88 Shelby TII vacuum questions..

[turbokid]

is the cruise vacuum operated?
Sry never knew that or really payed attention too much.
One of my autos has it but I dont recall seeing vacuum lines???

[wolf_walker]

Yeah, it is. Us old buggers like cruise control.

The cruise get's it's vacuum from the checkvalve on the brake booster. So does the HVAC. Near the cruise, it T's off and goes to a tiny opening on the intake side of the airfilter housing and then down to the outlet of the turbo, where it goes to the intercooler.
The reasoning of the latter I don't understand at all, never seen the like on any other turbo car from the 80's. Never seen one without a pressure relief valve either, how does the impeller not become damaged over time? Weird American cars..

[looneytuner]

Someone mentioned checking vac on each part separately. That is a good idea. I had a cracked cruise control that had a small leak.

[winc]

So I went to the dealer today to order check-valves & orifices, however the orifices are discontinued. Looks like my car has 3 of them: to the wastegate, the pressure guage, and near the pcv check-valve. Anyone know where I can either acquire those orifices or tell me the size of the restrictions so I can fabricate my own?

Much appreciated

TJ

[NAJ]

It is a long shot but did they run a parts locator or did you get the part #'s?
A parts locator will show any dealer in the country that may have them in thier stock.
I needed the turbo coolant line and it was discontinued, ran a parts locator and 1 dealer in the country had one and I bought it, he shipped it UPS, was there in 2 days.

[winc]

I don't have the part numbers, but they did run a locator and found none.

[wolf_walker]

Nobody has data on orifice inside diameter? It'd sure help..

[winc]

Okay... so this thread was started about my car, but it seems that vacuum may not be the only issue.

Stored codes: 15, 34, 45.

15 - Vehicle speed sensor. Was advised that it will cause a stall on decel issue, which it has stalled three random times since buying the car about a month ago.

34 - Cruise servo. Cruise works great at times, but sometimes it will cancel out of the blue, other times it just won't work at all.

45 - Overboost shutoff. Have encountered the shutoff three times also, and usually under moderate acceleration, maybe ¼-½ throttle the car took off harder than I intended those times, also random.

Engine cooling fan runs constantly with the key in ON position. Check engine light has not been on at all with the engine running, but light works and comes on for initial check when turning the key to on before starting, and also produces codes when key cycled 3 times like it should. The only warning light that has illuminated was for low fuel, as was expected when it did (glad to know it works).

When cruising at a steady 70 mph on the hwy, vac/boost is usually around 0. A/C on in PANEL position will divert flow to floor & defrost if not reading less than -5.

Vac lines have been checked multiple times by multiple mechanically-inclined people, each feels they are routed properly and check-valves positioned to vac the proper way.

I've installed two "incorrect" vac restrictors from Advance in 2 of the 3 orifice locations (not the boost guage line) and it didn't seem to hurt not help the situation.

What suggestions or procedures should I follow from here to try isolating my problems? Could it be wiring/ground/vac solenoid related causing vac to purge when it shouldn't? I'm stumped.

[Screamin4banger]

the speed sensor thing - most common manifestation of that is exiting the freeway - come to a stop at the bottom of the ramp and car dies.

the next thing i would do for the vac issue is to isolate the different systems. I would pull the vac line leading to the HVAC controls off the brake booster and cap the port. Then go for a drive and see if your problems don't clear up.

[Screamin4banger]

are you still using those ancient, hard, brittle, and probably cracked factory vacuum lines?

[winc]

Stubs of the 4 hard lines at the splitter is all, maybe 6" of them... the rest is all new fuel/vac line tubing. Spraying the lines throughout the engine bay makes no change in idle, which is pretty decent in the first place.

I'll try capping off the HVAC line tomorrow night or over the weekend.

The stalling happens more in town when slowing for a moving turn with the clutch-in/downshift to 2nd, lose power steering, pop the clutch and all is well again.