intake vacuum leak?

[Bangster]

I am getting P0174 and P0172, I replaced the MAF to squeak it by emissions testing but still getting the code(s).

Does this sound right? I know there is a little background wind, but this is the noisiest car I have ever heard. It has sat for awhile so the valve train noise doesn't scare me, but I think I need to fix a vacuum leak

http://www.youtube.com/watch?v=cyVSn8aaBqw

This is my 00 Grand Marquis. Half the cams and timing chains, but over double the mileage at 256k.

http://www.youtube.com/watch?v=gQitEILm0HQ

 

[chris2523]

check the brass plug in the bottom side of the throttle body.

 

[Bangster]

Thanks! I didn't feel that thing when I was blindly trying to cover the pressed in plug on the upper intake. I went back to the junk yard to see what the TB looks like (it is ~2 miles from my house, and I needed other things, so faster to drive there and look at one I removed from the 98), and sure enough, once I snake my hand up behind the TB and cover it with my finger no more leak! You saved me pulling the intake (I will eventually get to it, but I have other things I want to do first).

grr I guess I should have dug into the top end a little more. I did the EGR and IAC and vacuum lines, I was 5 bolts away from the answer. I almost took off the TB but without a gasket I didn't want to be stuck.

I bought an upper and lower to clean up to install when I swapped out the intake and IRMC gaskets, so I could see under the upper, but I didn't buy the TB (but I took a picture of it today in the junk yard):

this was literally finger tight (this isn't mine, but this is where mine is leaking)

I was blaming this...I can't reach it to block it off, I did spray a bunch of carb cleaner, then starting fluid, then propane, and butane, which never changed the idle or leak.

Hopefully I can take off the TB without tearing up the gasket.

 

[Bangster]

It wasn't loose, it was missing!

It is so wedged in I can't get it out. It will wait awhile until I pull the intake. I grabbed the one from the junk yard, they didn't charge me for it (I didn't hide it, I put it out with the other parts I got, an ignition switch, wiper arm, two COPs from a Continental). They usually don't charge for things like that when your spending 30 bucks. When I get charged for things like this it is .25 or .50.

The one that fell out looks different, it doesn't seem to have the big head like the one I got from the 98, but has the o-ring on the outside of it.

You can see it here, between the injector wiring, below and slightly left of the "3".

MUCH better. Idle is better, I lost that exhaust burble I had gained, not sure if the idle will be smoother or if I have a COP issue.
https://www.youtube.com/watch?v=P3kLA6JJZEc

 

[Bangster]

Idle is smooth (before if I had the door fully opened at the door handle you could feel a vibration and see the door move, that is gone), it hasn't completed all monitors so it still might throw a code, but I think this solves the CEL. However it still skips once warmed up and idling and under moderate load. I don't remember how I made the COP fail last time it ran like this. If the misfire tests work on this car, then none of the cylinders are showing any, which I find odd, because I see a few on my 00 Grand Marquis on all cylinders, it just isn't many, not nearly enough to trigger the CEL, set a pending code, or make the CEL blink.

I have 4 used spare coils, time to play random part replacement.

 

[chris2523]

yep, this is surprisingly common, and i have no idea why.

 

[Adams97Mark]

Bangster do you know 1. what that plug is even for? 2. the size of the alan key? 3. when you put your finger over it while engine was running did you get to feel or hear air flow stoping and starting?

 

[Bangster]

I don't know why it is there, I can only guess that it is there because a port has to be machined, or possibly it is used in another application for a vacuum port (just a wild guess). I think I used a 5/32 or 3/16 allen key, I think it is a 4mm hex, but 5/32 is close, there was no slop and not a lot of torque is needed. When I plugged it while running, the sound from the original post stopped, it was like turning off a vacuum cleaner. It was NOT a strong source, so I couldn't feel if it was a vacuum or pressure.

I think all monitors have passed and no CEL, so it seems to have fixed my CEL (and noise).