86 Camaro Quits Taking Gas But Idols When Warm - Team Camaro Tech
Troubleshooting Diagnosing problems done here.

 
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post #1 of 8 (permalink) Old Feb 4th, 03, 02:53 AM Thread Starter
 
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I have a 1986 2.8 Liter Fuel Injected Camaro. I have replace the Throtle positioning sensor, Fuel Pump, Fuel Filter, and mass air flow sensor. When it is cold and sits for a long time it starts and runs fine. When I stop for the first time and turn the car off when I get back in it it will run sometimes but other times I will be driving and it will just quit taking gas while i'm driving and pushing on the gas pedal will kill the engine. It idols fine, it just won't take gas. I replace the fuel pump and filter and I have checked that I do have fuel pressure during this problem. If I let the car sit for a while it will re-start and work fine again. Everytime I take it to a mechanic it works fine, the failing is intermitent but usually happens once a day. I have been pulling my hair out for a year on this with no luck. Any help would be appreciated.
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post #2 of 8 (permalink) Old Feb 5th, 03, 10:25 AM
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Hi Timmy,

Im thinking about the oxygensensor in the exhaust is causing the problem.

this sensor "snifs" for too much or to less oxygen in the exhaust and sends it to the computer.
BUT this sensor must be feed with 12 volts!
So if your battery is kinda low this sensor wont give good measurements to the computer and therefore the computer will be send too much/less fuel to the engine.

When your engine is hot and you start the engine, the starter is taking much more power from the battery then it normally would,(because the heat makes the baerings in the starter expand) so the battery isnt full after the hot start, and therefore the oxygensensor is not getting the volts it needed

replace it with a new sensor and make sure your battery is good and fully charged

[This message has been edited by rolling-robert (edited 02-05-2003).]
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post #3 of 8 (permalink) Old Feb 5th, 03, 03:22 PM
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A faulty ignition can cause this as well. Pressing the accellerator causes cylinder pressures to increase. Ignition system problems are typically worse at higher pressures. Is this a distributorless ignition system?

-dnult
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post #4 of 8 (permalink) Old Feb 5th, 03, 03:27 PM
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is the Service Engine Soon light on? if so, scan that for codes and tell us whats wrong. personally, it sounds like some sort of o2 sensor problem, or even a coolant temperature sensor problem. when you replaced the TPS, did you recalibrate it to the manufacturers specs?

rolling-robert, is there a 12 volt refrence on the 86 models? the o2 sensor produces voltage, it does'nt run off it. there is one wire coming from the sensor to the PCM. it reacts with the oxygen content in the exhause to produce a signal voltage between .1 and .9 volts.

[This message has been edited by nate (edited 02-05-2003).]
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post #5 of 8 (permalink) Old Feb 5th, 03, 07:40 PM
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if there is only 1 wire coming out of the oxygen sensor then its NOT fed by 12 volts.

my oxygen sensor have more wires 2 for getting 12 volts and the other(s) for sending the signas to the computer

So im wrong in this case then

i still advice to replace the oxygen sensor anyway

[This message has been edited by rolling-robert (edited 02-05-2003).]
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post #6 of 8 (permalink) Old Feb 6th, 03, 12:44 PM
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Sure, you can try to replace the O2 sensor. Problem is, without the proper diagnostic equipment and knowledge, you may end up spending a heap on parts only to find out it's a vacuum leak to the fuel pressure regulator, bad ground, bad ignition coil etc. No guarantees that an O2 sensor will fix it. Actually I would expect the computer to set a code and go open loop if the O2 sensor was bad and suspect you have a different problem. BTW: 12volt supplies to the O2 are for heating of the element.

-dnult
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post #7 of 8 (permalink) Old Feb 6th, 03, 02:16 PM
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oh, heating of the element. for quicker emission control. ok. yes, if you don't scan it for codes, then your chances of guessing the faulty sensor are not good. timmy, do you have a haynes manual? they tell you how to access your computer's memory and pinpoint the faulty sensor or circuit. any past codes or current codes will be recorded as a fault code in the PCM's memory and trigger the Service Engine Soon light.
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post #8 of 8 (permalink) Old Feb 7th, 03, 01:20 PM
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Also, does the check engine light come on for a few seconds when starting the car? It should, as a lamp test. I've seen the lamp burn out (or removed) so you're not aware that codes are set.

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