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SVXRide
11-08-2002, 11:47 AM
Okay, I checked old threads and didn't find one that had the same characteristics as what happened yesterday, so here I am. Drove a couple of miles running errands during my lunch hour and after I started it back up after the last stop the idle started bouncing between 750 and 250 rpm. Every time it dropped down in rpm I heard what sounded like a small door opening and closing under the hood, then the rpm would jump back up. Would have gotten out and looked under the hood, but I was in a drivethrough lane at the bank. Strange thing is that once I got back to work and it sat for a couple of hours it was fine all the way home (around a 35 mile drive with at least half a dozen lights I had to stop at).
Is there some sort of flapper valve in the air intake system that could be making the noise (i.e. choking the airflow and making the rpm drop)?
Thanks in advance for everyones' help on this.

laserx
11-11-2002, 10:26 AM
I had a very similar problem, although I didn't hear "something like a door opening and closing". After changing the pvc and two knocksenors I still had the problem. What finally fixed it for me was to put in a new air flow sensor. It's the square looking thing attached with 4 bolts along the air hose just past the air filter housing. regards dave

Aredubjay
11-11-2002, 11:21 AM
Well, you have a veritble plethera of "flappers." You've got two in the intake and you've got the IRIS "flapper." (as seen in the cutaway pic below).

I doubt that it's your "flappers" causing the problem. Probably more like the "flappers" reacting to the base problem. You may try cleaning the throttle body. Your MAF sensor may be at fault. You haven't put less octane in your tank than has been recommended, have you . . . . just thinking out loud.

gl1674
11-11-2002, 05:43 PM
That does sound pretty much like MAF sensor. You can try gently rocking the MAFG connector with the car running. If you find that touching connector heals the problem or causes it, read on.

The connector is solded to a printed circuit board inside MAF and apparently soldering goes bad quite often.

Most often these problems start after work done in the engine
compartment (new plugs, new rubber gaskets).

If it is the case, you may consider opening up MAF and soldering
the connector back on. Yeah, MAF can be opened up.

SVXRide
11-11-2002, 09:23 PM
Thanks for the responses!
I'm only on my second tank of 91 octane since I bought the car, I was getting low on the first tank when the "surge" showed up. Tossed some injector cleaner in with next fill up, so we'll see.
Very cool cut away -- need to see if I can find a good color printer to print it out on!
Where exactly is the MAFG connector -- is it right at the MAF?
Guess I'll need to pop the hood next time this happens...

Aredubjay
11-11-2002, 09:26 PM
Originally posted by SVXRide
Thanks for the responses!
I'm only on my second tank of 91 octane since I bought the car, I was getting low on the first tank when the "surge" showed up. Tossed some injector cleaner in with next fill up, so we'll see.
Very cool cut away -- need to see if I can find a good color printer to print it out on!
Where exactly is the MAFG connector -- is it right at the MAF?
Guess I'll need to pop the hood next time this happens...

Yeppers. Plugs right into the MAF sensor. Can't miss it. Good luck. Hope your better gas clears up your problem.

SVXRide
11-12-2002, 11:20 AM
You know, I'm starting to think that driving a SVX wouldn't be possible without this site! (note that I didn't say "owning":) )
Thanks!