question on '85 Refresh
09-16-2017, 10:43 PM
#31
Rennlist Member
Thread Starter
So there has been success, somewhat....
I pulled apart the throttle body and discovered that there were *no* o-rings in place at all.
With o-rings in place (boy, those springs on the throttle body are hard to get back on), i was able to get the throttle body up to 15 PSI. As the PSI got stronger, it got harder and harder to move the needle until at 15 PSI, the needle didn't move at all.
It took about 90 seconds for the vacuum to go from 15 to 13 psi. It took about 60 seconds to go from 12 to 11 psi.
Is this good enough or should I go hunting for more leaks?
Also, here is a pic of the apparatus I put together to test vacuum on the throttle body.
Again, thanks to all with the suggstions, I would not have made it this far without all your help.
-adam
I pulled apart the throttle body and discovered that there were *no* o-rings in place at all.
With o-rings in place (boy, those springs on the throttle body are hard to get back on), i was able to get the throttle body up to 15 PSI. As the PSI got stronger, it got harder and harder to move the needle until at 15 PSI, the needle didn't move at all.
It took about 90 seconds for the vacuum to go from 15 to 13 psi. It took about 60 seconds to go from 12 to 11 psi.
Is this good enough or should I go hunting for more leaks?
Also, here is a pic of the apparatus I put together to test vacuum on the throttle body.
Again, thanks to all with the suggstions, I would not have made it this far without all your help.
-adam
10-02-2017, 03:01 PM
#32
Rennlist Member
Thread Starter
Quick update: After replacing the o-rings on the rod for the throttle plate, the vacuum was holding *much* better. Not perfect, but it was at least holding vacuum. Thanks for bringing it up SMTCapecod!
After two week-ends of putting everything back together (not to mention dealing with a loose relay socket on the relay board
), I was finally able to get the car to run.
Initially, the idle was still sitting at 1200 (per tach on timing gun). Davek9's suggestion of marking the idle valve proved to be useful because i already had marked the original postion (BTW, it was 2.5 turns from fully closed). In short, with the valve fully closed, the engine idles at around 820, which is still a little high. Clearly, there's another leak to hunt down. However, i was able to drive the car and it had *pull*. First time since I've owned this car was I able to get the car over 70mph without being nervous.
There is a LOT of vibration if the throttle is pressed down too quickly, but I suspect that the engine and trans mounts have never been replaced.
First off, thanks to everyone for spending the time to respond and give suggestions. I'd still be lost without your help. The stuff that I've learned on this forum is amazing!
Second, what is the typical position for the idle valve? I suspect the 2.5 turns open was a bit high, but I'm also confident that it shouldn't be fully closed. Thoughts?
After two week-ends of putting everything back together (not to mention dealing with a loose relay socket on the relay board
), I was finally able to get the car to run. Initially, the idle was still sitting at 1200 (per tach on timing gun). Davek9's suggestion of marking the idle valve proved to be useful because i already had marked the original postion (BTW, it was 2.5 turns from fully closed). In short, with the valve fully closed, the engine idles at around 820, which is still a little high. Clearly, there's another leak to hunt down. However, i was able to drive the car and it had *pull*. First time since I've owned this car was I able to get the car over 70mph without being nervous.
There is a LOT of vibration if the throttle is pressed down too quickly, but I suspect that the engine and trans mounts have never been replaced.
First off, thanks to everyone for spending the time to respond and give suggestions. I'd still be lost without your help. The stuff that I've learned on this forum is amazing!
Second, what is the typical position for the idle valve? I suspect the 2.5 turns open was a bit high, but I'm also confident that it shouldn't be fully closed. Thoughts?
11-13-2017, 03:52 PM
#34
Rennlist Member
Thread Starter
Wow, I totally forgot about this thread [insert "hangs head in shame" emoji here].
In short, the vacuum leak was driving me bananas. Made me start doubting that it was a vacuum leak. I even bought Ken's fantastic cam timer needles, pulled the timing belt covers and double checked the timing marks (it was all good). After that, the car ran even worse and I flat-out gave up.
In short, I took the car to a porsche specialist (devito's in anaheim, *very* nice guy) just to see what he could find.
Well, it turns out that I transposed a number and mixed up two ignition wires; that's why it started to run worse.
However, the primary culprit for the vacuum leak turned out to be the hose going from the ICV to the air intake was collapsing (yes, it was brand new). As it collapsed, the ends opened up just enough to bring in air. A spring was put into the hose to help it keep its shape and the car now runs *much* better.
I never would have found this because a pressure test goes the opposite direction.
