Troubleshooting: Running hot > hanging throttle + wanting to stall

[Vovchandr]

I'll appreciate any help I can get on the matter but this is more of a way to me to drop things down in one place and keep the thought flow going. Maybe see if anybody else has similar issues

 

This left me temporarily stranded and having to push the car uphill at night on the highway, so I hope nobody will have to go through the same thing as me in the future.

 

I have trapped air problems in the over flow like others do

 

see

http://www.usa7s.net/vb/showthread.php?12847-Foaming-expansion-tank-at-revs-coolant-overflow-what-tank-do-I-have

 

This could potentially lead to a head gasket, which is something on the pending list.

 

 

Problem:

 

Car runs fine. Car idles for a while/gets stuck in traffic and starts to run hotter. From dead middle at 80 to creeping into 100 degrees or so.

 

At the same time throttle starts to hang a lot more and as of yesterday even started bouncing off the rev limiter with no further input. "run away revving" if you will.

 

While the running hot is an issue of its own, rev hang/acceleration is more of a problem.

 

Comments

• Pedal is coming back without an issue
  
• I've added extra springs to my ITBs to help the return
  
• I've adjusted the feed of the throttle cable to give it max slack possible
  
• The throttle problem seems to only happen once it starts to run hot and doesn't happen throughout the entire "running hot" period. Seems to happen and then go away/diminish as I continue on my trip
  
• TWM ITB's have never been serviced officially but have been taken apart and inspected during last event of working on the motor
  
• Sudden throttle snapping back has had varied success in the hanging throttle event. Sometimes it works, sometimes it doesn't
  
• As the car is having the running hot event, it occasionally wants to slowly sputter and stall at idle. Giving it mild throttle helps
  

 

Things that have been measured/tested

• ITB's flow has been tested. 3 are pretty matching at "7" at idle on the meter. One at "9"
  
• Compression test was good
  
• Leak down test was good
  
• Exhaust gasses contamination in coolant was a pass
  
• Disconnected the IAC hose to see if that causes a run away situation. My revs went to 3500 and stayed there. No run away event
  

 

Things to look at still

• Inspect the butterflies carefully
  
• Consider TPS being an issue
  
• Would eliminating running hot solve my problem? > Do water pump/head gasket
  

 

Questions with no answers

• Why is running hot causing the throttle issue > which parts could the heat be effecting
  
• Why is running hot causing the car wanting to stall/fail to maintain idle?
  
• Why does the issue seem to diminish/go away with time even if running hot
  
• What caused the recent run away/bouncing off the rev limiter event?
  
• What is causing the revs to hang/even accelerate without an input from the throttle?
  

[Vovchandr]

Since everybody likes pictures

 

This problem was part of chain of problems that left me stranded yesterday.

 

Car was running hot at idle at rest area

 

Revs were starting to be a little hangy but I thought it would be fine

 

Get on the highway just to have a run away rev situation with revs bouncing off rev limiter

 

Pull over and shut the car off.

 

Go to restart the car just to have immedeate full loss of electrical power. Taking out the hazards, at night. Convenient.

 

Had to push the car back uphill to rest area to troubleshoot as I didn't feel safe on highway without hazards at night.

 

Sign was very appropriate

 

 

 

Sent from my Pixel 3a XL using Tapatalk

[Pokey]

Oh man, sorry, not fun.

 

This doesn't explain all of the symptoms, especially the racing idle, but have you considered that perhaps you are suffering vapor lock?

Edited July 30, 2020 by Pokey

[ashyers]

My vote is a loose butterfly or misaligned linkage. Please don't drive it until it's sorted! A 7 stuck at WOT is not a good place to be.

 

Edit/Addition:

Is your throttle cable near a heat source (exhaust)? I've seen the plastic inner lining of some cables get soft and grab the inner cable leading to a "gummy" feel.

Edited July 30, 2020 by ashyers

[Croc]

Sorry to see this one Vlad. Bit a weird bunch of symptoms. Throttle linkage or throttle bodies would be revs situation. Did your alternator stop working and you had been on battery all the time - hence the electrical meltdown?

[Vovchandr]

Sorry to see this one Vlad. Bit a weird bunch of symptoms. Throttle linkage or throttle bodies would be revs situation. Did your alternator stop working and you had been on battery all the time - hence the electrical meltdown?

 

Electrical meltdown was due to battery losing ground.

 

Disconnecting and reconnecting the terminals got me power back and allowed me to troubleshoot further that day.

 

I'm thinking of disconnecting cable entirely at the bodies next time I catch the issue at home or elsewhere convenient to help partition out cable entirely.

[coffee break]

Does the ECU store run data?