Chasing codes on an 88 4Runner 3.0

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IslanderOffRoad

10 Year
Joined
Mar 27, 2012
Threads
4
Messages
37
Hi everyone

A couple weeks back I purchased an 88 4Runner 3.0 5spd. CEL was on on it. Engine was rebuilt about 30k ago, have the paperwork from the rebuild.

At the time I bought it it was throwing a code 11. Fixed that with a new ignition switch.

After I replaced that, the truck was throwing a code 22. I replaced the coolant temp sensor today. After replacing that the truck started much better than it had before, but still idled pretty bad at first, then jumped up to about 1400 before settling down to 800.

CEL still on.... now showing Code 22 and code 51, despite the fact that I had pulled the ECM fuse for a minute or so.

So now I guess I'm on to the code 51, for the TPS. I've searched and it sounds like cleaning is the recommended first step, followed by adjusting, then finally replacement.

Just wanted to post up and see if you all think I'm heading in the wrong direction. Right now I'm wondering what its gonna throw next after I fix this one.
 
Drove the truck to the gym this afternoon. When I got home I pulled the ECM fuse again for a couple minutes, then re-read the codes.

The 51 is gone now, just the 22 again.

Temp sensor is known to be good, brand new, so we're looking at wiring?

Would a bad cold start injector contribute? When the truck is cold it runs very rich at first.

Where is the ground for the ECM? The diagnostic manual I have for the truck says to check the ECM ground, but while I know where the ECM is I haven't started pulling the carpet to trace the wiring yet.
 
Cold start injector is out of spec, 6ohms, whereas the FSM says it should be reading 2-4ohms. But...

I was checking a few other things. The battery voltage is reading way too high... in the neighborhood of 30 on the multimeter. I also started troubleshooting why the code 22 was still showing using one of the FSM supplements for the early 3.0 and was not getting voltage readings on anything on the ECM.. and when I did get a reading it was typically very low, 8volts tops.

Started tracing the E1 (body ground) wire, removed some electrical tape and found this:

df7d8555.jpg


I'm guessing that wiring is not supposed to look like that. And that I'm probably going to need a new wiring harness if I want this thing to run right.

Where does the E1 wire run to, the diagnostic port? I was expecting it to ground off somewhere in the cab under the dash but it looks like it goes into the engine bay. Haven't disassembled under the hood yet, washed up to come share what I found before moving any further.
 
IslanderOffRoad said:
The battery voltage is reading way too high... in the neighborhood of 30 on the multimeter.
Click to expand...
:eek:

Start there. Recheck your reading again as 30V sounds high for a bad voltage regulator or anything else unless it has been converted to a 24VDC system. I'd be surprised if it had been. Check the battery voltage when the truck isn't running, then again when running.

On possibility is the engine ground is bad, and that could get the voltage all screwy. That screwyness could lead to codes being thrown because the reference voltages are off. When the engine is running the voltage difference between the block and - battery terminal should be very low. There may be a few milivolts difference due to the wire resistance. Note, on my '89, '94, and '95 I've had to replace the engine grounds.
 
I think I'm starting with a new multimeter. Tried testing a known good 9v battery and it was reading 0.1 volts on a 20 volt scale, then went crazy on any other scale.

For 20 bucks to get a good one, its worth it.
 
Re:
df7d8555.jpg


The shield grounds do usually goto a brown, grey, or black wire from the factory for noise suppression leading into and out of the ECU. That top one w/o the tape is a factory situation where they use these brass clips to hold it. Unwrap the lower one w/ the wider tape and I bet it's that one that's grounded wrong. If there's no gold clip like the other one you know for sure.

Let us know, in fact take a pic b/c if I'm right and someone just tapped into the wrong brown wire the pics here will make a good FAQ Thread addition.

:cheers:

~I'll see if I can get RMA to chime in too since wiring's his life these days w/ all the 1st Gen Runner UZ Swaps. :D
 
Note: For continuity's sake here anyone else trying to answer like I just did and not knowing the OP already got a similar answer cross reference this exact topic the OP posted: Here.

OP, no offense or attack intended, professionally I just prefer you get directed answers rather than possible back and forth supposition that may or may not already have been mentioned. This way you get the proper helpful steps in fixing this issue. :cheers:
 
NorCalBorn said:
Re:
The shield grounds do usually goto a brown, grey, or black wire from the factory for noise suppression leading into and out of the ECU. That top one w/o the tape is a factory situation where they use these brass clips to hold it. Unwrap the lower one w/ the wider tape and I bet it's that one that's grounded wrong. If there's no gold clip like the other one you know for sure.

