low vaccum at idle question
 

Hi all,
My first post, I love all the info here and plan on joining up in the next day or two but had a quick question for you guys.
First off, I'll introduce myself. My name is Joe and I live in San Antonio, Tx. I've had 4 944's over the years and still have three of them. My question involves my 86 Turbo. The car is a red/tan non-sunroof car, with sport seats, LSD, fuchs, and even has the factory emblem delete code on the option sticker.
Anyhow, I keep reading these post about people pulling 18-20 in. at idle. When I first start my car, I get about 12, then 15 when fully warm. On decel, I get approx~21in. I have just replaced all vacuum lines with the LR kit, deleted the venturi kit, new intake gaskets, TB seals and installed an EVO BOV (Paragon, thanks Jason). Ppressure tested the engine with no audible leaks to 20+ psi. My cars get full boost, 17psi in 4th at about 3300 rpm. My mods are HR chips, LR Boost Enh, cat -bypass, and a stage 1 Huntley cheater turbo. Does this sound acceptable to you guys or am I missing something. Thanks in advance and I love the info I've soaked up so far

Joe

here's some bad pics, I need to take some better ones

Joe, I have done all the things you have done, and mine pulls strong boost too. I get 10 inHg vacuum on cold start and it sits at 16-17 inHg max when hot. I've given up trying to get the 18-20 inHg that many others say they get. The car runs good, so I've learned to live with it - still a bit of a mystery though...

It is normal, i get 12Hg when cold and 16-17Hg when fully warmed up.

Joe,

Check your timing belt alignment (the cam mark needs to lineup with the flywheel mark)
Mine was off by a tooth which had the same symptoms.
Fixing the timing also netted me 30 hp on the dyno!

thanks for the replies guys. Raagi, I will check that out. I'll post what I find

Hey Joe, welcome to rennlist. I just did the same things you did and at start up get 12-13" Hg and when warm 18 to 20, decel 23 to 24. You did not mention if you sealed the ISV when you cleaned out the rats nest under the intake, which on mine had a leak at the top around the connector. If I plugged one port and applied pressure to the other you could hear the air escaping around the connector. I used JB weld but a high-temp epoxy would work just as well. Another place to check is the thermovalve that connects to the tb vac fitting and the fuel purge system. The little plastic barbs are easy to break when taking the ancient hoses off.

HTH John

Hi John,
thanks for the reply. I didn't seal the ISV but I inspected it closely and it seemed ok when I had it off. Also, when I pressurized the intake to 20+ psi, I didn't hear any leaks. I'll double check the vacuum fittings you mentioned when I check the timing marks. My guess is that they're ok though as I think the pressure test would have caught that. Thank you again and I really appreciate the help. I'll post what I find.

does anyone have any pictures or can they describe where exactly the mark is on the cam and flywheel to verify correct alignment between the two?

Chas,
Check out this link, scroll down the middle of the page and you'd find all the marks you need (balance shafts, crank shaft and camshaft).

Wow! Sunroof delete is sweet!!

thanks Ted, searched LONG and hard for it. Been trying to find some numbers on exactly how many US turbo's came in without the sunroof. I've seen a few models (NA), but mine is the only US turbo I've seen from the factory without one.
Also, checked the vacuum fittings and double checked the ISV (per John), seem to be leak free. Still need to check the timing marks though.
cheers,
Joe

PS- in the third pic, you can see my dad's 83 NA race car. It used to be my daily driver for a few years till we caught the racing bug. We're also starting an 89 944 2.7 race car from a minor fire car that someone's insurance decided to total. Should be another fun (read: expensive) project. Gonna have to sell the 83 to help finance that project though. Anyhow, back to the turbo:)

Joe

I'd love to have a sunroof delete car, it'd give me much more headroom with my helmet on!

ok, I've checked everything over again, and searched the boards for more clues. My guess is it's either a) ring wear
b) timing off a tooth
c) bent valve maybe?

To check timing, which I still haven't done :(, I can just turn the engine with a socket on the crank pulley to line it up, right? I heard a) and c) talked about in a few other threads, could that also be a feasible possibility? Thanks again
Joe