I'm trying to trace down my funky idle problems now. (non-cc qjet)
I'm plugging most of the vacuum holes with caps to try and find a vacuum leak.

Problem: When first starting it idles high (2500k), then after tapping the gas a few times, or walking around and pushing the high idle arm down, it'll drop down to around 700..but it kinda "
hunts". It tries to stall and just generally doesn't want to idle that low. I'm getting 15" of vacuum or so at idle, if I rev it, it jumps to 20".

aside from spraying on carb cleaner or propane, is there another way to check for vacuum leaks ? I have a stethoscope, but i'm worried about touching it too close to combustion and going instantly deaf....

Could vacuum lines be old and dried out/cracked to the point of leaking all throughout the line?

I'm now trying to check what vacuum lines are needed: at the back of the carb i've got the screw in line going to the brake booster, and another one at the base going to...? It goes back to the firewall and down, have no idea where it leads... anyone?

The only line coming from the manifold is right behind the carb,(right?) it appears to go towards the brake booster, then forward, towards the cruise control module. which for me is bypassed and not working, so I clamped that line to test it. (before I was getting 13" vacuum, now 15ish)

What about EGR? I don't need it here, so for the sake of testing I was going to disconnect it. If I simply disconnect the line going from EGR solenoid to carb, and plug the carb hole, but leave the solenoid dangling, no problems right?

I think the engine is shaking a bit more then normal, i'm also going to somehow try and figure out if the plugs are all getting spark.....

 

If the EGR valve itself is carboned and sticking open, the disconnection of the vacuum line won't make any difference - it will still leak vacuum.

Yes, vacuum lines can harden and crack just about anywhere along their length.

 

why not spray carb cleaner and see when the RPMs are affected? its really easy, cant think of a better way to check for a vacuum leak.

 

I suppose I'll try that... I'll also try and get some new vacuum line and replace any of the old stuff....

any ideas as to what that vacuum line on the back of the carb goes to?

 

It may have gone to a TVS on the intake, and then down to the heat riser valve on the RH exhaust manifold. It may also have gone to a MAP sensor. This might help:

 

yea, that's whats confusing me..
I'm running non-cc q-jet, my underhood sticker is similar to that one, CC-qjet style)

So i've got vacuum advance, PCV, EGR and power brakes hooked up. The rest are capped. (except the mysterious one at the back of the carb.)
The whole bottom of the diagram, below the carb (except for the PCV) is gone. (also the air cleaner doesn't have any vacuum hoses hooked up to it.)
Is this a problem? I don't have the canister, or at least I think I don't...
I have no idea what the TVS is, or EFE...are they needed?

Where is the vacuum sensor mounted? firewall? I'll try and trace that vacuum line to it, and see if it's cracked...
I've also found an article saying that the carb/intake gasket may be too small, and that the vacuum passages may not be covered by the gasket... I'll check that, maybe put some silicone around the base to be sure...
Thanks -J

 

Well I didn't have carb cleaner, or a hose for my propane bottle, so I tried brake-kleen... sprayed some down the primary throttle blades first to check, that almost stalled it...

Anyway, i'm pulling a fairly consistant 15" or 17", it's either one or the other, depends on idle speed... not fluctuating though... It doesn't want to idle below 1k.

I had the vacuum advance hooked up to the red arrow nipple on the right (ported?), and the left nipple (below fuel line), was the EGR.

front of carb

I unplugged it at idle (vacuum advance) and plugged the hole, to see what would happen... idle dropped to point of stalling... ? had to hold my hand on throttle cable to keep it running...I thought this was a ported vacuum slot? I checked it, it had 13-15"?

Also, after turning off the car, or it dying, steam comes up from here:
back of engine
What is that??

Anyway, right now i'm going to run back out to the garage, and disconnect the vacuum advance, and plug that on the engine, then set the timing again, make sure that's right, and set the idle... based on no vacuum advance... Then hook the vacuum advance to something higher up on the carb, and hope that's ported...

here's a few more carb pictures I took, if anyone sees something grossly wrong, feel free to point it out... I need all the help I can get...
other misc. carb pictures


Thanks -J

 

I'm also redoing my vacuum line and noticed that maybe something was missing but not sure. On the back of the EGR Soleniod is a vacuum nipple. The diagram does not indicate that there is one, but I'm sure it's a nipple because it has those two metal clips on both sides that hold the vacuum line onto it, like the ones on the under side of the stock air cleaner. I simply capped it off because I could find no vacuum line near it.

 

I have the same problem but that diagram is for a CC controled carb. Mine and likely yours isn't since they are Canadian cars with no CCC. 3 of my vac lines fell apart in so many places, I can not tell where they should go. (EFE, EGR and Dist. Vac. Adv) Missing the sticker under my hood too.

Do you have a vac. diagram sticker under your hood? If you do please take a pic and post it.

 

My underhood sticker is american. My car is an illegal alien. (long story..)
It now has non-cc qjet and vac dist. I only have 2 lines on my EGR :
egr solenoid

both plastic lines broke as I took that picture... hope that isn't a big deal... I tossed the solenoid, and capped the line on the carb, but not the one on the EGR itself. (that can't leak right?)
I think i'll get a block off plate soon....

Any idea's about the possible leak?

 

You can repair the breaks by sliding some windshield washer hose or what ever else fits over the break.

I have never tried brake cleaner for findting vac. leaks. I have used quick starting fluid in an aresol can, unlit propane torch and carb cleaner and those things work well.

Make sure that brake cleaner is suitable or go pick up a can of carb cleaner. Will need that at some point anyway.

Check around the edges of your intake and the base of the carb too.

My heap doesn't even have a an EGR selonoid and I am not sure if it should or not. I have 3 TVS's, two in the thermo housing and one to the pass side of the thermo housing.

 

What's a TVS???

Yea, I heard the base of the carb is bad for that... I think I have a big propane bottle with a hose that I can use... I forgot about it, I thought I only had the little bottles without an adjuster on it....

My "cracked" plastic lines are shattered... I don't need EGR, so i'll just scrap it... I'm going to get my helm manual and i'll see how that works... (just intake, or connected to the head??? etc..)

 

TVS is a thermal vacuum switch. There are a few types. One type will allow vacuum to pass only when below a certain temp, another will allow vacuum to pass when it is above a certain temp.


Don't worry about plugging the vac. connection on the EGR it's self. It just pulls the diaphram up and down and is isolated from the egr passages in the intake under it.

 

A bit of an aside from my current problem, but:
I'm reading the helm manual here, and it describes the EGR function... seems it sits in the intake manifold and does what you say. but where is it getting the exhaust gas from? If I remove the EGR from the intake manifold and use a blockoff plate is that it?

 

Exhaust port is the source. EGR valve allows it to go back into the intake and reburned again. You can leave the EGR valve there and that will work as a block off plate.

 

oh ok, so the EGR mounts in the intake manifold, but hangs right down into the head?
I'll just leave the EGR as is then... but when I replace the intake manifold eventually, and get non-egr, do I have to modify the heads?

Anyway, i'll try the propane trick in the next few days here...

 

No the valve doesn't go all the way down into the head, it's all done in the intake. There is a port in the head that mates to a port in the intake and that's where the exhaust gas comes from.

 

oh ok, I get it. So if I replace the manifold with a non-egr one, it'll block off the hole in the head no problem?
that'll be an "eventually" sorta thing...

I'll update with the propane test later in the week when I have some time...