1989 s10 knocking

[chevyluver37]

i have a 1989 s10 with a 2.5 liter 4cyl with 199000 miles almost all hwy and i just recently put new high flow exhaust on and it has developed a really bad knocking worse than just the normal old worn out engine knocking and pinging but it only really does it when im going down the hwy and i try to excelerate in 4th or 5th gear ive checked the water and it is good it uses a little oil but i keep up on it regularly other than that i dont know any help would be good i dont really want to put a 350 or other v8 in it because i still am getting about 30mpg so and parts info or repair info would help try to keep in mind i have a small buget thank you

[DelCoch]

It sounds like you have a bad case of pinging. Check the timing with the timing wire under the glove box disconnected and make sure the timing is within specs.

[chevyluver37]

Originally Posted by DelCoch

It sounds like you have a bad case of pinging. Check the timing with the timing wire under the glove box disconnected and make sure the timing is within specs.

timing wire under the glove box huh? kinda confused about that one im only used to old vehicles

[gmctruck06]

the connection Delcoch is talking about is behind the carpet under the glovebox. Disconnect that and then do a timing check.