holding brakes causing bad idle? Also missing vacuum hose (Page 1/2)
tricktickler JUN 22, 06:21 PM
86 SE V6. I have engine code 35. The service engine light comes on while stopped in traffic, when the engine starts lugging while holding the brakes. 100% there is a correlation with the idle and brakes as I can let off and the engine idles more normal.

Also I have a vacuum hose, that I assume, leads from under the air filter housing to the metal tube along the firewall, but I don't know where the hose on the other end is supposed to go to. Any help with that?

I am quite a novice mechanic. Had this car since April.
tricktickler JUN 22, 08:54 PM
I've found posts on google and here about the metal tube at the firewall, but haven't found a direct answer. Only people asking the same question as me.

It is such a mystery to me.
I know the regular vacuum lines are all plastic and seem to be intact. The engine light is off and I can drive miles until finally I have to stop in traffic it comes on and It feels like the car will stall, but I let off the brakes and it idles normally.
Patrick JUN 22, 11:34 PM

quote
Originally posted by tricktickler:

I've found posts on google and here about the metal tube at the firewall, but haven't found a direct answer.



That metal tube on the firewall has been explained here at least a hundred times over the years. It used to be part of the original PCV system, but was disconnected and replaced during a recall. The end is supposed to be blocked off. Otherwise, engine bay air gets sucked through it into the filtered side of the air filter canister.

[This message has been edited by Patrick (edited 06-22-2019).]

tricktickler JUN 22, 11:54 PM

quote
Originally posted by Patrick:

That metal tube on the firewall has been explained here at least a hundred times over the years. It used to be part of the original PCV system, but was disconnected and replaced during a recall. The end is supposed to be blocked off. Otherwise, engine bay air gets sucked through it into the filtered side of the air filter canister.




I havnt owned a fiero for long enough and havnt found relevant results from searching. It doesn't matter? out of interest, where does the passenger side of the metal tube lead to?

What about my brake booster system? what is most logical thing to do now that I am 100% certain the engine runs fine til I am holding the brake pedal down?
Patrick JUN 23, 12:16 AM

quote
Originally posted by tricktickler:

I havnt owned a fiero for long enough and havnt found relevant results from searching. It doesn't matter? out of interest, where does the passenger side of the metal tube lead to?



It only matters if the end of the tube hasn't been blocked off.


quote
Originally posted by tricktickler:

out of interest, where does the passenger side of the metal tube lead to?



You referring to the now disconnected end? It used to connect to the front valve cover.


quote
Originally posted by tricktickler:

What about my brake booster system? what is most logical thing to do now that I am 100% certain the engine runs fine til I am holding the brake pedal down?



I've heard of a poor taillight ground causing issues... as from what I understand, the brake lights draw a fair amount of current when applied. There are pictures posted where the taillight ground is located. It's attached to the passenger side upper frame rail above the rear wheel well liner.
viperine JUN 23, 04:18 AM
What is your idle speed when fully warmed up, at a stop/redlight? Vacuum leaks like the EGR tube or EGR valve gasket are likely. Code 35 pops up in closed loop and says the closed loop idle is too high. A scan tool will read the idle accurately. Your instrument cluster is quite inaccurate. It can be a help for obvious differences in values, but a scan tool will tell you what the computer sees, and furthermore tell you why the computer is igniting your SES light.
tricktickler JUN 23, 09:47 AM

quote
Originally posted by viperine:

What is your idle speed when fully warmed up, at a stop/redlight? Vacuum leaks like the EGR tube or EGR valve gasket are likely. Code 35 pops up in closed loop and says the closed loop idle is too high. A scan tool will read the idle accurately. Your instrument cluster is quite inaccurate. It can be a help for obvious differences in values, but a scan tool will tell you what the computer sees, and furthermore tell you why the computer is igniting your SES light.


True I will have to invest in one. My tach doesnt really work at all. If the needle is not stuck itll idle around 4k rpm which I assume is about 1k, but while holding the brakes, the rpms start to drop almost as if it will stall.
tricktickler JUN 23, 09:04 PM
http://www.fiero.nl/forum/A...090219-2-079337.html

I found this thread. Sounds like the same problem and he fixed it with a new distributor?

Also I do see the brake booster check valve is leaking brake fluid. Ordered a new one. Was driving around today and pulled the E brake at stop lights instead of using the brake pedal and the SES light still came on.
Patrick JUN 23, 10:29 PM

quote
Originally posted by tricktickler:

Also I do see the brake booster check valve is leaking brake fluid.



Say what?

tricktickler JUN 24, 08:16 AM

quote
Originally posted by Patrick:

Say what?



I mean it may be coming from elsewhere, but I can see its wet.