Let us know, in fact take a pic b/c if I'm right and someone just tapped into the wrong brown wire the pics here will make a good FAQ Thread addition.
Click to expand...

Both of the other two wrapped ones had brass clips on them... pics below.

64e073ab.jpg


2293d5f0.jpg


If you look on the second photo, the thing I'm curious about is the fact that the 2 brown/black stripe wires y into 1 wire... one of those is the E2, which is part of the coolant temp sensor circuit, which I keep throwing the code on. But if its brass clipped, I suppose thats how it's supposed to be?
 
The wiring looks good. I'm not seeing obvious corrosion or any other issues. I'd wrap them back up and look elsewhere. BTW, crimps have a better chance of lasting twenty plus years than solder joints. Solder joints produce a hard spot in the wire where it may flex crack from vibration. Also the flux from the solder is highly corrosive and will eat up the wires.
 
TPS was bad and would not adjust into spec.

Will update once the new one gets here and I get it dialed in.

Still throwing a code 22 though. Wiring looks fine, the ecu and the cts are both reading in spec.
 
I give up. Replaced the TPS, spent a long time getting it in spec, now the truck's throwing a 41 in addition to the 22.

Taking it to someone for an estimate then determining if I'm gonna keep it.
 
So I drove the 4runner yesterday.... rather unsuccessful drive.

Got about 6 miles or so from home to meet some friends for lunch, then got about 2 miles back towards home when it started surging again, then stalled at an intersection, and has refused to start since.

It will crank, and occasionally seems to "start" but then immediately dies, doesn't even get up above 200rpms

The fuel tank is full. I wanted to run some seafoam through so I poured in a bottle of that and filled the tank before heading to lunch.

The computer is now throwing the code 11 again.

If I jump FP to B+ I can hear the fuel pump running, but it still will not start.

any thoughts on where I should be looking next?
 
Have you thought about borrowing an ECU from someone or buy a used one at a j-yard? Every time you do something you need to be systematic. That is for example when you hear the pump running you need to check if you have fire at the plugs. You could also try to try to spray starting fluid inside the plenum to see if the truck tries to run. Overall, I do not think is a good idea to mess with the wiring and expose its insulation it could be another source of trouble. Code 11 culprits are: IG switch circuit, IG switch, Main Relay circuit, Main relay, and ECU. Thus if trying another ECU does not get any good results it means one of the components or circuits listed are faulty. There is also a procedure for testing the main relay check the manual for specifics. I could write it but it is better if you read it with the picture in front. Applying battery voltage to terminals 1 & 3 should give you continuity between terminals 2 & 4. All you are really doins is closing the circuit to allow current to flow.
 
I have already replaced the ignition switch and the efi main relay... that cleared the 11 for about a week prior to this.

I did buy a used ecu off ebay, its on the way.

As far as the wiring... I was told (either here or on yotatech) that the ecu's rarely fail and my issue is probably due to wiring. Hence checking through wiring. I saw ugly tape, and to me, that looked like someone had done a hack job on the wiring harness because in my opinion, it looked too sloppy to be factory.
 
BTW, on both 22RE and 3VZE engines codes 22, 41, and 52 are "Open or short in XXX". That is telling me something common to all of them is failing. Maybe like the ground path. They are also all engine mounted sensors. It could also be a very bad connector having multiple pin contact failures. Another possibility is the ECU its self is damaged.

Have you checked you engine ground? The wire goes from the battery (-) terminal to the frame, then on to a stud on the engine block. Note: I've had to replace this wire on all of my mini trucks. There is also a small wire from the battery negative to the fender. It could be heavily corroded, broken or missing.

Also check other grounds like the ground for the ECU.
 
True they rarely fail but you never know. Besides you just bought the truck and who knows what the other owner did to it. For example some Hondas 91-93 are known to have burned resistors in their ECUs. If you can open it you may want to give it a physical inspection.
 
I do not what to suggest. Just to make sure that nothing mechanically is mascarading the problem check engine compression and distributor rotor rotation. This will sound repetitive but make sure the truck is firing and getting gas. There is a chance that the fuel pump is unable to maintain pressure and cause the erratic idling and power loss. Also depending on where you live the tank may be rusted inside causing the pump to plug temporarily. The thing that confuses me is that you get code 22 after you replaced the t-sensor. This would suggest also to check continuity of the t-sensor circuit from the sensor itself to the ECU. Hopefully this fishing expedition will flag something somewhere. I suspect the previous owner had these problems for a while.

Also it would seem obvious but you may want to check your termosthat. Some of those are designed to remain open once the engine has overheated. If yours stays open it may be fooling the computer to trigger DTC 22.
 
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