(New to Fieros) High Idle, Bad MPG, and Stalling in 86 GT (Page 2/2)
Jeffdylanproctor JUN 27, 12:18 PM

quote
Originally posted by Vintage-Nut:

Check the eight plastic vacuum lines for leaks as they can get brittle over time; the vacuum line to the EGR valve gets a lot of heat from the exhaust manifold.




Are there any diagrams out there of how these 8 vacuum lines are routed?
Vintage-Nut JUN 27, 01:38 PM
I have a diagram of the SIX plastic vacuum lines under the plenum, however not a photo.....

(2) Under Throttle Body: one to the EGR solenoid, the other to the dual vacuum connecter next to the PVC
(1) EGR Valve to the EGR solenoid
(1) Plenum side next the distributor to the dual vacuum connecter next to the PVC
(1) Fuel Pressure Regulator (on the rail) to a 'T' at the plenum side and also go to the MAP Sensor
(1) Under plenum to the PVC

EDIT: The big (3/8") vacuum line on the plenum side next to the MAP Sensor goes to the brake booster. Test the line from the plenum to the booster.

[This message has been edited by Vintage-Nut (edited 06-27-2023).]

Jeffdylanproctor JUN 27, 08:09 PM
Update: I picked up a new coolant sensor today, and upon removing the old one I found that it was broken in half (the plastic section with the plug was totally detached).

So that sensor was for sure bad, and now I am trying to get the intake sorted out so I can start it and see if that helped with the problem.
Jeffdylanproctor JUN 27, 09:02 PM
I replaced the Coolant Temperature Sensor beneath the thermostat (the plastic was broken) and the car started up fine and after a few minutes it idled down to 1000 rpm or less. The codes also went away, though I had also disconnected the battery for about an hour before starting.

So, it appears the ECM Coolant Temperature Sensor issue may have solved the high idle problem!

Also when installing the intake plenum last night at 1am I accidently caught a ground wire in between the plenum and lower intake, which must have produced the severe vacuum leak thus the wide open throttle.

When doing this I found that the air filter was extremely rotten, so much so that it was impressive.

Thanks everyone for the advice.

[This message has been edited by Jeffdylanproctor (edited 06-27-2023).]