Odin

I just picked up a 1991 base pickup- 2WD, 5spd, 22RE with Cruise Control. Looking under the hood I can see someone has been screwing around under here. I found a hard vacuum line with no hose on it and a connector hanging down attached to nothing. I think someone has removed part of the emissions and they might have been connected to it from the factory. You can also see a steel plug that someone has fitted in the FI system.

I looked at the diagram that's on the hood but I can't tell what's what following that. I've never been able to follow those diagrams or the ones listed on line. Also as far as I can tell it's not a CA model with excessive emissions pieces. I do not have A/C either.



So what are they supposed to connect to and will it effect the way it runs?
(Yes I did plug the vacuum line for now)

The Vacuum Hose comes out of a hard line that has about 4 other lines grouped around it exiting around the rear of the valve cover.


The mystery connector


The connector wire comes out of a bundle of wires near the FI manifold. It is the lower cable with the loose black tape on it.
You can also see the rusty fitting someone has added to take place of.. most likely another vacuum fitting.

toyota4x4907

I can't remember where that first hose goes, exactly.
Pic 2: that's an extra plug. I'm pretty sure it has to do with A/C
Pic 3: Factory plug where the /C Idle Up valve would be located.

PapaChulos4U

That vacuum line runs to the charcoal canister, the port near the firewall. 4907 is right about the other two plugs.

Odin

Ok so it sounds like the engine will not be effected as long as the vacuum line is plugged.
The truck doesn't have A/C so I should be good there.

That plug is pretty clean so it made me think it was connected to something in that area but I just don't see anything obvious.

PapaChulos4U

You'll be fine. My A/C was shot so I just removed the whole system. If you don't want to look at it you could just cut the connector and wrap it safely with tape and loom, but if you want AC in the future it's probably not the best option...

Odin

Thank's
I'm not too worried about the looks of it, I purchased it as a daily driver.
I'll probably just zip tie it up out of the way.

Odin

So I just looked and I still have the charcoal canister hooked up.
Toyota part# 77740-35240

I followed the hose that comes off the Charcoal Canister and it's connected to the bottom pipe in this view.
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Then I followed that pipe and it's hose to the port on my throttle body that has the masking tape on it. That port in the throttle body is labeled P in the casting. I'm pretty sure that much is correct.
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Odin

Just space to separate the pictures to help keep things straight.
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Odin

I followed the pipe that isn't connected to anything

back to a blue Vacuum Switch (Toyota# 90910-12085 pictured below) on top of the valve cover that has two hoses leading to it before exiting as one.
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I followed the other vacuum hose and pipe that it merges with to the throttle body. It's the one with red tape on it.
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Once the two lines are merged into one by means of the blue Vacuum Switch the single hose that emerges connects with a another valve at the very back of the intake plenum.
Picture

Odin

I took a picture of the underhood vacuum line routing diagram and printed out the picture. I highlighted the areas of interest with different colors so I could more easily follow the routing.

I then dove under the hood and carefully followed the vacuum hoses and pipes one by one.
After following the pipe that wasn't connected to anything several times and comparing it to the diagram in shock I discovered it is supposed to connect to the Fuel Pressure Regulator.
Instead someone had left it uncapped as a slight vacuum leak.

So what the H was my Fuel Pressure Regulator hooked to then?
I didn't know what it even looked like so I hunted images of it on the net then I located it and followed the hose and pipe it was hooked to.
Turns out it was hooked to a different brown/red Vacuum Switch. (Toyota# 90910-12086)

I re-routed the Fuel Pressure Regulator hose to the correct pipe according to the diagram and placed my vacuum cap on the pipe that was supposed to be hooked to something called an AS Valve.
I then fired the cold engine up. Despite sitting all day it seemed to idle down quicker and the idle stayed consistent.
I had been having problems with that and thought maybe someone installed too cold of a thermostat or the coolant sending unit was really dirty, perhaps it was faulty.
Before this just a few days of intermittent driving made all of the plugs black and sooty. That's part of why I wanted to get the vacuum lines sorted out.
New plugs are coming tomorrow and we'll see how that does.


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Back on topic- Now that means I still have a vacuum pipe that was at one time attached to the AS Valve.
Uh, what's that? I tried a search on here with no hits, I tried Google image search, I even tried a Toyota dealer part search and didn't get anything. What's the full or real name of it?

Here's my underhood Vacuum Hose Diagram in case anyone is curious. I know it's not the greatest photo but it was dark and getting into the AM hours.

PapaChulos4U

On most that is called a PAIR valve. It's under the intake near the rear (see the pics). The middle vacuum hose in the metal grid runs to it.

Odin

Ah the PAIR Valve, thank you very much Sir.

A quick question about that brown/red Vacuum Switch (Toyota# 90910-12086)
The round end of it looks odd, is it adjustable or something?

