Hello.

My cousin and I recently completed a COMPLETE engine rebuild on a 1989 22RE. I have a 1987 4Runner and we used the '87 sensors, accessories/brackets, and exhaust manifold. The only '89 22re parts that were used were mechanical (block, rods, head, timing cover) AND the lower/upper intake and throttle body with the upgraded IACV. We replaced nearly everything on the engine and "zero timed" it. Here is the build thread: https://www.yotatech.com/forums/f199/22re-build-307813/

We installed the engine and it started up without major problems! Unfortunately we were a tooth off with the timing chain, but we were able to move the chain over one tooth without removing the timing cover. 500 miles on the break in with Joe Gibbs oil. At 100 miles the filter was changed. Then at 500 miles, oil change to conventional oil with a new filter.

The engine really runs good. No stumbling idle or lack of power.
Two small problems:

1. The engine does not idle up at a cold start. We rebuilt the IACV and think we might be off with the adjustment.
2. The engine idles smoother when cold vs warmed up (believe this is related to running rich).

One major problem: running rich.

After a recent 500 mile road trip, I discovered the engine is getting poor MPG. Calculated hwy MPG was around 13.5.
Before the engine swap hwy MPG was around 20.
The tail pipe is black on the inside. However, no check engine light is on indicating a rich condition (code 26). But it is definitely running rich.

So here is what I am planning to check:

• AFM
• O2 Sensor
• Coolant temp sensor (we bought a new one but I am going to put factory back on)
• Cold start injector time switch
• Plugs
• TPS adjustment

The cold start injector was cleaned and checked before installing on the new engine. Also the fuel injectors were rebuilt.
The engine is not flooded with fuel but we are thinking a sensor is off telling the computer to add more fuel.

My questions:

1. Does anyone know the factory adjustment for the IACV? How many turns?
2. Can a misadjusted IACV cause poor MPG?
3. Has anyone else had a similar problem?

Fully Rebuilt 22RE

 

I don't think a miss adjusted iacv would cause a miss unless you are seeing higher than normal idle speed. The low idle on cold start is due to the iacv being stuck or needing adjustment. How did you go about adjusting the iacv? Running rich could be a bad o2 sensor or the engine temp sensor that the computer uses is giving a false temp signal.

 

Thanks for the reply.
The IACV has a threaded body that you can adjust the pressure on the spring. The IACV is not supposed to be adjusted. We forgot to mark the factory setting before taking it apart.
Check out this video, skip to the 3 minute mark.

 

The auxiliary air valve is fully closed when the engine reaches operating temperature, you can bench test this with a pot of hot water, it's not a reason for it to be running rich.

You can also translate the cold vs hot dimensions of the wax valve to how far down to run the throat (threaded piece) to get a fully opened valve when at room temperature.. Your guy on the video says this is about 1/4 inch.

Now assuming you figured all this out when you put it back together on your own and actually didn't run the spring all the way down. If your not seeing a warm to cold idle speed change you've got another path around the throttle plate, like the PS/AC bypass (video guy said to ignore for some reason) the PCV system or some other source large enough to "leak" more air than the AAV.

...
Unless your cold start injector has power and ground (which is easy to check with a DMM) or leaks (also easy to check, pressurize the system and look) your problem isn't in the cold start system.

...
There is a big clue here! If it is in fact running rich and not setting an out of bounds code (injector on time adjustment limit reached, which I'll.assume.is actually code 26 because I don't want to go find the chart), this means it's still in the warm up enrichment phase and in fact not entering closed loop control of the injectors. Test the engine coolant temperature sensor resistance curve and its signal at the ECU.

...
And for piece of mind, how about a friendly "Hey bro are you running rich" conversation with your O² sensors diagnostics port.

 

Thanks for the detailed response @Co_94_PU.

How do I have a "conversation" with the O2 sensor?

The spring on the IACV is not threaded all the way down. I'll have to do some more research on alternate air paths around the throttle plate. I am not sure where the alternate air path could be because the PS/A/c bypass was not touched from the origainal '87 engine. And the PCV system is new.

