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I'm just learning my way through this (new to me) '86 928s.
I've done some basic maintenance to the car (and just had a new clutch installed) and after new coils, oil, alternator rebuild every little bit is improving, but I still have a slight miss/hesitation around 3K RPM's under load (going uphill). I also have what appears to be a slightly high idle (if I'm trusting the tach it's about 900 RPM when the car is warmed up).
The PO mentioned that he had a shop do some work on vacuum lines. Before I start tearing things apart I have access to a smoke machine and was going to start there.
I don't know these engines super well (like I said, just learning) but I'm hoping someone could point me to a good vacuum source for the smoke machine.
Fattest route is the line that connects to the brake booster.
Before you do that hook up a mityvac to the small vacuum line that goes to the diverter valve (probably attached to the cross brace on your car) and get a reading there, 17-18 inches is normal, anything less and you definitely have a leak someplace. Note that the behaviors you are describing may not be related.
Red arrow, right side of engine bay. Some cars have that valve on the cross brace instead of that location, makes it a lot easier to put the air tubes back when its there.
Thanks! For reference - here is a pic of my engine compartment. I do have a valve as in the 2nd picture, thanks!
For the vacuum at the brake booster to smoke test - I assume you mean the small hose at the top with the check valve? Or directly into the big main line?
One more dumb question - if I want to check the condition of my plug wires and or plugs - can I just remove the large distribution tubes above each valve cover? Is there any trick to that? Otherwise I don't see how I change the plugs and wires?
Yes, you will need to remove those plenums on each side to get to the plugs. The PS side comes off easily, but on the DS it can be hard to get wiggle room to detach the brake booster vacuum hose setup. You can see it peeking out from under the plenum and attached to a hard line that that crosses over the front off the cam cover. It is held in position by a bracket, which is bolted to the block (hidden from view). Loosening the bolt should make disconnecting that line easier (don't confuse it with the socket head cap screw that holds the FPR bracket, it's behind it and hard to see). Also the plug wires are held in place by small plastic clips attached with screws to the cam covers- soak in PBblaster or whatever and give them time, they like to break.
No, you don't have to remove the intake plenums to get the spark plugs out. Just remove those black plastic intake tubes that go to the air filter and you will be able to access the spark plugs and even the wires if needed. You will need to use either the tool in the trunk of your car or make one up using a universal joint and a proper length extension.
07-06-2016, 01:25 AM
Best port for a Smoke Test ('86 32v Motor)
