dmoffitt

ok i've searched the boards and it looks like nobody ever came up w/ a list of what lenghts, diameters, fittings, etc. are needed for a full vacuum line replacement on the 951... i've got terrible stumbling, and this hissing sound and am pretty darn sure it's either a vacuum leak (bad line or fitting or maybe a boot like the throttle-body one or off of the intercooler or turbo) or possibly the intake-manifold gasket.

anyhow i figured while i had it all apart i'd like to either rebuild the turbo (seals/bearings) myself, or maybe send it out / sell it / buy a better one (money and options dependant). any ideas what i might do for under 15-1600 on this one?


any other ideas that might cause the following:

i push on the throttle, and it revs up to right at 0hg (aka 1 bar on our stock gauge) and then pretty much NOTHING happens. if i back off and then give it gas agian, i start to build power very slowly... if i just hold it down, it sorta sputters/coughs and then starts building boost normally. seems to me that this plus the hissssss sound under the hood would be vacuum related but is there anything else i'm overlooking or should check?

TIA all <img src="graemlins/beerchug.gif" border="0" alt="[cheers]" />

special tool

What is your idle speed?

Brian McCoy

*snickers* Deja vu.....

dmoffitt

[quote]Originally posted by special tool:
<strong>What is your idle speed?</strong><hr></blockquote>

roughly 1k. occasionally it stutters and drops to like 6-700 - another reason i am suspecting a vac. leak...

if the idle speed is extremely important i can go out, start the car, let it warm up / drive it around a bit, and give you an exact answer...

special tool

You sure about that 1k? Could it be a little higher? If it is, it is probably tps. Check fault codes with an led at the diagnostic port - 3-3 is tps and 4-1 is tps loose wiring harness. Loosen the two side adjusting screws on the tps, and rotate slightly until you hear click (engine off) at throttle closing, and throttle opening. If this doesn't do it, get a new one (+/-$35.)
Any vac leak and these things don't idle, or very poorly - they certainly won't idle higher.

dmoffitt

ok maybe i described the problem poorly. it doesn't idle any higher than before, it just has an intermitent rough idle (fine for a min or 30 sec, then a little cough/stumble... nothing major). the real problem is the coughing/loss of power...

i'm gonna grab a can of carb cleaner and see if i can't pinpoint the leak.

tazman

For the vac lines search on the main 944 board it was covered over there. I think it was said 15 feet was enough for some but I could not make that work I would order at least 20 feet then you should not have to order more like I had to. I think you need 4 or 5 T's but that number I am really unsure of.

David Floyd

[quote] i'm gonna grab a can of carb cleaner and see if i can't pinpoint the leak.

<hr></blockquote>

OH MAN !!! be carefull with that stuff it tends to ignite easy and I have first have knowledge of this, burnt eyelashes and a few wires for proof.

dmoffitt

ok i think i'll forgoe the carb cleaner then and just opt for replacing the intake manifold gaskets (one per runner i beleive, approx $2 each) and then follow that w/ the vac. lines themselves. thx for the heads-up i'll search the main 944 board for that info...

Danno

Leaky vacuum lines can't really leak enough volume to really cause stumbling and zero boost. Most likely it's a hose or hose-clamp in the intake plumbing. Start at the turbo-outlet and inspect every single hose and clamp carefully. Check around the back side of the big hose coming out of the turbo, I had a split in mine and couldn't trace the leak for weeks! Also check those little pieces that hold the intercooler pipes to the intercooler. They're thin and can get slit by overtightening the hose-clamps.

special tool

Don't waste your money and time on manifold gaskets - it ain't them. You can find your leak in 5 minutes with a rubber tipped blow gun from a compressor and some moving tape. Put the moving tape over your afm intake and run 10 lbs. into one of the ports between the intake manifold runners. The slight hissing coming from the lower passenger side of your engine will be the relief from your wastegate (factory), which is normal.

dmoffitt

thx danno - yeah i blew up one of those earlier this year - i put on the lindsey intercooler and got brand new ones for the inlet and outlet of the intercooler, but i'm wondering about the condition of the one coming outta the turbo as well as the one going from the intercooler into the throttle body. i'm gonna replace the TB one tomorrow (a friend has a new one @ his place hopefully it's the right size) and also pull off the one from the turbo and see if that might be it.

special tool, i do think the manifold gaskets are leaky (the one closest to the front of the car is where the sound SEEMS to be coming from, but i could be way off... a guy around here w/ a 600hp 300zx suggested just using gasket maker / sealer instead of new gaskets (that's what he's done on his car and he's had no problems w/ leaks etc). can anyone assess the validity of that claim/suggestion?

i think i'm gonna replace all of the vac. lines / fittings within the next few weeks anyway, not only will it eliminate any potential leaks that i might be overlooking, but the idea of having stuff w/ dif. colors (ake the lines not being black like everything else under the hood) will make it easier for me to visualize / work on stuff on the car