Mystery Hose?
09-21-09, 02:28 PM
#1
Junior Member
Thread Starter
Join Date: Jun 2007
Location: Wisconsin
Posts: 39
Likes: 0
Received 0 Likes
on
0 Posts
Mystery Hose?
I had a prior post about whether or not it was time for a rebuild and received a number of ideas concerning things to check.
The symptoms were, after taking it in to a dealer for not idling when warm (just dieing when deceling to a stop) and getting it back; unable to idle at 750 rpm (set at about 1000 ~ 1100rpm), loss of power and pinging at about 3000 rpm and above. They rebuilt the carb (said it was flooding), replaced the coasting valve (not activating during decel), replaced the cap, rotor, wires, and plugs (old, burned and brittle) and the fuel filter. They checked the compression with their tester and found it to be good (above 6 Kg/cm3 and only about 0.5 variations, well below the 1.5 limit). They also tested the vacuum and found it to be 10 " rather then about 18-20" as expected. They claimed that the problem was internal and needed a rebuild.
I checked the routing of the ignition wires and they are correct. The timing is also right on, but remember the idle is up at 1000~1100 rpm and not at 750. Will the advance be affecting the reading? The other thing that seemed strange was that on the slot that the distributor lock down bolt rides in, it looked like it the distributor had been adjusted quite a bit counterclockwise from the position it appears it was in for the past 24 years. The old position was clearly visible. Could something be wrong with the way the cap/rotor are installed? I'm trying to think of something that could have caused/required such a change in position.
I also checked the vacuum hose that runs from the #2 anti-after burn valve to the back of the intake manifold and it seemed fine without holes, brittleness or softness. While replacing this hose I noticed another hose that ran from the 90 degree elbow which is mounted just above the where the hose from the #2 AABV connects to the intake manifold was not connected to anything at the lower end.
It is a rather large hose and there are clamp marks at the lower end indicating that it was attached to something at one time. I have looked in the area for what it could have been attached to (it's about 8" or so in length) and couldn't find anything. I tried just putting some tape over the end of it to see if it made any difference and it didn't really appear to. Maybe I didn't get it plugged well enough though. Could this be the cause of all my problems? Could the dealer really have missed this?
The symptoms were, after taking it in to a dealer for not idling when warm (just dieing when deceling to a stop) and getting it back; unable to idle at 750 rpm (set at about 1000 ~ 1100rpm), loss of power and pinging at about 3000 rpm and above. They rebuilt the carb (said it was flooding), replaced the coasting valve (not activating during decel), replaced the cap, rotor, wires, and plugs (old, burned and brittle) and the fuel filter. They checked the compression with their tester and found it to be good (above 6 Kg/cm3 and only about 0.5 variations, well below the 1.5 limit). They also tested the vacuum and found it to be 10 " rather then about 18-20" as expected. They claimed that the problem was internal and needed a rebuild.
I checked the routing of the ignition wires and they are correct. The timing is also right on, but remember the idle is up at 1000~1100 rpm and not at 750. Will the advance be affecting the reading? The other thing that seemed strange was that on the slot that the distributor lock down bolt rides in, it looked like it the distributor had been adjusted quite a bit counterclockwise from the position it appears it was in for the past 24 years. The old position was clearly visible. Could something be wrong with the way the cap/rotor are installed? I'm trying to think of something that could have caused/required such a change in position.
I also checked the vacuum hose that runs from the #2 anti-after burn valve to the back of the intake manifold and it seemed fine without holes, brittleness or softness. While replacing this hose I noticed another hose that ran from the 90 degree elbow which is mounted just above the where the hose from the #2 AABV connects to the intake manifold was not connected to anything at the lower end.
It is a rather large hose and there are clamp marks at the lower end indicating that it was attached to something at one time. I have looked in the area for what it could have been attached to (it's about 8" or so in length) and couldn't find anything. I tried just putting some tape over the end of it to see if it made any difference and it didn't really appear to. Maybe I didn't get it plugged well enough though. Could this be the cause of all my problems? Could the dealer really have missed this?
09-21-09, 04:21 PM
#2
Junior Member
Thread Starter
Join Date: Jun 2007
Location: Wisconsin
Posts: 39
Likes: 0
Received 0 Likes
on
0 Posts
The hose that I am refering to can be see in this thread. It is the hose that is going out of the bottom of the first picture.
https://www.rx7club.com/1st-generation-specific-1979-1985-18/hose-question-750125/
https://www.rx7club.com/1st-generation-specific-1979-1985-18/hose-question-750125/
09-21-09, 04:35 PM
#3
The guy who labeled that picture should have finished
That hose should connect to a long metal tube coming from the the cat converter. The tube is often missing, having rusted off at the converter. It supplies cooling air from the air pump to the converter, nothing vacuum related. Makes little to no difference in performance. Without it the cat has no cooling air. This can cause the honeycomb material inside the cat to clog and/or collapse. When the flow through the cat is blocked performance will suffer dramatically. I think it is unlikely that this is related to your idle problem.
The dealer in Naples was going to charge one of the members $1500 to remove the intake manifolds and throttle body from his GSLSE. Apparently they were going to replace the gaskets and clean the injectors to fix his problem. We removed his AFM and cleaned the obvious rubbery black goo that was left from numerous melted air filter seals. The goo had run down inside the AFM onto the trap door that sends signals to the ECU. We fixed it in a couple hours. Rarely does a dealership have someone who has a clue about our old cars.
Your problem sounds like it could be timing related. Do you have a timing light? If not, I would just loosen the 10mm bolt and set the distributor back to where it was. If it solves or at least changes the problem you know you are on the right track. BTW good compression numbers show you likely do not need an engine rebuild.
That hose should connect to a long metal tube coming from the the cat converter. The tube is often missing, having rusted off at the converter. It supplies cooling air from the air pump to the converter, nothing vacuum related. Makes little to no difference in performance. Without it the cat has no cooling air. This can cause the honeycomb material inside the cat to clog and/or collapse. When the flow through the cat is blocked performance will suffer dramatically. I think it is unlikely that this is related to your idle problem.
The dealer in Naples was going to charge one of the members $1500 to remove the intake manifolds and throttle body from his GSLSE. Apparently they were going to replace the gaskets and clean the injectors to fix his problem. We removed his AFM and cleaned the obvious rubbery black goo that was left from numerous melted air filter seals. The goo had run down inside the AFM onto the trap door that sends signals to the ECU. We fixed it in a couple hours. Rarely does a dealership have someone who has a clue about our old cars.
Your problem sounds like it could be timing related. Do you have a timing light? If not, I would just loosen the 10mm bolt and set the distributor back to where it was. If it solves or at least changes the problem you know you are on the right track. BTW good compression numbers show you likely do not need an engine rebuild.
09-21-09, 05:58 PM
#4
Banned. I got OWNED!!!
iTrader: (7)
Join Date: Dec 2008
Location: Oregon
Posts: 1,326
Likes: 0
Received 0 Likes
on
0 Posts
theres also a brake booster vac line in that general area. its affected by heat. mine caught fire. I think I spilt a little gas on it while replacing the carb. but yeah car wouldn't idle after that happend.
Thread
Thread Starter
Forum
Replies
Last Post
LongDuck
1st Generation Specific (1979-1985)
12
10-07-15 08:12 PM