Stock 2000 Z28 going lean + knocking
Stock 2000 Z28 going lean + knocking Picked up this car on Monday and I checked codes with a scanner, it had P0137 and P0157 in its history (lean bank 1 and 2 sensor 2). I cleared them out and drove it some more to see if any would come back. It was fine all week and then on friday I started hammering on the car and the SES light came on shortly.
I went to my friends shop and put his snap-on scanner on it. Sure enough same two codes. I looked at the raw data and at idle and low loads the fuel trims are pretty good. I took it for a spin and hammered on it and sure enough right at about 4k the all 4 o2 sensor voltages drop and it starts audibly knocking a bit. I just changed the fuel filter today before doing this and no help.
It's definitely going lean considering the knocking (and somewhat lack of power), and the fact all 4 o2's drop at the same time (they also cycle fine). The car is bone stock, never molested as far as I know and has 29k miles on it. The injectors seem balanced the car idles smooth as glass and also the trims are fine under low load so I'm betting they're not clogged up. So only thing I can think of is the fuel pump isn't putting out what it should. I will try cleaning the MAF but since it's fine normally I don't have much faith in that.
Any thoughts?
I went to my friends shop and put his snap-on scanner on it. Sure enough same two codes. I looked at the raw data and at idle and low loads the fuel trims are pretty good. I took it for a spin and hammered on it and sure enough right at about 4k the all 4 o2 sensor voltages drop and it starts audibly knocking a bit. I just changed the fuel filter today before doing this and no help.
It's definitely going lean considering the knocking (and somewhat lack of power), and the fact all 4 o2's drop at the same time (they also cycle fine). The car is bone stock, never molested as far as I know and has 29k miles on it. The injectors seem balanced the car idles smooth as glass and also the trims are fine under low load so I'm betting they're not clogged up. So only thing I can think of is the fuel pump isn't putting out what it should. I will try cleaning the MAF but since it's fine normally I don't have much faith in that.
Any thoughts?
Welp, after posting this I rigged up a fuel pressure gauge mounted to my windshield wiper to monitor pressure. At idle I'm around 55, but sure enough right at around 4k at WOT it drops to 38 or so... definitely time for a fuel pump.
Thinking about one of these, but not sure how 'direct fit' it is. Any suggestions on fuel pumps?
http://www.racetronix.biz/itemdesc.a...%2D001&eq=&Tp=
Thinking about one of these, but not sure how 'direct fit' it is. Any suggestions on fuel pumps?
http://www.racetronix.biz/itemdesc.a...%2D001&eq=&Tp=
