ok i have a 96 blazer 4.3 4wd 4dr. it has 196xxx on it. about six months ago it started to act like i had my foot on the gas when i didnt. it would literaly drive itself. if i stood on the brake for a min in gear it would go down to idle. now it will do 55mph and i cant stop it. i had a code for a bad tps. replaced it and no change. yesterday i still had the code, replaced the 6 month old tps senser. still no change. i also have a code for the bank 1 senser1 o2 senser no activity. could my cat be clogged and causing all my problems? any input would be greatly appreciated and thanks in advance.

 

usually clogged cats make it bog down and have less power. is the throttle cable or butterfly sticking?

will it accelerate or just get stuck where you were holding it?

 

and you're still driving it?!!!

Blazinloud is right, it's not the cat. i'd also look @ the cable & throttle body for any obstructions or a kink in the cable. also check your cruise control system.

before any of this happened, did you do any work to the truck?

what's your fuel pressure like? any surges? does any of the engine acceleration happen while out of gear? (in Park or Neutral)

 

i did not do any work to it before this happened. it does it when i first start it then a few secs later it will idle. but as soon as it goes into gear off it goes. and im not driving it anymore. i checked the throttle cable, abd throttle body. all is well. i have unhooked the cruise and still the same. i can hear the cat rattling. it has been sinse i got it. as far as loss of power it has NO ***** what so ever. still stumped. thanks for the quick responses.

 

you could at least make your posts a little easier to understand what your saying.

so what i gather is, you turn the key, it starts and idles fine, then when you put it in gear the engine races.

is that correct? will it just bounce off the rev limiter or what. usually something like that means vacuum leak, but it should do it in park also.

 

sorry about that. sometimes when i start it it will be just fine and sometimes when i start it, it will rev up to what sounds like around 4k rpms.(i dont have a tach). after i replaced the tps it will do it everytime and i cant get it to idle at all.this started out being a every now and then thing but now its everytime

 

so i jus went out and started my truck and it ran at around 1700rpms, never went down or anything jus stayed there. so a min later i shut it off and it sounded like the fuel pump kept runnin after i shut it off for maybe 10 or15 secs. could this possibly have somethin to do with my issue??

 

suspect vacuum leak..Jerry

 

no, fuel pumps do run for a few moments after the key is shut off.

try spraying carb cleaner around spots on the engine (around intake, TB) and see if the engine rpm changes. thats a cheap easy way to check for vacuum leaks.

 

i checked for vacuum leaks and used carb cleaner aroun the intake and tb and there was no change in rpms and i didnt find any leaks. i have been looking at every thing icould think of. everything i check is fine or gets fixed and there is no change.