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3.0 carbureted engine stalls while in closed loop

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    3.0 carbureted engine stalls while in closed loop

    I have a 1985 Century with a 3.0 with the Rochester E2ME. If I deactivate the ECM or just unplug the metering rods, the engine runs great. If those components are active the engine hesitates or even stalls while beginning to accelerate, however, it will cruise down the road okay.

    #2
    That's a survivor! Those feedback carbs were in production for such a short time. If it were mine, I'd be trying to acquire a FSM, else I 'd retrofit to the DualJet or 2GC.

    Ken T.

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      #3
      I know what you mean, but I want to keep it original just to make it a challenge. The sensors and all still work. I'm going to get an inexpensive dwell meter and try to tune it.

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        #4
        I got the engine to stall less by getting the carburetor tuned somewhat. The engine was running lean due to the float not being set correct. I hooked a scan tool with a dwell setting on it to the metering system but I was going some whacky readings. I realized later that I didn't have the MAP sensor plugged in and the ECM was running open loop. I tuned to carb as best I could to keep the engine running but it's rough right now. I'll need to acquire my own dwell meter and spend more time on it. The magic number is 35°of dwell. The ECM does function as I can tell it was trying to make it's own corrections as best as it could. There is still plenty of hesitation while the engine is cold but it's not as bad.

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          #5
          Originally posted by KH990j View Post
          I got the engine to stall less by getting the carburetor tuned somewhat. The engine was running lean due to the float not being set correct. I hooked a scan tool with a dwell setting on it to the metering system but I was going some whacky readings. I realized later that I didn't have the MAP sensor plugged in and the ECM was running open loop. I tuned to carb as best I could to keep the engine running but it's rough right now. I'll need to acquire my own dwell meter and spend more time on it. The magic number is 35°of dwell. The ECM does function as I can tell it was trying to make it's own corrections as best as it could. There is still plenty of hesitation while the engine is cold but it's not as bad.
          I believe that car has GM's very first attempt at computer controls. I appreciate you wanting to keep her original. Are you aware of nylon timing gears they put in those vintage FWD Buick engines. Poke around this site and you'll find a lot of good info on the 3.0. It's not real common, but we've had a few come through here through the years.

          Ken T.

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            #6
            I figured they started just before '85 with computer control. Wee tried to hook a very modern snap on scan tool to communicate with the ECM but it didn't want to. There could possibly be an issue with the DLC but I have noticed that the check engine light doesn't come on at startup.
            I actually just learned about GM putting nylon gears on those. GM did plenty of weird things like that such as using plastic thrust washers on the TH440 transmission that this car uses. I'll have to keep an eye out for those 3.0 posts. I agree with people that it is by far not the greatest engine to grace the roads, but I want to keep it going because it's there and it's unusual.

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              #7
              Originally posted by KH990j View Post
              I figured they started just before '85 with computer control. Wee tried to hook a very modern snap on scan tool to communicate with the ECM but it didn't want to. There could possibly be an issue with the DLC but I have noticed that the check engine light doesn't come on at startup.
              I actually just learned about GM putting nylon gears on those. GM did plenty of weird things like that such as using plastic thrust washers on the TH440 transmission that this car uses. I'll have to keep an eye out for those 3.0 posts. I agree with people that it is by far not the greatest engine to grace the roads, but I want to keep it going because it's there and it's unusual.
              I with you on the keeping her original. If memory serves, GM's first Computer Command Control systems made their first appearance in the 1981 model year in the Peoples Republic of California. And, I _think_ they started to appear on some of the federal emissions cars in '82. I'm thinking about the G-body Malibu. My thinking is that thing probably communicates primarily via blinking check engine light.

              Look for posts here from "Turbokinetic" He's THE authority on the Buick engines, and has experience with the 3.0; he's also done a number of rebuilds on the 440-T4 . He's got some really, really, really good YouTube tutorials including a complete teardown of the TH440-T4.

              Ken T.

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                #8
                I had that setup on my 1982 Buick Regal w 231V6 Vin Code A. That E2ME carb was a nightmare. It never ever ran right and the engine always ran rough as long as the ECM had control. Those are lean burn carbs and programmed to be lean to try and pass the then emissions standards. When you disconnect all the ECM controls the engine runs beautifully, hook up all the emissions again and it runs awful. I remember those very well. I couldn't tune out that rough running. Most guys would raise the idle speed screw to try and compensate for the lean condition and then disconnect the check engine light in the dash. The ECM in those things was nothing more than a glorified fuse box.

