throttle surge on startup (Page 1/3)
novafish JUL 09, 08:35 AM
so i just finished replacing a valve cover gasket and installing the stainless steel vacuum lines from the fiero store on my 87 GT. it ran perfectly fine before i did this project. now however, whenever I start the car the throttle surges to redline and stays open. its as if someone is pressing the gas pedal. i looked at the throttle body and it feels fine, it doesn't look like its stuck open. any other possible places where there might be a significant enough leak to cause this? i dont have a ton of experience working on cars, especially old cars so apologies if this is a dumb question




Vintage-Nut JUL 09, 09:19 AM
Double Check all the Vacuum Lines including the brake booster line.....

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Original Owner of a Silver '88 GT
Under 'Production Refurbishment' @ 136k Miles

Patrick JUL 09, 02:59 PM

What the heck is this mess? Do you not have the proper fittings for where the PCV valve plugs into the valve cover? Is the PCV valve even there?
Patrick JUL 09, 03:16 PM
And why is there no heat shield on your alternator?

[This message has been edited by Patrick (edited 07-09-2024).]

82-T/A [At Work] JUL 09, 06:22 PM
I want to echo what Vintage Nut said... definitely check all the vacuum lines. You may have left one disconnected... or perhaps one of the plastic ones broke. Make sure you trace all of them. You should even hear a sucking sound. If the surging is as bad as it sounds though, it's more than likely the brake booster vacuum line.

Also, on what Patrick said, you definitely want to put back that heat shield for the alternator. With the exhaust manifold so close, you're basically cooking your alternator every time you're driving it.
Patrick JUL 09, 06:42 PM

quote
Originally posted by 82-T/A [At Work]:

...it's more than likely the brake booster vacuum line.



Keep in mind... if there's no actual PCV valve plugged into that "mess" around valve cover (or if the connections are as bad as they look), that there would be massive amounts of air being drawn into the intake manifold.
montegut JUL 09, 11:27 PM
I had the same thing happen when I replaced the vacuum lines on my 87 GT. I removed the throttle body and upper plenum to replace the lines. Then life happened. When I got back to finish the project a few weeks later and started it up, it went WOT! I then realized that when I put the throttle body back on the intake plenum, I had only finger tightened the throttle body bolts. Major air leak. I tightened it’ down and no more problem.


Go back and check all the vacuum lines, fittings and bolts. And PCV. I’ll bet you will find something simple you overlooked. Good luck!
novafish JUL 10, 10:00 PM

quote
Originally posted by Patrick:


What the heck is this mess? Do you not have the proper fittings for where the PCV valve plugs into the valve cover? Is the PCV valve even there?




ah yeah, i dont have the original fitting, when i bought the car it had the line going straight from the pcv valve to the intake manifold with that rubber elbow bit nowhere to be found. this was my makeshift solution in the meantime. i can't seem to find that fitting anywhere online though.
novafish JUL 10, 10:02 PM

quote
Originally posted by Patrick:

And why is there no heat shield on your alternator?






damn, didn't know there was supposed to be one. i bought this car less than 2 months ago and it came like that when i bought it. i will definitely try to get one though
theogre JUL 10, 10:44 PM
⚠️ Alt Heat Shield Missing maybe because has upgraded to CS130 & didn't fit.

Look @ side plug.
12SI plug only take 2 wires & nothing but only grease/oil if lucky to keep "water" out of it.
CS130 have space to take 4 wires in "water proof" plug.

See https://web.archive.org/web...~fierocave/cs130.htm

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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