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  • #1

    I'm stumped

    Ok, here's the deal, my cousin just bought a '90 Camaro RS 2.8 (with dizzy). The car has 96k and has been generally well maintained. I've been driving it for the past week and noticed it has a really rough idle and misfires and so on and so forth. I know the car has vac. leaks in the climate control so I figured thats what was causing the stumbling. Not a big deal, I can fix that whenever I get ready. Today I take my dad to a Dr.s app. (3 hours from home) and it takes to stalling and backfiring (NOT GOOD for someone who has PTSD). When we pull into the hosp. the car backfires hard and bogs so badly I couldnt save it by pumping the gas (while in neutral, of course). Tried cranking it again but to no avail. Pushing a f'ing lowrider camaro into a tight parking spot aint easy, TRUST ME!!! When I was finally able to catch my breath I noticed the car had an extremely strong gassy smell. OK, so it flooded, but why? Vac. leaks cause cars to run lean, not rich. On the way home I headed off all problems by throwing the car into neutral and shutting it off @ red lights but it still ran like sh!t.
    Any ideas guys? My cousin is kinda counting on me getting the car sorted out before I give it back to him and I have no clue. Before he bought the car a bunch of sensors & relays were replaced along with the fuel pump and a host of other stuff. Oh, while I was figuring out the vac leaks, I did take the car to A/Z for a diagnostic scan and got codes 32,33,42,43 (map sensor, egr valve, something else, and the TPS being out of adjustment). 3 of the 4 codes could definately be caused by a vac leak which is why I have so far discounted the codes.
    Please help guys, I hate driving a non electric hybrid.
    Tuning a car is full of compromises. You must decide if you are willing to give up either reliability, performance, or a whole load of cash. Also remember that repairs will seem to come up much more often as you strive for even more performance
    Tags: None
  • #2
    Is the dist cap and rotor in good shape?
    sigpic New 2010 project (click image)
    1994 3100 BERETTA. 200,000+ miles
     16.0 1/4 mile when stock. Now ???
    Original L82 Longblock     with LA1, LX9, LX5 parts
    Manifold-back 2.5" SS Mandrel Exhaust. Hardware is SS too.

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    • #3
      Brand new, along with the plugs & wires
      Tuning a car is full of compromises. You must decide if you are willing to give up either reliability, performance, or a whole load of cash. Also remember that repairs will seem to come up much more often as you strive for even more performance

      Comment

      • #4
        My truck did that and what I did was adjusted the choke/throttle screws on the carb until it had a nice lopey idle and ran without flooding out.

        But mine didn't mis-fire it just had a high idle when it was cold and needed to be adjusted.

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        • #5
          the MAP sensor can cause that, try swapping that with a known good one.
          Past Builds;
          1991 Z24, 3500/5 Spd. 275WHP/259WTQ 13.07@108 MPH
          1989 Camaro RS, ITB-3500/700R4. 263WHP/263WTQ 13.52@99.2 MPH
          Current Project;
          1972 Nova 12.73@105.7 MPH

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          • #6
            Originally posted by X11_STE View Post
            Ok, here's the deal, my cousin just bought a '90 Camaro RS 2.8 (with dizzy). The car has 96k and has been generally well maintained. I've been driving it for the past week and noticed it has a really rough idle and misfires and so on and so forth. I know the car has vac. leaks in the climate control so I figured thats what was causing the stumbling. Not a big deal, I can fix that whenever I get ready. Today I take my dad to a Dr.s app. (3 hours from home) and it takes to stalling and backfiring (NOT GOOD for someone who has PTSD). When we pull into the hosp. the car backfires hard and bogs so badly I couldnt save it by pumping the gas (while in neutral, of course). Tried cranking it again but to no avail. Pushing a f'ing lowrider camaro into a tight parking spot aint easy, TRUST ME!!! When I was finally able to catch my breath I noticed the car had an extremely strong gassy smell. OK, so it flooded, but why? Vac. leaks cause cars to run lean, not rich. On the way home I headed off all problems by throwing the car into neutral and shutting it off @ red lights but it still ran like sh!t.
            Any ideas guys? My cousin is kinda counting on me getting the car sorted out before I give it back to him and I have no clue. Before he bought the car a bunch of sensors & relays were replaced along with the fuel pump and a host of other stuff. Oh, while I was figuring out the vac leaks, I did take the car to A/Z for a diagnostic scan and got codes 32,33,42,43 (map sensor, egr valve, something else, and the TPS being out of adjustment). 3 of the 4 codes could definately be caused by a vac leak which is why I have so far discounted the codes.
            Please help guys, I hate driving a non electric hybrid.
            A vacuum leak on a MAP equipped car can make it run rich if the leak is near the MAP vacuum port. If the MAP measures less than acurate vacuum it will think the engine is running harder(think closer to full throttle) than it actually is and in turn the PCM will add fuel to compensate. Try plugging off the vacuum port feeding the climate controls and see what happens.
            Your local OBDII moderator

