Progress! But what does it mean?

Z06C5R · 06-12-2008, 02:33 PM

So, I seem to have stumbled onto what could be the source of my fluctuating idle issue... I was fiddling around with the AAV and related hoses without any luck, and decided I'd just start pulling vac lines off stuff and see what happened. I yanked a small line on the right side of the TB, and the idle instantly smoothed itself out, and settled down at 1250rpm (about what it "idles" at anyway on the rare occasion that it runs steady). I plugged the hole with my finger and it slowed down a few hundred RPM, but stayed smooth. At that point I noticed the line was dripping fuel, so I plugged it back in and the car died. I then followed the line up to the two pod-whosamajeggers on the back of the fuel rail, and also to some kind of apparatus over on the driver's side fender. No idea what anything is or what it does, but disconnecting them seems to have largely solved my issues...

In pictorial review:

I pulled this line...

Which split up and ran to these...

And this.

Ideas / hints / suggestions???

jmd_forest · 06-12-2008, 03:00 PM

One or both of the whosamajeggers (fuel pressure regulator and fuel damper)at the back of your fuel rail are most likely shot and are leaking gas into the vacuum line. Pull the vacuum line off each, one at a time, attach a spare vacuum hose to it , and use your mouth to suck on it. The one that provides raw gas into your mouth is bad and must be replaced.

jmd_forest

Z06C5R · 06-12-2008, 03:27 PM

Sounds healthy...

jmd_forest · 06-12-2008, 03:33 PM

Seriously.....one or both are probably bad and you'll know immediately.

jmd_forest

kdjones2000 · kdjones2000's Garage

Just replace them both. If one is bad, the other is almost dead.

I just did the damper, and the car would take forever to start. Replaced the regulator, and things were back to normal.

Keith

Z06C5R · 04:40 PM

I'm liking this - I think I might kill all 3 birds with one stone... Hard starting, wicked idle fluctuations, and terrible MPGs could all potentially be corrected with this fix - cool!

Still though, I'm starting to see an (expensive) trend of "If one, then the other" type things here. A good measure for sure, but it's a bit depressing at the same time... "Cool, the part I need is only $60! But wait, I need 20 more!!!"

Ah well, what can ya do?

bholmes · bholmes's Garage

ineed it's a great fix! I just did it to mine. I haven't got to check mpg, but my idle is much better and it starts great now.

phoenix_iii · 06-13-2008, 05:58 AM

Great example of what a few pics can do for a thread. =)

AKCJ · 06-13-2008, 07:31 PM

Yes, great pictures. You keep asking questions this well & you'll keep getting great answers!

Getting back to the story . . . what's the item in the last pic? I have one just like it but not exactly sure what it does.

Z06C5R · 06-14-2008, 12:40 PM

My guess was some kind of regulator valve.

pauloregon · 06-14-2008, 03:15 PM

Z06, you'll start getting used to the line "well, while i'm in there, i might as we replace this other thing and the other thing....etc"

My 85/2 944 is just now calming down after a long string of replacing seals, gaskets and other deteriorating things on this 23 year old car. Heck, my car doesn't leak oil now for the first time in 5 years!

If I paid my mechanic to do this work, I would have been broke years ago. I like working on cars and have the motorcycle as an alternate vehicle, so it works.