under vacuum and has a reading of 7.9K ohms. Max is 5.9K ohms. New TPS it is.
Click to expand...

You're welcome Jerod. I'm curious, what did you use to apply vacuum to the hose?
 
mtbtim said:
You're welcome Jerod. I'm curious, what did you use to apply vacuum to the hose?
Click to expand...

A vacuum, go figure. I have a 20V hand held vacuum that has a pretty narrow opening with good suction so I just stuffed a long piece of vacuum tubing inside, taped it up airtight and put the hose on the vacuum barb on the throttle body. I've done this a few times for diagnosing and works like a charm.
 
gamefreakgc said:
A vacuum, go figure. I have a 20V hand held vacuum that has a pretty narrow opening with good suction so I just stuffed a long piece of vacuum tubing inside, taped it up airtight and put the hose on the vacuum barb on the throttle body. I've done this a few times for diagnosing and works like a charm.
Click to expand...

Good MacGyering with the handheld vacuum.
 
I just replaced my tps as well actually cause I got a p0120 code on the last camping trip I went on.. Just went on a test drive, I used to have a slight hesitation/felt like it was going to stall occasionally after coming out of a stop but now it seems like it’s gone. Hoping it stays that way.. Curious to see if it fixes your problem.
 
gamefreakgc said:
Thank you once again Tim! I only have the free online one for the 2002 so it didn't have the full testing procedure since the TPS changed. Turns out VC-E2 is out of spec under vacuum and has a reading of 7.9K ohms. Max is 5.9K ohms. New TPS it is.
Click to expand...


The tps has a vacuum port?


Sent from my iPhone using Tapatalk
 
Could be a bad fuel injector, bad spark plugs, bad coil. What cylinder? Swap the coil on the bad cylinder and see if the issue migrates to test the coils.

My 2005 SR5 with 150,000 miles has never had a miss or CEL. No offroading.
My evaporator coil just failed. Second time. The first time was in 2009 when the dealer replaced one. I paid $800 for that job. You have to take down the dash to get to the evaporator. Big job. labor-intensive. :hunter:
 
My 01 has had a quirk for a bit that I think is TPS related, dead/hesitation spot, leaving stop at 2-3 shift point speed.
Been waiting to see if code would set, going by posted you don't always get a code. Hhmm, wonder what set's the code.
[MENTION=115347]gamefreakgc[/MENTION], good thinkin with Vac. On the bright side not a problem finding 3 wire TPS not so with 4-wire year ago 1 place had them, guess it time to put it on.
 
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