km93yota

I'm new to Yotatech so i apologize if i'm not doin any of this right, but here we go. haha

Drive a 1993 pickup ext. cab with the 3.0

I replaced the radiator about a month ago and since haven't had any problems until last night. Started the truck drove about 100 yards and the CEL came on. Today i ran a jumper wire in the diagnosis box from TE1 to E1 to see what the ECU said the problem was and came up with these codes:

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

I got these OBD1 Codes from http://www.troublecodes.net/Toyota/ i assume they're accurate but then again i could be wrong.

Also i've noticed in the last two days that under acceleration at about 1500 to 2100 rpm the engine seems to bog down quite a bit. I hadn't previously noticed this and am wondering if its some kind of vacuum leak. Also the Oil Pressure gauge does not seem to be fluctuating as it normally does with these motors between engine speeds.

What should i infer from the codes, i have a decent amount of automotive knowledge but am thinking maybe this is too extensive and i should just go get it checked out.

Any suggestions on what i should start looking for under the hood? i dont fully understand what the codes mean and want to know what i should look for. thanks


-km

yayfortrees

Diagnosing automotive electrical isn't my forte either, but here's what I have to offer.

From my understanding, a CEL will signal whenever a component signal either isn't there (open condition), or a reading is out of spec (faulty sensor and / or short/ground condition). Besides the fact that one of these conditions exist, the ECU can't pinpoint it anymore than that.

Since you suddenly got 4 codes, I doubt all 4 sensors went bad at the same time. I would check for loose connectors around any of those sensors. Possibly a connector going in to the ECU became loose?

As far as the low power between 1500 to 2100 RPM, that doesn't sound like a vacuum leak to me. Usually, a vacuum leak will cause an erratic idle, and will affect running in all RPM ranges (usually). Hopefully, taking care of the CEL issue will also take care of your loss of power. If it doesn't, some further diagnosis will be required.

I would rule out some simple things first, like loose/dirty/corroded battery connections; broken grounds; maybe even fuses. For sure check the body ground coming directly off the battery negative, and attaching to the body in front of the fuse box. Seems these always have a butt connector splice from a PO, and they always fall apart at some point. (Or was this factory? I've seen too many trucks with this to think every PO had to do this at some point.)

And while this isn't the likely culprit for your problems, have you replaced the fuse box power supply wire? There is a really good thread on here about it, just search fuse box supply wire. It's a good thing to do while you're checking that ground. I replaced both the supply wire and that body ground with some heavy duty 4 gauge cable.

You sound like a very capable tech, so I would hold off on taking it to a shop, at least for now.

Good luck and welcome to YT! Keep us posted on your progress and findings.

km93yota

awesome thanks for the help! i've definitely found something

I was noticing today that everytime i turned the truck off i could smell coolant. It looks like i have a leak where the TB (Throttle Body) coolant passage comes out of the top of the intake manifold. There's a small pool of coolant on top of the intake down under the fuel pressure regulator.

I'm not sure what the part is called but its the metal outlet that screws into the intake which seems to be leaking.

Do you think the leak is related to those codes? i think it would explain the intake air temp signal, and I know the knock sensor is right in the middle of the intake manifold (or under it); possibly its been damaged by the leak?

I'm not too sure if this is the source of all my problems, but its one that certainly needs to be addressed

I'm wondering what the ignition signal and air flow meter signal are all about...


thanks again for your help! i'll keep you posted

iselloil

air flow meter.

yayfortrees

IMHO, the errors *might* be caused by a coolant leak, but that is unlikely. I guess anything is possible.

Perhaps the coolant has run down into a connector, and is shorting some wiring?

I'm not quite sure what iselloil is pointing out, but from what I can tell he is either suggesting it's bad, or to look at that. It seems that he knows what he's talking about from other posts.

iselloil

24 is the thermal sensor in the mass air.Try cleaning it with mass air flow spray.

myyotacrawls4x4

1993 pickup 3.0 will not stay running unless your hitting the gas. Changed the knock sensor and now have codes: 12,13,14,42,43,52. Know a solution??????

iselloil

When you did the knock sensor, did you change the pigtail?

TNRabbit

"When you did the knock sensor, did you change the pigtail?"

^^this^^

Also, when you pulled the VAFM, did you take out the screws or remove with the steel clip? If you tried to pull the screws, you FUBAR'd your VAFM.

scope103

Well, what do those codes mean? Or did you hope that someone on this forum would look them up for you?

If you're at a point where the diagnostic codes are all mysteries to you, and you're not willing to follow the stickies to look them up yourself, taking it to a mechanic is probably your best solution.

If, on the other hand, you know what the codes mean, why don't you tell us what you think you did wrong? We'll have somewhere to start from.