89sportside
Newbie
Okay so!
I'm having an issue with my 1989 K1500 350. A few weeks ago I was getting rich fuel, no start (flooding) problems. I did some tweaking and got that fixed, and after that the off-idle stumble surfaced. After some more tweaking I found that plugging the vacuum hose at the EGR valve eliminated the stumble, but I soon noticed I had a knocking sound under a load.
Basically, with the EGR plugged in it will die just off idle (backing out of a parking spot, pulling off from a stoplight) and no SES light. and with the EGR plugged I get a knock in my engine and sometimes SEE light. Octane Booster helps but doesnt eliminate the knock. What I want to find out is which component is failing me.
Here's what I've already done:
New cap, rotor, plugs, wires.
New coolant temp sensor
New MAP sensor
TPS is known to be good
Checked PCV valve and hose operation
Replaced all hose between intake, solenoid, and EGR
Replaced vacuum line to charcoal can
Set ignition timing to 0*
New fuel filter
New air filter
I also pulled out the EGR valve and by applying positive and negative pressure to the vacuum inlet I can hear the diaphragm (poppet?) move in and out. Also, by applying battery voltage to the solenoid I can hear it open and close accordingly. The vacuum routes between the vent and inlet correctly when I do this.
My theory is as follows:
Either a) my EGR valve isn't closing all the way (carbon buildup? I sprayed an obscene amount of carb cleaner through it just in case) which is allowing exhaust to seep in at low rpm
b) the solenoid is opening earlier than it should, which allows exhaust to seep in at low rpm
Or C) my exhaust gas has the incorrect chemical makeup, causing the fuel to fail to ignite (which seems unlikely)
I don't care whether the EGR stays part of the intake or not. I'm hoping someone can either help me diagnose and fix the problem with the EGR, or figure out a way to lower my engine temperature without it so as to cure the knock. Retarding the timing is a last resort since its at manufacturer specifications (which is 0* TDC) now.
I know someone here will be able to help with this. There are some sharp people on this forum. Thank you all
I'm having an issue with my 1989 K1500 350. A few weeks ago I was getting rich fuel, no start (flooding) problems. I did some tweaking and got that fixed, and after that the off-idle stumble surfaced. After some more tweaking I found that plugging the vacuum hose at the EGR valve eliminated the stumble, but I soon noticed I had a knocking sound under a load.
Basically, with the EGR plugged in it will die just off idle (backing out of a parking spot, pulling off from a stoplight) and no SES light. and with the EGR plugged I get a knock in my engine and sometimes SEE light. Octane Booster helps but doesnt eliminate the knock. What I want to find out is which component is failing me.
Here's what I've already done:
New cap, rotor, plugs, wires.
New coolant temp sensor
New MAP sensor
TPS is known to be good
Checked PCV valve and hose operation
Replaced all hose between intake, solenoid, and EGR
Replaced vacuum line to charcoal can
Set ignition timing to 0*
New fuel filter
New air filter
I also pulled out the EGR valve and by applying positive and negative pressure to the vacuum inlet I can hear the diaphragm (poppet?) move in and out. Also, by applying battery voltage to the solenoid I can hear it open and close accordingly. The vacuum routes between the vent and inlet correctly when I do this.
My theory is as follows:
Either a) my EGR valve isn't closing all the way (carbon buildup? I sprayed an obscene amount of carb cleaner through it just in case) which is allowing exhaust to seep in at low rpm
b) the solenoid is opening earlier than it should, which allows exhaust to seep in at low rpm
Or C) my exhaust gas has the incorrect chemical makeup, causing the fuel to fail to ignite (which seems unlikely)
I don't care whether the EGR stays part of the intake or not. I'm hoping someone can either help me diagnose and fix the problem with the EGR, or figure out a way to lower my engine temperature without it so as to cure the knock. Retarding the timing is a last resort since its at manufacturer specifications (which is 0* TDC) now.
I know someone here will be able to help with this. There are some sharp people on this forum. Thank you all