Is there anything you can adjust on an 81 carburator without screwing up the computer? I want to increase my idle speed.

 

Been a while since I have been under mine, there is a adjustment on the linkage side, I believe the kick up A/C solenoid does it for a simple adj. Darn, been too long.

 

if the carb has ever been rebuilt most likely the plugs have been pulled. if so, it is very much like any other q-jet. you can adjust your primary needles with a carb adjusting tool. one 'fine tune' adjustment i make is to the M/C solenoid but for this one you have to make a special tool, or go to the snap on guy and buy it for $30. the M/C adjustment uses a similar driver as the primary jets but it is much smaller. a small round screw driver can be used if it's trash. you have to cut off the blade end and cut a vertical slot about 1/8" deep in it so you can turn the adjustment stop. this adjustment doesn't change the speed or duration of the cycle, just the stroke of the inner jets. to my knowledge, there are no adjustments that you can make that will 'screw up the computer'. you can make your car drive really crappy but i don't think you can damage the computer from it.

 

Idle speed is an easy one. The E4ME has fast and slow idle screws just like every other quadrajet. The slow (warm idle) idle screw is a straight head screw located on the side of the carb underneath the linkage. You have to reach in from the front to get a screwdriver on it. The fast (cold idle) idle screw is on the other side of the carb (passenger side) and is also a straight head screw. They both get screwed in to speed up the idle and out to slow down. If you are setting the cold idle you need to do it while the engine is idleing cold with the choke on. If you are setting the warm idle do it once the choke is off and the engine is up to temp.

Has the carb ever been apart before? I ask because I would highly recommend not messing with the M/C selenoid or mixture screws if the car is completely stock and the carb has never been apart. It can be done, but takes some studying. If you do need to do some other adjusting, let me know, I've been through every single part of my E4ME and had every single problem 1000 times before I got it completely figured out. Later.

-Justin
:seeya

 

Oh yeah, one more thing. It is also important to ask yourself why the idle is not correct in the first place. It was right when it left the factory, so something changed along the way. Could be that it's not a carb problem. I'm not saying that's the way it is, but it is something to consider, even if just for a brief second. Later.

 

What Justin (Hi!) says is bang on..... unless you've got one of the models that has the ECU controlling the idle speed. Never seen one, but according to my manual you can't adjust it if you have. Don't confuse the solenoid at the front D. side with the ECU idle speed control (it's to "up" the idle when the aircon is on).
When adjusting the hot idle screw (which isn't that easy to get to), use a short screwdriver & be careful not to shove your fingers in the fan (I did, & it hurts!!!). Always make sure everything else is set up OK with no vacuum leaks etc b4 adjusting the idle speed.
If you really do need to adjust the mixture screws etc with a special tool, then you can make one up by getting a piece of tube & shaping the end to a square by shoving the tang of a file up it & hitting it with a hammer etc etc as described in Doug Roe's book. I found it easier getting a piece of tube that was about the right size & filing a slot down it (use the edge of a small file) to make 2 prongs with the gap between them about the width of the adjusting screw head. You may have to gently :smash: the prongs together just enough to grip the screw head. A piece of solid bar can also be used, it just takes longer to file a slot. You can then drill a hole through the bar/tube further up & stick a nail or something through it (Bubba? Me?) to act as a Tommy bar &, more importantly, allow you to see how much you are adjusting things. After you've made the tool then get rid of the hammer - if you start getting problems setting the mixture/idle speed you may be tempted to use it again ;)
Remember exactly how much you adjust everything so that you can always go back to your starting point if the computer starts flashing the Check Engine light or if you can't get it to run right.
Have fun! The ECU controlled carb makes perfect sense when you suss it out - but it can take a while to suss out :)
:cheers:

 

Ben, I think the posts so far have covered the problem. All I want to add is why is the idle speed down? Look at you ignition, plugs, and the EGR valve. Is it slightly open or are the ports plugged up.
If I remember correctly......
Do you have a dwell meter that you can look at the M/C dwell time on the 6cyl scale. Should have a test lead (green plug) coming off the M/C plug. Hook up the dwell lead to this point. Should be cycling after warm up between 10-50 degrees as you rev the engine, and idling about 25-35 degrees. If stuck on 10 or 50 you have a max rich or max lean condition. Also, have you pulled the codes from the ECU to see what is going on?
PS - you won't screw up the computer unless you start shoring things out on the connectors.

