Unhooked battery while running


dirtkat
08-21-2011, 12:17 PM
I have a 1995 Chevy S10 4x4 4.3Vortec (W) CMFI

I had recently unhooked the battery while the truck was running and now the truck runs great for 10mins then will not accept throttle. Still idles but backfires through the throttle body when attempting to accelerate. All sensors are fine, coil is new, has had tune-up, is not fuel pump, fuel pressure is fine (over-fueling issue is not the problem, it is a result of the actual problem). I feel this cannot be a mechanical issue with the motor because it was a direct result of unhooking the battery while the vehicle was running. The alternator shows 14V at the battery and in the cab. The only way I can get a code to come up is unplugging the sensors, otherwise codes don't come up. Computer??? Is it possible? THERE WAS ABSOLUTELY NOTHING WRONG WITH THE ENGINE UNTIL THE UNPLUGGING OF THE BATTERY!!! :banghead:

j cAT
08-22-2011, 09:01 PM
I have a 1995 Chevy S10 4x4 4.3Vortec (W) CMFI

I had recently unhooked the battery while the truck was running and now the truck runs great for 10mins then will not accept throttle. Still idles but backfires through the throttle body when attempting to accelerate. All sensors are fine, coil is new, has had tune-up, is not fuel pump, fuel pressure is fine (over-fueling issue is not the problem, it is a result of the actual problem). I feel this cannot be a mechanical issue with the motor because it was a direct result of unhooking the battery while the vehicle was running. The alternator shows 14V at the battery and in the cab. The only way I can get a code to come up is unplugging the sensors, otherwise codes don't come up. Computer??? Is it possible? THERE WAS ABSOLUTELY NOTHING WRONG WITH THE ENGINE UNTIL THE UNPLUGGING OF THE BATTERY!!! :banghead:


before we had computers in vehicles , removal of the battery connection with engine running , was common , to see if the alternator/generator was working...that was a few decades ago...

In todays computer vehicle world , doing this , can cause a computer failure..


As most know ,,,,,computers do no like voltage spikes , and thats what occurs with what you did.

I would check compression...

Tony Silva
08-23-2011, 12:48 AM
You will not see the 'check engine light' comming on due to the fact that the vehicle needs to run thru what is called "drive cycles". Drive cycles are what the computer uses to analyze the engines (sensors) perimeters to determine if there is a fault with what the engine is doing. The vehicle may need to rev to 3,000 rpm's thirty times to 'know' the rate of acceleration or heat up to normal operation temp twenty times to know what is 'regular' rate of engine temp increase or start and end operating procedures 25 times...just ALOT of stuff. Sounds to me that you must've unhooked the battery while the truck was 'warmin' up and that messed up the computers' analysis of the throttle position sensor and now the computer is NOT giving you the code for a (possibly) bad throttle position sensor because the computer doesn't know what the throttle position sensor should be reading. My sugestion to you would be to go to a wrecking yard and buy a TPS and replace it into your vehicle to see if it fixes the problem.

MT-2500
08-23-2011, 07:02 AM
I have a 1995 Chevy S10 4x4 4.3Vortec (W) CMFI

I had recently unhooked the battery while the truck was running and now the truck runs great for 10mins then will not accept throttle. Still idles but backfires through the throttle body when attempting to accelerate. All sensors are fine, coil is new, has had tune-up, is not fuel pump, fuel pressure is fine (over-fueling issue is not the problem, it is a result of the actual problem). I feel this cannot be a mechanical issue with the motor because it was a direct result of unhooking the battery while the vehicle was running. The alternator shows 14V at the battery and in the cab. The only way I can get a code to come up is unplugging the sensors, otherwise codes don't come up. Computer??? Is it possible? THERE WAS ABSOLUTELY NOTHING WRONG WITH THE ENGINE UNTIL THE UNPLUGGING OF THE BATTERY!!! :banghead:
Yes if it was running good before and not good after.

You may have spiked your PCM/VCM.

Engine off unhook neg battery cable for 5 minutes and then hook it back up.

Also a code clear with a eninge capable scanner may help.

MT-2500
08-24-2011, 02:56 PM
How did it go?

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