QuestionThe engine (4.5L) surges and i had to raise the idle to about 1000rpm so the car would stop stalling when i started it. I have adjusted the TPS so that it reads .50 volts with the throttle completely closed. When i remove the serpentine belt, it runs almost perfect. I have an aftermarket alternator, but the pulley spins fine.
I think i have a vacuum leak, but i have no clue where it is; if it helps, the parking brake doesnt automatically disable itself when the tranny is put in reverse or park. And im not 100% sure my evap unit is working correctly, the cabin and engine bay reek of gasoline and the injectors are not leaking...Any help is appreciated. Thanks.
AnswerHi Ben,
That is kind of interesting that the engine runs better without the alternator chargeing. I suppose leaving the belt off and driveing is out of the question. LOL. The problem may be a dirty negative battery cable where it attaches to the engine. If the cable is bolted to the engine mount bracket unbolt it and clean both sides of the terminal with sandpaper to it is clean. Then remove the "L" bracket from the end of the starter and sand the engine block and both sides of the bracket so it is bare metal. If the bracket is missing then get a M8 X 1.25 X 1" bolt and attach the cable to the block at that location. If the bracket is there put the cable between the engine and the bracket and tighten it up. You will need to bend the bracket slightly to allow the cable to fit.
As for the surgeing doing the adjustments to the base idle, tps, and maximum ISC motor extension are critical to how the engine runs. You will need to get a book because I don't have the procedure in front of me. But basically the ISC needs to be retracted so the throttle lever is on the idle screw and with the engine warmed up it needs to idle at 525rpm. The TPS should be .50V Then with the ISC motor fully extended with the engine off and key on the TPS should read 1.07V and is adjusted by turning the ISC motor screw.
I would suspect that 1 or more of your fuel injectors are shorting out. If you measure the resistance of the injector with the connector off it should be around 12 ohms. I would measure all of them and if one or more differ 1 ohm or more from the average resistance then replace those or take the car to your mechanic and have a diagnostic done to make sure which ones are shorting.
As for the fuel smell it could be due to a faulty MAP/manifold absolute pressure sensor or open vacuum hose to the sensor. The oxygen sensor might be stuck to the rich setting or injectors being shorted or stuck open could be overfueling the engine. Just make sure that there isn't a fuel leak from a rusty fuel line or a fire could start at a moments notice. It is common for an older car to have a hole in the release solinoid for the parking brake so it might not have anything to do with the way the engine runs.
Give those things a try and let me know what happens if you need more help. Bill
