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  • #1

    EGR Question

    I was told that on a good EGR vlave I should be able to puch the diaphragm inside it with my fingers. I tried this with mine and could not do it. Could this be the source of a backfire on acceleration and very bad 1/4 mile times? Oh yeah, I'm not getting an SES light.

    Andy
    '94 Formula M6, XE224/230 w/1.6 RR's, hardened pushrods, Comp R lifters, SLP ceramic coated shorties, Random Tech cat., Flowmaster cat-back, CSI water pump, vented opti, PCM tuning by Spraytheway, BMR k-member, SFC's, DSL, LCA's & brackets, adj. PHR
    339 RWHP, 341 RWTQ
    '00 S-10 ZR2
    Tags: None
  • #2
    Best way to check it, without a scanner, is to put a vacuum pump on it and give a couple pumps, the car should stumble and start to stall at an idle.

    Your not able to move the diaphram by hand? In other words, the valve is STUCK closed? If the valve doesnt open, it should trip a light.
    96 WS6 Formula: Ram Air, 383 Stroker, Ported LT4 Heads and Manifold, 1.6 Crane Rollers, 58MM T.B., AS&M Headers, Borla Exhaust, Meziere Elec. H2O Pump, Canton Deep Sump Oil Pan, 100 HP OF TNT N2O!! , T56 Conversion w/ Pro 5.0 shifter, SPEC Stage 3 Clutch, Hotchkiss Subframe Conn., Lakewood Adj. Panhard Bar, Spohn Adj. LCA's, BMR Adj. T.A., Custom 12 bolt w/ 3:73's, Moser Axles, Eaton Posi, Moser Girdle
    11.6 @ 123mph (1.6 60' - getting there )

    Comment

    • #3
      I'm not sure if it's stuck closed or open. But it sure won't move when trying to squeeze it. I'm going to pull it off the car tomorrow morning and compare it with a new one at the dealer. I don't have a vacuum pump to put on it. Where would I atteach it if I got one?

      Andy
      '94 Formula M6, XE224/230 w/1.6 RR's, hardened pushrods, Comp R lifters, SLP ceramic coated shorties, Random Tech cat., Flowmaster cat-back, CSI water pump, vented opti, PCM tuning by Spraytheway, BMR k-member, SFC's, DSL, LCA's & brackets, adj. PHR
      339 RWHP, 341 RWTQ
      '00 S-10 ZR2

      Comment

      • #4
        The 94 OBD-I EGR diagnostic is not very accurate, and seldom sets a code, or turns on the SES light for a missing or faulty EGR valve.

        You apply the vacuum to the vacuum connection on the EGR valve.... that's what normally makes the diaphragm move. There is a vacuum nipple on the top/backmost part of the valve, as shown in the photo, and it connects to the solenoid on the drivers side of the intake manifold. Ignore the vacuum line coming from the passenger side in the pic, that one fell off the fuel pressure regulator.

        Fred

        381ci all-forged stroker - 10.8:1 - CNC LT4 heads/intake - CC solid roller - MoTeC engine management - 8 LS1 coils - 58mm TB - 78# injectors - 300-shot dry nitrous - TH400 - Gear Vendor O/D - Strange 12-bolt - 4.11's - AS&M headers - duals - Corbeau seat - AutoMeter gauges - roll bar - Spohn suspension - QA1 shocks - a few other odds 'n ends. 800HP/800lb-ft at the flywheel, on a 300-shot. 11.5 @ 117MPH straight motor

        Comment

        • #5
          So, I just disconnect that top vacuum line and connect the pump to it. Then apply vacuum and the car should want to stall if it's working properly?

          Andy
          '94 Formula M6, XE224/230 w/1.6 RR's, hardened pushrods, Comp R lifters, SLP ceramic coated shorties, Random Tech cat., Flowmaster cat-back, CSI water pump, vented opti, PCM tuning by Spraytheway, BMR k-member, SFC's, DSL, LCA's & brackets, adj. PHR
          339 RWHP, 341 RWTQ
          '00 S-10 ZR2

          Comment

          • #6
            That means the valve is opening and closing and probably working correctly unless its not getting vacuum or something like that. If you cant move the diaphram at all with the car OFF, then its probably shot.
            96 WS6 Formula: Ram Air, 383 Stroker, Ported LT4 Heads and Manifold, 1.6 Crane Rollers, 58MM T.B., AS&M Headers, Borla Exhaust, Meziere Elec. H2O Pump, Canton Deep Sump Oil Pan, 100 HP OF TNT N2O!! , T56 Conversion w/ Pro 5.0 shifter, SPEC Stage 3 Clutch, Hotchkiss Subframe Conn., Lakewood Adj. Panhard Bar, Spohn Adj. LCA's, BMR Adj. T.A., Custom 12 bolt w/ 3:73's, Moser Axles, Eaton Posi, Moser Girdle
            11.6 @ 123mph (1.6 60' - getting there )

            Comment

            • #7
              They are known for getting carbon fouled.
              2002 Electron Blue Vette, 1SC, FE3/Z51, G92 3.15 gears, 308.9 RWHP 321.7 RWTQ (before any mods), SLP headers, Z06 exhaust, MSD Ignition Wires, AC Delco Iridium Spark Plugs, 160 t-stat, lots of ECM tuning

              1995 Z28, many mods, SOLD

              A proud member of the "F-Body Dirty Dozen"

              Comment

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