3000GT/Stealth International Message Center - View Single Post - Lean Misfires at 2700-2800 rpm

davidm5287 · 01-10-2007, 07:56 PM

Well I recieved my car back from ESP a few days ago with no luck finding the problem. I decided yesterday that I would try and tinker around with things, check some connections and small stuff like that. I figured I would try unplugging my O2 sensors and taking it for a drive. As soon as I drove the car without the sensors plugged in the problem is gone. Now the front 02 sensor is brand new, and the back one seemed to be working fine. Either the back one isn't working the best it should be, causing this hesitation or having the car in open loop the entire time is masking this problem. If that is the case it leads me to believe I am coming close to figuring out this problem.

The things that I have done so far are:

-Unplug ECS
-Bypass Fuel pump relay
-Tested and adjusted TPS
-Replaced ISC
-Replaced and rebuilt ECU
-Changed plugs and wires
-no boost/vacuum leaks
-fuel pressure is in check
-I tried advancing the timing to 7.5 without success
-coil packs are fine
-ptu is fine
-replaced PCV valve
-replaced MAS

I am sure there are other things I have tested, but my question is, what other sensors operate as a switch telling the ECU to go from closed loop to open loop. I haven't changed the coolant temp sensor, but I was wondering if this may have any correlation to the problem. Any other input is greatly appreciated.

01-10-2007, 07:56 PM	#120 (permalink)
davidm5287 Forum Member Join Date: May 2005 Location: Massachusetts Drives: 92 Stealth TT Trader Rating: (4)	Re: Lean Misfires at 2700-2800 rpm Well I recieved my car back from ESP a few days ago with no luck finding the problem. I decided yesterday that I would try and tinker around with things, check some connections and small stuff like that. I figured I would try unplugging my O2 sensors and taking it for a drive. As soon as I drove the car without the sensors plugged in the problem is gone. Now the front 02 sensor is brand new, and the back one seemed to be working fine. Either the back one isn't working the best it should be, causing this hesitation or having the car in open loop the entire time is masking this problem. If that is the case it leads me to believe I am coming close to figuring out this problem. The things that I have done so far are: -Unplug ECS -Bypass Fuel pump relay -Tested and adjusted TPS -Replaced ISC -Replaced and rebuilt ECU -Changed plugs and wires -no boost/vacuum leaks -fuel pressure is in check -I tried advancing the timing to 7.5 without success -coil packs are fine -ptu is fine -replaced PCV valve -replaced MAS I am sure there are other things I have tested, but my question is, what other sensors operate as a switch telling the ECU to go from closed loop to open loop. I haven't changed the coolant temp sensor, but I was wondering if this may have any correlation to the problem. Any other input is greatly appreciated.