I am now onto the O2 sensor where I discovered that a PO used various 1/2" and 7/16" bolts on the exhaust flanges (they need to be disconnected to reach the O2 sensor). While I'm there, I'm going to check the flex plate.
Thanks for asking and thanks to everyone who contribute to this forum. I'd be completely lost without all of your input.
In short, the vacuum leak was driving me bananas. Made me start doubting that it was a vacuum leak. I even bought Ken's fantastic cam timer needles, pulled the timing belt covers and double checked the timing marks (it was all good). After that, the car ran even worse and I flat-out gave up.
In short, I took the car to a porsche specialist (devito's in anaheim, *very* nice guy) just to see what he could find.
Well, it turns out that I transposed a number and mixed up two ignition wires; that's why it started to run worse.
However, the primary culprit for the vacuum leak turned out to be the hose going from the ICV to the air intake was collapsing (yes, it was brand new). As it collapsed, the ends opened up just enough to bring in air. A spring was put into the hose to help it keep its shape and the car now runs *much* better.
I never would have found this because a pressure test goes the opposite direction.I am now onto the O2 sensor where I discovered that a PO used various 1/2" and 7/16" bolts on the exhaust flanges (they need to be disconnected to reach the O2 sensor). While I'm there, I'm going to check the flex plate.
Thanks for asking and thanks to everyone who contribute to this forum. I'd be completely lost without all of your input.
11-13-2017, 05:25 PM
#35
Captain Obvious
Super User
Super User
The amount of air that gets pulled in by the throttle shaft is statistically insignificant when compared to the amount of air the engine uses even at idle. For an engine to run rough at idle, you need a huge leak. Easiest was to find a leak that big is with some starter fluid and some small controlled bursts. With that, you would have found the leak at the ISV really easily.
11-13-2017, 05:31 PM
#36
Rennlist Member
"...Second, what is the typical position for the idle valve? I suspect the 2.5 turns open was a bit high, but I'm also confident that it shouldn't be fully closed. Thoughts? .."
About 1.5 turns, as this is a air to fuel mix adjustment you need the "blinker" to see what the stock O2 sensor is doing or an after market AFR and wide band O2 to adjust.
Glad to hear you made progress, don't remember if you checked, but the Fuel tank charcoal system can cause a vacuum leak, it can be blocked off too.
Dave
About 1.5 turns, as this is a air to fuel mix adjustment you need the "blinker" to see what the stock O2 sensor is doing or an after market AFR and wide band O2 to adjust.
Glad to hear you made progress, don't remember if you checked, but the Fuel tank charcoal system can cause a vacuum leak, it can be blocked off too.
Dave
11-13-2017, 06:25 PM
#37
Rennlist Member
Thread Starter
Well I currently have the idle at about 1.25 turns and it idles around 875-900. Not ideal, but not as bad as it was. Acceleration is MUCH better than where it was at.
I think the charcoal cannister is linked to the 7 way splitter. If so, then I know everything on the 7 way splitter held 20 psi for 10 minutes without any loss.
O2 sensor is next on the list to be replaced!
I think the charcoal cannister is linked to the 7 way splitter. If so, then I know everything on the 7 way splitter held 20 psi for 10 minutes without any loss.
O2 sensor is next on the list to be replaced!
11-13-2017, 07:06 PM
#38
Rennlist Member
its not on the 7 way, it feeds from the lower port on the firewall side of the Throttle body and goes directly to the vacuum temp switch on the head attached to the Heater control valve's spigot thing. Then on to the diaphragm module on the fender below the coolant tank.
The larger hose goes to the other vacuum modular on the cross bar, that one has a feed to the 7 way as the tank vapor system is both temp and throttle dependent.
If you still have the air pump, then the other vacuum fitting (one that is not blocked off) in the front of the TB feeds that, all can be plugged if not required.
However I see you are in the social republic of Cali, where it ALL is
Dave
The larger hose goes to the other vacuum modular on the cross bar, that one has a feed to the 7 way as the tank vapor system is both temp and throttle dependent.
If you still have the air pump, then the other vacuum fitting (one that is not blocked off) in the front of the TB feeds that, all can be plugged if not required.
However I see you are in the social republic of Cali, where it ALL is
Dave
11-13-2017, 08:34 PM
#39
Rennlist Member
Thread Starter
Yup, in So Cal it's all required. Though having grown up in So Cal in the 80's (transplant from Michigan), its remarkable to see how much the air quality has improved, so no complaints on the smog laws. 
I will check out the charcoal cannister, thanks for the heads-up.
Though having grown up in So Cal in the 80's (transplant from Michigan), its remarkable to see how much the air quality has improved, so no complaints on the smog laws. I will check out the charcoal cannister, thanks for the heads-up.