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I'd suspect AMM Posted by Ari [Email] ![]() ![]() In Reply to: Sooty Plugs, Help EDU or What??, Rmc, Thu, 27 Jan 2005 18:37:33 Members do not see ads below this line. - Help Keep This Site Online - Signup |
The O2 sensor controls 25% of the fuel flow; the Air Mass Meter controls 100% of the fuel flow. If the gas pedal acts like it's ignoring you, then the first place I'd suspect is the AMM. If you go to full throttle, does the engine rev up? If so that means that the ECU can at least read the throttle position switch (and it is a switch in an '88), and it adds gas then.
The 0.68 on the O2 sensor is a bit puzzling; the O2 sensor voltage should swing between 0.9 and 0.2 volts about 1/second, spending 50% of the time above 0.5 volts, 50% below. That's where the 0.5 volts comes in; the voltage should swing. Of course, that assumes everything is right and adjusted properly; we know that's not true. If the plugs are black, the O2 sensor should be stuck at 0.9 volts, which is rich. When you measured the O2 sensor, did you leave it connected to the ECU? You need to, otherwise the system won't work (or won't work more than it's not working now).
Here's something I posted a while back to check the AMM:
Get yourself a good digital volt meter. CAREFULLY peel back the rubber boot on the back of the AMM connector, and get the positive lead into pin 5. Put the negative lead to ground, and set the meter to VOLTS. The other place to get this signal is on pin 7 of the Engine Control Computer (passenger side foot well). Start the car, and at idle you should see around 1.2 to 1.5 volts. Rev the engine, and the voltage should go up to 3 or 4 volts. It should go up to 5 volts under load. If the voltage doesn't change, or doesn't change much when you rev it, the AMM is probably bad.
The -005 AMM leadout is:
1 To ECU 8 burn-off (RD/VT)
2 +14V from main relay (BR/VT)
3 To ECU 6 ground (BL/VT)
4 Gnd (SV)
5 To ECU 7 signal (OR)
6 To ECU 14 (VT)
I'd check the AMM first, and go from there.
posted by 192.249....
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