1993 Nissan Sentra Repair Question
Mileage: No information provided.
Rough idle black smoke when engines hot
new fuel pump, distributor assembly
rough idle, black smoke when hot?
Asked by CRisJOhnAnswer
Check plugs and leads, sounds like a chronic misfire problem, pull plugs, faulty cylinder will have a very black and sooty plug.
Thank You for your responce.
New plugs,cap,rotor,wires,and fuel pump. Checked Mass Air Flow Sensor good. Recleaned plugs. Did Two Compression tests first one when Cold (1to4) 145psi. Did second when hot 1 and 4 was 85psi, then 2and3 was 115psi. Is this good or bad?
Do a wet test on the low cylinder, just a small squirt of oil to seal the rings, if the comp comes up it will be rings if not valves, do the test hot as well.
Thanx
Would the the two low readings cause all four plugs to have carbon build up? Thank you for rapid responce.
Normally not, but with 2 low comps we need to establish the cause of this, a problem with an inlet valve may impact on other cylinders.If you can do or get a leak down test done, this will isolate the main problem, such as which valve is leaking or if a ring problem.
Removed the fuel rail (with injectors connected) Turned on vehicle with out cranking over to check for any stuck opened injectors, was test good or bad?
You must find where the compression is going first, that type of test will be fairly inconsequential at this stage.
It's near midnight here in Australia, so i am signing off soon , let me know how you get on. if you need more help re post here.