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somethings missing 900 1994

The company I work for recently sold a 94 940 non-turbo,w/egr, 4 cyl. engine to a customer who had it installed in the same year vehicle, at a local muffler shop. The motor ran good for me, but had been in storage for a year or so. The shop that did the instillation seemed to do a good job of it. They put on a new timing belt, plugs, and wires, but called us up for help because the car was missing.They dropped off the car for me to look at, and it started up fine and ran smooth for a minute or two before it started to miss and the more it warmed up the more pronounced the miss became. I checked to make sure he put the belt on correctly. I put a vacuum guage on the motor, and did a cylinder kill test to determine if any one cylinder was the culprit, but the vacuum remained steady despite the missing and all cylinders were firing equally. Compression was about 185 across the board, there was no smoke to indicate that a head gasket was leaking, and the car ran at normal temp. Somethings missing (pun intended) and I'm not sure what. Help!








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    somethings missing 900 1994

    As it warms up and starts to miss is it running rich, as in perhaps the coolant temperature is not functioning?

    Randy








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      somethings missing 900 1994

      It doesn't seem to be running rich, the spark plugs were new, so it is hard to tell by color, but they were niether wet,nor black. The engine is not running hot. It sounds like an ignition miss, but it gets progressivly worse as the motor heats up.Has me baffeled.
      Thanks
      Poorgie








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      somethings missing 900 1994

      Check the plugs, plug wires, distributor, and dist. cap.

      My 74 144 started to miss few miles after a complete rebuild, and the problem was traced to a faulty new spark plug.








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        somethings missing 900 1994

        check,check,check,check. changed the cap and rotor when I got it bacause it was oily. The shop that did the installation changed plugs (Autolite),and wires (high temp 7mm silicon). I put in some Bosch platinums--- no change, checked for spark by grounding each while I did the compression check---all had strong spark.








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          somethings missing 900 1994

          Dear Poorgie,

          Hope you're well. It is the temperature rise, that suggests the problem could be: (a) the ignition module, which is affixed to the inner fender well, on the driver's side of the engine, bay, just to the rear of the headlamp. This module has an aluminum base, with a gray cap. It has a single electrical connector. When heated, this module can fail, producing misses.

          Alternatively, the radio interference suppression relay - aka the fuel injection relay - could also be failing, or have a corroded connector. This relay is location on the inner fender wall, passenger side of the engine bay (North American models). It is rectangular, and very dark brown, almost black.

          These two components are major causes of misses or rough-running.

          Hope this helps.

          Yours faithfully,

          Spook







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