1997 CHEVY TAHOE. 5.7 Changed THE FOLLOWING: COIL, Ignition module and SPARK PLUGS, WIRES. TOOK IT TO FIRESTONE AND THEY COULD NOT FIND ANY THING WRONG.
Question = ENG STALL AT DIFFERENT SPEEDS. WILL START RIGHT UP. HAVE TRIED TO SEE IF ANY CODES AND THE EQUIPMENT COMES BACK WITH NONE. FIRESTONE STOCKTON CA HAS TROUBLE SHOT AND CANNOT FIND ANY PROBLEM. HAVE CHANGE THE ABOVE PARTS AND HAD THE ALT BENCH TESTED AND IT CHECK GOOD.
HOWEVER WHEN I DISCONNECT THE POSITIVE WIRE ON THE BATTERY THE ENG DIES. PLEASE HELP
Answer: Thank you for tip/donation. Intermittent stalling problems are one of the most difficult things to diagnose. Without any trouble codes to go on makes it even more difficult. A fairly common problem on these trucks is a faulty ignition switch, especially if the truck just shuts off. The switch distributes power to many of the electrical systems. They can cause this condition of a stall and re-start ok. One way to check that is to have the lower steering column cover removed to gain access to the switch.
Tapping on the switch, or pulling on the harness at the switch AND the other end of the harness under the dash while the truck is running will usually cause a faulty switch/harness to act up. Fuel pump going bad is also a common problem, but they will usually cause the truck to chug a little before stall, hard to re-start, and also A.M. Starting problems.
Have also had a problem with a ground wire causing electrical problems on the rear top portion of the passenger side cylinder head. All grounds should be checked.
Does not sound like a battery or alternator because it starts right up. Removing the cable is not really a good test of the charge system on todays vehicles as it used to be. Although you should have the battery cable checked and wiggled to see if possible poor connection.
I will attach a picture of ignition switch/harness that may be helpful to you or your mechanic. That should be the area to concentrate on. Thanks again for tip/donation. I will send a pic. To help you/your mechanic.
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