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                  #9
                  Originally posted by Century7667 View Post
                  If memory serves, GM's first Computer Command Control systems made their first appearance in the 1981 model year in the Peoples Republic of California. And, I _think_ they started to appear on some of the federal emissions cars in '82. I'm thinking about the G-body Malibu. My thinking is that thing probably communicates primarily via blinking check engine light.
                  Ken T.
                  Close, 1980 is the unique CCC for California and 1981 is Federal for GM cars. Apparently, the 1980 was fairly different as Cali got to be the beta testers. I could always tell the '81 federal cars by the 'Check Engine' light being on all the time
                  I see a fair number of Cali cars here in the yards as people come here to 'Californicate' Idaho. I'll have to take a picture of an Ultra Low Emission Vehicle 3100 V6 with air injection for everyone's amusement.
                  Jerry

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                    #10
                    Jerry I have seen one of those few years back down in Florida that was a true California car I believe it was a 1994 .

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                      #11
                      Originally posted by Skip View Post
                      I had that setup on my 1982 Buick Regal w 231V6 Vin Code A. That E2ME carb was a nightmare. It never ever ran right and the engine always ran rough as long as the ECM had control. Those are lean burn carbs and programmed to be lean to try and pass the then emissions standards. When you disconnect all the ECM controls the engine runs beautifully, hook up all the emissions again and it runs awful. I remember those very well. I couldn't tune out that rough running. Most guys would raise the idle speed screw to try and compensate for the lean condition and then disconnect the check engine light in the dash. The ECM in those things was nothing more than a glorified fuse box.
                      I think the lesson here is GM hadn't mastered emissions control equipment just yet. I think 1987 was the year it all really started to come together emissions + drivability + performance.

                      Ken T.

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                        #12
                        Originally posted by CorvairGeek View Post
                        Close, 1980 is the unique CCC for California and 1981 is Federal for GM cars. Apparently, the 1980 was fairly different as Cali got to be the beta testers. I could always tell the '81 federal cars by the 'Check Engine' light being on all the time
                        I see a fair number of Cali cars here in the yards as people come here to 'Californicate' Idaho. I'll have to take a picture of an Ultra Low Emission Vehicle 3100 V6 with air injection for everyone's amusement.
                        I knew they were one year apart! My father has a 1980 Malibu with the Chevy 229; and that thing ran pretty good with the DualJet. 150k before the car was retired, and the carb never needed rebuilding. She was starting to use oil though....my father regrets sending that car to Pick-a-part. Straight body and ultra clean, but Mom needed new wheels, and I didn't have room for another project. At the time, I don't think he realized what he had. Nobody did.

                        Ken T.

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                          #13
                          Originally posted by Century7667 View Post
                          I think the lesson here is GM hadn't mastered emissions control equipment just yet. I think 1987 was the year it all really started to come together emissions + drivability + performance.

                          Ken T.
                          Yes indeed. The 70's and early to mid 80s were rough on The Big 3. But I think all car manufacturers were going thru there own growing pains. In the mean time I just disconnected all that crap and "properly" tuned my cars.

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                            #14
                            Originally posted by Skip View Post
                            Yes indeed. The 70's and early to mid 80s were rough on The Big 3. But I think all car manufacturers were going thru there own growing pains. In the mean time I just disconnected all that crap and "properly" tuned my cars.
                            Yep. On my 70's era cars, I didn't hesitate to disable the emissions gear, except evaporative and catalytic converters. The EGR business and distributor timing were all just disasters. This was why I had suggested to KH990j to consider a retrofit to a DualJet carb. I think that would be close enough to original, not like ripping out the 3.0 and replacing with with the 2.8 or the 3.8 or even a 3.3. The DualJet would be a period correct carb for the car. In my opinion sometimes you have to make some changes for reliablity. Still I respect his desire to keep it all original.

                            Ken T.

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                              #15
                              Originally posted by Century7667 View Post
                              Still I respect his desire to keep it all original.
                              Ken T.
                              Yes, I understand and agree completely.

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