Tanro
10+ Year Contributor
- 2,458
- 90
- Jul 22, 2009
-
Montgomery,
Alabama
I've got a 99 GST with a 16g running wastegate pressure. It has a cylinder 3 misfire code, and is missing in boost underpartial throttle, wot, and sometimes rarely out of boost at low throttle or idle.
I've replaced the plugs with NGK bpr6es and gapped @ .028. I have good NGK Wires, coils ohm out correctly. I've tried swapping the wires, swapping the coils, and swapping injectors. It still has a cyl 3 misfire. I've verified timing marks are correct and performed a boost leak test. My only leak is the throttle body, which I'm not sure if its the freeze plug for the IACV, or the shaft seals. I am going to pull it off and seal the freeze plug with some RTV. The FIAV has been closed down by removing the plug and turnin the adjustment until it is bottomed out, and the coolant lines removed.
Could a boost/vacuum leak from the throttle body be the main cause of a Misfire?
I also verified fuel pressure at idle, I am getting 37-39 psi with the regulator hooked up, and 44-46 psi with the regulator vacuum line pulled and the port capped off. Seems to be doing its job, fuel pump seems to be supplying plenty of fuel. Reall quite stumped as to what the cause could be.
I've replaced the plugs with NGK bpr6es and gapped @ .028. I have good NGK Wires, coils ohm out correctly. I've tried swapping the wires, swapping the coils, and swapping injectors. It still has a cyl 3 misfire. I've verified timing marks are correct and performed a boost leak test. My only leak is the throttle body, which I'm not sure if its the freeze plug for the IACV, or the shaft seals. I am going to pull it off and seal the freeze plug with some RTV. The FIAV has been closed down by removing the plug and turnin the adjustment until it is bottomed out, and the coolant lines removed.
Could a boost/vacuum leak from the throttle body be the main cause of a Misfire?
I also verified fuel pressure at idle, I am getting 37-39 psi with the regulator hooked up, and 44-46 psi with the regulator vacuum line pulled and the port capped off. Seems to be doing its job, fuel pump seems to be supplying plenty of fuel. Reall quite stumped as to what the cause could be.