85 Camaro won't idle without gas & running rich after battery disconnect

Asked by Apr 19, 2017 at 04:50 PM about the 1985 Chevrolet Camaro Z28 Coupe RWD

Question type: Maintenance & Repair

I recently bought a 1985 Z28 Camaro with the TPI
(Fuel injected) 5.0L 305 in it. The car was tunnjng
fine until I disconnected the battery. Upon
reconnecting it the car started dying at start up and
refusing to idle on it's own if I didn't give it gas. I
figured a sensor problem was the case so I
removed and cleaned the:

- Maf sensor
- Throttle Body
- Idle Air Control Valve

After putting everything back, the car now is
experiencing the same idke problems but is also
running rather rich and putting out a lot of black
amoke from the exhaust. I should also mention that
trying to apply too much throttle will occasionally
stall the engine as well.

I am trying to figure this out but am torn on what to
direct my attention to. My guesses are problems
with: MAF Sensor, Throttle Position Sensor, EGR
Valve, or the Idle Air Control Valve.

Any experience or advice?

5 Answers

109,845

Try resetting the ECM again, disconnect t the negative battery cable and turn on the headlight switch, wait at least 30 seconds, turn off the headlight switch, reconnect the battery, start the engine and step on the brake and put it in gear if an automatic and then turn on every electrical componet it's got, heater radio headlights etc. let the idle smooth out if it will, if it will not smooth out then the system will need a live data check or scan to locate what componet has failed or if you have an intermittent wiring problem, could be a sensor ground. There should be a bundle of them right on the thermostat housing bolt, that would be a good place to start.

I've tried driving it and it will stall when coming to complete stops if I don't give it gas. Also, upon accelerating from a stop there's a noticeable absence of power, and I can feel the transmission shifting hard/not wanting to shift so easily

109,845

Is the check engine light on? If so it has set a code and that would be a starting point, if no light then check those grounds and if those check good then move onto a data scan.

79,105

If the engine is holding back when you try to accelerate, may be a plugged catalytic converter.

1 of 1 people found this helpful.
75,625

Simply disconnecting the battery shouldn't have done anything. Except lose the clock and radio presets. How did you disconnect the battery? Which terminal? Positive (+) or negative (-)? What was the reason for disconnecting the battery? Where you doing a repair? If you disconnected the positive (+) cable first did the terminal or your tools touch something metal, causing a spark? If so you probably fried the ECM (Computer). The pigtail that comes off the positive battery cable is a direct power connection to the ECM. Let's remember that this is an OBD I vehicle. To get any trouble codes from the computer you'll need a scan tool designed for OBD I (1981 thru '95) GMs or a paperclip to flash out the codes. HTH. -Jim

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