So far I have checked with the factory service manual:

1. Cold start injector resistance
2. AFM
3. Coolant temp sensor cold and hot
4. Cold start time switch resistance
5. Egr system

Everything checked out.

I pulled the air inlet piping off of the throttle body and looked inside. Not really dirty inside, was sparking clean when assembled. Did not smell like raw fuel inside, more so of oil. But I think that is normal because of the PCV system.

I can check the signal for the coolant temp sensor at the ECU but I highly doubt that is the problem. The harness was not damaged when pulling the engine.

I want to check the O2 sensor but I do not have a 1987 FSM, which covers a single wire O2 sensor. Does anyone have the procedure?

I also need to pull the plugs and inspect. Will also do a compression check.

Also, oil does not smell like fuel.

Variables after engine rebuild/swap:

1. New Denso O2 sensor
2. Late model lower/upper intake and throttle body
3. No '87 aux. air valve, plug is now disconnected (have read this is not a problem)
4. Rebuilt '87 plug injectors (not the originals on my factory engine but Toyota originals off another engine)
5. '89 fuel rail and pressure regulator
6. No fuel dampener on '89 fuel rail

 

Maybe you should consider being more objective here. Approach the vehicle as if you have no affiliation with it, the owner, or the rebuild. On one hand you admit to not understanding the problem and on the other you make comments such as this.

It’s a 33 year old truck with 33 year old wiring. Did you open the loom and inspect the entire harness? While it may be that the harness was not physically noticeably “damaged” when pulling the engine, copper corrodes and both copper and insulation fatigue, and there was certainly bending and manipulation of the harness. Therefore in order to be thorough, a mechanic would check all signals at the ecu and at each sensor via back probing to insure proper function. Could be as simple as terminals not engaged. There’s a chart in the fsm for both resistance values and voltage values.

Again, it is not safe to assume the 33 year part is functioning correctly just because it “was not touched.”

There is a diaphragm and an o-ring inside the ac/ps idle up valve that are notorious for drying up, degrading, and failing. Cap the system off, verify no change.






Oxygen sensor test

The above link is from a 97. But the diagnostic port on the 87 works the same, just doesn’t have all the functions. Ill find the Ox test in the 87 fsm later today.
You’re looking for the analog multimeter to fluctuate voltage at least 8 times in 10 seconds with the engine at 2500rpm. That link is cool though, you can fiddle around read vf1 voltage and read your fuel trims.

 

He makes a very good point here on the old copper. After my rebuild, 85 4runner sr5 4wd 22re 5 speed, I had a rig that ran great and then would cut out. Mostly for just a moment but she left me needing a short tow once. After messing with it for a few days I took it to a buddy. It was a bad winter and we had snow on the ground for 5 months and over 10' total snowfall that year so I was not going to stand in it and trace wires in 20 degree weather. He found that I had 2 different broken wires going to my injectors. They were broken inside the insulation and were touching most of the time so they would work fine. But when the connection failed so did the rig...

 

Fair point @RASALIBRE.

I made those statements because the original engine had great fuel economy. But, I did think about the possibility of a damaged harness too. I should have reworded myself.

I will check the signals at the ECU.

Thanks for the pictures and link.
I didn't know about the o ring in the ps/ac idle up valve, another thing to check.

One last note, @thefishguy77 my cousin who helped me with the rebuild, cleaned and inspected the harness (seen in our build thread). He could have missed something, but I trust his work.
Not ruling anything out yet.

 

You say cleaned and inspected the wiring harness. I assume thats a visual inspection without breaking open the loom. The only way to verify a harness would be if it was actually testes for continuity on every pin. Most of the damage I am talking about will be completely hidden. Much like when I replaced my grounds. Even though the connections were bright at the time of replacing as soon as I pealed back the old insulation there was a lot of corrosion. The PO had done everything they could to keep the connections in good conditions. But there is only so much you can address if you cant see it.

 

This is very true!

