First of all - great site! It is nice to see all of the fine 914 work and excellent advice in one place. I have been a fan of the 914 since I was a kid and finally bought one.
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1974 Zambezi Green 2.0...2 owners, 36K Miles. Had not run for 6 years, but the engine was free. Drained gas, charged battery, new oil, oil filter, fuel filter, new plugs & wires, checked point gap, adjusted valves. It fired up with a majestic roar and ran decently. It is far from perfect, but it is complete and unmolested. There are some hell hole issues and some rust under the rocker panel covers.

My goal is to get the engine running perfectly before dropping it to repair the rust. Hopefully, I will only have to drop the engine once if I do it this way.

The car runs very well, but I still have a consistent high idle (about 2500 RPM). I am running factory fuel injection. The problem persists even after completing all of the following:

- new plugs & wires
- new air cleaner
- inspected points and set gap to .016
- replaced all vacuum lines (bought kit from AA) & fittings, including the "stacked vacuum fitting"
- replaced intake runner boots & intake gaskets
- checked dwell and found it to be well within limits
- set timing IAW Haynes Manual

I just tried to adjust the idle speed using the screw on the air intake...it had very little effect on idle speed even at the adjustment limits.

Any help would be greatly appreciated. Thanks

You can probably take care of the rocker panel rust without dropping the engine, depending on how severe the rust is.

Check all vacuum hoses for leaks.

Remove all the vacuum lines from the plenum.
ALL OF THEM.

Leave just one...the line to the MPS.
Cap off the rest.
Get idle correct, set timing correct and use idle air bypass screw.

Now that the idle is perfect...put ONE line at a time back on the plenum...
Rev up the car for a minute then let it go back to idle...
You will locate which vacuum circuit leaks, then fix it.

Rich

The connection to the thermoswitch that controls the cold start fuel injector is broken so the wire can not be connected. Could this be the problem (if the cold start injector is always firing fuel into the plenum)? Thanks

No. There are other issues. The VERY FIRST thing to check is the auxiliary air regulator (AAR). Just plug the hose from the air cleaner and see if the idle drops. Disconnect the vacuum retard hose and plug it. The idle should go up. Recheck the timing, hose(s) off and plugged. The full advance mark is next to one of the thick supports of the fan. The Cap'n

Thanks Cap'n - appreciate the help. Will check it out and report back.

Idle that high means an air leak of some kind. Could be the AAR being stuck open, could be the big "manifold boots" (the very large vacuum hoses from the plenum to the intake runner pipes), could be a crack in the plenum, could be other things.

The CSV only opens when the starter is cranking, because its power comes from the starter circuit. They can get stuck open, but this isn't that common to my knowledge.

Have you read through http://members.rennlist.com/pbanders yet?

--DD

Hey Cap'n

Was that you with all the boxes of parts up at the Parts Heaven Swap Meet?

I was talking to you for a bit, but didn't put two and two together to figure out who you were.

Next time I'll make sure to introduce myself proper.

Randal

You definitely have a vacuum leak below the butterfly in the throttle body. With a 2500rpm idle, it's a pretty big one.

A stuck AAR could do it, so plug that off first like the Cap'n said.

If that doesn't do it, plug the other lines like Rich said.

Don't pull the MPS, that one is essential. Actually, pulling that line WILL drop the idle but don't let that fool you. That's because it would run full rich. That also raises a point about your CSV question: If it was constantly spitting extra fuel in, it would make a richer mixture. More fuel without more air will cause it to run slower and rougher, not faster. A lean mixture, more air, will idle faster.

If plugging the vacuum lines doesn't change it, and you are positive you have tight seals around the intake runners, then you might have a crack in the plenum.

Let us know what you find.

I had a similar situation. I eventually found the main culprit to be a leak at the PCV valve (a little RTV fixed that). I found it by doing as suggested above and plugged everything but the MPS. I vacuum leak in anything downstream of the throttlebody will raise the idle.

I also have a small leak around the throttlebody shaft (again a little RTV helped here). I found this using the starting fluid method.

Plugged vacuum line to AAR and the idle dropped. I was then able to adjust the idle using the idle air bypass screw. Looks like I have a stuck AAR. Next step - pull the AAR and try to free it up?

i guess thats a common problem, stuck aar on a djet. I have seen 2 d-jets both using an 1.8 aar. i guess they are more plentiful? There must be a way to unstuck it.

You can try hosing it out with WD-40 or an actual penetrating oil. Sometimes that helps. If that fails, you can disassemble it and free it up. Make sure the heating element is still there--you should get about 13 ohms resistance from the wire on the bottom of the AAR to the case of the AAR.

I opened one up by un-crimping the lip of the "can" and pulling the top out; some people have said they can pull the top part out of the lid of the can.

--DD

Letting it soak overnight in WD-40. Will check it tomorrow night. Man Dave, you are everywhere! I saw your comments on testing the AAR on shoptalkforums.com. Your knowledge is much appreciated. Hoping the WD-40 frees it up and the heating element is OK. If not, it is coming apart.

Hey Man,
Its good to see another local here. You seem to have the problem on the run. If you need parts locally, or a hand with your care I may be able to help.

did anyone mention a vac leak at an injector seal?

Thanks Mike. Getting this thing going has been quite a learing expereince - but a lot of fun as well. I really dig the car - hoping to have it done by the end of the year. I have seen at least four members now from the Central PA area. Small world - my girlfriend works in newborn medicine at Hershey Med.
Bob

I think someone did mention it...but all injector seals are brand new.

Rookie question but, when you disconnect hoses at plenum are you them capping the hoses or do you cap the the plenum connecting points?

Thx

Cap the plenum.

Here is a tip I picked up buried in another post. Used it tonight and it paid off right away.

Darken your garage and shine a flashlight down the throttle body (make sure throttle is open). If you have light leaks, chances are you have air leaks. I quickly discovered bad gasket where the AAR valve attaches to plenum.

Very cool. This site is like that pylon thing in "2001". Every time we apes touch it we become smarter .

Aar gasket? Please elaborate.

100% should put you in the right direction,,, make sure you check the gasket where the manifold connects to the Head..