            2000 Grand Am GT w/ WOT parts

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            • #7
              OK heres the update. I went through, replaced nearly all the vac hoses I could find. Determined that the climate control panel was bad. As long as everything on the cc panel is off the vac leak is minimal. Replaced the MAP sensor (my cuz insisted, I think that was a waste of money but its not my car so my opinion only goes so far). Oh, FWIW, the car is a fuelie so no carb to fiddle with. Now the car runs better than it did but still shizzy. Now it still misses, runs overly rich, and bogs. But at least it hasnt backfired unless I stomp the gas and TRY to get it to go WOT. Then it backfires *hard*, loses all power and really throws a tantrum but at least tonight I was able to fire the car back up while rolling under no power (50mph).
              I dunno guys, whats up?? Now there is one more posibility that I've so far rejected but being as I've got 4 votes for it, I have to face it. That suggestion is a bad ECM. Possible I suppose, but I just dont see it. You guys think that would be worth a shot?
              TIA.
              Tuning a car is full of compromises. You must decide if you are willing to give up either reliability, performance, or a whole load of cash. Also remember that repairs will seem to come up much more often as you strive for even more performance

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              • #8
                Check for any restrictions in the exhaust, check connections at the ecm for corrosion, and is it an automatic? Could be tcc locking up and not disengaging.
                Lifting my front wheels, one jack at a time.

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                • #9
                  No restrictions in the exhaust and even if there was, the backfires should have cleared them up. No cat.

                  I will check the ecm connections. I did have the dash completely apart and didnt notice any corrosion but wasnt looking for it so will check.

                  The car is an automatic & has the 700r4 tranny but there is no possibility the the tcc is acting up because I can literally feel it shift up and down. That and even when I drive @ 60mph with it in Drive (not Overdrive) it still acts up.

                  Keep the ideas coming guys, Thanks.
                  Tuning a car is full of compromises. You must decide if you are willing to give up either reliability, performance, or a whole load of cash. Also remember that repairs will seem to come up much more often as you strive for even more performance

                  Comment

                  • #10
                    Sounds to me like a case of bad timing. Verify the timing with the ECS wire disconnected. you should be around 10*BTDC. Also remove the plugs and check for gas. I would also check the oil if it has been running rich for that long.
                    1993 EXT. CAB, 3.4L V6 TBI, 5spd manual. Sonoma
                    1990 4Door, 3.2L V6 TBI, 5spd manual. 4X4. Trooper
                    Because... I am, CANADIAN

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                    • #11
                      [QUOTE=X11_STE;354856](map sensor, egr valve, something else, and the TPS being out of adjustment). 3 of the 4 codes could definately be caused by a vac leak which is why I have so far discounted the codes.[QUOTE]

                      check to see that the voltage of the TPS sensor goes smoothly from 1v up to 4.5 or 5v whatever... put your voltage meter on the with KOEO and slowly open the throttle... if that looks alright, trying ohming the coolant temp sensor... or because its so cheap.. just replace it.. I think theres one CTS for the gauges and one going to the ECM... it's likely one code causes many others to pop up... i'll have more suggestions after you check this crap

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                      • #12
                        My EGR shaft had stuck (open/closed?) causing it to run similar to what you described. I took some needle nose pliers and wd40 to it and hasn’t given me anymore trouble. good luck.
                        Mike

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                        • #13
                          All really great suggestion, Thanks. I think the problems solved and heres what happened: Against my suggestions my cuz bought a new ECM. I installed it and it helped some but it was still running rich (but thankfully not backfiring) and throwing code 43 (lean O2 sensor). I told him I would replace that but it would be a couple weeks before I could get to it. He gets extremely impatient and takes the car to the guy he bought it from (I dont approve this guys diagnostic procedures) and says "fix it". Later that day I get a call saying the coolant temp sensor was replaced & now everythings honky dory. Today my cuz drives the car & reports no problems other than the VATs sytem freaking out (big deal!)
                          Please feel free to comment/ discuss your thoughts/ opinions on how or why this could possibly what was wrong the whole time.
                          Tuning a car is full of compromises. You must decide if you are willing to give up either reliability, performance, or a whole load of cash. Also remember that repairs will seem to come up much more often as you strive for even more performance

                          Comment

                          • #14
                            cuz coolant temp has a lot to do with the fuel managment. if the temp sensor reports for example the engine is cold.. more fuel will be added to the mixture, making you run rich

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