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1989 4Runner Diagnostic Code 12

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Old 02-06-2011, 02:07 PM   #1
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I just picked up an '89 4runner with a 22re + 5 speed and have been driving it around with no problem. Today coming up a steep hill the truck lost power and barely made it home.

The gas tank was 1/4 full so I went to add gas and when the cap was off it vented a ton of air. Also, the exhaust was really hot although engine was 1/2 way on the gauge and has plenty of coolant and didn't show signs of overheating.

The truck starts fine, but idles rough and is still down on power. Has more of a pop to it than it has before.

I jumped the diagnostic port and it returned code 12 RPM Signal, no NE signal input to ECM for 2 secs or more after sta turns.

My initial thoughts were fuel filter clogged, or cat clogged, but now I'm stumped on the error code as I don't know what it means nor affects.

Any input on a code 12 error?


Last edited by Cmayer; 02-10-2011 at 11:15 AM.
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Old 02-07-2011, 07:49 PM   #2
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I replaced the rotted out pcv grommet and valve, but that didn't change anything. Won't be able to get under the truck this week, but picked up a new fuel filter and will give that a go.

Is there an easy way to reset the codes? I wonder if it threw the code 12 while doing the compression check.

Compression check showed 170-175 across the board. Replaced the spark plugs while I was there and checked vacuum lines for obvious signs of wear.

Last edited by Cmayer; 02-07-2011 at 07:52 PM.
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Old 02-07-2011, 08:20 PM   #3
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Please google code 12 OBDI
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Old 02-10-2011, 11:13 AM   #4
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1989 4Runner Injector Issue?

Narrowed down the Code 12 to performing the compression test with the coil disconnected. I cleared the codes and have no codes showing now.

As stated above, 170-175 compression on all cylinders and all grounds that I can find appear to be good and clean.

While the engine was running, I started pulling plug wires and when I removed the #3 wire it made no difference in performance. I swapped plug wires with a known good plug wire and that made no difference, so I swapped plugs with a properly gaped and known good plug and that too made no difference. I tested the spark and it's getting a strong spark to the plug.

Next I started pulling injector wires/clips and when I got to the #3 it made no difference in running, so I assume it's the injector. I ran an ohm meter across the injector itself and it's within spec from the FSM. I also tested the plug itself and it's getting 12 volts with the ignition on.

When I put a long extension on the #3 injector it has a faster and more "tingy" click to it than the other injectors have? So I know it's at least clicking, but not at the same speed nor sounds, although close, than the others.

Are there any more tests that I can do prior to taking the intake off and swapping injectors? I'll just send them all out for cleaning and flow matching when I do. However, has anyone experienced this before and had it not be the injector? I know the splices in the factory harness can go bad, but not sure that is my problem as I have power to the injector and the other 3 work fine.

All four cylinders have spark and air, but it appears #3 doesn't have fuel

Sorry for the

Last edited by Cmayer; 02-10-2011 at 11:16 AM.
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