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| '87 Iron Duke Stalling (Page 1/1) |
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Homunculus
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JUL 23, 07:54 PM
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I was wondering if someone might have and idea as to what might be the cause of the strange performance of my Fiero. It's a 1987 SE 2.5l Iron Duke with a 5 speed manual transmission. Essentially what has been happening is the vehicle has been inconsistent at idle, specifically lower RPM. It starts up every time, but will then either hold an idle of 1k or stall if you don't pulse the throttle. Initially, I thought that it might be the fuel pump going, but I've been able to get the car up to highway speeds and maintained them without any variation in speed. That and the fact that the car starts up every time led me to think that it might not be the fuel pump going (I know that doesn't entirely rule out the fuel pump since I haven't done a fuel pressure test yet). When the car fails to sustain idle, it runs extremely rich and will stall if the throttle is slowly depressed, but I'm not getting an engine code for a rich exhaust. Given that the air-fuel mixture is improperly balanced, I can't get the car up past 2k RPM when it's like this. Below 1K, the car bucks and stalls. My current guess is that there's something wrong with the TBI and the fuel injector more specifically. I'd like to test it, but I'm not quite sure the best way to do so.
Any ideas as to what it might be would be greatly appreciated
Engine Codes:
-25 (All of the literature/online sources I've found say that this code is the MAP sensor in the V6)
-44 (Exhaust is rich, but I'm getting a code for lean)
Symptoms:
-Irregular performance. Sometimes normal, other times poor
-Running rich while performing poorly
-Unable to maintain idle while performing poorly
-Stalling
-Bucking under 1k RPM while performing poorly
-Increased fuel consumption
List of new/ checked parts
-IAC valve
-EGR valve
-TPS
-O2 Sensor (new from previous owner)
-TBI (new from previous owner)
-Exhaust manifold
-Vacuum lines (checked for leaks)
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shemdogg
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JUL 24, 02:30 AM
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Check your fuel pressure but it sounds electrical. Check all your grounds and the ecm connectors
shem
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theogre
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JUL 24, 10:31 AM
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Do you have old TBI? Likely nothing was wrong w/ it.
New TBI likely needs to check fuel pressure and idle stop but hard to set the stop w/o good idle.
Check for vacuum leaks again. Vac leaks can cause high idle and DTC 44. Move the rubber/plastic lines to open up cracks.
DTC 25 is NOT MAP but MAT and is valid for this motor. MAT could be bad (common), bad wires or plug(maybe), or unplugged.
Check/replace plugs and wires. Problem w/ either or both makes DIS engines very unhappy.
Could be ECM is dying... Overheated ECM can cause weird problems. pull console and see if problems go away. If Does then get a new ECM. Save the PROM!
New Exhaust manifold likely means old one broke? Then look of melted wires etc.
See my Cave, 700 TBI, Idle Stop, TBI Test Adaptor, Vac Leaks, DIS Ignition, ECM Heat and likely other pages.
------------------
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[This message has been edited by theogre (edited 07-24-2017).]
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KurtAKX
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JUL 24, 10:45 AM
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| quote | Originally posted by theogre:
DTC 25 is NOT MAP but MAT and is valid for this motor. MAT could be bad (common), bad wires or plug(maybe), or unplugged.
Check/replace plugs and wires. Problem w/ either or both makes DIS engines very unhappy.
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^This.
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85tbi
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AUG 15, 07:49 AM
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Did you ever figure it out
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