shortbus Posted December 27, 2004 Share Posted December 27, 2004 Hey guys, I'm having a problem with my Brat (85, EA81, 4-speed, stock carb). A few days ago it started having problems at idle. It will run fine as long as I'm driving or the clutch is not depressed but as soon as I press the clutch and it gets down to idle it will idle way down liek it wants to stall before surge=ing back up. It will continue doing this until you press on the gas or start driving again. Also, if you repeatedly press the brakes while idling it will actually stall which leads me to believe it is probably vacuum related. I've looked over almost all of the hoses, plugs and lines under the hood and don't see anything obvious, anybody have any ideas that might narrow the search? I need to get it tracked down ASAP since I'm selling my backup driver tommorow and wil be relying solely on the Brat for transportation for awhile. Thanks in advance! Quote Link to comment Share on other sites More sharing options...
Cougar Posted December 27, 2004 Share Posted December 27, 2004 Have you done the normal tune up procedures? You might also try plugging the vacuum line to the brake booster to see if that helps. It may have a small leak. Quote Link to comment Share on other sites More sharing options...
Skip Posted December 27, 2004 Share Posted December 27, 2004 sounds like the EGR valve leaking Quote Link to comment Share on other sites More sharing options...
swiftt Posted December 27, 2004 Share Posted December 27, 2004 I agree with your vacuum leak diagnosis. You'll have to do the work of tracking it down. Larger leaks can be found with a water filled mist bottle. Spray water around any potential vacuum leak and listen for a change in the idle. If there is a leak, it will draw the water into the engine and the idle will drop. This method doesn't always work for smaller leaks though. Additionally, all your lines can be checked by removing their connections one by one and replacing them, on the intake side, with a rubber vacuum cap. Again, listen for a change in the idle with the vacuum circuit disconnected. Note: If your distributor has a vacuum retard machanism, the idle will change when this connection is checked. Areas to check: Carb base gasket Intake gasket EGR valve and piping Carb throttle shaft All vacuum lines and connections Brake booster Vacuum advance unit Good luck! Quote Link to comment Share on other sites More sharing options...
Skip Posted December 27, 2004 Share Posted December 27, 2004 sorry gents i beg to differ with you a small vacuum leak like you describe will increase the idle speed. yep - take a look at a fuel injected car they control idle speed with a controlled vacuum leak. (air for the leak is drawn through the air cleaner) An EGR valve that is leaking exhaust gas into the intake stream at idle will cause the idle to drop and can cause stalling. The test for an EGR valve is to manually open it at idle. The EGR is closing properly if the idle speed drops. I don't believe you will believe me. old precognitions are hard to give up. Try pulling a small vacuum line off. Quote Link to comment Share on other sites More sharing options...
Seahag1978 Posted December 28, 2004 Share Posted December 28, 2004 By the by... the "Flatuous Blather" in his title, is just "Flatuous Blather". He has nailed every problem I've had from ring and pinion to EGR, ADS and gave me every remedy. Subarus can make you grey, until someone with experience enlightens you Quote Link to comment Share on other sites More sharing options...
swiftt Posted December 28, 2004 Share Posted December 28, 2004 I will conditionally agree with you that a vacuum leak raises idle. The condition being that this happens if the vacuum leak is small and the carb was previously adjusted properly. If the carb is set too lean to begin with or there are large and/or multiple vacuum leaks, the engine will begin to lean misfire. The driveability will be poor with little power and rough idle. Perhaps some backfiring too. I also agree the EGR is a likely fault. Speaking of all these details, I should take a step back and suggest starting with the basics such as, checking ignition components (cap, rotor, wires, plugs, points, condensor, etc), timing, plug gaps, valve clearance (solid lifter engines), carb mixture and idle adjustments. If you're not certain all those things are right, it will be difficult to diagnose other faults. Quote Link to comment Share on other sites More sharing options...
shortbus Posted December 28, 2004 Author Share Posted December 28, 2004 Thanks so much for the replies, as for tune ups; I'm sure it needs one. It runs fine but I really have not done much other than change an axle (and oil, filters...etc) since I got it over a year ago. I just changed the oil pan gasket last night (those bolts in the back were a P.I.T.A.!) and I wanted to get to the valve cover gaskets and plugs tonight but got suckered into shopping with my SO and her sister. I'll check the EGR valve and do that water bottle check tommorow night and probably get the plugs changed out as well. Hopefully I can get it tracked down; thanks again for the help. Quote Link to comment Share on other sites More sharing options...
shortbus Posted January 5, 2005 Author Share Posted January 5, 2005 Ok, Plugs have been replaced, cap & rotor had some minor oxidation on them but nothing too bad so they were cleaned and reinstalled, found one very minor crack in a hose to what I think is a vacuum sensor (fixed that), also changed the fuel filter under the bed and the PCV valve which seemed ok anyways, I just got to the EGR valve tonight and it was almost completely clogged up with carbon deposits so I changed that out with a pretty decent one I found in a yard today and tried to clean out the manifold side of that system as best I could (lots of crud built up in there as well). I got all excited thinking surely that will fix it but it still runs like crap. I've looked all over the vacuum hoses and they all seem ok. One thing I'm wondering about is the small filter thing in the upper (rear) of the engine bay on the driver side. It looks like a fuel filter but I can't seem to find a replacement for it. Is there a secondary fuel filter? I can't even find anything about it in the service manual. Also, I've noticed that if I turn the AC on the engine will idle high (~1500 RPM) and get hot but it will be steady (no surging or stalling), maybe that will help someone recognize what it is. I'm about to go nuts trying to find it. Thanks Quote Link to comment Share on other sites More sharing options...
Skip Posted January 5, 2005 Share Posted January 5, 2005 Shortbus, This sounds like it might just be the carb wants the idle speed turned up a bit. To adjust the idle you will need a long thin phillips head screw driver. The idle screw is very hard to see - it is on the left side facing the carb. Deep in the labyrinth of throttle levers it will be the screw that hits the main throttle control lever. Note the fast idle screw will also be in this area, do not confuse the two. See if turing the idle speed up to 900 RPM helps. The problem may be worn throttle shaft bushings - common on these carbs. The higher idle speed will result in 1) higher oil pressure at idle 2) higher charge rate from the alt. and make it easier to pull out from a stop. The high idle with AC on, is normal. If you look at the carb with the air cleaner housing removed you will see a diaphragm devise with a lever going over to the throttle area. This is the idle advance for the AC. (Offsets the drag imposed by the compressor) Hope this helps Quote Link to comment Share on other sites More sharing options...
shortbus Posted January 6, 2005 Author Share Posted January 6, 2005 I adjusted the idle (I hope I got the right screw) as well the other night, mine has actually always run high (about 1000 - 1100 RPM). I didn't even realize that was high until I got into my service manual and saw that its supposed to be around 650 or so. After driving a bit today it seemed somewhat better but still stalls out occasionally, I also noticed that my fuel economy has gone to crap, I used to get between 28-30 MPG, I just filled it up last night and after 188 miles I'm already down to 1/4 tank. I've been thinking about just taking it off the road and spending some time restoring it, I'm beginning to think I may just do that. I've found a couple of minor rust spots that need some attention and I'd really just like to take it all apart and rust proof the whole thing, clean & reseal the engine...etc. I wanna make sure it will be around for another 20 years (Probably won't but I can always dream ;-) Thanks for all the help. Quote Link to comment Share on other sites More sharing options...
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