DFI and ECMDiscuss all aspects of DFI (Digital Fuel Injection), ECMs (Electronic Control Module), scanners, and diagnostic equipment. Fine tune your Third Gen computer system for top performance.
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1990 T/A TPI 5.7L, A family friend had this car, it is completely stock. He jumped it one day because the break lights stayed on and killed the battery. Since then it doesn't run right.......put a new battery in, bought it from him and this is what it still does: starts fine , everything works great, when its cold. it idles fine , drives fine, when it starts to warm up the idle surges, more so with an electrical load ( the lights on), when you drive, it is fine under acceleration but if your cruising with just a touch of gas to maintain speed, it surges. Once it warms up it surges real bad at a stop, in gear ( its an auto) my primary (drivers side ) fan kicks in at 210 when its just sitting in the garage, when it does kick on it almost kills the car for a split second, dims the dome light then it goes back to surging, the passenger side fan has never come on yet even with the A/C on and around town it stays mostly at the 200-210 range with a new 180 thermo. I put in new plugs ,wires,cap, rotor, throttle body gaskgets and a new map and o2 sensor . I was told it might be the ECM is there a way to check them? or anyone got another idea
__________________ '90 T/A 5.7L auto (of course, I beleive they all were) bone stock,.........for now.
1) Stop! and check alternator (verify that you are getting 13.8 to 14.1 volts at idle). Also make sure that alternator does not put excessive transient and noise onto its output under load. You'll need Oscilloscope for this test. The chances are your CS series alternator has been toasted - these units are not as robust as earlier SI series alternators.
2) Check if ECM has trouble codes set (short pin A&B on ALDL connector)
Sorry I've gone for awhile, yes the alternator is putting out proper volts, it doesn't sound bad, is magnitized on the back, and the car starts fine every time if this all matters. I have not changed it though, can I go to the stronger SI instead, if so what do i request to get it? Thanks. Still wondering why sec. fan never seems to kick on even at 220* , and when I turn A/C on. I did switch terminals with the pri. fan and it takes of, but then the driver side won't kick on , so the fan is functional ( not froze up)
