abecedarian

I'm still leaning towards a stuck valve or something related to the valve train...
Even more now given what you said about your 'finger clearance'.

Did you do that vacuum check yet?

91Toyota

lol...yep

Well, the vacuum gauge that I have is a bleeder for drum brakes. Like it has a pump and everything on it. I've used it before to tune my carb on my Chevy truck. But I can't find a hose or anything to fit that is the right size. Would clamping it on somewhere work just as good?

Thanks

abecedarian

1- you are not tuning the carb on the Chevy truck.
2- clamping it "somewhere" only works if the clamp does not leak and you can get something meaningful from the gauge (like maybe readings in "inches mercury (HG)")
3- the gauge MUST be connected to a 'full' vacuum souce. Not some port off of the throttle body, nor a line to the EGR valve or the like. It HAS to come from the plenum.
4- don't use a vacuum 'pump', use a gauge.

Personally, after a week of horking with what you've been saying, I would've taken it down to a shop and had a "leak down" test done. If you don't know what it is, Google it. But let it suffice to say you will find leaking valves, blown head gaskets and worn rings with this fairly simple test. You could do it yourself with vacuum/pressure gauges (with 'hold') and a stethoscope.

So, fix the compression problem FIRST! Then worry about how the engine runs. Otherwise, you'll get the engine running fine, then you'll be back here asking for advice after you find and fix that other problem.

thook

Yep, a leaking valve would explain the goo in the throttle body. It'll never run right with that.

Generally, with worn rings you'd see a loss of compression on all four cylinders and not such an extreme on just one.....unless, you had a severe mechanical failure with the one piston ring set. In that case, you'd likely hear ugly signs of it. So, I'm in agreement with the valve issue.....considering what I said and abecedarian said above. Also, considering the shape of the oil in the pic and that there's no oil in the coolant which would point to the headgasket.

If it is a valve....I'm thinking intake...fixing that issue (and consequently installing another headgasket) would be cheaper and easier than another motor.

Get the leakdown test done. If you're reluctant because it means pulling it apart again.....well, in any case, you'll be doing that to repair your problem, anyway.

abecedarian...
I don't know exactly how it works, but do you think it could a bad or stuck lifter?

smishgibson

In the case of most other engines, yes it could be. But with the 22r(or a few other OHC engines), the valve train design omitted lifters altogether. The cam applies force directly to the rocker arm, that in turn directly applies force to the valve its self. I guess that at least when they were building the 22r(e) they stuck tight to the KISS principle.

As far as having a "fingers clearance" I don't believe this is possible, no mater how loose the lash adjuster is, unless there is cam/rocker wear.

It is possible that you had a lob on your cam wipe out, or the end of the rocker arm that rides on the cam my be excessively worn.

Any way, I believe your best bet from here is to take it to a shop and get a leak down test performed. They should be able to give you a good idea where you are loosing your compression.



Humm sorry if this seems a little bit off subject. As I know 91Toyota's original question was about idle surging. But I can't imagine wanting my motor to idle, if I had one cylinder with less than 120 psi cranking compression

Good luck,
Smish

thook

I meant rocker arm, but said lifter. So, there could be a rocker arm or even rocker rail problem, no?

Thanks, Smish.

smishgibson

Its ok thook. I thought about it after I posted. Should have ask you if thats what you really meant.

Yes, sounds to me like something out of the ordinary is going on with the rocker arm, the rocker shaft, or the cam.

Lets say there is a problem there, and the lash is so huge that the rocker never reaches the valve. I'm not 100% sure, but it may be possible that an intake valve not opening could lower cranking compression. Simply by not letting any air into the cylinder. Perhaps if no air gets in, there isn't any to build up pressure.

Of course exhaust could revert some, when the exhaust valve was open, but I believe enough of it would be forced back out on the exhaust stroke enought to clear the cylinder of any potential compression.

hummm

Do you have any pics of your head with the valve cover off 91? I would be interested to see your huge lash, and your cam/rocker/shafts in general.

Smish

91Toyota

Thats my car

That is NOT my trucks oil. There is NO antifreeze in my oil...and NO oil in my antifreeze.

Isn't a leak down test where I stick that piston up to the top and somehow pressurize that cylinder and then listen for a hissing sound somewhere? Like if its coming out of the intake it is an intake valve, if its coming out of the exhaust it is the exhaust valve...right?

I had a valve job done on the head...just to let you guys know.

91Toyota

Well, sadly I DID NOT take any pics of it when I first too it apart. I did however take a couple pics of it when I put it back together with the valve job done to it. Here are the pics....

91Toyota

O.K, you don't have to believe the finger clearance. I didn't believe it at first either. I don't know why or how, but I did. If you don't believe me I could care less. I'm not here to prove that, I am here to fix my truck.

I know where I am loosing compression. Why do I need a leak down test when I can just put oil in that cylinder and watch the compression rise?

Well, my truck has a pretty smooth idle for having 3 cylinder...and a 1/3...lol.