Odin

It looks like someone removed the PAIR Valve (AS Valve) and capped the pipe that runs back from the exhaust manifold.
As far as I can tell everything else that the truck came with from the factory is still there and hooked up, correctly now.
The vacuum line that ran to the PAIR Valve (which I plugged) is the exception.


Is that going to cause me problems anywhere else if I leave it like that or am I going to have to take all the hoses associated with it off?
I don't care if all the other hoses are there they don't bother me as long as it doesn't create other problems because of the PAIR Valve being removed.

PapaChulos4U

Some people do eliminate the PAIR; I don't recommend it but if it was done correctly you should be fine. Just pull the codes and see if there is something lurking you can't see....

As for the brown VSV, the top is just a cap. Just let that one be (probably the easiest fix you've had in a while right?)

Odin

Somewhat easy lol, I just hate dealing with all those vacuum hoses but it's nothing compared to the 78 Civic I had about 10 years ago.

Now when cold the engine fires up good ( a little excessive cranking) and the idle speed comes down in a normal manner and stays there like I would expect.
After some driving the sooted up plugs cleaned up a great deal but were never going to make a full recovery so I fitted new plugs (Denso (3031) W16EXR-U) that I gaped at .031

"if it was done correctly" - That's what I'm worried about.

Another thing to look into, shorting pins and looking for codes.
I should probably disconnect the battery for a while to clear the old codes then drive it to check for current codes.
This is probably going to take me a few days because the weather is rather nasty right now.

But wait, if some codes were being thrown wouldn't the check engine light be on?
I've never seen it come on, but who says the bulb is even good or maybe someone just pulled it...


It really doesn't seem to be getting the best mileage (I have not checked it) even though all the ignition components are new and I've been staying below 65 mph (mostly 55mph) on the highways.
Guess I should also figure out what pins to short and check the timing.

I'm wondering what things to check that would make the MPG lower?
The previous owner said it blew the head gasket 10,000 miles ago and was repaired.
I wonder if at that time the factory 192-195f thermostat was replaced by an aftermarket 180f and it's running an incorrect air/fuel ratio when at normal operating temperature, costing me mpg.
1991 22RE- Fuel Injected


I'm 99.9% sure it's not a 160 thermostat as I've used one before in a different vehicle= heater, what heater lol

PapaChulos4U

The CEL doesn't always come on for a code, if it's something little and not really causing a huge problem with the engine.

For the MPG, what are you getting? These things really aren't the best for mileage. I average around 21, which is pretty good since it's 4X4 with oversize tires. To increase it first thing would be help it breathe better, either with an exhaust, header or even just a simple air filter. You could do the intake/battery swap too, pretty simple and REALLY makes a difference.

Odin

21 is pretty good for 4wd and tall tires. I suspect that may be all mine is getting but it's just a 2wd base model with 5spd and 205/70-14 tires.

Under normal driving usage is the check engine light supposed to come on at all when you first turn the key? I've never noticed it with this truck, I thought all cars did that.

scope103

Yes (to both statements). If your light doesn't come on, it may be as simple as a burned-out bulb. Or the prior owner pulled the bulb so he could sell it ....

Odin

Usually I'm a little OCD when it comes to my vehicles, but not this time.
Last night I unhooked the + battery cable and let it sit overnight to clear any old stored codes.
I hooked it back up today and turned the key until I witnessed the dash lights come on.
The Check Engine Light has been working, it just hasn't been staying on.
So I'm hoping that's a good thing meaning no major codes have been activated.
I also found the Diagnostic Trouble Codes and Possible Causes article over at 4crawler.com that should help out.
(I still have to wait a couple of days before I can drive it again because I'm waiting on some parts)

However to me when it was fouling the plugs the Check Engine Light should have come on. Early systems are pretty limited in what they can do though.

Odin

Had a break in the weather today so I installed my parts. I then cleared the codes -again- then had to fire it up to move it so someone could get out of the driveway, the engine didn't have time to warm up before I shut it off.

I decided to give the code check a shot (short TE1 and E1) even though I hadn't gone anywhere.
I saw four flashes then three flashes then it repeated.

Code 43, I did some searching and found this:
"Well that code is for No starter signal to ECM, Have you checked all of the computer and sensors and engine grounds? If even 1 of them is bad it can cause running problems. If those all check good and clean it is possible that the pressure regulator is going bad causing an intermittent problem."

More reading informed me that it can cause hard starting because the engine doesn't get enough fuel on initial cranking.
That is definitely something that my engine does. It takes roughly 6 revolutions to start the thing and seemes a little excessive.

I know better but I was hoping...
The area around my starter is dirty and I don't really care for the looks of the power and ground wires. Guess it's time to do my normal thing of cleaning up the wiring and making my own ground straps and battery cables. The weather has been really wet and windy for the last few days so I haven't had much drive to get blown around and rained on lol
With any luck tomorrow will be just as nice as today so I can get some more done.