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Any 2.5L “Iron Duke” Specialist? EGR Problems

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  • #558886
    AaronAaron
    Participant

      Hey Folks,

      So, I have a 1993 S10 2.5L 2wd with a 5 speed, and throughout it’s entire life I have owned it, I have been fighting with the emissions system. When I first got it (And actually the reason I got it for next to nothing) was because the EGR Valve, and a few other things, were bad. Now, that being said, I can’t afford tossing out a Benjamin to get a OEM new one, so I ended up going to the junkyard and finding a “Good” one. Good meaning it held pressure when you put your thumb over the vacuum end. I put it on and it was much better then before, but on acceleration it feels like an automatic transmission slipping. That being said, when I had no check engine lights once I got my new-ish EGR on. One thing is the EGR Valve I got from the junkyard was much harder to “push open” then the previous, but I don’t know whether they are supposed to be hard to open or not, I also don’t know whether someone could lubricate the pushrod like thing and maybe that would help. I’m almost to the point of thinking it is the “EGR Soloniod”, which, of course, is unique to 1993 and is going to be a hassle and a half to get.

      Sorry for the novel guys, but thank you for reading!

    Viewing 9 replies - 1 through 9 (of 9 total)
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    • #558896
      college mancollege man
      Moderator

        What type of emission problems are you experiencing?
        Can’t pass emissions,hesitation????

        #558898
        AaronAaron
        Participant

          Just like it said, it feels like an automatic tranny slipping on acceleration.

          #558906
          george gonzalezgeorge gonzalez
          Participant

            A slipping tranny will sound like the engine is revving up much higher than expected for the amount of gas pedal push.

            A problem with EGR usually shows up as poor emissions if it sticks closed, poor idling if it sticks open.

            #558908
            AaronAaron
            Participant

              Okay, well, let’s say it has a very, very good amount of hesitation and a “studder” like feel when under acceleration. Is that a better way of describing it?

              #558995
              college mancollege man
              Moderator

                [quote=”mraw” post=77402]Okay, well, let’s say it has a very, very good amount of hesitation and a “studder” like feel when under acceleration. Is that a better way of describing it?[/quote]

                See if this link helps you. match your symptoms and click. I don’t think
                its tranny/clutch related. If it was I would think you would smell the slipping
                clutch.

                http://www.ericthecarguy.com/faq/solving-automotive-performance-issues

                http://www.ericthecarguy.com/faq/solving-transmission-problems

                #559148
                BillBill
                Participant

                  If my memory serves me I think that engine used a positive backpressure EGR. If it’s plugged with carbon inside the valve (where you can`t see) or you bought a negative backpressure EGR it would explain your problems.

                  You will need to get the part number off of the original valve to get the correct one.

                  #559165
                  Kevin CriswellKevin Criswell
                  Participant

                    [quote=”wysetech” post=77498]If my memory serves me I think that engine used a positive backpressure EGR. If it’s plugged with carbon inside the valve (where you can`t see) or you bought a negative backpressure EGR it would explain your problems.

                    You will need to get the part number off of the original valve to get the correct one.[/quote]

                    It does. And you need the right valve for that engine.

                    I have the same engine in my 1994 S-10. Had a bad EGR when I got it also. They also have ignition wire and coil problems that often cause an acceleration misfire. I had a coil that was going bad and would cut out when you accelerate and demanded more from the coil. I replaced the EGR to get the light off and to prevent the cylinders from overheating during lean times.

                    #559492
                    AaronAaron
                    Participant

                      The ’93 was the last of the Dukes, your talking about the 2.2L. The back-pressure thing makes sense, I supposed buying a used one wasnt my best idea. Thanks for all the help guys!

                      #559528
                      Kevin CriswellKevin Criswell
                      Participant

                        Very true, but the basic design of that engine remained the same. That is one of the reasons I personally think the 2.2 turned out to be such a good engine. The iron duke was basically the Pontiac 301 re modified into a four cylinder. One of the biggest problems was the duke using a micarta cam gear until the last 3 years of it’s run. The 2.2 LM3 like in my S-10 was a combination of the iron duke and the Opel 2.0.

                        Now the emissions systems on the iron duke were always a problem, I always felt that the duke suffered from having to conform to CAFE standards without the manufacturers knowing just exactly how to do that without compromising power and economy with air standards. I felt it suffered from the same issues that the Chrysler 2.2/2.5 did, good solid engines that the engineers tried to “bolt on” emissions controls instead of engineering them into the engine platform. Another issue I used to see with the duke was bad EGR valves, since fuel control was very primitive in that engine design the manufacturers often used EGR flow to help lean the mixture out more than current EGRs provide. A clogged or inoperative EGR lead to rich running conditions and damaged rings and valve seats. One of the hard parts of diagnosing a iron dukes EGR issues is that contemporary testing does not work on the duke’s EGR valve, being of a backpressure design certain criteria have to be met to get it to work properly so usually I recommend replacement if symptoms point to a EGR issue. Also Chevy made changes to the calibration of the EGR over the years so taking one off of another Tech4 might not work as it’s calibration could be different from yours.

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