castnet
10-10-2010, 10:03 PM
After installing a secondhand auto, my car would almost die when opening the thottle quickly whilst stationary. Sounded like it was only running on a couple of cylinders, its a 3.0 litre V6, but it would rev up OK if I opened the thottle more gradually. On the highway, would have to nurture it up to a 100kph, and it would run fine so long as I didnt slow down or try to overtake another car, then it would run even worse, missing, backfiring, and Id have to nurse it slowly homeward.
Had spoken to a couple of mechanics in town, problem is there were no check engine codes for this problem, and the belief was that nothing would show up on their scanners to pinpoint the problem. Id replaced the plugs, fuel filter, fuel pump, maf sensor (it actually did fail but the underlyng trouble still existed), cleaned the thottle body off the vehicle thoroughly, replaced intake plenum gasket, throttle body gasket, checked various sensors with a multimeter, replaced gaskets where the exhaust meets the manifolds, and either side of the cat converter, still no improvement. One mechanic suspected fuel pump or pressure regulator, the other mechanic thought it sounded ignition related, said it almost sounded like it was crossfiring. Glad I didnt leave the car with one, as one of them had been trying to solve a clients fuel injection woes for 40 hours with no luck, Im sure they will be very happy to pay a fortune without the problem solved.
Was about to start pulling off the injectors and swapping them over with ones off another motor I have, or burn the car, when I noticed a puff of exhaust smoke coming from behind the motor, could only see this whilst reving her up, and luckily the sun was in the right spot. Removed the rear manifold shroud, couldnt see or feel any obvious leaks around the manifold. So decided to retighten all the nuts, and then found the culprit, the upper nut closest to the timing belt had vibrated loose, could remove it by hand, so tightened it up with the wrench, and now the car is restored back to normal power and the tranny works flawless.
Had spoken to a couple of mechanics in town, problem is there were no check engine codes for this problem, and the belief was that nothing would show up on their scanners to pinpoint the problem. Id replaced the plugs, fuel filter, fuel pump, maf sensor (it actually did fail but the underlyng trouble still existed), cleaned the thottle body off the vehicle thoroughly, replaced intake plenum gasket, throttle body gasket, checked various sensors with a multimeter, replaced gaskets where the exhaust meets the manifolds, and either side of the cat converter, still no improvement. One mechanic suspected fuel pump or pressure regulator, the other mechanic thought it sounded ignition related, said it almost sounded like it was crossfiring. Glad I didnt leave the car with one, as one of them had been trying to solve a clients fuel injection woes for 40 hours with no luck, Im sure they will be very happy to pay a fortune without the problem solved.
Was about to start pulling off the injectors and swapping them over with ones off another motor I have, or burn the car, when I noticed a puff of exhaust smoke coming from behind the motor, could only see this whilst reving her up, and luckily the sun was in the right spot. Removed the rear manifold shroud, couldnt see or feel any obvious leaks around the manifold. So decided to retighten all the nuts, and then found the culprit, the upper nut closest to the timing belt had vibrated loose, could remove it by hand, so tightened it up with the wrench, and now the car is restored back to normal power and the tranny works flawless.