It USED to idle nice, now it surges. Hell, me and my brother could NOT tell it had a bad cylinder when we bought it. He has pretty much the same truck...and we thought it was a steal...I guess not

Anyway, the other cylinder aren't at 180. I'll update the latest compression results.

smishgibson

I did not intent to sound like I was questioning your credibility, I don't believe anyone has intentionally done so. I should have said that if you have that much lash, then there must be some outstanding wear on your valve train.

I apologize if I sounded derogatory.

Yes that is what I mean by a leak down test. If your compression rises when you put oil in the cylinder this doesn't necessarily indicate poor ring seal. It can mean other things.

Anyway, all of this would seem somewhat irrelevant if you had low compression back when your idle was smooth.

thook, Did you find your TB? If not I also have a few junk TB's laying around. If thook doesn't find his, would you still wanna try an idle screw 91?

Smish

thook

Very sorry. I obviously wasn't paying close enough attention.

No, Smish.....I can't find my throttle body. If you have a screw for him, fantastic.

91Toyota

Yeah, I understand. I didn't mean to sound as much as a jack ass but it just came out that way.

Amazingly my compression has been slowly rising lately with the latest product that helps with sludge in the ring packs. It is working though...which I first didn't believe.

Anyway, I can't explain it. It was fairly smooth, and it still is. You can definitely tell your missing a piston when your trying to go fast, because it tops out at 95mph, and take 12-13 seconds for 0-60mph.

So, about my idle. Most likely a Auxiliary Air Valve? I'm seriously considering replacing it. Thanks!

91Toyota

No hard feelings. I kind of thought that would happen when I put that picture up

So, Auxiliary Air Valve? Or do you guys still think it's something else?

Also, anyway to test it while I have it out on the bench? I took it off to inspect and clean it once again and I don't know what I am doing. Can I heat it up and see if the spring moves? Clean it?

Thanks!

91Toyota

So, I found a throttle body for $25 and it is off of a turbo 22ret. I am wondering, the setup would be different for the AAV right? Would it still work?

Thanks

thook

I don't know what to tell you on that.....the bench testing, anyway. I don't even know what one looks like on the inside. I've never had my TB apart on my '92. You could try, I guess, but at you're own risk, eh.

If I were to suggest anything, it would be to put in a freezer bag in a pot of hot water and let it warm up. See if it moves to a closed position. Then, pop it the freezer and see if it opens.

91Toyota

Good idea. Thanks. I can't push the thing at all. Want me to take some pics of it?

thook

That's okay. I'm remote viewing and can see it in my mind's eye....

(Yeah....a pic would be good... )

abecedarian

A leak-down test is like a compression test on steroids. It can detect weak rings, burnt or stuck valves and cooling system problems such as blown head-gasket(s) or cracked cooling passages in the head or block.

Basically, the piston is put at bottom-dead-center between the intake and compression strokes and the cylinder is pressurized through the spark plug hole. Sometimes (actually should be always) a static compression test is done as well in order to establish a baseline for how well the rings are sealing the cylinder- to determine the desirable results so a cylinder can be accurately compared to every other cylinder. No matter what one may think, a compression test is 'ok' for some things but you cannot get a true image of what's going on inside the combustion chamber without doing a leak-down test.

Escaping air pressure during a leak-down test will indicate where a problem is:

1. hissing in the intake means something is wrong with the intake valve (bent stem, carbon build-up, warped seat improper lapping, etc.- something holding the valve open or causing it to not seat properly), camshaft (incorrect base-lobe radius) and/or rocker arm/lifter (too tight adjustment or blocked bleed passage {for hydraulic lifters} causing the valve to be held open when it should be closed).
2. hissing in the exhaust will be caused by the same issues as would cause noise in the intake
3. bubbles into the radiator will indicate a blown head gasket or compromised (cracked?) water passage in the block or cylinder head.
4. noise/hissing into the crankcase is the norm for a leakdown test since rings are generally not air-tight. However a cylinder with the rings in good condition should retain a certain amount of pressure after a certain amount of time.

Low static compression in a cylinder is caused by one of the 4 things a leak-down test will find.
So, why not do it?

@ 91Toyota:
Just because you just had a valve job done recently does not mean the valve job was done properly... does not mean the head-gasket is in good condition... does not mean the head-bolts are torqued properly (and were re-torqued when they should have been)... and does not mean there is nothing else wrong with the engine and thus causing other problems such as idle and driveablility issues.
I hate to sound condescending, but you should NOT be trying to fix problems with the intake / throttle body, etc. until you find out what is causing your low compression. Fixing the low compression problem could fix your idling problems. Not fixing the compression issue will only compromise the other 3 cylinders' reliability and accelerate their wear.

91Toyota

Yeah, I get what your saying. No offense to you, but this problem has nothing to do with the low compression. I had low compression before...so why wasn't my idle f'd up before? It is now, that's all I can say. Maybe it is the head, but how do I hook up my air compressor to the spark plug hole?