I am stumped with my 84......
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Pro
Joined: Dec 2002
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From: 84 383 XFire Chandler, AZ
I am stumped with my 84......
I was cruising down the freeway and the motor just died. It acted like it was out of fuel. Then it picked back up and I was limp home.
The real odd thing is the motor idles rough and the injectors spurt in a rythmic manner and they are just dumping fuel. I checked the o2 voltage with winaldl and it is pegged at 1.065v but there are no codes. I expected a rich reading but that seems a tad out of wack. I also just unplugged the map sensor and I got a code 34 which is the map sensor voltage low. So I assume the ecm is working properly. I have checked everything, o2, map, ignition module etc.
Needless to say I am stumped.
The real odd thing is the motor idles rough and the injectors spurt in a rythmic manner and they are just dumping fuel. I checked the o2 voltage with winaldl and it is pegged at 1.065v but there are no codes. I expected a rich reading but that seems a tad out of wack. I also just unplugged the map sensor and I got a code 34 which is the map sensor voltage low. So I assume the ecm is working properly. I have checked everything, o2, map, ignition module etc.
Needless to say I am stumped.
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Joined: Sep 2000
Posts: 17,298
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From: The Top of Utah
My ECM seems reluctant to show codes. Often my car is so rich you can smell it and see black smoke, but it doesn't set a code. In fact, the only code I have ever seen was a "34", once, when the MAP was inadvertently left unplugged. I think that the abacus used in our '84s are lightyears behind all the other C4 ECMs. Your dieing episode may have been a temporary shutdown of the fuel pump. Your 1.065 volt reading indicates a rich mixture, which you are describing. I would start by looking at the wiring, especially to and from the aba, I mean ECM. IF the ECM were to receive the 1+ volt reading, it should go lean to correct the rich mixture. I agree, that is an interesting problem.
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Joined: May 2002
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From: Kalama WA
I'm not an expert on 84's by any means. But if your information is correct, something is telling the injectors that the engine needs more fuel. I'd start by finding out what sensor or sensors call for fuel. Also check proper fuel pressure and or faulty pressure regulator. Being that the injectors are dumping fuel, the ecm is being told to supply. O2 sensors are strange- I had one that never threw codes and was just plain not working. Bad fuel with contaminants will wreck havic on fuel system. Wiring problems will also cause ecm to incorrectly provide proper fuel amount- aka shorted wires. Hopefully you have a factory service manual. It is the wealth of information.
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Joined: Sep 2000
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From: The Top of Utah
I had originally written to check the fuel pressure, but after the forum (?) dumped my post and reread yours, I decided that wasn't applicable. BUT, kize's post make me wonder if some foreign material didn't temporally block off your fuel supply and cause your engine to die. Then it may have worked it's way up to the regulator and (partially) blocked it. You could check the fuel pressure, or it is reasonably easy to pull the regulator apart and have a look.
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Joined: Dec 2002
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From: 84 383 XFire Chandler, AZ
Oddly enough I did fill the tank before I headed out. This occurance happened on the return trip. Hmmmm.... bad gas?
My fuel pressure is good - I have it set at 18lbs. I am running a 383 with 90lb injectors and 2.13" TBs. The fuel pressure was set when I originally fired the motor back in May and it has not changed..... I also have a fuel pressure gauge between the TBs and the reading is correct.
I have another ECM (Prominator Pro) and I may just throw it in for giggles.
My fuel pressure is good - I have it set at 18lbs. I am running a 383 with 90lb injectors and 2.13" TBs. The fuel pressure was set when I originally fired the motor back in May and it has not changed..... I also have a fuel pressure gauge between the TBs and the reading is correct.
I have another ECM (Prominator Pro) and I may just throw it in for giggles.
Last edited by elkabong; Dec 17, 2005 at 12:40 PM.
Thread Starter
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Joined: Dec 2002
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From: 84 383 XFire Chandler, AZ
Dom - Yep there is a XRam sitting on top. Why do you ask? I agree it sure does seem like limp home mode. I have checked the EST visually but not with a ohm meter. I have the dizzy out becasue I noticed a little oil on the back of the manifold and I need to put in a small shim to seal it off. I am also going to check the ignition components with a ohm meter while it is out.
It has to be ignition related or possibly my ECM is having problems.
It has to be ignition related or possibly my ECM is having problems.
