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biggene
10-01-2005, 08:10 AM
Ok I found the post about what the different codes mean and I searched to find exactly how to read them, but didnt find anything. So can anyone explain to me how I go about counting the flashes to make sure I come up with , the correct codes for my car? If not, maybe you can tell me what is wrong.
I have an 88LX,carb, manual, new tuneup, new O2 sensor, and when I start the car it idles around 2k rpm, after 10 mins or so of driving, it will idles down to about 600 rpm or so and run rougher than crap. It isnt overheating [new tstat, water pump, rad, hoses, temp sensor and fan sensor] that I can tell and it runs great, just crappy when you are sitting at a light and have to keep your foot on the gas to keep the car running.

I am getting horrid mileage, probably not more than 20 mpg. Another thing I noticed this morning ont he way to work was one of my belts squealing when I first started up the car. Then when I got here it was idling like crap, but when I turned the headlights off it started running better all of the sudden.
Could it possibly be my alternator about to lock up, because that would explain the car idling down when I put the brakes on, because of the brake light coming on.

I talked to a friend who is a manager at a pop in mechanic place (express lube), he said whatever I do dont jack with the vacuum hoses. There are over 80 of them underneath the hood, from what he says.
I dunno if it is a vacuum problem or not, but I know I have got to get it fixed asap. I drive 120 miles round trip to work every day and this thing is eating me alive in gas right now. I spend between $70 and $80 every week, filling up every 2 days after only 240 to 250 miles.
:(

Yeah that is kinda what I am leaning towards also. It kinda sounds like I have an exhaust leak sometimes anyways so...
How do I go about testing for an exact vacuum leak or do I just visually check all of the hoses etc??

Yeah if it isnt too much trouble I might try to get that done this weekend, the intake gasket that is. Like I said, it was running a little rough, so I swapped a new O2 sensor on and it ran great for a couple of days then started running worse than befroe.

OK finally got it figured out over the weekend.
I took off the air cleaner and found a broken vacuum line, the after looking a little closer I found another busted line on the back of the carb. After replacing these 2 lines, I had to reset the timing as it was prolly around 10 degrees off or so.
The car runs much better now than it did before, but I still am not getting prolly more than 20 - 25 mpg.
Anybody got any more ideas what could be causing this??

:uh: OOPS LOL
doubled up

cardoc33
10-01-2005, 09:09 AM
So, is your check engine lite on, or is it just idling slow? 600rpm is too slow and will idle rough. I would turn up the idle first. you will need a long blade type screwdriver. If I remember correctly, the idle screw is on the driver side. Am I correct, anybody? It is a bit hidden.

avi b
10-01-2005, 03:38 PM
Have an 86 dx. when am at idle at stop light at 600-700 rpm, when I put my foot on the brakes the rpm drop down about 100 rpm. Is this normal or what is the cause of the problem. Thanks
Also, biggene what kind of mpg are you getting?

I'll be glad to hear a response from someone about idle going down when step on brakes and or turn on headlights. Same thing happens to my 86 dx 5 speed.

A20A1
10-01-2005, 06:27 PM
You do not have an ECU like the LXI (EFI) does, you are LX / DX (Carbureted) you will not get any codes.
Get a vacuum gauge and see if your vacuum is at 24" hg
The vacuum gauge is the carbs CODE reader. :)
They should be cheap to buy, but you may be able to rent one.
At 600 rpm you probably wont get 24", it could be a vacuum leak or some other adjustment or part causing bad idle.
See if you can raise your idle using the idle adjustment screw.
If you need help removing your air filter box check out the links below:
LINK 1 (http://www.3geez.com/showthread.php?t=5350)
LINK 2 (http://www.3geez.com/showthread.php?t=38108)
http://www.3geez.com/attachment.php?attachmentid=4510
http://www.3geez.com/attachment.php?attachmentid=4511
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Some images in the diagram below assume you don't have a vacuum leak, or poor idle.
For example, in Figure #4 & #7 where it says 14" of vacuum.
The Low Vacuum Signal could be from low idle, or could be from a vacuum leak.
If you ruled out a vacuum leak and had okay idle then in the diagram, Figure #4 & #7 are more likely to be the cause.
Late Ignition Timing is possible with 14" of vacuum since you'll have less vacuum pulling on the Distributor Advance Diaphragm which would normaly give you Early Ignition Timing. The Vacuum Lines to the Distributor Advance Diaphragm are #25 and #2.
You might want to take a look at this thread when adjusting your idle speed.
IDLE ADJUSTMENT RECOMMENDATIONS (http://www.3geez.com/showthread.php?t=44074)
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http://www.3geez.com/attachment.php?attachmentid=3692
http://www.3geez.com/attachment.php?attachmentid=3693

Brake booster uses vacuum, so if you press the brake and the engine dies you might have a vacuum leak.
Here is a good thread.
GMECH posted some good info, scroll down to post #12
http://www.3geez.com/showthread.php?t=28698
If you disconnect the brake booster vacuum line from the intake manifold and plug the port ont he intake manifold that will be a way to test if the brake booster may be leaking. Plug it, press the brake, if the problem doesn't happen then it may be the booster. reconnect the booster vacuum line to the intake manifold.

Blkblurr
10-07-2005, 08:19 AM
Anytime you turn any electrical load on in your car it puts load on the alt. the more current the load takes the more load on the alt. (makes it more difficult to spin). If your engine is not running right the additional load will make it worse. I would check for a vacuum leak as well. also check for a loose alt belt if it's squealing.

86commuter
10-07-2005, 10:30 AM
You might have a bad intake manifold gasket.


Yeah that is kinda what I am leaning towards also. It kinda sounds like I have an exhaust leak sometimes anyways so...
How do I go about testing for an exact vacuum leak or do I just visually check all of the hoses etc??
just visually inspect each hose making sure they are not hard and brittle or cracked on the ends. it might take a while tho. yours sounds like mine did then i took off the intake and sure enough there were big missing pieces. threw on a newbie and blam it idled like a champ

FyreDaug
10-07-2005, 01:22 PM
You can get a vacuum tester, its just a little gauge you plug into one of the vacuum lines. They arent expensive