I purchased an 85 GS automatic with 94k miles, bad transmission. It will not idle and runs rough, and I am at wits end trying to figure out the problem.


The car had been sitting for at least two years, and would not start when I picked it up. Drained the old gas, tested fuel pump, cleared fuel lines, and put in new fuel filter.


The choke cable is broken. I am able to get it started with some difficulty, but it starts. I have to keep it running at about 2500 rpm as it runs rough and will not idle. I figured there is a vacuum leak somewhere, so I used carb cleaner spray to try and track it down. Found a couple hoses that were cracked (one of the vacuum hoses on the rats nest and the large one that always goes bad down by the exhaust manifold on the back).


This improved things somewhat but it still ran rough and would not idle below 1500 rpm. More carb cleaner spray, and it appeared the shaft on the shutter valve butterfly in the manifold was loose (it was), so I disconnected the shutter valve from the butter fly, and epoxied the butterfly in the open postion. No change.

More carb spray and now when I spray from the top towards the back where the linkage is, the rpms smooth out considerably until the carb spray is used up.

The other symptom through all this is the ACV seems to remain "open", making the loud noise when it pumps air to the air filter housing. When I spray on what appears to be a vacuum leak, it "closes" and the noise goes away. I have swapped the ACV with a known good one, and it does the same thing.

I am still assuming this is a vacuum leak, as the symptoms go away with carb spray. I don't know where there might be a vacuum leak at this point, and looking for suggestions. The plastic hoses with the rubber ends don't seem to be the culprit, and I don't see any other hoses on that side of the carb. I was going to take the carb off again and look, but before I did, I thought I would ask you guys for ideas.


Thanks in advance.

 

could be a leak in the bushing arund the linkage

that is a commom prob with older cars that dont have alot of miles


BTW good thing the auto is bad, they suck *** in RX-7's and a 5-speed swap isnt expensive or hard

 

how long are you running it before you try to let it idle? with the choke cable broken, you will have to hold on the gas for a while for it to warm up... about 5-8 minutes till mine is warmed up. only then it will be able to idle correctly. i highly doubt that this is your problem, but i always check the most obvious or easiest places first

 

Have you tried adjusting the idle and mixture on the carb?

 

i am putting my money on a vaccum leak somewhere

i found several in my car and it runs smoother than ice now..

-greg

 

Thanks for the ideas.

- I will definitely check the bushings around the linkage.

- The car is fully warmed up and still does this.

- I seriously doubt if this is an idle speed or mixture problem for two reasons: the car was running fine prior to the tranny going bad and being parked 2 years ago, and when the carb cleaner is sprayed around the spot mentioned on the carb, the engine smooths out

Another hose I will focus on is the vacuum line for the automatic transmission. Other ideas welcome!

When I find it, I will report back.

 

If it's been sitting for two years you may need to tear the carb apart and clean the sucker to get rid of all the varnish that's probably built up. As good as any a time to rebuild it.

May also want to make sure the exhaust/catalytic is clear. Mine wouldn't run at a low idle (and it ran like crap at a high idle), turned out to be plugged cat.

 

Throttle shaft did, in fact, have play resulting in vacuum leak. Fortunately, I had access to a free '85 carb; bolted it on and it runs fine. Thanks!

 

so i thought it was good that my flight was bumped back to this wed. so that i could put the car away properly, except today while i was driving i hear a crash coming from the transmission and pull over check it out and i think the tranny mount just undid itself. I managed to slowly drive it back home fine. Question is can i drive it around town to the gas station and to get the oil change ( i have no time to do it myself)?

 

glad it worked out