Ok, need some help on this one haven’t been able to find anything remotely close to my problem. Had plugs, wires, rotator, cap, and fuel injection spider all replaced couple of months back. In the process they snapped the plug connection on the temp sensor. So I’ve been without my temp gauge. Thinking it was just unplugged, I tried to reseat the connection, but the whole plug assembly in the sensor is snapped. Never gave it much thought since my thermostat is new, flushed the heater core, and I use an OBD checker every few weeks. Needs an 02 sensor, but other than that didn’t throw any other codes. Few weeks ago my pulley seizes up and I end up changing that thing out, and runs fine. Last week all of a sudden, the truck surges and randomly accelerates on its own. The temp gauge shoots up to about half and the truck shudders then accelerates and acts like the cruise is engaged, and then the gauge drops back to 0. I can bring it back down with the brakes, but just randomly disturbing. Throttle cables moves freely and is not sticking and cleaned it with some carb cleaner to make sure it moves ok.
will the disconnected temp sensor gauge throw a voltage reading and make everything out of whack? I’m not completely sure if this truck is a voltage throttle or cable driven. Or anyone smarter than me have any ideas or insight?

2002 Blazer 4.3 4WD 4 door
248,967 miles

 

The engine computer uses the ECT sensor input in part to determine fuel delivery. I don’t know if an alternating full signal/zero signal can cause this behavior but you get normal gauge temp/zero reading at the same time so I would get that fixed.

which O2 code are you getting? If it’s the heater circuit, no big deal as far as this problem is concerned but if the sensor reading itself is wacky then that can cause problems. Can you look at live data to see if the sensor is behaving properly.

another thing to look at if you have live data is the TPS output by moving through the pedal range and watching the output voltage.

George