Also continuity checks can be misleading. Let’s say it’s an 18 gauge stranded wire and it takes 50 individual strands to make it 18 gauge. You could have 30 of the 50 strands severed at some point in the circuit and the remaining 20 strands would ring out giving you pretty much a false positive in a continuity check. Is there continuity? Sure. But really the bigger problem is voltage drop. That 18 gauge wire is now functioning as a 24 gauge wire.

So visual inspection is huge! Continuity checks can be misleading! Learning how to properly check for voltage drop is key! Voltage drop check will help narrow down what circuit and where to look in the harness and save ya some time.

 

oxygen sensor test/logic map via 1987 fsm.

 

Thanks for the pics from the FSM!

I understand with the wiring.
Plan to do some testing tomorrow.

Update:

Tonight I did try a cold start with the PS/AC idle up valve capped off and there was no high idle at cold start. Think I can cross that off the list, although not related to the poor mpg.

 

Update:

O2 sensor checked out.

Voltage/resistance at ECU checked.

Coolant temp sensor, voltage was below the range (slightly) and resistance was a little higher.
FSM voltage range (0.5-2.5v), meter read 0.43v.
FSM impedance range (200-400 ohms), meter read 467ohms.

Not terribly off but the physics check out.
Did not see any cut wires or pins sticking out of connectors.

Interesting observation, the fuel pressure gauge on the intake we installed is reading about 28psi at idle. After the engine is shut off and cooling down, fuel pressure increased to around 32psi.
After a quick search, it appears that the fuel pressure is low, should be around 33-37psi running (according to this thread on marlin crawler). Need to confirm this in the FSM.

Could low fuel pressure cause the ECU to think it needs more fuel and therefore runs rich?

https://board.marlincrawler.com/index.php?topic=17977.0


Next check:

1. Continuity on coolant temp sensor wiring
2. Fuel trims, with link provided by @RASALIBRE
3. Spark plugs
4. Compression check
5. Fuel pressure regulator

Hopefully the world doesn't end before I find out the cause of this!

 

I posted pics from the 87 fsm for the fuel pressure regulator, fuel pressure, and fuel pump in the linked thread.

https://www.yotatech.com/forums/f116...d-gear-310267/

 

i don't believe the ECU measures fuel pressure, so that shouldn't be an issue. and 28 at idle isn't out of range, especially with an off-the-shelf guage measuring it. i'd be more concerned if the pressure was reading in the low 20s or teens - i've been there with my '87, when i went through 7 or 8 failed fuel pumps in 2 years. fwiw, the pressure reading on my permanent gauges on both of my '87 4runners' 22re, at idle, is about 28 to 29 psi. two different gauge manufacturers, but close enough reading to not worry me. it confirms that the occasional rough idle in #2 following a warm start isn't a pressure issue (in my case). i'll dig into it at some point.

 

Your sensor signal is switching back and forth between rich and lean? This tells you it is in fact running in closed loop. This means your fuel delivered is calculated based on VS (load from vafm), VTA (throttle angle from tps).

Make sure those are giving nice clean and smooth signal levels by checking the resistance or voltage as they sweep from open to closed.

 

I have not done any testing yet, but I am a little bit confused.


RASALIBREshared a pic in another thread of the test procedure for fuel pressure from an '87 FSM. Correct?

Here is the picture



Fuel pressure should be between 33-38 psi without engine running and jumper between terminals.

When I looked in the '88 FSM I have, it says the fuel pressure for a 22re should be 38-44psi and 33-38psi for a 22rte.


Do you think this is a typo?

What is the correct number?

 

The only thing I know for sure is that the 1988 22re has fuel injectors specific to that year.

I think they are specific to only 1988.

I think this is the run down:
1985-87 22re same injectors
1986-87 22rte same injectors
1988 22re one year only injectors
1989-95 22re same injectors.

I do not recall there being discrepancies in fuel pressure between the years, but 88 was its own beast injector wise.

 

as far as i know, those numbers are correct for the different years.

 

Ok. Thanks.

Just to confirm @RASALIBRE your FSM is for an 1987 Truck/4Runner, correct?