 

If there's no test lead coming off the m/c, which is the dwell wire? I've got a black and a pink w/black stripe.

Also, can you connect a dwell meter to the distributor tach to ground without damaging the module or ecm?

 

The lead is a green connector and doesn't come directly off of the M/C selenoid plug, but it spliced in the wire that goes to the plug a few inches back and is stuck out through the black wire loom. Follow the 2 wires from the M/C selenoid connector back to the loom and look for a green connector sticking out of the loom that's not connected to anything. That's the one. The dwell advice is good to check. I personally use some gauging tools to set mine with the top off of the carb, then fine tune it from there, but that's just because my dwell meter died and I haven't gotten another one yet.

UKPaul, this brings back some memories doesn't it? :crazy: :) I think for awhile there we both got so good at taking the top off of these carbs we could do it in our sleep. :lol:

-Justin

 

I think the question of the where the test point for the M/C has been answered. Hope no one snipped it off. Otherwise, it should be the pink wire or the one with the stripe. Looking here can give you clues of what the ECM is seeing and doing to control the M/C solenoid to help you determine what the low idle is caused by - adjustments or a failure somewhere.

As far as the tach line goes, you can connect your dwell/tach to that line and read RPM's on the 8cyl scale.

 

If it helps the connector on mine seems to lay between the air pump and the A/C compressor

Dalannex - where did you get the gauges for setting up the carb, I rebuilt mine and I think I messed up the setting for the mixture, or is this the same thing that using the dwell meter acomplishes??

 

Hi Justin :)
It sure does, but I don't think I got much sleep while doing battle with that carb :lol: Happy days though - it was warm, the sun was shining & every minor adjustment needed a road test just to check it :) And after all that, the main problem was a gaping hole in the EGR relay (or bleed relay?) where somebody had pulled the vacuum hose off & didn't plug the hole!

The test connector may not be in the harness. Mine had been cut off but it's not a problem: if you look inside the harness itself there should be a solder joint in the wire to the M/C solenoid which you can connect a dwell meter to.
Have fun with it ;)
Paul

 

I got my adjustment gauges at a locally owned auto parts store. They can be had at NAPA as well. They are a set of three tools. One goes under the selenoid when the top is off to set the lean mixture screw, then the top goes back on, then one measure the travel of the primary jets to set the rich stop screw, then there is a hook shaped thing to set the initial adjustment of the idle air bleed screw, which requires further tuning on the car when it is running.

Paul, EGR bleed caused all that trouble huh? Mine was certainly the carb. Bubba had been there before, so I had to learn how to properly tune it to run, and boy does it ever run now. :cool: And it'll feel even faster this year because I just got a K&N air filter (even if it doesn't really help HP, I know it's in there) and with the new interior, paint, tires, windshield, etc, etc. I can't wait for spring so I can get it out and put some miles on.


[Modified by Dalannex, 12:27 PM 3/12/2002]

 

Here's a link for anybody interested in the part numbers of the tools at NAPA.
http://www.aros.net/~rbuck/tech/carbtool.html

 

Found the green test lead. It was out of the wire loom towards the air pump and wrapped in electrical tape. Always wondered what that bulge was... The dwell check varied from 30 to 38 degrees (idle to about 2k rpm's). What are the right numbers here and what should I be looking for?

I pulled the air horn off today and replaced the tps. Turned out to be less complicated than I thought it would be. The tps was definitely bad. The plunger was rough when depressed and had several opens with a resistance check. That ohmmeter was jumping all over the place! Now I get a steady .56V at idle and a smooth increase with throttle to just over 4 volts. Big improvement, both with the car and my attitude towards the ecm stuff!! :cheers:

 

Glad to hear it's looking up. Do you happen to have the little plug that connects between the TPS and the TPS connector and has a couple of wires sticking out so you can easily hook on the TPS with your multimeter and check the voltage through the throttle position? I have been looking for one of those and can't find them anywhere. I could make one, but it would just be easier to buy one if I could find it. If so, where did you get it?

 

I've got one that I made up from a 6" PC power supply Y adapter. Those pins happen to be the perfect size needed to fit into or over the tps plug pins. I just removed the plug housing from two ends of the Y and left the third attached (that's the one I use for the meter). Only problem I noticed is that my wife's PC quit working!! :lol: :lol: :lol:

 

Thanks for the tip. I'll have to get on that. :D