Vacuum leak? (Page 1/2)
Wacko1Jacko12 MAY 17, 08:00 PM
Hi everyone,

I am having an issue where I will drive my car around for a while, and park somewhere. Come back and my car will start up and go up to 600RPM and then it will go down and die. I found out if I wait for about 30 minutes, I can start it up and it drives okay. Also, on my tachometer, sometimes it can be 0 RPMs in park (but engine is running) and sometimes it seems like it struggles to keep RPMs. Seems like on colder days my engine struggles to keep right amount of RPMs in the beginning but runs fine when driving more, and on hot days it seems worse I believe. I want to look at the codes but sadly I cannot even see them. Tried doing the paperclip test but the "check engine light" never even comes on to see the codes. Grant it I have a digital dash the owner put in previously and have no idea if he installed everything properly for it.

I also noticed on the back of my vehicle I have an air breather where a vacuum tube used to be on the back of the engine, could this be an issue? I hear a whistling sound somewhere and I believe it's just this.
Patrick MAY 17, 08:13 PM

quote
Originally posted by Wacko1Jacko12:

Tried doing the paperclip test but the "check engine light" never even comes on to see the codes. Grant it I have a digital dash the owner put in previously and have no idea if he installed everything properly for it.



Considering the previous owner also monkeyed around with the breather system, there's no telling what all has been done to this car.

Did you ever get the PROM and MAT situations resolved?

Plug a scanner and/or a cable for WinALDL into the ALDL port and find out what's going on with this engine.
Wacko1Jacko12 MAY 17, 08:34 PM

quote
Originally posted by Patrick:

Considering the previous owner also monkeyed around with the breather system, there's no telling what all has been done to this car.

Did you ever get the PROM and MAT situations resolved?

Plug a scanner and/or a cable for WinALDL into the ALDL port and find out what's going on with this engine.



I am ordering chip from sinister performance pretty soon (got in contact via email).

I wired up the MAT sensor and installed the original air intake canister (w/ its bracket, put a filter in there as well). Here are images of what I ended up doing for that:





I ordered a OBD1 scanner (comes with CD for drivers and cable) from Phonedawgz, should be here tomorrow or Monday.

I am not sure where in Tuner Pro you can see the codes however. I watched the videos he made about how to see real time values, but not sure where it says the codes?
theogre MAY 18, 01:57 AM
Vac leaks can cause 3 problems most times...
Leak is very small so ECM just adjust IAC to counter that but still has a vac leak & may affect other things.
Leak is Bigger to cause High Idle.
Leak is so Big Idle surfers or kill the engine. Example: Problem w/ brake booster vac line can do this but bad booster itself often does either of the above.

see https://web.archive.org/web...ierocave/vacleak.htm

------------------
Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave

cartercarbaficionado MAY 18, 02:35 AM

quote
Originally posted by Wacko1Jacko12:

Hi everyone,

I am having an issue where I will drive my car around for a while, and park somewhere. Come back and my car will start up and go up to 600RPM and then it will go down and die. I found out if I wait for about 30 minutes, I can start it up and it drives okay. Also, on my tachometer, sometimes it can be 0 RPMs in park (but engine is running) and sometimes it seems like it struggles to keep RPMs. Seems like on colder days my engine struggles to keep right amount of RPMs in the beginning but runs fine when driving more, and on hot days it seems worse I believe. I want to look at the codes but sadly I cannot even see them. Tried doing the paperclip test but the "check engine light" never even comes on to see the codes. Grant it I have a digital dash the owner put in previously and have no idea if he installed everything properly for it.

I also noticed on the back of my vehicle I have an air breather where a vacuum tube used to be on the back of the engine, could this be an issue? I hear a whistling sound somewhere and I believe it's just this.





test your icm and spray non flammable brake clean over the lines while running to find a vaccumm leak
my tach was bouncing around like yours due to a faulty icm and broken wiring to my tach filter
the whistling sound is not that breather since I have one on mine I installed a few days ago after my rubber intake boot split and I had to replace it, it is definitely a vacc leak or a broken intake gasket
Wacko1Jacko12 MAY 18, 08:23 AM
Thank you all for your suggestions, I sprayed around the vacuum lines and did not notice anything. However, I did find what appears to be where a vacuum line used to be and it is not even plugged up!
It was right under the throttle body. Should I just cap this off? I would rather understand where it went first and see if I need to reroute that line. Does anyone know where this vacuum line goes to? It also appears there is one capped off next to it as well.

Thank you for telling me about the brake booster, I had all my break lines and calipers rebuilt/checked. When I got it back from the shop the brake still felt spongy maybe that vacuum leak is a result or maybe its just the brake booster itself.

olejoedad MAY 18, 08:52 AM
For now, just cap it off.
Patrick MAY 18, 11:35 PM

quote
Originally posted by Wacko1Jacko12:

I hear a whistling sound somewhere...




quote
Originally posted by Wacko1Jacko12:

I did find what appears to be where a vacuum line used to be and it is not even plugged up! It was right under the throttle body. Should I just cap this off? I would rather understand where it went first and see if I need to reroute that line. Does anyone know where this vacuum line goes to? It also appears there is one capped off next to it as well.

CLICK FOR FULL SIZE



No wonder you hear "a whistling sound".

The smaller of the two ports on the underside of the TB is supposed to be connected to the EGR solenoid. The larger port is supposed to be routed to the fuel vapor canister. Does your engine still have either? Whomever worked on this Fiero prior to you buying it shouldn't be allowed access to a toolbox.

[This message has been edited by Patrick (edited 05-18-2024).]

Wacko1Jacko12 MAY 22, 12:39 PM

quote
Originally posted by Patrick:

No wonder you hear "a whistling sound".

The smaller of the two ports on the underside of the TB is supposed to be connected to the EGR solenoid. The larger port is supposed to be routed to the fuel vapor canister. Does your engine still have either? Whomever worked on this Fiero prior to you buying it shouldn't be allowed access to a toolbox.




1. I ended up plugging it off and replacing the cap next to it (old one was deuterated). My engine does not have a fuel vapor canister and cruise control. I know I do not need the EVAP canister, but I would like it back in (I like things original).

2. I then started my car and could still hear a whistle noise but not as bad (somewhere else there's a leak I bet). I will take a look based off this diagram. Thank you for sending that!

3. I then used Tuner Pro RT to see some data, surprised I did not see anything about the EGR and no-fault codes at all (hope I am reading it correctly). If there was an alarm, does it say FAULTED near the code?
-Makes me believe whichever owner at the time actually properly deleted the EGR on the chip (SHOCKED!).

4. Based off this data, is there anything concerning? I am not sure what most of these values are supposed to be close to during idle.



[This message has been edited by Wacko1Jacko12 (edited 05-22-2024).]

82-T/A [At Work] MAY 22, 01:09 PM

quote
Originally posted by Wacko1Jacko12:

Thank you all for your suggestions, I sprayed around the vacuum lines and did not notice anything. However, I did find what appears to be where a vacuum line used to be and it is not even plugged up!
It was right under the throttle body. Should I just cap this off? I would rather understand where it went first and see if I need to reroute that line. Does anyone know where this vacuum line goes to? It also appears there is one capped off next to it as well.

Thank you for telling me about the brake booster, I had all my break lines and calipers rebuilt/checked. When I got it back from the shop the brake still felt spongy maybe that vacuum leak is a result or maybe its just the brake booster itself.





Hah... oh man...

Only other thing I'd add here is that if you can, I'd try to find an original air canister to throttle body connector. That dryer hose really isn't great. The factory (replacement) connector is much better and will give you the correct flow you need... it's also a more gradual transition from large to small.