I have a suzuki grand vitara 2001 the problem is it started to have poor acceleration going uphill I replaced the sparking plugs but the problem still exist can you please tell me what could it be?
My car has an automatic transmission.
When a vehicle runs well in all situations but under load (such as climbing a hill), this can be a tricky thing to diagnose. The easiest and first thing I would be testing is the fuel pressure. Specifically, I would tape a fuel pressure gauge to the windshield and drive it up a hill to see what the fuel pressure does in a high load situation. During these times more fuel is required to produce more power. Often times, this results from a plugged fuel filter. This is a maintenance item that should be replaced on a regular schedule.
If fuel pressure is good, I would be looking at camshaft timing. This symptom is quite complicated so I would recommend having a certified mechanic inspect your acceleration firsthand to pinpoint the problem.