12 replies to this topic

[bmarshall1]

After cleaning and re-installation of the intake manifold on my 99, I have an 'extra' vacuum fitting and no hose to put on it that I can find.  Currently i have it capped with a (white) hose nipple, can someone look at the picture and identify the missing hose? I am pointing to it with a white pencil, you can see it behind/under the throttle cable.

 

Thank you

 

 Vacuum Nipple.png   136.12KB   6 downloads

[DrDomm]

I believe there's a hose that comes from a "boost" sensor on the right side of the engine bay that goes there.  I bet if you google "miata vacuum lines" you'll get a decent diagram.

 

Edit: I was wrong.  Looks like it comes from the "purge solenoid valve"...part of the emissions/evaporative system...

 

http://ww2.justanswe..._154828_vac.gif

[bmarshall1]

Thanks Dom, I googled and read the service manual but none of the pictures or diagrams had enough detail to make out the proper routing.

 

I am hoping someone with a 99/00 can take a quick look at their car.

[DrDomm]

Here's someone's image.  His arrow on the left points to the hose.  Follow it back.

 

http://www.joehender...ngine_small.jpg

[bmarshall1]

Thanks Domm  that helped a lot.  But now I have an empty nipple on the T under and to the right of the TB, directly above the alternator and pointing forward.  it 'appears' there may/should be a cap on that one by looking at the diagram?  Can you confirm.

[Bench Racer]

Isn't it a bitch guys when only two guys in the whole wide world own a 99 Spec Miata.

 

Ya know guys, I been called a lot of things on this site. I call myself, well intended.  If I owned a 99, I'd walk to the shop and directly find the answer to the vacuum line question. 

 

Try this address, second row, diagram with yellow hoses. https://www.google.c...BA&ved=0CBQQsAQ

[bmarshall1]

thanks Bench, I had looked at the diagram and that's why I believe the nipple is capped off, I'm just looking for confirmation.

 

Can anyone address my other thread "Weird Idle Issue"...  I set the timing to 14 degrees on my 99, after a few minutes it goes back to 10 degrees and then wont hold a partial throttle at about 2000 RPM, it wants to climb and then drop.  Upon restart the timing is back to 14 and then drops to 10 again

[Bench Racer]

There are a gazzillion other diagrams show, didn't look at them all. Just finished a post at your timing post/oscillating issue, from an experience with my 1.6.

[bmarshall1]

Bench,

thanks for you help, I just finished a tranny and diff fluid change and have put the car to bed for the night and will resume tomorrow.

 

I'm sure there is an easy answer but i don't know what it is.

[bmarshall1]

Vacuum routing issue is SOLVED, thanks everyone.

 

The main issue now is that once fully warm, it will not hold a steady 2000 rpm at @1/8 throttle, it wants 1/2 or more, otherwise it revs to @ 2000 rpm them drops back to 600 rpm and repeats the cycle

[davew]

Could be the wrong intake manifold gasket. NA 1.8 has the same bolt pattern but different port shapes. Don't ask why I know!!!!

 

dave

[bmarshall1]

Thanks Dave, I'll take a look at the gasket and ports to assure they match up.

[bmarshall1]

Best Answer

The timing and idle issue seems to be solved at this point.  For all of those who were pointing to a vacuum leak - give yourself a pat on the back.  The interesting thing is where I found the leak...

 

I took the upper manifold to replace a leaky injector ring and decided to test the VICS check valve, it is supposed to be a one way valve, but mine was open in both directions, possibly flowing air backwards and when it should not have been, perhaps giving the appearance of a vacuum leak.

 

While I can't say for certain this was the problem, I can tell you a new VICS check valve made all my problems go away.  The timing is steady, the idle smooth, and it will hold a partial 2000 RPM throttle.

 

THANK YOU everyone for all of your input!!  Miata people are a great resource and awesome community.

 

Bruce