Hi guys and gals!
I have a question about what to do next....
I have a 1984 Pontiac Trans Am 305 LG4 with stock I believe E4ME carburetor. I have been having issues with flat spots, high idle (2500+rpm in drive) stuttering and surging...
This has been going on for a year or more had it in multiple shops and multiple techs hands but no one in my area seems to know anything about this carb....Had the carb rebuilt and replaced all electric parts, no vacuum leaks or so they say, timing is fine, etc.
I just replaced the cap, rotor, coil, wires with BWD Select parts and the Plugs with E3 DiamondFires, replaced fuel filter and air filter. No more stuttering or surging, but still high idle.
I searched a bit of the forums and deduced that the culprit is the Fast Idle Cam behind the choke.. It seems to drop down into the third stage but not fully...I now have the piece locked down with a metal rod so it can't come back up from the final stage, but as you know it is now hard to start and running poorly until it warms up....after its warm it runs fine....I'm almost happy.

???
Should I buy a rebuilt E4ME online and hope for the best or go upgrade the intake and carb to something less computer and three stage choke?
If change is due, what should I look for to keep my clearance in line with the room under the hood? I'm on a budget, and I can't rebuild the E4ME myself....I could rebuild a normal carburetor with proper documentation, but this (computer controlled..dwell..and all) is a bit too much for me.
Thanks in advance!

 

Guess I should also add this question,
If I change to a non-computer controlled carb...will it affect my computer or performance in any way other than the check engine light?

 

Yes, it will affect your computer. The computer needs the input from the throttle position sensor built into the carb, and without that, will not properly control ignition timing (goes into "limp home" mode), will not properly control the mixture, and will not lock up the torque converter clutch (assuming you have an automatic transmission - can't tell with the information you've provided).

Sure sounds like a simple choke adjustment issue, either the condition or adjustment of the choke thermostat , or adjustment of the fast idle speed (located on the same side of the carb as the fast idle cam - there is an adjustment screw toward the bottom of the carb; see https://www.thirdgen.org/forums/carb...e-rebuild.html , Figure 6C1-7).

Just for the sake of completeness, do you know if the ignition timing has been set, and how it was done?

 

Sorry for the lack of info....I tried to be thorough but wasn't
Yes it is an automatic transmission, has ac, and the E4ME is the Electric Choke non-rear vacuum break variation from figure 6C1-8

I took your advice right after I got home from work and read the link (again) this time finding the adjustment screw location you spoke of.
I ran out and re-started my car and adjusted the screw out then pulled the linkage block that I made (the idle came down) kicked the throttle just for measure, then I screwed it in until the idle went back up and then backed it back out half a turn. Idle is down but waiting for it to cool to test the rest. Wife has to take it to school tonight, so I will drive it myself tomorrow and report back. Thank you I hope this is all that it has been!

As far as the timing...I am completely taking the word of a local shop (they have three locations in town) when I say that the timing is right. But I don't know how reliable that is since they had my car for 7 days on a diag and I got it back not knowing anything nor was I charged...

 

well the car failed on its way home Once it got warmed up it started running super rich and sputtering real bad. Finally died and I went to get it.

I adjusted on the screw again (blindly I might add...) and upped the idle with the fast idle cam screw...the idle screw on the opposite side is so far back the throttle linkage already won't touch it....now it seems to run better fully warmed up but my flat spot at first throttle is back....and the throttle is back to sticking if you lay into it...but the idle is still reasonable at this point...
Will test in the morning and post after work. I'll take it city streets to work and highway back...to get a better idea of what more info I can give.

 

It seems that this is the culprit ... is there anyway to adjust it without the angle gauges or feeler gauges? And will a miss adjusted fast idle cam cause a flat spot at early throttle?

 

Fast idle cam should only be engaged when the choke is on- even a little bit. Once the choke is FULLY open the fast idle cam drops to it's lowest step (completely disengaged) and the idle speed is controlled by the curb idle speed screw over on the throttle arm side of the carb.

Remember when you start it cold it should quickly settle in at about 1200 RPMs in Park/Neutral. And then drop down in little steps as the choke opens up until you are finally down at normal curb idle speed. Shouldn't take more than 5 minutes run time for the choke to open fully on a room-temperature day starting from overnight-cold.

Special tools are not required. You can rough it in with a 1/8" drill bit and some basic observation.

Here's how it goes....

On an overnight-cold engine tap the gas pedal to unload the choke linkage. The throttle plate should SNAP fully closed. The throttle stop lever should take a set hovering about 1/8"-3/16" off the end of the curb idle speed screw.

Start the motor. As soon as it fires up the vacuum can on the front/passenger side of the carb should retract fully and pop the choke plate open about 1/8" to prevent an immediate flood-out condition. You measure this with the 1/8" drill bit stood up stright between the choke plate and the choke airhorn casting. (This can be adjusted more easily by simply applying vacum to that canister and watching it open the choke plate slightly without starting the engine.) Ajdustment is via the phillips-head (or torx-head) screw on the vacuum canister arm. 1/8" is just the "bench" setting. Yours might want a little more or less opening. Usually a little more is better than a little less, to prevent any possibillity of loading it up with fuel or completely flooding it out.

Make you initial fast idle speed adjustment as soon as the idle stabilizes. Fast idle adjustment is the screw directly under the choke lingake, passenger side, screw head facing straight forward. Usually torx-head on later model carbs, but can be slotted or phillips head. Shoot for about 1200 RPMs but remember you don't have much time to get it close before the choke and the engine start to warm up. You get maybe one or two shots at it each morning (maybe a minute of time tops) before things warm up- the choke, the engine, etc. and render the adjustment moot.

Once it's running the choke will start to slowly open more and more as the choke element heats up (single wire electrical connection on the side of the round choke element supplies 12V to a small heater element inside the choke). As it does so, each time you blip the throttle it will unload the linkage and allow it to drop to the next lower step of the fast idle cam. Idle speed will drop as the fast idle linkage drops down each step. Finally, when the choke is FULLY open (vertical) the fast idle cam will drop off it's lowest step and the idle speed will be controlled only by the curb idle screw on the other side of the carb.