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| High idle cracked manifold (Page 2/2) |
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GabeBjerk
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MAY 12, 08:23 AM
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GabeBjerk
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MAY 12, 08:31 AM
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82-T/A [At Work]
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MAY 12, 12:07 PM
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Oh **** ! You have an 87 SE/L4... that's like one of the rarest Fieros made. People will balk at this, because it doesn't in fact mean that it's more valuable... but there were only 1,401 of those ever built. I've only ever seen one in person, and there was one other person on here that had one. All of them were medium metallic red (what yours is).
I mean, that doesn't help you, but it's kind of cool. Basically, they took what would have essentially been a 4 cyl coupe, and then stuck all the V6 stuff on it, including the dual exhaust, aero-package (like on the 84 Indy), with all the SE trim, and many of them even got the auxiliary gauge cluster.
I don't know if it'll ever be worth more or less than any other Fiero... but it was essentially the rarest / lowest production number Fiero out of any of the models... so long as you're not counting a Fiero MERA, or a T-TOP Fiero as a model (which it isn't because it's an option).
Anyway, back to your problem...
Going to 1,100 rpms on startup is actually quite normal until it warms up (and should drop to about 700-800). But the easiest way to diagnose this problem now, is to start the car at various points after it's cooled off, and each time, have a new vacuum line reconnected back onto the intake manifold. As soon as you start the car and it jumps back up to 2,000 rpms... you've identified the SOURCE at least of your vacuum problem, and then you can follow / trace that vacuum line to wherever it's connected to on the other side. My guess is likely the brake booster or something like that.
Let us know...
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GabeBjerk
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MAY 13, 10:23 AM
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So I started hooking up the lines to find the leak and I found that when you hook up the map sensor it revs back up to 2000rpms. So i'm guessing it's broken.
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82-T/A [At Work]
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MAY 13, 03:36 PM
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| quote | Originally posted by GabeBjerk:
So I started hooking up the lines to find the leak and I found that when you hook up the map sensor it revs back up to 2000rpms. So i'm guessing it's broken. |
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Yes, either the MAP sensor is bad, or the map sensor vacuum line itself is bad.
You can diagnose this by disconnecting the pigtail on the MAP sensor (with the vacuum line connected), and then starting the car. If the idle is fine, then the MAP sensor is likely bad. If the idle is still high, then it's the vacuum line itself that's bad.
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GabeBjerk
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MAY 13, 08:23 PM
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I capped all the vacuum lines and it went to 1500rpms. then I hooked up a good map sensor without the plug and it stayed the same but when I plugged it in it went right up to 2500rpms. I don't know why it does that.
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82-T/A [At Work]
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MAY 14, 12:02 AM
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| quote | Originally posted by GabeBjerk:
I capped all the vacuum lines and it went to 1500rpms. then I hooked up a good map sensor without the plug and it stayed the same but when I plugged it in it went right up to 2500rpms. I don't know why it does that. |
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If I'm not mistaken, disconnecting the MAP also puts it into "Limp Mode," which means the ECM is defaulting to the use of some other sensors, like the O2, TPS, and one other (I think). I guess the good news here is that you don't actually have a vacuum leak... which is usually the culprit. But I'm kind of at a loss.
The only thing that I think is frustrating though, is that most new sensors that you buy are going to be made in China, so they produce garbage voltage results which often cause erratic behavior. I think you said the check engine light doesn't come on either, right? So it sounds like it's just running a bit high and trying to warm up... though that is certainly not ideal for the engine to be blasting to 2,000 rpms the second it cranks over.
Gunna hope that some other people have some advice too...
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Patrick
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MAY 14, 01:13 AM
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Okay, full disclosure. I've been ignoring this thread because it ticks me off that people don't indicate in their opening post what year Fiero they have and which engine it has. So much time and bandwidth is wasted with people giving advice for the wrong engine and/or year Fiero. Totally unnecessary.
Alright, with that out of the way, read this thread... '88 2.5L Duke high rpm on start-up normal? Except for the oil filter mount and internal balance shafts, the '87 and '88 dukes are very similar.
As stated in that thread, I had an '87 duke (was my first Fiero)... and I hated that engine.
And make sure to also click on the two hyper-links I posted in that thread.[This message has been edited by Patrick (edited 05-14-2023).]
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GabeBjerk
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MAY 14, 09:17 AM
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82-T/A I tried a MAP sensor that was good from a 94 chevy and it did the same thing as the brand new one. And the check engine light is off.
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GabeBjerk
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MAY 14, 09:37 AM
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So I let it idle at 2500rpms and after 2-3mins it went to 800-1200rpms then it dropped to 600rpms and died now it won't run it starts goes to 1000rpms and right away dies.
Never mind it just ran out of gas![This message has been edited by GabeBjerk (edited 05-14-2023).]
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