Black306

I've got a '92 DLX 2wd V6 pickup with a few codes and I'm hoping you can help me keep racking up the miles on this truck. 211k ain't enough!

Check engine light popped up and when I check codes, I get the following.

14
24
31
52

Looking at the codes, I have a hard time believing all those parts went bad at once. I believe a common [ground] wire might have been damaged. Anyone have an idea of what might be going on? Or at the very least, have a wiring semantic?

Any assistance would be greatly appreciated!

nv4runner

52 is usually the pigtail between the cylinder head and intake manifold. If you replace head gaskets always replace that wire! Has any work been done to it recently, even something small or not related to the engine? Are there driveability problems? The light came on out of nowhere or its been on for a while?

wyoming9

iTrader: (1)

It would be nice to post what the codes are??

Me being quite slow can`t have them all memorized .

Could some be old codes never cleared ??

Might be the ECU dieing thinking it is not seeing the data from the sensors.

Black306

14 Ignition signal.
24 Intake Air Temperature Sensor signal.
31 Air Flow Meter signal (Vacuum Sensor signal).
52 Knock Sensor Signal.

nv4runner, I'm not sure where the pigtail you are describing is installed. However, while looking around, I found a ported vacuum switch with a broken nipple. That probably explains code 31. Might even explain code 52 if the engine ran lean enough.

Last time code 14 came up was when my TPS was bad. Until recently, that didn't come up after replacing the TPS.

I fixed the leak and reset the computer. So far so good (knocks on wood.)

scope103

Uh, no. Even though I've never seen your engine, channeling the Great Carnac (okay, you're not old enough to know the Great Carnac) I can tell you the broken nipple was on your Thermal Vacuum Valve (TVV) which drives the Evap Canister. All vacuum "leaks" are bad and should be fixed, but your code 31 just tells you the signal from the VAF is missing. The VAF is nowhere near the TVV. The GOOD news is that the Intake Air Temperature is measured inside the VAF, so if the connector to the VAF is loose you can easily get both codes. Since you now have no codes, I'm guessing they were caused by an open connector at some point and got stored, you fixed the connector (or jiggled it into place) and the codes got reset. If you get them again, you now have a place to look.

Code 52 has nothing to do with running lean. Code 52 has nothing to do with whether your engine is knocking! It just says the ECU has lost touch with the Knock Sensor. When that happens, the ECU can't tell if the engine is knocking or not, and since knocking can blow a hole in a piston the ECU dramatically retards timing to save the engine.

Unfortunately, the knock sensor wiring is in a hellish environment, and it is carrying a very subtle signal. So if a wire breaks ever so slightly, or if the shield is sufficiently compromised, you'll get the code. As others have stated, the mostly likely culprit is the "pigtail," as it the most mis-treated part of your whole engine. But even if the pigtail is good, the signal hasn't gotten back to the ECU yet.

Good luck!