Tuesday, March 20th, 2007 AT 3:51 PM
I have a 1998 Lincoln Navigator with a 5.4 V8 and 90400 miles. The truck runs fine except for a rough idle(slight but noticible shaking) in drive and reverse when warmed up. There is no coolant/oil mix, it does not stall, the idle is static while stopped in drive at 650 rpm, no sweet smoke or steam from the exhaust, no overheating, but I am not sure if it lacks power as I have never driven such a vehicle. The check engine light came on after an oil change, they reset the light and it has not come back on, but the rough idle is still there. The error code was P0171 system too lean (bank 1). Took it to several small mechanics, none could isolate the problem. I took it to a Ford dealer who conducted a compression check with all four cyclinders low on the bank.5, 6, 7, &8. The mechanic seems to think that due to the lack of other problems this is a timing chain issue, does this sound right, if not what else should I be looking for before pouring more $$$s into diagnostics?
