vac still low checked and fixed vac leaks???

1

1990_XR7SC

Registered User
well I have pressurized my entire intake system and have fixed 4 leaks.(intake hose at tb, hose on back of cool charge pipe by rear of the throttle body, both charge pipes at the intercooler) my vacume when hot @ idle is only at the "h" in inch hg. 12-14 in vac? I have also used a couple of cans of carb clean to try and see if idle changes found nothing? the engine has 97k on it and head gaskets were changed at 86k. is my engine tired? I'm going to check compresson and change plugs here in a couple of weeks. just though I'd check and see if there were any other spots I could check? the car also only boosts 9-10psi at 6400ft elv.(car is a 1990) I have run a can of bg 44k in the tank, two cans of bg injector cleaner using an induction tool and two cans of bg throttle body spray. and still is low.(though it could be excessive carbon buildup)(I get bg stuff at cost so it wasn't to bad ;) ) I also don't know if it has a no load miss or if it's just the collapsed engine mount causing a vibration? well thanks for reading this. :)
 
Could be that your cats are screwed and have worn them selves out. I recently got new downpipes and the cats that were on my SC were hollowed out, not from someone but just overtime got worn out. No this could be why your not building up boost, but the vacuum I'm not sure about.


NICK
 
Other areas to check are the vacuum tree, power brake booster hose, and the vacuum line(s) that connect at the firewall. I started with a avuum diagram and checked each hose connections and crossed them off as I inspected them. I found the hose that connects between the PCV valve pipe and the steel tube on the fender to be cracked really bad.
I would also check these gasket areas;
  • Between the intake ports and heads
  • The rear of the blower and the intake plenum
  • The bypass pipe and the intake
If you need any illustrations I can forward them to you from my Ford Tech CD-ROM.
LMK and good luck!
Bill
 
blue94sc said:
Other areas to check are the vacuum tree, power brake booster hose, and the vacuum line(s) that connect at the firewall. I started with a avuum diagram and checked each hose connections and crossed them off as I inspected them. I found the hose that connects between the PCV valve pipe and the steel tube on the fender to be cracked really bad.
I would also check these gasket areas;
  • Between the intake ports and heads
  • The rear of the blower and the intake plenum
  • The bypass pipe and the intake
If you need any illustrations I can forward them to you from my Ford Tech CD-ROM.
LMK and good luck!
Bill
Click to expand...

thanks pm sent. :)
 
Same Problems

I have the same issues with my 92 sc. I am only getting 8-10 inches of vacume at idle and only making about 10 pounds of boost at wide open. The car also doesnt have the power or performance that it should be giving me for all of the aftermarket mods that are on the car. It idles erratic with it in gear and the brake applied. I resealed all of the intercooler tubing but without a vacume line diagram I am unable to trace the lines. For some reason I cant find one of these diagrams anywhere on the internet. I am also getting an intermittent check engine light. I replaced the O-2 sensors as per the advice of auto zone but to no avail, still have the same symptoms. Does it sound like purely a vacume issue? The engine only has 6500 miles on it.
 
Same Problems

I have the same issues with my 92 sc. I am only getting 8-10 inches of vacume at idle and only making about 10 pounds of boost at wide open. The car also doesnt have the power or performance that it should be giving me for all of the aftermarket mods that are on the car. It idles erratic with it in gear and the brake applied. I resealed all of the intercooler tubing but without a vacume line diagram I am unable to trace the lines. For some reason I cant find one of these diagrams anywhere on the internet. I am also getting an intermittent check engine light. I replaced the O-2 sensors as per the advice of auto zone but to no avail, still have the same symptoms. Does it sound like purely a vacume issue? The engine only has 6500 miles on it.
 
Same Problems

I have the same issues with my 92 sc. I am only getting 8-10 inches of vacume at idle and only making about 10 pounds of boost at wide open. The car also doesnt have the power or performance that it should be giving me for all of the aftermarket mods that are on the car. It idles erratic with it in gear and the brake applied. I resealed all of the intercooler tubing but without a vacume line diagram I am unable to trace the lines. For some reason I cant find one of these diagrams anywhere on the internet. I am also getting an intermittent check engine light. I replaced the O-2 sensors as per the advice of auto zone but to no avail, still have the same symptoms. Does it sound like purely a vacume issue? The engine only has 6500 miles on it.
 
Same Problems

I have the same issues with my 92 sc. I am only getting 8-10 inches of vacume at idle and only making about 10 pounds of boost at wide open. The car also doesnt have the power or performance that it should be giving me for all of the aftermarket mods that are on the car. It idles erratic with it in gear and the brake applied. I resealed all of the intercooler tubing but without a vacume line diagram I am unable to trace the lines. For some reason I cant find one of these diagrams anywhere on the internet. I am also getting an intermittent check engine light. I replaced the O-2 sensors as per the advice of auto zone but to no avail, still have the same symptoms. Does it sound like purely a vacume issue? The engine only has 6500 miles on it.
 
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