In a perhaps misguided attempt at fixing a boost problem, I decided to remove the intake manifold to check the hoses underneath. It was much more work than I thought, and about half way through I decided to back out. This was after I had removed the throttle body and had the intake manifold mostly off, but not completely. I put everything back together, re-using the original gasket to the throttle body (it was metal and looked fine). When I first started the car I was getting a really lumpy weak idle and heard this high pitched hissing/squealing sound so I shut it off. I looked around and discovered that the hose to the thingy that says "boost sensor" wasn't connected. So I plugged it in and started it up again. This time things were much smoother, but I noticed that it was idling really high (around 2500rpm) even after I blipped the throttle to stop the warmup and it was still making the noise, then the check engine light came on so I shut it off again. I looked around and realized that one of the electrical plugs underneath the manifold wasn't plugged into anything so I plugged it in and started it up. This time no engine light, but still the noise and high idle.

Since it was late I admitted defeat and left the car in the garage. Any idea what might be connected wrong? One other piece of info is that I dropped two nuts while working, and the plastic extension from one of those compressed air cleaner things (like the little red tube from wd-40). I was hoping to find and remove them once I had it running. In the meantime I only have one of the nuts on the top of the throttle body where it connects to the manifold extension the other 3 are still there.

Anyway, thanks in advance for any help, I don't even care about the original problem anymore, just hoping I haven't done any permanent damage.

 

I don't understand what nuts you are missing? The ones connecting the LIM to the UIM or the ones from the UIM to the throttle body?...

...Either way, I find the easiest way to take the UIM off is to disconnect it from the LIM and then disconnect the elbow from the Intercooler...and take the whole thing off...i.e. UIM, throttle body, elbow.

 

i am willing to bet you placed the ground that gets put on the last stud inbetween the plenum and LIM.
the sound you describes would lead one to believe you have an intake leak. this would also cause a high idle. that is the most realistic scinerio i can come up with.

btw...no need to take off the TB to pull plenum off.

 

Can you describe the ground again, I'm not sure I know what you're describing. Do you mean the two ground wires that attach to the plenum may be accidentally in between the UIM and LIM? Thats possible and should be easy to check. Thanks for the hint.

BTW - Anybody know what happened to all the other responses on this thread? They seemed to disappear early today.

 

the sever crashed and a day old backup had to be used.

correct. it will make a whistle noise because it is sucking air in through a tiny opening.
it may not be a ground, maybe the *post* that holds the throtle cable up. it is sort of like a "L" shape. it goes on the last stud twords the firewall.
if you start the car and spray carb-cleaner there, the idle should go down a bit, and you will see the leak suck the carb cleaner in....

 

Just wanted to thank everyone for the helpful hints. I figured out the problem tonight, it did turn out to be an intake leak, but was entirely my fault. I forgot to tighten down the 5 nuts that attach the UIM to the LIM, they were just finger tightened. So now all I have to do is find the correct cap nut for the fourth bolt on the throttle body and I'll be good to go. Anybody have any idea what the exact specs are or where to find one? I checked home depot but they don't have much metric stuff.

 

home depot does not carry metric.
take any 10mm nut off of anywhere on your car. most every thread and pitch is the same on a Mazda. try an inconspicious place like your trunk
btw...how did you loose nuts on such a little job? always keep a small box or cup whith you when tearing things apart.

 

I dropped it while removing it, a friend was talking to me and I guess I was distracted. It was amazing how quickly it disappeared in that mess of wires...

 

well, i have dropped many nuts down in that area in my several times of takint he UIM off ( i think 20+ times)... anyway, after removing all the solenoids and vacuum hoses i know have all original shiny bolts and nuts on my TB and UIM, lol!