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[Amphicar770]

Good, now go drive it.
Told you we have ALL done it.

Real close to that test drive.

First have to get the idle down below 3,500. Probably just a hose or other vacuum issue.

[MarkV]

We have all done it. When you change a bunch of different parts at once it is always hard to figure out what is causing the problem.

I used to have an XJ6. Great car as long as you didn't drive it. Lucas, the knight of darkness.

[BeatNavy]

Probably just a hose or other vacuum issue.

Or timing way too advanced. Check for leaks / disconnected hoses, but also verify timing since you were in and around the dizzy.

[Amphicar770]

I think I found it! I can't test until the AM as my 3 year old is asleep in room above the garage.

When I cleaned up / repainted the plenum I took the plastic piece that the AAR valve connects to off. The gaskets did not look that great but since I did not have replacements I figured I could reuse them.

Tonight I did a flashlight test. I turned out all the lights and shined a bright flashlight down the throttle body. Guess where the light was coming through? Yup, right about where that old gasket sits.

I cut two new gaskets, put everything back and no more leaking light or presumably leaky air.

I'll let you all know the outcomes tomorrow.

[Amphicar770]

Oh well, never that easy. Still idling fast.

I capped all the ports on the plenum (or hoses leading to plenum). That brought it down some.

Need to check ignition timing but before I do wanted to check ...

What hoses or ports need to be capped? Should the mps or distributor vac lines be disconnected or capped. Are there any that should remain connected?

Set knob in timing light to 27 degrees, idle at 3500, look for TDC mark on fan. Correct?

Thanks again.

[BeatNavy]

Oh well, never that easy. Still idling fast.

I capped all the ports on the plenum (or hoses leading to plenum). That brought it down some.

Need to check ignition timing but before I do wanted to check ...

What hoses or ports need to be capped? Should the mps or distributor vac lines be disconnected or capped. Are there any that should remain connected?

Set knob in timing light to 27 degrees, idle at 3500, look for TDC mark on fan. Correct?

Thanks again.

Pull the vacuum advance and retard lines to the dizzy and cap those (only those). Check/set the dwell first, as that can impact timing. Do you have stock ignition? I lost track...

Here's a good reference: http://www.pelicanparts.com/techarticles/9.../914_timing.htm

[Amphicar770]

Oh well, never that easy. Still idling fast.

I capped all the ports on the plenum (or hoses leading to plenum). That brought it down some.

Need to check ignition timing but before I do wanted to check ...

What hoses or ports need to be capped? Should the mps or distributor vac lines be disconnected or capped. Are there any that should remain connected?

Set knob in timing light to 27 degrees, idle at 3500, look for TDC mark on fan. Correct?

Thanks again.

Pull the vacuum advance and retard lines to the dizzy and cap those (only those). Check/set the dwell first, as that can impact timing. Do you have stock ignition? I lost track...

Here's a good reference: http://www.pelicanparts.com/techarticles/9.../914_timing.htm

Thanks. Yes, saw that article.

My dizzy only uses the one line, other is open. Do I just pull the line off or do I need to cap / plug anything?

There is a pertronix or similar in there. No points so dwell should not be an issue.

What's best way to view timing port? Just lie on the trunk?

[BeatNavy]

Thanks. Yes, saw that article.

My dizzy only uses the one line, other is open. Do I just pull the line off or do I need to cap / plug anything?

There is a pertronix or similar in there. No points so dwell should not be an issue.

What's best way to view timing port? Just lie on the trunk?

I know not all dizzies have both advance/retard, but not sure what you mean when you say "other is open." Just disconnect and plug the one that is connected and make sure any other lines are capped or connected to where they belong.

You should be able to view the timing port without any problem leaning over the trunk from the side. Helps to have a helper bring the car to 3500 rpm (or whatever is spec).

Again, I'm not sure what ignition or engine you have, so you'll have to set it based on your specs.

[iankarr]

I had a high idle issue that was caused by leaky intake manifold gaskets. Have you checked those?

[Amphicar770]

I had a high idle issue that was caused by leaky intake manifold gaskets. Have you checked those?

Those are both brand new. I figure I will make sure timing is right first.

[76-914]

Block everything off except the MPS. Then add in one at a time until the high idle returns and you've identified the culprit(s). (IMG:style_emoticons/default/beerchug.gif)

[Amphicar770]

Block everything off except the MPS. Then add in one at a time until the high idle returns and you've identified the culprit(s). (IMG:style_emoticons/default/beerchug.gif)

Yup, thats what I did. At best a 200 rpm diff with everything capped. I will go after the timing first. My other vehicles are conspiring against me at the moment. This evening, the wife's car needed brake pads for inspection. My daily driver (Jag XJR) needs a new power steering pump arriving tomorrow.

[iankarr]

You could also try the WD-40 trick. Spray it around gasket and hose areas and see if/when the idle changes.

[ChrisFoley]

2.0L plenums sometimes develop cracks on the bottom surface.
They can be difficult to find since the leak may only be noticeable at high manifold vacuum (ie. idle).

[Amphicar770]

2.0L plenums sometimes develop cracks on the bottom surface.
They can be difficult to find since the leak may only be noticeable at high manifold vacuum (ie. idle).

I've been thinking about that possibility. If timing turns out to be spot on, or close, then that is the next thing to explore.

I did bead blast and repaint the plenum so I *think* I would have noticed a crack and / or it would have shown up with the flashlight test. Then again, I was certain I had the plug wires in the right spot so I am not ruling out anything!

Thanks

[r_towle]

Oh well, never that easy. Still idling fast.

I capped all the ports on the plenum (or hoses leading to plenum). That brought it down some.

You need to become a lot more precise.

Remove all hoses from the plenum.
Don't skip this step and lie, you won't find the,issue.

Remove the hoses from the plenum and cap off the hole at the plenum.
If there is a fitting with gasket, remove it and cap off th hole.

Then y will know.

[Amphicar770]

Hope to get back to it this weekend. I do think I capped everything but if timing is not off will try again.

Has anyone tried using smoke testing for plenum or other leaks, seems like that would work well. Pump some smoke in thru the throttle body and see where it escapes?

[Bob L.]

Hope to get back to it this weekend. I do think I capped everything but if timing is not off will try again.

Has anyone tried using smoke testing for plenum or other leaks, seems like that would work well. Pump some smoke in thru the throttle body and see where it escapes?

Since the plenum is not under pressure (pushing air out) you wont see smoke escape. It is under vacuum and will suck extra air in.

Not sure about the mentioned WD-40 trick unless it's the same as Carb cleaner. Spray cleaner aruond the vacuum hose connections and when the idle dips/stumbles, you have found a leak. possibly, one of several.

[BeatNavy]

You could try the carb cleaner "trick." Never seemed to work for me, but then maybe I didn't have any bad leaks at the times I tried it.

Just check the timing. It's easy and quick. If it's not significantly too far advanced you can scratch it off your list rather than chasing down vacuum leaks that may or may not be there.

[76-914]

Did you check the injector seals to be sure the injectors are properly seated? Have you checked the gasket on the oil filler?