USA_muscle
New Member
- Joined
- Jun 8, 2009
Hello all,
I have an 86GN that has began to knock. Now here is the weird part, I am not under any boost when it does it. Just subtle changes in RPM. Running down the highway at about 2K-2100RPM, asI gently press the accel pedal and the RPMs go up about 200-400, the knock gauge will start changing lights. I have a SM and although I have not had time to pull a complete set of numbers to give you guys, I can tell you that during that drive, the retard would range from 0-about 6 (at which point I would take my foot off the pedal and decel which would bring it back to 0). I am well below the point at which my turbo starts building pressure (about 2900-3K) when all this happens. When I got home I, noticed 3 things when I popped the hood: 1) the engine made a noticeable putting noise ("putt, putt, putt") which sounded like exhaust to me (also louder under the car, but have not had time to jack up and climb under; possible culprit???), 2) the fuel pressure had dropped to ~37 (no vac) from previously set 42 (set in Jan when I did a tune up), and 3) a slight fuel odor (not strong but noticeable) but could find any leaks around rail, injectors or regulator and nothing I could see under the car as far as leaks. Turned the pressure back up to 42 but still no change in the aforementioned noise. Looked for loose or cracked vacuum hose(s) but did not find any. I do not see any smoke from tailpipes, temp is normal, have not pulled plugs yet but they looked good when changed in Jan. I can pull some numbers when I get home this afternoon. In Jan I changed oil (w/filter), plugs, fuel filter, cleaned air filter. Any thoughts??? Sorry so long just trying to provide as much info as possible.
I have an 86GN that has began to knock. Now here is the weird part, I am not under any boost when it does it. Just subtle changes in RPM. Running down the highway at about 2K-2100RPM, asI gently press the accel pedal and the RPMs go up about 200-400, the knock gauge will start changing lights. I have a SM and although I have not had time to pull a complete set of numbers to give you guys, I can tell you that during that drive, the retard would range from 0-about 6 (at which point I would take my foot off the pedal and decel which would bring it back to 0). I am well below the point at which my turbo starts building pressure (about 2900-3K) when all this happens. When I got home I, noticed 3 things when I popped the hood: 1) the engine made a noticeable putting noise ("putt, putt, putt") which sounded like exhaust to me (also louder under the car, but have not had time to jack up and climb under; possible culprit???), 2) the fuel pressure had dropped to ~37 (no vac) from previously set 42 (set in Jan when I did a tune up), and 3) a slight fuel odor (not strong but noticeable) but could find any leaks around rail, injectors or regulator and nothing I could see under the car as far as leaks. Turned the pressure back up to 42 but still no change in the aforementioned noise. Looked for loose or cracked vacuum hose(s) but did not find any. I do not see any smoke from tailpipes, temp is normal, have not pulled plugs yet but they looked good when changed in Jan. I can pull some numbers when I get home this afternoon. In Jan I changed oil (w/filter), plugs, fuel filter, cleaned air filter. Any thoughts??? Sorry so long just trying to provide as much info as possible.
