Cadillac Repair: cad 92 deville hesitation, negative battery cable, autolite plugs

Question
92 sed.deville 4.9. had a major tune up. still hesitates spits and sputters. codes e71,e98,e90.

Answer
Hi Walt, By major tune-up I will assume that the AC delco plugs were installed along with the cap, rotor, plug wires fuel filter and air filter if needed. If anything other than AC delco plugs were installed they could be a problem especially if bosch or autolite plugs were installed. Have that shop remove them and sent them back to the parts store as defective and install the correct plugs. While they have the car they need to clear the codes because they are history codes. Then when the service light turns on you can diagnos the current or EE codes.

     A couple things could be going on here. First there is a negative battery cable down by the starter that needs to be cleaned, the starter bracket needs to be cleaned to bare metal and the engine block needs to be cleaned. Then the battery cable needs to be installed between the starter bracket and the engine.

    The other thing that happens frequently is the fuel injectors short out. The way to tell that this is happening is to start up the engine cold like overnight and then as the engine warms up it will idle rougher. If that is the case the injectors need to be tested for shorting and fuel flow. On extreme cases I have had to replace 5 bad injectors at 1 time. However the GM tech hotline says that if 3 or more are found to be shorting out then all of them should be replaced.

     Let me know if you need anymore help. Bill